Systemic inflammation in nonalcoholic fatty liver disease is characterized by elevated levels of CCL2

Noninvasive diagnostic criteria for nonalcoholic steatohepatitis based on gene expression levels in peripheral blood mononuclear cells

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) consists of nonalcoholic fatty liver (NAFL) and nonalcoholic steatohepatitis (NASH); the latter progresses to liver cirrhosis and hepatocellular carcinoma. Discriminating NASH from NAFL typically involves liver biopsy. The mechanism of NASH progression is unclear but may involve immunological pathways. In this study, we examined expression levels of cytokine- and chemokine-encoding genes in peripheral blood mononuclear cells (PBMCs) from NAFLD patients and established immunological criteria for discriminating NASH from NAFL.

METHODS

PBMCs were obtained from 54 patients diagnosed histologically with NAFLD (NAFL, 18; NASH, 36). mRNA was extracted from PBMCs, and expression levels of cytokine- and chemokine-encoding genes were determined by quantitative real-time PCR. Statistical analysis was performed by nonparametric test.

RESULTS

Expression levels of interferon (IFN)γ, interleukin (IL)2, IL15, C-C-motif chemokine ligand (CCL)2, IL10, and C-X-C-motif chemokine ligand (CXCL)11 were significantly upregulated in NASH patients compared with NAFL patients. Moreover, their expression levels were positively correlated with the degree of ballooning of hepatocytes but not of steatosis or lobular inflammation. We focused on those encoding IL10, IFNγ, and CCL2, and developed a scoring system to discriminate NASH from NAFL. The discriminatory power of the criteria was validated in an independent cohort.

CONCLUSIONS

Expression levels of the cytokine- and chemokine-encoding genes in PBMCs were positively correlated with ballooning, suggesting their utility for the diagnosis of NASH. The data indicate that peripheral as well as intrahepatic immunity is involved in the progression of NASH. Our findings afford new insight into immunological mechanisms of NASH and will facilitate its noninvasive diagnosis.

Assay validation and clinical performance of chronic inflammatory and chemokine biomarkers of NASH fibrosis

Nonalcoholic steatohepatitis (NASH) is a chronic liver disease that can lead to cirrhosis, liver transplant, and even hepatocellular carcinoma. While liver biopsy remains the reference standard for disease diagnosis, analytical and clinical development of non-invasive soluble biomarkers of NASH are of great importance to advance the field. To this end, we performed analytical and clinical validation on a series of pro-inflammatory cytokines and chemokines implicated