Cytokines in the pathogenesis of fatty liver and disease progression to steatohepatitis: implications for treatment

Dehydrotrametenolic acid methyl ester, a triterpenoid of Poria cocos, alleviates non-alcoholic steatohepatitis by suppressing NLRP3 inflammasome activation via targeting Caspase-1 in mice

Non-alcoholic steatohepatitis (NASH) has emerged as a prevalent chronic liver disease with a huge unmet clinical need. A few studies have reported the beneficial effects of Poria cocos Wolf (P. cocos) extract on NASH mice, but the active components were still unknown. In this study we investigated the therapeutic effects of dehydrotrametenolic acid methyl ester (ZQS5029-1), a lanosterol-7,9(11)-diene triterpenes in P. cocos, in a high-fat diet plus CCl4 induced murine NASH model and a GAN diet induced ob/ob murine NASH model. The NASH mice were treated with ZQS5029-1 (75 mg·kg-1·d-1, i.g.) for 6 and 8 weeks, respectively. We showed that ZQS5029-1 treatment markedly relieved liver injury, inflammation and fibrosis in both the murine NASH models. We found that ZQS5029-1 treatment significantly suppressed hepatic NOD-, LRR-, and pyrin domain-containing protein 3 (NLRP3) inflammasome activation in both the NASH murine models, and blocked lipopolysaccharides (LPS)+adenosine 5'-triphosphate (ATP)/Nigericin-induced NLRP3 inflammasome activation in bone marrow-derived macrophages (BMDMs) and Kupffer cells in vitro. We demonstrated that ZQS5029-1 directly bound to the H236 residue of mouse Caspase-1, thereby inhibiting NLRP3 inflammasome activation. The effects of ZQS5029-1 on macrophage-hepatocyte/HSC crosstalk were analyzed using the supernatants from macrophages preconditioned with LPS + ATP introduced into hepatocytes and hepatic stellate cells (HSCs). We found that the conditioned medium from the BMDMs induced injury and death, as well as lipid accumulation in hepatocytes, and activation of HSCs; these effects were blocked by conditioned medium from BMDMs treated with ZQS5029-1. Moreover, the protective effects of ZQS5029-1 on hepatocytes and HSCs were eliminated by H236A-mutation of Caspase-1. We conclude that ZQS5029-1 is a promising lead compound for the treatment of NASH by inhibiting NLRP3 inflammasome activation through targeting Caspase-1 and regulating the macrophage-hepatocyte/HSC crosstalk.

Systematic pharmacology and experimental validation to elucidate the inflammation-associated mechanism of Huanglian Wendan (HLWD) decoction in the treatment of MAFLD associated with atherosclerosis

ETHNOPHARMACOLOGICAL RELEVANCE

Metabolic-associated fatty liver disease (MAFLD) and atherosclerosis are very common disorders that frequently coexist. The therapeutic efficacy of Huanglian Wendan (HLWD) decoction, a traditional Chinese medicine (TCM) prescription, is satisfactory in treating MAFLD associated with atherosclerosis. However, the underlying mechanisms through which HLWD exerts its effects need to be elucidated. Given the complex composition of HLWD and its multiple therapeutic targets, pharmacological investigation is challenging.

AIM OF THIS STUDY

This study aimed to identify the effective compounds in HLWD and elucidate the mechanisms involved in its therapeutic effect on MAFLD associated with atherosclerosis.

MATERIALS AND METHODS

We used a systematic pharmacology method to identify effective compounds present in HLWD and determine the mechanism by which it affects MAFLD associated with atherosclerosis. The effective components of HLWD were identified through ultrahigh-performance liquid chromatography-q exactive-orbitrap high resolution mass spectrometry (UHPLC-Q-Orbitrap HRMS). Next, a comprehensive in silico method was used to predict potential related targets and disease targets for these compounds to establish corresponding pathways. The accuracy of our assumed systemic pharmacology results was determined by conducting follow-up experiments.

RESULTS

By conducting UHPLC-Q-Orbitrap HRMS combined with network analysis, we identified 18 potentially active components of HLWD and assessed the inflammatory regulatory mechanism by which it affects MAFLD associated with atherosclerosis on the basis of 52 key targets. We used a high-fat, high-cholesterol (HFHC)-induced mice model of MAFLD associated with atherosclerosis to confirm our results. We found that administering HLWD significantly improved the appearance of their liver and reduced their body weight, liver weight, blood lipids, hepatic damage, and hepatic pathology. HLWD also decreased atherosclerotic lesion areas, foam cells, and inflammatory cells in the aorta. HLWD showed anti-inflammatory effects, suppressed M1 polarization, and promoted M2 polarization in the liver and aorta. HLWD might also regulate peroxisome proliferator-activated receptor-γ (PPARγ)/nuclear factor kappa-B (NF-κB) signaling to influence macrophage polarization and inflammation.

CONCLUSIONS

Our results showed that HLWD protected against HFHC diet-induced MAFLD associated with atherosclerosis by regulating PPARγ/NF-κB signaling, thus adjusting macrophage polarization and inflammation. Additionally, pharmacochemistry research, network pharmacology analysis, and experimental verification can be combined to form a comprehensive model used in studies on TCM.

Development and validation of a model for early survival prediction following liver transplantation based on donor and recipient characteristics

BACKGROUND

Circulating cytokine levels not only correlate with the progression of liver disease but also serve as indicators for the infection status of the body. Growing evidence points to the connection between donor cytokines and graft function following transplantation. This study set out to explore the clinical significance of donor cytokines in predicting liver transplantation prognosis.

METHODS

Data from 172 deceased donor liver transplantations conducted between 2017 and 2022, with available donor serum cytokine information, were collected. The subjects were randomly divided into estimation (n = 120) and validation (n = 52) groups to establish and validate the model. The newly developed SA10 score was compared against established models EAD, MEAF, L-GrAFT7, and L-GrAFT10.

RESULTS

Donor IL-10, along with donor age and recipient AST peak value within the first 7 days post-operation, was identified as an independent factor associated with recipient survival and was incorporated into the SA10 score. SA10 exhibited robust predictive capability, particularly for 1-month survival (AUC = 0.90, 95% CI = 0.84-0.96), outperforming EAD (AUC = 0.75, 95% CI = 0.60-0.90, p = 0.04) and L-GrAFT7 (AUC = 0.65, 95% CI = 0.49-0.81, p < 0.01). Comparable performance was observed between SA10, MEAF, and L-GrAFT10.

CONCLUSION

Donor IL-10 independently influences recipient survival, with the SA10 score demonstrating comparable and even superior predictive ability compared to existing models.

Exploring the pathogenesis and immunological profiles of psoriasis complicated with MASLD

BACKGROUND

Both psoriasis and metabolic dysfunction-associated steatotic liver disease (MASLD) are immune-mediated chronic inflammatory diseases. Psoriasis manifests itself mainly as skin damage, while MASLD mainly involves the liver promoting liver fibrosis, which has a significant impact on patient health and quality of life. Some clinical studies have shown that there are mutually reinforcing mechanisms between these two diseases, but they are not clearly defined, and this paper aims to further explore their common pathogenesis.

METHODS

Gene expression profiling datasets (GSE30999, GSE48452) and single cell datasets (GSE151177, GSE186328) for psoriasis and MASLD were downloaded from the Gene Expression Omnibus (GEO) database. Common differential gene sets were obtained by gene differential analysis, and then functional enrichment of differential genes was performed to find associated transcription factors and PPI protein network analysis. Single-cell datasets were validated for gene expression and explored for cellular communication, gene set differential analysis and immune infiltration analysis.

RESULTS

We identified seven common differential genes, all of which were upregulated.The IL-17 pathway, tumor necrosis factor (TNF-α) pathway were shown in strong association with both diseases, and five transcription factors regulating the differential genes were predicted. Two key genes (MMP9, CXCL10) and three key transcription factors (TF) (IRF1, STAT1, NFKB1) were obtained by PPI protein network analysis. Single cell dataset verified the expression of key genes, and combined with gene set differential analysis, immune infiltration revealed that CD4+ T cells, NK cells and macrophages were heavily infiltrated in both diseases. IL-17, IL-1 and cGAS-STING pathways were highly expressed in both diseases, and both diseases share a similar immune microenvironment.

CONCLUSIONS

Our study reveals the common pathogenesis of psoriasis and MASLD from gene expression to immune cell similarities and differences, identifies key genes and regulatory pathways common to both, and elucidates the similarities in the immune microenvironment of both diseases, providing new ideas for subsequent studies on targeted therapy.

Multifunctional role of oral bacteria in the progression of non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) encompasses a spectrum of liver disorders of varying severity, ultimately leading to fibrosis. This spectrum primarily consists of NAFL and non-alcoholic steatohepatitis. The pathogenesis of NAFLD is closely associated with disturbances in the gut microbiota and impairment of the intestinal barrier. Non-gut commensal flora, particularly bacteria, play a pivotal role in the progression of NAFLD. Notably, Porphyromonas gingivalis, a principal bacterium involved in periodontitis, is known to facilitate lipid accumulation, augment immune responses, and induce insulin resistance, thereby exacerbating fibrosis in cases of periodontitis-associated NAFLD. The influence of oral microbiota on NAFLD via the "oral-gut-liver" axis is gaining recognition, offering a novel perspective for NAFLD management through microbial imbalance correction. This review endeavors to encapsulate the intricate roles of oral bacteria in NAFLD and explore underlying mechanisms, emphasizing microbial control strategies as a viable therapeutic avenue for NAFLD.

TNF-α blockage by etanercept restores spatial learning and reduces cellular degeneration in the hippocampus during liver cirrhosis

Hepatic encephalopathy (HE) is one of the most debilitating cerebral complications of liver cirrhosis. The one-year survival of patients with liver cirrhosis and severe encephalopathy is less than 50%. Recent studies have indicated that neuroinflammation is a new player in the pathogenesis of HE, which seems to be involved in the development of cognitive impairment. In this study, we demonstrated neurobehavioral and neuropathological consequences of liver cirrhosis and tested the therapeutic potential of the tumor necrosis factor-α (TNF-α) inhibitor, etanercept. Sixty male adult Wistar albino rats (120-190 g) were allocated into four groups, where groups I and IV served as controls. Thioacetamide (TAA; 300 mg/kg) was intraperitoneally injected twice a week for five months to induce liver cirrhosis in group II (n = 20). Both TAA and etanercept (2 mg/kg) were administered to group III (n = 20). At the end of the experiment, spatial learning was assessed using Morris water maze. TNF-α was detected in both serum and hippocampus. The excised brains were also immunohistochemically stained with glial fibrillary acidic protein (GFAP) to estimate both the number and integrity of hippocampal astrocytes. Ultrastructural changes in the hippocampus were characterized by transmission electron microscopy. The results showed that blocking TNF-α by etanercept was accompanied by a lower TNF-α expression and a higher number of GFAP-positive astrocytes in the hippocampus. Etanercept intervention alleviated the neuronal and glial degenerative changes and impeded the deterioration of spatial learning ability. In conclusion, TNF-α is strongly involved in the development of liver cirrhosis and the associated encephalopathy. TNF-α blockers may be a promising approach for management of hepatic cirrhosis and its cerebral complications.

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.

NCOA5 Haploinsufficiency in Myeloid-Lineage Cells Sufficiently Causes Nonalcoholic Steatohepatitis and Hepatocellular Carcinoma

BACKGROUND & AIMS

The nuclear receptor coactivator 5 (NCOA5) is a putative type 2 diabetes susceptibility gene. NCOA5 haploinsufficiency results in the spontaneous development of nonalcoholic fatty liver disease (NAFLD), insulin resistance, and hepatocellular carcinoma (HCC) in male mice; however, the cell-specific effect of NCOA5 haploinsufficiency in various types of cells, including macrophages, on the development of NAFLD and HCC remains unknown.

METHODS

Control and myeloid-lineage-specific Ncoa5 deletion (Ncoa5ΔM/+) mice fed a normal diet were examined for the development of NAFLD, nonalcoholic steatohepatitis (NASH), and HCC. Altered genes and signaling pathways in the intrahepatic macrophages of Ncoa5ΔM/+ male mice were analyzed and compared with those of obese human individuals. The role of platelet factor 4 (PF4) in macrophages and the underlying mechanism by which PF4 affects NAFLD/NASH were explored in vitro and in vivo. PF4 expression in HCC patient specimens and prognosis was examined.

RESULTS

Myeloid-lineage-specific Ncoa5 deletion sufficiently causes spontaneous NASH and HCC development in male mice fed a normal diet. PF4 overexpression in Ncoa5ΔM/+ intrahepatic macrophages is identified as a potent mediator to trigger lipid accumulation in hepatocytes by inducing lipogenesis-promoting gene expression. The transcriptome of intrahepatic macrophages from Ncoa5ΔM/+ male mice resembles that of obese human individuals. High PF4 expression correlated with poor prognosis of HCC patients and increased infiltrations of M2 macrophages, regulatory T cells, and myeloid-derived suppressor cells in HCCs.

CONCLUSIONS

Our findings reveal a novel mechanism for the onset of NAFLD/NASH and HCC initiated by NCOA5-deficient macrophages, suggesting the NCOA5-PF4 axis in macrophages as a potential target for developing preventive and therapeutic interventions against NAFLD/NASH and HCC.

The Presence of Periodontitis Exacerbates Non-Alcoholic Fatty Liver Disease via Sphingolipid Metabolism-Associated Insulin Resistance and Hepatic Inflammation in Mice with Metabolic Syndrome

Clinical studies have shown that periodontitis is associated with non-alcoholic fatty liver disease (NAFLD). However, it remains unclear if periodontitis contributes to the progression of NAFLD. In this study, we generated a mouse model with high-fat diet (HFD)-induced metabolic syndrome (MetS) and NAFLD and oral P. gingivalis inoculation-induced periodontitis. Results showed that the presence of periodontitis increased insulin resistance and hepatic inflammation and exacerbated the progression of NAFLD. To determine the role of sphingolipid metabolism in the association between NAFLD and periodontitis, we also treated mice with imipramine, an inhibitor of acid sphingomyelinase (ASMase), and demonstrated that imipramine treatment significantly alleviated insulin resistance and hepatic inflammation, and improved NAFLD. Studies performed in vitro showed that lipopolysaccharide (LPS) and palmitic acid (PA), a major saturated fatty acid associated with MetS and NAFLD, synergistically increased the production of ceramide, a bioactive sphingolipid involved in NAFLD progression in macrophages but imipramine effectively reversed the ceramide production stimulated by LPS and PA. Taken together, this study showed for the first time that the presence of periodontitis contributed to the progression of NAFLD, likely due to alterations in sphingolipid metabolism that led to exacerbated insulin resistance and hepatic inflammation. This study also showed that targeting ASMase with imipramine improves NAFLD by reducing insulin resistance and hepatic inflammation.

From Non-Alcoholic Fatty Liver to Hepatocellular Carcinoma: A Story of (Mal)Adapted Mitochondria

Non-alcoholic fatty liver disease (NAFLD) is a global pandemic affecting 25% of the world's population and is a serious health and economic concern worldwide. NAFLD is mainly the result of unhealthy dietary habits combined with sedentary lifestyle, although some genetic contributions to NAFLD have been documented. NAFLD is characterized by the excessive accumulation of triglycerides (TGs) in hepatocytes and encompasses a spectrum of chronic liver abnormalities, ranging from simple steatosis (NAFL) to steatohepatitis (NASH), significant liver fibrosis, cirrhosis, and hepatocellular carcinoma. Although the molecular mechanisms that cause the progression of steatosis to severe liver damage are not fully understood, metabolic-dysfunction-associated fatty liver disease is strong evidence that mitochondrial dysfunction plays a significant role in the development and progression of NAFLD. Mitochondria are highly dynamic organelles that undergo functional and structural adaptations to meet the metabolic requirements of the cell. Alterations in nutrient availability or cellular energy needs can modify mitochondria formation through biogenesis or the opposite processes of fission and fusion and fragmentation. In NAFL, simple steatosis can be seen as an adaptive response to storing lipotoxic free fatty acids (FFAs) as inert TGs due to chronic perturbation in lipid metabolism and lipotoxic insults. However, when liver hepatocytes' adaptive mechanisms are overburdened, lipotoxicity occurs, contributing to reactive oxygen species (ROS) formation, mitochondrial dysfunction, and endoplasmic reticulum (ER) stress. Impaired mitochondrial fatty acid oxidation, reduction in mitochondrial quality, and disrupted mitochondrial function are associated with a decrease in the energy levels and impaired redox balance and negatively affect mitochondria hepatocyte tolerance towards damaging hits. However, the sequence of events underlying mitochondrial failure from steatosis to hepatocarcinoma is still yet to be fully clarified. This review provides an overview of our understanding of mitochondrial adaptation in initial NAFLD stages and highlights how hepatic mitochondrial dysfunction and heterogeneity contribute to disease pathophysiology progression, from steatosis to hepatocellular carcinoma. Improving our understanding of different aspects of hepatocytes' mitochondrial physiology in the context of disease development and progression is crucial to improving diagnosis, management, and therapy of NAFLD/NASH.

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.

Identification of alternative splicing events related to fatty liver formation in duck using full-length transcripts

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is one of most common diseases in the world. Recently, alternative splicing (AS) has been reported to play a key role in NAFLD processes in mammals. Ducks can quickly form fatty liver similar to human NAFLD after overfeeding and restore to normal liver in a short time, suggesting that ducks are an excellent model to unravel molecular mechanisms of lipid metabolism for NAFLD. However, how alternative splicing events (ASEs) affect the fatty liver process in ducks is still unclear.

RESULTS

Here we identify 126,277 unique transcripts in liver tissue from an overfed duck (77,237 total transcripts) and its sibling control (69,618 total transcripts). We combined these full-length transcripts with Illumina RNA-seq data from five pairs of overfed ducks and control individuals. Full-length transcript sequencing provided us with structural information of transcripts and Illumina RNA-seq data reveals the expressional profile of each transcript. We found, among these unique transcripts, 30,618 were lncRNAs and 1,744 transcripts including 155 lncRNAs and 1,589 coding transcripts showed significantly differential expression in liver tissues between overfed ducks and control individuals. We also detected 27,317 ASEs and 142 of them showed significant relative abundance changes in ducks under different feeding conditions. Full-length transcript profiles together with Illumina RNA-seq data demonstrated that 10 genes involving in lipid metabolism had ASEs with significantly differential abundance in normally fed (control) and overfed ducks. Among these genes, protein products of five genes (CYP4F22, BTN, GSTA2, ADH5, and DHRS2 genes) were changed by ASEs.

CONCLUSIONS

This study presents an example of how to identify ASEs related to important biological processes, such as fatty liver formation, using full-length transcripts alongside Illumina RNA-seq data. Based on these data, we screened out ASEs of lipid-metabolism related genes which might respond to overfeeding. Our future ability to explore the function of genes showing AS differences between overfed ducks and their sibling controls, using genetic manipulations and co-evolutionary studies, will certainly extend our knowledge of genes related to the non-pathogenic fatty liver process.

Low-molecular weight oligosaccharides from gum tragacanth (Astragalus gossypinus) ameliorate nonalcoholic fatty liver disease (NAFLD) in Wistar male rats

Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease affecting 25% of the world's population. The effects of oligosaccharides from Gum tragacanth (Astragalus gossypinus) (GT) on oxidative stress, glucose metabolism, and expression of autophagy genes were investigated in induced non-alcoholic fatty liver. Twenty-four male healthy rats were divided into four groups, Control; high-fat diet, high-fat diet + 100 mg GT oligosaccharides/kg body weight, high-fat diet + 200 mg GT oligosaccharides/kg body weight and fed with the trial diets for 70 days. At the end of the experiment, the results indicated that GT oligosaccharides affected the weight gain and liver weight in NAFLD-induced rats. In addition, the results showed that the use of GT oligosaccharides significantly decreased oxidative stress, liver injury, and hyperglycemia (p < .05) and upregulated the expression of autophagy genes in NAFLD-induced rats.

Practical applications

Overall, the results of the current study demonstrated that the use of GT oligosaccharides obtained from Gum tragacanth (Astragalus gossypinus) showed significant antioxidant properties and hypoglycemia in NAFLD induced rats and could be used as a useful nutritional strategy for the prevention and treatment of NAFLD.

Targeting hepatic sulfane sulfur/hydrogen sulfide signaling pathway with α-lipoic acid to prevent diabetes-induced liver injury via upregulating hepatic CSE/3-MST expression

BACKGROUND

Diabetes-induced liver injury is a complication of diabetes mellitus of which there are no approved drugs for effective treatment or prevention. This study investigates possible hepatoprotective effect of alpha-lipoic acid (ALA), and sulfane sulfur/hydrogen sulfide pathway as a novel protective mechanism in a rat model of type 2 diabetes-induced liver injury.

METHODS

Thirty Sprague-Dawley rats underwent fasting for 12 h after which fasting blood glucose was measured and rats were randomly assigned to diabetic and non-diabetic groups. Type 2 diabetes mellitus (T2DM) was induced in diabetic group by administration of nicotinamide (110 mg/kg) and streptozotocin (55 mg/kg). Diabetic rats were treated daily with ALA (60 mg/kg/day p.o.) or 40 mg/kg/day DL-propargylglycine (PPG, an inhibitor of endogenous hydrogen sulfide production) for 6 weeks and then sacrificed. Liver, pancreas and blood samples were collected for analysis. Untreated T2DM rats received distilled water.

RESULTS

Hypoinsulinemia, hyperglycemia, hepatomegaly and reduced hepatic glycogen content were observed in untreated T2DM rats compared to healthy control group (p < 0.001). Also, the pancreas of untreated T2DM rats showed severely damaged pancreatic islets while liver damage was characterized by markedly increased hepatocellular vacuolation, sinusoidal enlargement, abnormal intrahepatic lipid accumulation, severe transaminitis, hyperbilirubinemia, and impaired hepatic antioxidant status and inflammation compared to healthy control rats (p < 0.01). While pharmacological inhibition of hepatic sulfane sulfur/hydrogen sulfide with PPG administration aggravated these pathological changes (p < 0.05), ALA strongly prevented these changes. ALA also significantly increased hepatic expression of hydrogen sulfide-producing enzymes (cystathionine γ-lyase and 3-mecaptopyruvate sulfurtransferase) as well as hepatic sulfane sulfur and hydrogen sulfide levels compared to all groups (p < 0.01).

CONCLUSIONS

To the best of our knowledge, this is the first experimental evidence showing that ALA prevents diabetes-induced liver injury by activating hepatic sulfane sulfur/hydrogen sulfide pathway via upregulation of hepatic cystathionine γ-lyase and 3-mecaptopyruvate sulfurtransferase expressions. Therefore, ALA could serve as a novel pharmacological agent for the treatment and prevention of diabetes-induced liver injury, with hepatic sulfane sulfur/hydrogen sulfide as a novel therapeutic target.

Spotlight on liver macrophages for halting injury and progression in non-alcoholic fatty liver disease

INTRODUCTION

Non-alcoholic fatty liver disease (NAFLD) is considered the hepatic manifestation of the metabolic syndrome and is rapidly emerging as the leading cause of liver-related morbidity and mortality. Macrophages play an essential role in the development and progression of NAFLD.

AREAS COVERED

In this review, we provide an update on recent studies of drugs, which directly or indirectly affect macrophages in NAFLD, and discuss the implication of macrophage biomarkers to monitor the disease stage and progression/regression.

EXPERT OPINION

There is an unmet need for better understanding of disease pathogenesis from hepatic fat accumulation to disease progression with inflammation and fibrosis. We expect that future research will uncover additional objects/pathways as treatment targets. We speculate that this will involve better characterization of the gut microbiome, damage-associated molecular patterns (DAMPS) or molecules and pathways involved in development of DAMPS, and advanced molecular biology studies including single-cell sequencing of macrophage subpopulations. In addition, we speculate that studies focusing on pharmaceuticals that improve insulin resistance, diminish the metabolic syndrome and reduce fibrosis will prevail.

SLAMF1 is expressed and secreted by hepatocytes and the liver in nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is one of the most prevalent forms of chronic liver disease in the United States and worldwide. Nonalcoholic steatohepatitis (NASH), the most advanced form of NAFLD, is characterized by hepatic steatosis associated with inflammation and hepatocyte death. No treatments are currently available for NASH other than lifestyle changes, and the disease lacks specific biomarkers. The signaling lymphocytic activation molecule family 1 (SLAMF1) protein is a self-ligand receptor that plays a role in orchestrating an immune response to some pathogens and cancers. We found that livers from humans and mice with NASH showed a more prominent immunohistochemistry staining for SLAMF1 than non-NASH controls. Furthermore, SLAMF1 levels are significantly increased in NASH plasma samples from mice and humans compared with their respective controls. In mice, the levels of SLAMF1 correlated significantly with the severity of the NASH phenotype. To test whether SLAMF 1 is expressed by hepatocytes, HepG2 cells and primary murine hepatocytes were treated with palmitic acid (PA) to induce a state of lipotoxicity mimicking NASH. We found that PA treatments of HepG2 cells and primary hepatocytes lead to significant increases in SLAMF1 levels. The downregulation of SLAMF1 in HepG2 cells improved the cell viability and reduced cytotoxicity. The in vivo data using mouse and human NASH samples suggests a potential role for this protein as a noninvasive biomarker for NASH. The in vitro data suggest a role for SLAMF1 as a potential therapeutic target to prevent hepatocyte death in response to lipotoxicity.NEW & NOTEWORTHY This study identified for the first time SLAMF1 as a mediator of hepatocyte death in nonalcoholic fatty liver disease (NASH) and as a marker of NASH in humans. There are no pharmacological treatments available for NASH, and diagnostic tools are limited to invasive liver biopsies. Therefore, since SLAMF1 levels correlate with disease progression and SLAMF1 mediates cytotoxic effects, this protein can be used as a therapeutic target and a clinical biomarker of NASH.

Tyrosol Ameliorates Liver Inflammatory Response in a Mouse Model of Nonalcoholic Fatty Liver Disease (NFALD) by Regulating JAK1/STAT3

Nonalcoholic fatty liver disease (NAFLD) is becoming one of the major health issues globally. NAFLD is usually associated with obesity and other metabolic syndromes, and there is no specific cure to address this issue so far. Featured by lipid accumulation in hepatocytes, and later progressing to fibrosis, inflammatory responses are involved in the various levels of the pathological changes. In the present study, we added a natural compound, tyrosol, which in our previous study had demonstrated anti-inflammatory properties, to a high-fat diet-induced NAFLD mouse model and investigated whether tyrosol could mitigate the liver damage by attenuating the inflammation response. The treatment with tyrosol significantly improved the liver function and decreased the fasting glucose level in NAFLD mice. Morphologically, our results showed that tyrosol could reduce the fat deposition and lipid droplets accumulation in liver tissue. The key regulating factors, JAK1 and STAT3, were increased in NAFLD mice, but tyrosol treatment could effectively prevent the upregulation. The expression levels of pro-inflammatory cytokine genes in liver tissue of the NAFLD mice were upregulated, which could be effectively prevented by the treatment with tyrosol. Overall, in the high-fat diet-induced NAFLD mouse model, tyrosol could improve the liver function and, more importantly, ameliorate the inflammatory response triggered by the high-fat diet. Although our data here are consistent with the previous report that tyrosol could exert beneficial effects on the NAFLD animal model, we also provide solid evidence that tyrosol is able to conquer the inflammatory response in liver, which is related to the high-fat-diet feeding. Tyrosol could be a promising candidate for the treatment of NAFLD in the future.

A Greater Improvement of Intrahepatic Fat Contents after 6 Months of Lifestyle Intervention Is Related to a Better Oxidative Stress and Inflammatory Status in Non-Alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) is a disorder characterized by the excessive accumulation of lipids in the liver parenchyma. To date, there is no effective pharmacological treatment against NAFLD. Objective: To assess the relationship between the improvement of the intrahepatic fat content (IFC) in patients with NAFLD and metabolic syndrome and biomarkers of oxidative stress and inflammation after 6 months of lifestyle intervention. Patients diagnosed with NAFLD (n = 60 adults; 40-60 years old) residing in the Balearic Islands, Spain, were distributed in tertiles attending the improvement of IFC calculated by magnetic resonance imaging (MRI). Anthropometrics, blood pressure, maximal oxygen uptake, and pro/antioxidant and inflammatory biomarkers were determined in plasma before and after the lifestyle intervention. The improvement in IFC levels was higher in tertile 3 with respect to tertiles 2 and 1. The greatest improvement in IFC is related to cardiorespiratory fitness and adherence to the Mediterranean diet (ADM). Higher reductions in weight, body mass index (BMI), and alanine aminotransferase (ALT) were observed in tertile 3 with respect to tertile 1 after 6 months of intervention. The improvement in catalase, irisin, and cytokeratin 18 plasma levels were higher in tertile 3, whereas no differences were observed in superoxide dismutase activity. Malondialdehyde and protein carbonyl levels, as biomarkers of oxidative damage, remained unchanged in all groups. The present data show that the reduction of IFC is associated with an improvement in pro/antioxidant and pro-inflammatory status and a better cardiorespiratory fitness in NAFLD patients.

Non-immune functions of inflammatory cytokines targeted by anti-psoriatic biologics: a review

PURPOSE

Psoriasis is an inflammatory disease characterized by skin thickening with silvery white desquamation due to dysregulated inflammatory pathways and elevated levels of inflammatory cytokines. Biologic agents targeting these inflammatory cytokines have brought about significant improvement in clearing psoriatic lesions in patients with moderate-to-severe psoriasis. Moreover, biologics exert both beneficial and detrimental effects on comorbidities in psoriasis, which include increased risk of cardiovascular events, metabolic syndrome, among other conditions. However, non-immune functions of cytokines targeted by biologics, and, hence, the potential risks and benefits of biologics for psoriasis to different organs/systems and comorbidities, have not been well elucidated.

RESULTS

This review summarizes current understanding of the pathogenesis of psoriasis-related comorbidities and emerging discoveries of roles of cytokines targeted in psoriasis treatment, including tumor necrosis factor α and interleukins 12, 23, and 17, aiming to complete the safety profile of each biologics and provide therapeutic implications on psoriasis-related comorbidities, and on diseases involving other organs or systems.

Periodontal disease-related nonalcoholic fatty liver disease and nonalcoholic steatohepatitis: An emerging concept of oral-liver axis

Periodontal disease, a chronic inflammatory disease of the periodontal tissues, is not only a major cause of tooth loss, but it is also known to exacerbate/be associated with various metabolic disorders, such as obesity, diabetes, dyslipidemia, and cardiovascular disease. Recently, growing evidence has suggested that periodontal disease has adverse effects on the pathophysiology of liver disease. In particular, nonalcoholic fatty liver disease, a hepatic manifestation of metabolic syndrome, has been associated with periodontal disease. Nonalcoholic fatty liver disease is characterized by hepatic fat deposition in the absence of a habitual drinking history, viral infections, or autoimmune diseases. A subset of nonalcoholic fatty liver diseases can develop into more severe and progressive forms, namely nonalcoholic steatohepatitis. The latter can lead to cirrhosis and hepatocellular carcinoma, which are end‐stage liver diseases. Extensive research has provided plausible mechanisms to explain how periodontal disease can negatively affect nonalcoholic fatty liver disease and nonalcoholic steatohepatitis, namely via hematogenous or enteral routes. During periodontitis, the liver is under constant exposure to various pathogenic factors that diffuse systemically from the oral cavity, such as bacteria and their by‐products, inflammatory cytokines, and reactive oxygen species, and these can be involved in disease promotion of nonalcoholic fatty liver disease and nonalcoholic steatohepatitis. Also, gut microbiome dysbiosis induced by enteral translocation of periodontopathic bacteria may impair gut wall barrier function and promote the transfer of hepatotoxins and enterobacteria to the liver through the enterohepatic circulation. Moreover, in a population with metabolic syndrome, the interaction between periodontitis and systemic conditions related to insulin resistance further strengthens the association with nonalcoholic fatty liver disease. However, most of the pathologic links between periodontitis and nonalcoholic fatty liver disease in humans are provided by epidemiologic observational studies, with the causal relationship not yet being established. Several systematic and meta‐analysis studies also show conflicting results. In addition, the effect of periodontal treatment on nonalcoholic fatty liver disease has hardly been studied. Despite these limitations, the global burden of periodontal disease combined with the recent nonalcoholic fatty liver disease epidemic has important clinical and public health implications. Emerging evidence suggests an association between periodontal disease and liver diseases, and thus we propose the term periodontal disease–related nonalcoholic fatty liver disease or periodontal disease–related nonalcoholic steatohepatitis. Continued efforts in this area will pave the way for new diagnostic and therapeutic approaches based on a periodontologic viewpoint to address this life‐threatening liver disease.

Dieckol Decreases Caloric Intake and Attenuates Nonalcoholic Fatty Liver Disease and Hepatic Lymphatic Vessel Dysfunction in High-Fat-Diet-Fed Mice

Increased inflammation is the main pathophysiology of nonalcoholic fatty liver disease (NAFLD). Inflammation affects lymphatic vessel function that contributes to the removal of immune cells or macromolecules. Dysfunctional lymphatic vessels with decreased permeability are present in NAFLD. High-fat diet (HFD) is known to increase body weight, food intake, and inflammation in the liver. Previously, it was reported that Ecklonia cava extracts (ECE) decreased food intake or weight gain, and low-calorie diet and weight loss is known as a treatment for NAFLD. In this study, the effects of ECE and dieckol (DK)-which is one component of ECE that decreases inflammation and increases lymphangiogenesis and lymphatic drainage by controlling lymphatic permeability in high-fat diet (HFD)-fed mice-on weight gain and food intake were investigated. ECE and DK decreased weight gain and food intake in the HFD-fed mice. NAFLD activities such as steatosis, lobular inflammation, and ballooning were increased by HFD and attenuated by ECE and DK. The expression of inflammatory cytokines such as IL-6 and TNF-α and infiltration of M1 macrophages were increased by HFD, and they were decreased by ECE or DK. The signaling pathways of lymphangiogenesis, VEGFR-3, PI3K/pAKT, and pERK were decreased by HFD, and they were restored by either ECE or DK. The expression of VE-cadherin (which represents lymphatic junctional function) was increased by HFD, although it was restored by either ECE or DK. In conclusion, ECE and DK attenuated NAFLD by decreasing weight gain and food intake, decreasing inflammation, and increasing lymphangiogenesis, as well as modulating lymphatic vessel permeability.

Regulation of hepatic fibrosis by carcinoembryonic antigen-related cell adhesion molecule 1

OBJECTIVE

NAFLD is a complex disease marked by cellular abnormalities leading to NASH. NAFLD patients manifest low hepatic levels of CEACAM1, a promoter of insulin clearance. Consistently, Cc1^-/- null mice displayed spontaneous hyperinsulinemia/insulin resistance and steatohepatitis. Liver-specific reconstitution of Ceacam1 reversed these metabolic anomalies in 8-month-old Cc1^-/-xliver+ mice fed a regular chow diet. The current study examined whether it would also reverse progressive hepatic fibrosis in mice fed a high-fat (HF) diet.

METHODS

3-Month-old mice were fed a high-fat diet for 3-5 months, and metabolic and histopathological analysis were conducted to evaluate their NASH phenotype.

RESULTS

Reconstituting CEACAM1 to Cc1^-/- livers curbed diet-induced liver dysfunction and NASH, including macrovesicular steatosis, lobular inflammation, apoptosis, oxidative stress, and chicken-wire bridging fibrosis. Persistence of hepatic fibrosis in HF-fed Cc1^-/- treated with nicotinic acid demonstrated a limited role for lipolysis and adipokine release in hepatic fibrosis caused by Ceacam1 deletion.

CONCLUSIONS

Restored metabolic and histopathological phenotype of HF-fed Cc1^{-/-xliver+xliver+} assigned a critical role for hepatic CEACAM1 in preventing NAFLD/NASH including progressive hepatic fibrosis.

Natural Aldose Reductase Inhibitor: A Potential Therapeutic Agent for Non-alcoholic Fatty Liver Disease

Aldose reductase (AR) has been reported to be involved in the development of nonalcoholic fatty liver disease (NAFLD). Hepatic AR is induced under hyperglycemia condition and converts excess glucose to lipogenic fructose, which contributes in part to the accumulation of fat in the liver cells of diabetes rodents. In addition, the hyperglycemia-induced AR or nutrition-induced AR causes suppression of the transcriptional activity of peroxisome proliferator-activated receptor (PPAR) α and reduced lipolysis in the liver, which also contribute to the development of NAFLD. Moreover, AR induction in non-alcoholic steatohepatitis (NASH) may aggravate oxidative stress and the expression of inflammatory cytokines in the liver. Here, we summarize the knowledge on AR inhibitors of plant origin and review the effect of some plant-derived AR inhibitors on NAFLD/NASH in rodents. Natural AR inhibitors may improve NAFLD at least in part through attenuating oxidative stress and inflammatory cytokine expression. Some of the natural AR inhibitors have been reported to attenuate hepatic steatosis through the regulation of PPARα-mediated fatty acid oxidation. In this review, we propose that the natural AR inhibitors are potential therapeutic agents for NAFLD.

Cordycepin attenuates high-fat diet-induced non-alcoholic fatty liver disease via down-regulation of lipid metabolism and inflammatory responses

Cordycepin (CRD), an adenosine analog derived from traditional Chinese medicine, is an active component in Cordyceps militaris. It has been shown to have many protective effects during liver injury and ameliorate liver disease progression, but little is known about its effect on non-alcoholic fatty liver disease (NAFLD). This study aims to explore the effects of CRD on obesity-induced NAFLD. In this experiment, C57BL/6 J mice were randomly assigned into normal control group (NC), high fat diet group (HFD) and HFD + CRD group for 8 weeks. The body weights were recorded weekly, at the end of the experiments, the liver and serum samples were collected. We found that CRD administration reduced body weight and decreased the weight of adipose and liver, and CRD relieved liver injure through diminishing of histopathological changes and decreasing serum levels of AST, ALT, TG, TC, LDL-C and increased the level of HDL-C. Furthermore, treatment with CRD significantly alleviated expression of inflammatory factors (TNF-α, IL-6 and Il-1β) and macrophage markers (MCP1, MIP2, mKC and VCAM1). On the other hand, compared with HFD group, the CRD treated group markedly down-regulated relative proteins of lipid anabolism (SREBP1-c, ACC, SCD-1, LXRα and CD36) and up-regulated relative proteins of β-oxidation (p-AMPK, AMPK, CPT-1 and PPARα). In summary, our results suggest that CRD can be a potential therapeutic agent in the prevention and treatment of NAFLD, which may be closely related to its effect on lipid metabolism and inflammatory responses.

Nonalcoholic fatty liver disease is associated with intrahepatic cholangiocarcinoma and not with extrahepatic form: definitive evidence from meta-analysis and trial sequential analysis

BACKGROUND

Cholangiocarcinoma is a cancer with poor prognosis. The detection of risk factors is fundamental to identify subjects at higher risk of cholangiocarcinoma. Nonalcoholic fatty liver disease (NAFLD) represents a leading cause of chronic liver disease worldwide. Recent data suggested that NAFLD increases the risk of cholangiocarcinoma development. However, it is necessary to better explain the strength of association between NAFLD and cholangiocarcinoma.

METHODS

A systematic research of current case-control, cohort, clinical trial and meta-analysis on the main electronic databases was made. A recent systematic review was recognized. We performed cumulative meta-analyses with sensitivity analysis excluding studies with large sample size and with great clinical heterogeneity, then we checked for further studies. At the final step, three trial sequential analyses were done as well.

RESULTS

NAFLD determines an increased risk of total cholangiocarcinoma and intrahepatic cholangiocarcinoma (iCCA) development: odds ratio (OR) (95% confidence interval [CI]): 1.88 (1.25-2.83), OR (95% CI): 2.19 (1.48-3.25), respectively. On the contrary, NAFLD does not show a significant effect on extrahepatic cholangiocarcinoma (eCCA) (OR (95% CI): 1.48 (0.93-2.36). The trial sequential analyses regarding total cholangiocarcinoma and iCCA showed that z-curve was outside computed alpha boundaries, proving that the positive association was conclusive. The trial sequential analysis about eCCA showed that z-curve was inside computed futile boundaries, proving that negative results were conclusive.

CONCLUSION

The performance of new sensitive analyses and the respective trial sequential analyses, after withdraw of confounding factors, suggested the existence of definitive association only between NAFLD and iCCA development and not with eCCA.

Microfluidic organ-on-a-chip models of human liver tissue

The liver is the largest internal organ of the body with complex microarchitecture and function that plays critical roles in drug metabolism. Hepatotoxicity and drug-induced liver injury (DILI) caused by various drugs is the main reason for late-stage drug failures. Moreover, liver diseases are among the leading causes of death in the world, with the number of new cases arising each year. Although animal models have been used to understand human drug metabolism and toxicity before clinical trials, tridimensional microphysiological systems, such as liver-on-a-chip (Liver Chip) platforms, could better recapitulate features of human liver physiology and pathophysiology and thus, are often more predictive of human outcome. Liver Chip devices have shown promising results in mimicking in vivo condition by recapitulating the sinusoidal structure of the liver, maintaining high cell viability and cellular phenotypes, and emulating native liver functions. Here, we first review the cellular constituents and physiology of the liver and then critically discuss the state-of-the-art chip-based liver models and their applications in drug screening, disease modeling, and regenerative medicine. We finally address the pending issues of existing platforms and touch upon future directions for developing new, advanced on-chip models.

NRF-2 and nonalcoholic fatty liver disease

Currently, chronic liver diseases have conditioned morbidity and mortality, many of these with a metabolic, toxicologic, immunologic, viral, or other etiology. Thus, a transcription factor that has been of huge importance for biomedical research is NRF-2. The latter is considered a principal component of the antioxidant mechanism, and it has been acknowledged that it impairs the function of NRF-2 in many liver diseases and that it forms an essential part of the pathologic changes that occur in the liver to contain inflammation and damage. Within the investigations and experiments carried out, there are isolated drugs, many of them related to plants and natural extracts that possess antioxidant properties through the NRF-2 signaling pathway, or even involving the stimulation of the transcription target proteins of NRF-2. Notwithstanding all of these experimental findings, to date there is not sufficient clinical evidence to justify the use of NRF-2 in medical practice.

Deficiency of CD147 Attenuated Non-alcoholic Steatohepatitis Progression in an NLRP3-Dependent Manner

Cluster of differentiation 147 (CD147) is a transmembrane glycoprotein belonging to the immunoglobulin superfamily. CD147 overexpression has been reported to facilitate the development of hepatocellular carcinoma (HCC) and influence immunologic disorders. Although increased expression of CD147 was reported in non-alcoholic steatohepatitis (NASH), functions of CD147 in NASH have not been evaluated. Firstly, we confirmed that CD147 expression was increased in the liver tissues from methionine-choline-deficient (MCD) diet-induced NASH model mice and NASH patients. Mice with hepatocyte-specific CD147 deletion exhibited attenuated NASH phenotypes, including reduced steatosis, liver injury, hepatocyte apoptosis and inflammatory cytokines IL-1β/IL-18 secretion. Following the administration of the MCD diet, NLRP3 expression was increased gradually along with CD147 expression. Furthermore, CD147 deletion inhibited the NF-κB/NLRP3 signaling pathway in both MCD diet-induced mice and primary hepatocytes. Finally, CypA inhibitor TMN355 attenuated liver steatosis and injury and inhibited NF-κB/NLRP3 signaling pathway. Therefore, our results suggest that CD147 played a vital role in NASH pathogenesis by regulating the inflammatory response, and CypA/CD147 could be attractive therapeutic targets for NASH treatment.

Non-alcoholic fatty liver disease in patients with psoriasis: therapeutic implications

Non-alcoholic fatty liver disease (NAFLD) is the most common liver pathology in the western countries. Psoriatic patients are at higher risk of having NAFLD, and at higher risk of experiencing a more severe form of the disease with poorer outcomes. The components of the metabolic syndrome - obesity, lipid abnormalities, hypertension, and type 2 diabetes - significantly correlate with NAFLD progression. The inflammatory state present in psoriasis plays a significant role in development of NAFLD and the metabolic syndrome. All patients with psoriasis and insulin resistance and risk factors for metabolic syndrome should also been screened for NAFLD, and planning of the treatment options should always take into consideration the possible risks related to the liver, especially in patients with NAFLD.

Sweroside ameliorates NAFLD in high-fat diet induced obese mice through the regulation of lipid metabolism and inflammatory response

ETHNOPHARMACOLOGICAL RELEVANCE

Sweroside, an iridoid derived from Traditional Chinese Medicine, is an active component in Swertia pseudochinensis Hara. Swertia pseudochinensis Hara is first recorded in "Inner Mongolia Chinese Herb Medicine"and is considered as a folk medicine for treating hepatitis in northern China.

AIM OF THE STUDY

This study sought to elucidate the role of sweroside in high fat diet induced obesity and fatty liver by using mouse model and investigated the primary molecular mechanism via transcriptomics analysis.

MATERIALS AND METHODS

C57BL/6 mice were fed high-fat diet (HFD) for 14 weeks to induce obesity, hyperglycemia, and fatty liver. These mice were subsequently treated with HFD alone or mixed with sweroside (at a daily dosage of 60 mg per kg of BW, 120 mg per kg of BW and 240 mg per kg of BW) for 6 weeks. BW and food intake was monitored weekly. Biochemical and pathological analysis were conducted to investigate the effect of sweroside on NAFLD. RNA-sequence and RT-qPCR analysis were performed to analyze the potential mechanism.

RESULTS

The mice treated with sweroside were resistant to HFD-induced body weight gain, insulin resistance and hepatic steatosis. Ingenuity pathway analysis (IPA) demonstrated that hepatic gene networks related to lipid metabolism and inflammatory response were down-regulated in the HFD + sweroside group. PPAR-ɑ was located in the center of the hepatic gene network, and the significantly altered genes were CD36 and FGF21, which are related to hepatic inflammation and lipid metabolism. Consistently, upstream-regulators analysis revealed that the main enriched upstream-regulator was PPAR-ɑ.

CONCLUSION

Our results indicate that sweroside may ameliorate obesity with fatty liver via the regulation of lipid metabolism and inflammatory responses. The beneficial effects of sweroside might be closely associated with the regulation of PPAR-α.

Psoriasis and fatty liver: a harmful synergy

Numerous epidemiology studies confirm the increasing prevalence of non-alcoholic fatty liver disease in severe psoriasis, with more than double the risk reported for patients without psoriasis (odds ratio [OR] 2.15). Liver disease is more severe in patients with psoriasis than in controls without psoriasis and is associated with the severity. Similarly, patients with fatty liver disease have more severe psoriasis. This harmful synergy has a common pathogenic origin, resulting from the frequent association between both diseases, insulin resistance and the metabolic syndrome. The disease manifests with a greater intensity when both conditions co-occur than when each manifests separately. Furthermore, psoriasis and fatty liver also have a common cytokine-mediated inflammatory background, which involves an imbalance between pro-inflammatory and anti-inflammatory cytokines. In fact, each disease plays a role in the course of the other. The dermatologist should usually detect liver disease after a specific assessment of patients who present with the metabolic syndrome. The hepatologist should be aware of the more severe condition of these patients. Various medications, such as acitretin, cyclosporine and methotrexate may prove harmful for patients with liver disease. Biologics have proven to be safe in patients with chronic liver disease. Hepatologists and dermatologists should work together to ensure the careful evaluation of the optimal therapy for each patient depending on the severity of both diseases, taking care to avoid, where possible, hepatotoxic drugs and select options that may even have a shared benefit for both diseases.

The cellular pathways of liver fibrosis in non-alcoholic steatohepatitis

Non-alcoholic steatohepatitis (NASH) is considered the advanced stage of non-alcoholic fatty liver disease (NAFLD). It is characterized by liver steatosis, inflammation and different degrees of fibrosis. Although the exact mechanisms by which fatty liver progresses to NASH are still not well understood, innate and adaptive immune responses seem to be essential key regulators in the establishment, progression, and chronicity of these disease. Diet-induced lipid overload of parenchymal and non-parenchymal liver cells is considered the first step for the development of fatty liver with the consequent organelle dysfunction, cellular stress and liver injury. These will generate the production of pro-inflammatory cytokines, chemokines and damage-associated molecular patterns (DAMPs) that will upregulate the activation of Kupffer cells (KCs) and monocyte-derived macrophages (MMs) favoring the polarization of the tolerogenic environment of the liver to an immunogenic phenotype with the resulting transdifferentiation of hepatic stellate cells (HSCs) into myofibroblasts developing fibrosis. In the long run, dendritic cells (DCs) will activate CD4+ T cells polarizing into the pro-inflammatory lymphocytes Th1 and Th17 worsening the liver damage and inflammation. Therefore, the objective of this review is to discuss in a systematic way the mechanisms known so far of the immune and non-proper immune liver cells in the development and progression of NASH.

Chitosan Oligosaccharide Attenuates Nonalcoholic Fatty Liver Disease Induced by High Fat Diet through Reducing Lipid Accumulation, Inflammation and Oxidative Stress in C57BL/6 Mice

Nonalcoholic fatty liver disease (NAFLD) has become the most common chronic liver disease closely associated with metabolic syndrome, but there are no validated pharmacological therapies. The aim of this study was to investigate the effect of chitosan oligosaccharide (COS) on NAFLD. Mice were fed either a control diet or a high-fat diet (HFD) with or without COS (200 or 400 mg/kg body weight (BW)) by oral gavage for seven weeks. Administration with COS significantly lowered serum lipid levels in the HFD-fed mice. The hepatic lipid accumulation was significantly decreased by COS, which was attributed to decreased expressions of lipogenic genes and increased expressions of fatty β-oxidation-related genes. Moreover, pro-inflammatory cytokines, neutrophils infiltration, and macrophage polarization were decreased by COS in the liver. Furthermore, COS ameliorated hepatic oxidative stress by activating the nuclear factor E2-related factor 2 (Nrf2) pathway and upregulating gene expressions of antioxidant enzymes. These beneficial effects were mediated by the activation of the adenosine monophosphate-activated protein kinase (AMPK) signaling pathway. Therefore, COS might be a potent dietary supplement to ameliorate NAFLD.

Neurobehavioral dysfunction in non-alcoholic steatohepatitis is associated with hyperammonemia, gut dysbiosis, and metabolic and functional brain regional deficits

Non-alcoholic steatohepatitis (NASH) is one of the most prevalent diseases worldwide. While it has been suggested to cause nervous impairment, its neurophysiological basis remains unknown. Therefore, the aim of this study is to unravel the effects of NASH, through the interrelationship of liver, gut microbiota, and nervous system, on the brain and human behavior. To this end, 40 Sprague-Dawley rats were divided into a control group that received normal chow and a NASH group that received a high-fat, high-cholesterol diet. Our results show that 14 weeks of the high-fat, high-cholesterol diet induced clinical conditions such as NASH, including steatosis and increased levels of ammonia. Rats in the NASH group also demonstrated evidence of gut dysbiosis and decreased levels of short-chain fatty acids in the gut. This may explain the deficits in cognitive ability observed in the NASH group, including their depressive-like behavior and short-term memory impairment characterized in part by deficits in social recognition and prefrontal cortex-dependent spatial working memory. We also reported the impact of this NASH-like condition on metabolic and functional processes. Brain tissue demonstrated lower levels of metabolic brain activity in the prefrontal cortex, thalamus, hippocampus, amygdala, and mammillary bodies, accompanied by a decrease in dopamine levels in the prefrontal cortex and cerebellum and a decrease in noradrenalin in the striatum. In this article, we emphasize the important role of ammonia and gut-derived bacterial toxins in liver-gut-brain neurodegeneration and discuss the metabolic and functional brain regional deficits and behavioral impairments in NASH.

Organokines in disease

Studies have linked obesity, metabolic syndrome, type 2 diabetes, cardiovascular disease (CVD), nonalcoholic fatty liver disease (NAFLD) and dementia. Their relationship to the incidence and progression of these disease states suggests an interconnected pathogenesis involving chronic low-grade inflammation and oxidative stress. Metabolic syndrome represents comorbidities of central obesity, insulin resistance, dyslipidemia, hypertension and hyperglycemia associated with increased risk of type 2 diabetes, NAFLD, atherosclerotic CVD and neurodegenerative disease. As the socioeconomic burden for these diseases has grown signficantly with an increasing elderly population, new and alternative pharmacologic solutions for these cardiometabolic diseases are required. Adipose tissue, skeletal muscle and liver are central endocrine organs that regulate inflammation, energy and metabolic homeostasis, and the neuroendocrine axis through synthesis and secretion of adipokines, myokines, and hepatokines, respectively. These organokines affect each other and communicate through various endocrine, paracrine and autocrine pathways. The ultimate goal of this review is to provide a comprehensive understanding of organ crosstalk. This will include the roles of novel organokines in normal physiologic regulation and their pathophysiological effect in obesity, metabolic syndrome, type 2 diabetes, CVD, NAFLD and neurodegenerative disorders.

Associations of circulating chemerin and adiponectin concentrations with hepatic steatosis

OBJECTIVE

Chemerin and adiponectin are adipokines assumed to be involved in the development of metabolic syndrome-related phenotypes like hepatic steatosis. We aimed to evaluate the associations of circulating chemerin and adiponectin concentrations with liver enzymes, liver fat content, and hepatic steatosis in the general population.

METHODS

Data of 3951 subjects from the population-based Study of Health in Pomerania (SHIP-TREND) were used. Hepatic steatosis was assumed when either a hyperechogenic liver (assessed via ultrasound) or a magnetic resonance imaging (MRI)-quantified liver fat content >5% was present. Adjusted sex-specific quantile and logistic regression models were applied to analyze the associations of chemerin and adiponectin with liver enzymes, liver fat content and hepatic steatosis.

RESULTS

The observed associations of chemerin and adiponectin with liver enzymes were very divergent depending on sex, fasting status and the specific enzyme. More consistent results were seen in the analyses of these adipokines in relation to MRI-quantified liver fat content. Here, we observed inverse associations to adiponectin in both sexes as well as a positive (men) or U-shaped (women) association to chemerin. Similarly, the MRI-based definition of hepatic steatosis revealed strongly consistent results: in both sexes, high chemerin concentrations were associated with higher odds of hepatic steatosis, whereas high adiponectin concentrations were associated with lower odds.

CONCLUSION

Our results suggest a role of these adipokines in the pathogenesis of hepatic steatosis independent of metabolic or inflammatory disorders. However, experimental studies are needed to further clarify the underlying mechanisms and the inter-play between adipokine concentrations and hepatic steatosis.

Cholinergic Control of Inflammation, Metabolic Dysfunction, and Cognitive Impairment in Obesity-Associated Disorders: Mechanisms and Novel Therapeutic Opportunities

Obesity and obesity-associated disorders have become world-wide epidemics, substantially increasing the risk of debilitating morbidity and mortality. A characteristic feature of these disorders, which include the metabolic syndrome (MetS) and type 2 diabetes, is chronic low-grade inflammation stemming from metabolic and immune dysregulation. Inflammation in the CNS (neuroinflammation) and cognitive impairment have also been associated with obesity-driven disorders. The nervous system has a documented role in the regulation of metabolic homeostasis and immune function, and recent studies have indicated the important role of vagus nerve and brain cholinergic signaling in this context. In this review, we outline relevant aspects of this regulation with a specific focus on obesity-associated conditions. We outline accumulating preclinical evidence for the therapeutic efficacy of cholinergic stimulation in alleviating obesity-associated inflammation, neuroinflammation, and metabolic derangements. Recently demonstrated beneficial effects of galantamine, a centrally acting cholinergic drug and cognitive enhancer, in patients with MetS are also summarized. These studies provide a rationale for further therapeutic developments using pharmacological and bioelectronic cholinergic modulation for clinical benefit in obesity-associated disorders.

The role of macrophages in nonalcoholic fatty liver disease and nonalcoholic steatohepatitis

Nonalcoholic fatty liver disease (NAFLD) and its inflammatory and often progressive subtype nonalcoholic steatohepatitis (NASH) are becoming the leading cause of liver-related morbidity and mortality worldwide, and a primary indication for liver transplantation. The pathophysiology of NASH is multifactorial and not yet completely understood; however, innate immunity is a major contributing factor in which liver-resident macrophages (Kupffer cells) and recruited macrophages play a central part in disease progression. In this Review, we assess the evidence for macrophage involvement in the development of steatosis, inflammation and fibrosis in NASH. In this process, not only the polarization of liver macrophages towards a pro-inflammatory phenotype is important, but adipose tissue macrophages, especially in the visceral compartment, also contribute to disease severity and insulin resistance. Macrophage activation is mediated by factors such as endotoxins and translocated bacteria owing to increased intestinal permeability, factors released from damaged or lipoapoptotic hepatocytes, as well as alterations in gut microbiota and defined nutritional components, including certain free fatty acids, cholesterol and their metabolites. Reflecting the important role of macrophages in NASH, we also review studies investigating drugs that target macrophage recruitment to the liver, macrophage polarization and their inflammatory effects as potential treatment options for patients with NASH.

Molecular pathways of nonalcoholic fatty liver disease development and progression

Nonalcoholic fatty liver disease (NAFLD) is a main hepatic manifestation of metabolic syndrome. It represents a wide spectrum of histopathological abnormalities ranging from simple steatosis to nonalcoholic steatohepatitis (NASH) with or without fibrosis and, eventually, cirrhosis and hepatocellular carcinoma. While hepatic simple steatosis seems to be a rather benign manifestation of hepatic triglyceride accumulation, the buildup of highly toxic free fatty acids associated with insulin resistance-induced massive free fatty acid mobilization from adipose tissue and the increased de novo hepatic fatty acid synthesis from glucose acts as the "first hit" for NAFLD development. NAFLD progression seems to involve the occurrence of "parallel, multiple-hit" injuries, such as oxidative stress-induced mitochondrial dysfunction, endoplasmic reticulum stress, endotoxin-induced, TLR4-dependent release of inflammatory cytokines, and iron overload, among many others. These deleterious factors are responsible for the triggering of a number of signaling cascades leading to inflammation, cell death, and fibrosis, the hallmarks of NASH. This review is aimed at integrating the overwhelming progress made in the characterization of the physiopathological mechanisms of NAFLD at a molecular level, to better understand the factor influencing the initiation and progression of the disease.

Folic Acid Supplementation Attenuates Chronic Hepatic Inflammation in High-Fat Diet Fed Mice

Nonalcoholic fatty liver disease (NAFLD) is the most common form of chronic liver disease worldwide. Hepatic inflammation is an important pathogenic mediator of NAFLD. There is currently no pharmacological agent approved for the treatment of NAFLD. Folic acid is a water-soluble B vitamin that has been shown to have lipid-lowering and antioxidant effects. The objective of this study was to investigate the effect of folic acid supplementation on hepatic inflammation and to identify the underlying mechanisms. Male C57BL/6 J mice were fed a control diet (10% kcal fat), a high-fat diet (HFD) (60% kcal fat), or a HFD supplemented with folic acid (26 mg/kg diet) for 8 weeks. HFD feeding led to increased body mass gain, lipid accumulation, activation of transcription factor nuclear factor-κB (NF-κB), and elevation of inflammatory cytokine gene expression in the liver. Folic acid supplementation attenuated hepatic lipid accumulation and aggregation of inflammatory foci induced by HFD feeding. This was associated with a significant reduction of NF-κB activation and inflammatory cytokine expression. These results suggest that the hepatoprotective effect of folic acid in NAFLD may be attributed, in part, to its anti-inflammatory action.

Anti-inflammatory properties of ursodeoxycholyl lysophosphatidylethanolamide in endotoxin-mediated inflammatory liver injury

AIM

Endotoxin-mediated liver inflammation is a key component of many acute and chronic liver diseases contributing to liver damage, fibrosis and eventually organ failure. Here, we investigated ursodeoxycholyl lysophosphatidylethanolamide (UDCA-LPE), a synthetic bile acid-phospholipid conjugate regarding its anti-inflammatory and anti-fibrogenic properties.

METHODS

Anti-inflammatory properties of UDCA-LPE were evaluated in a mouse model of D-galactosamine/lipopolysaccharide (GalN/LPS)-induced acute liver injury, LPS treated RAW264.7 macrophages and murine primary Kupffer cells. Furthermore, anti-inflammatory and anti-fibrotic effects of UDCA-LPE were studied on primary hepatic stellate cells (HSC) incubated with supernatant from LPS±UDCA-LPE treated RAW264.7 cells.

RESULTS

UDCA-LPE ameliorated LPS-induced increase of IL-6, TNF-α, TGF-β, NOX-2 in the GalN/LPS model by up to 80.2% for IL-6. Similarly, UDCA-LPE markedly decreased the expression of inflammatory cytokines IL-6, TNF-α and TGF-β as well as the chemokines MCP1 and RANTES in LPS-stimulated RAW 264.7 cells. Anti-inflammatory effects were also observed in primary murine Kupffer cells. Mechanistic evaluation revealed a reversion of LPS-activated pro-inflammatory TLR4 pathway by UDCA-LPE. Moreover, UDCA-LPE inhibited iNOS and NOX-2 expression while activating eNOS via phosphorylation of AKT and pERK1/2 in RAW264.7 cells. HSC treated with conditioned medium from LPS±UDCA-LPE RAW264.7 cells showed lower fibrogenic activation due to less SMAD2/3 phosphorylation, reduced expression of profibrogenic CTGF and reduced pro-inflammatory chemokine expression.

CONCLUSION

In the setting of endotoxin-mediated liver inflammation, UDCA-LPE exerts profound anti-inflammatory and anti-fibrotic effect implying a promising potential for the drug candidate as an experimental approach for the treatment of acute and chronic liver diseases.

Nonalcoholic fatty liver disease in patients with psoriasis: a consequence of systemic inflammatory burden?

Patients with psoriasis are at an increased risk for nonalcoholic fatty liver disease (NAFLD) compared with the general population. However, the pathophysiology underlying this comorbidity and elucidation of effective treatment strategies are unclear. This review provides insights into the possible role of chronic, low-grade inflammation in the pathogenesis of NAFLD in patients with psoriasis. Both conditions are associated with increased levels of proinflammatory adipokines (such as tumour necrosis factor-α and interleukin-6) and hepatokines, and decreased levels of adiponectin, an anti-inflammatory adipokine. This imbalance in inflammatory mediators could result in insulin resistance and, thereby, facilitate the occurrence and progression of NAFLD in a multistep manner. All patients with psoriasis should, therefore, be considered candidates for NAFLD screening and managed accordingly. Given the common aetiology of inflammation between these conditions, it is hypothesized that biological therapies for psoriasis may attenuate the systemic inflammatory process and progression of NAFLD in patients with psoriasis.

Peroxisomal β-oxidation regulates whole body metabolism, inflammatory vigor, and pathogenesis of nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD), a metabolic predisposition for development of hepatocellular carcinoma (HCC), represents a disease spectrum ranging from steatosis to steatohepatitis to cirrhosis. Acox1, a rate-limiting enzyme in peroxisomal fatty acid β-oxidation, regulates metabolism, spontaneous hepatic steatosis, and hepatocellular damage over time. However, it is unknown whether Acox1 modulates inflammation relevant to NAFLD pathogenesis or if Acox1-associated metabolic and inflammatory derangements uncover and accelerate potential for NAFLD progression. Here, we show that mice with a point mutation in Acox1 (Acox1Lampe1) exhibited altered cellular metabolism, modified T cell polarization, and exacerbated immune cell inflammatory potential. Further, in context of a brief obesogenic diet stress, NAFLD progression associated with Acox1 mutation resulted in significantly accelerated and exacerbated hepatocellular damage via induction of profound histological changes in hepatocytes, hepatic inflammation, and robust upregulation of gene expression associated with HCC development. Collectively, these data demonstrate that β-oxidation links metabolism and immune responsiveness and that a better understanding of peroxisomal β-oxidation may allow for discovery of mechanisms central for NAFLD progression.

Mitochondria in non-alcoholic fatty liver disease

NAFLD is a common disease in Western society and ranges from steatosis to steatohepatitis and to end-stage liver disease. The molecular mechanisms that cause the progression of steatosis to severe liver damage are not fully understood. One suggested mechanism involves the oxidation of biomolecules by mitochondrial ROS which initiates a vicious cycle of exacerbated mitochondrial dysfunction and increased hepatocellular oxidative damage. This may ultimately pave the way for hepatic inflammation and liver failure. This review updates our current understanding of mitochondria-derived oxidative stress in the progression of NAFLD.

Non-alcoholic fatty liver disease as a risk factor for cholangiocarcinoma: a systematic review and meta-analysis

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) has been recently identified as a risk factor of gastrointestinal tract cancers, especially hepatocellular carcinoma, and colorectal cancer. Whether NAFLD is a risk factor for cholangiocarcinoma (CCA) remains inconclusive. The aim of this study is to determine a potential association between NAFLD and CCA, stratifying by its subtypes; intrahepatic CCA (iCCA), and extrahepatic CCA (eCCA).

METHODS

A search was conducted for relevant studies published up to April 2017 using MEDLINE, EMBASE, Scopus and Cochrane databases. Odds ratio (OR) and adjusted OR with 95% confidence interval (CI) were estimated using a random-effects model. Subgroup analyses were conducted with study characteristics.

RESULTS

Seven case-control studies were included in the analysis, with a total of 9,102 CCA patients (5,067 iCCA and 4,035 eCCA) and 129,111 controls. Overall, NAFLD was associated with an increased risk for CCA, with pooled OR of 1.95 (95%CI: 1.36-2.79, I 2 =76%). When classified by subtypes, NAFLD was associated with both iCCA and eCCA, with ORs of 2.22 (95%CI: 1.52-3.24, I 2 =67%) and 1.55 (95%CI: 1.03-2.33, I 2 =69%), respectively. The overall pooled adjusted ORs were 1.97 (95%CI: 1.41-2.75, I 2 =71%), 2.09 (95%CI, 1.49-2.91, I 2 =42%) and 2.05 (95%CI, 1.59-2.64, I 2 =0%) for all CCAs, iCCA, and eCCA, respectively.

CONCLUSIONS

This meta-analysis suggests that NAFLD may potentially increase the risk of CCA development. The magnitude of NAFLD on CCA risk is greater for iCCA than eCCA subtype, suggestive of a common pathogenesis of iCCA and hepatocellular carcinoma. Further studies to confirm this association are warranted.

TRIAL REGISTRATION

The protocol for this study was registered with PROSPERO (International Prospective Register of Systematic Reviews; no. CRD42016046573).

Anti-steatosis compounds from leaves of Mallotus furetianus

There is no drug administration-approved therapy for non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH). In this study, eight compounds, gallic acid (1), methyl gallate (2), corilagin (3), 3,4,8,9,10-pentahydroxydibenzo[b,d]pyran-6-one (4), repandinin B (5), (Z)-3-hexenyl-β-D-glucopyranoside (6), (+)-lyoniresinol-3α-O-α-L-rhamnopyranoside (7) and mallophenol A (8) were isolated from the active fractions of Mallotus furetianus. Three compounds, (6, 7 and 8) revealed potent anti-steatosis activity in the oleic acid (OA)-induced steatosis cell model, with the minimum effective concentration of 0.05 (6), 0.0005 (7) and 0.0005 (8) μg/mL, which were much lower than the control compound, fibrate (72.4 μg/mL).

Non-alcoholic fatty liver disease: A sign of systemic disease

Non-alcoholic fatty liver disease (NAFLD) is the most common form of liver disease and leading cause of cirrhosis in the United States and developed countries. NAFLD is closely associated with obesity, insulin resistance and metabolic syndrome, significantly contributing to the exacerbation of the latter. Although NAFLD represents the hepatic component of metabolic syndrome, it can also be found in patients prior to their presentation with other manifestations of the syndrome. The pathogenesis of NAFLD is complex and closely intertwined with insulin resistance and obesity. Several mechanisms are undoubtedly involved in its pathogenesis and progression. In this review, we bring together the current understanding of the pathogenesis that makes NAFLD a systemic disease.

Tumor Necrosis Factor-Alpha: Role in Development of Insulin Resistance and Pathogenesis of Type 2 Diabetes Mellitus

Pathogenesis of type 2 diabetes mellitus (T2DM) and development of insulin resistance are characterized by multi-stimuli factors notably glucolipotoxicity, generation of reactive oxygen species (ROS), epigenetic factors, activation of various transcriptional mediated pathways along with the augmented levels of various pro-inflammatory cytokines. Among the various pro-inflammatory cytokines, tumor necrosis factor-alpha (TNF-α) is one the most important pro-inflammatory mediator that is critically involved in the development of insulin resistance and pathogenesis of T2DM. TNF-α is mainly produced in adipocytes and/or peripheral tissues, and induces tissue-specific inflammation through the involvement of generation of ROS and activation of various transcriptional mediated pathways. The raised level of TNF-α induces insulin resistance in adipocytes and peripheral tissues by impairing the insulin signaling through serine phosphorylation that leads to the development of T2DM. Anti-TNF-α treatment strategies have been developed to reduce the incidence of insulin resistance and development of T2DM. In this article, we have briefly described how TNF-α plays crucial role to induce insulin resistance and pathogenesis of T2DM. To block the inflammatory responses by blocking TNF-α and TNF-α signaling may be an effective strategy for the treatment of insulin resistance and T2DM. J. Cell. Biochem. 119: 105-110, 2018. © 2017 Wiley Periodicals, Inc.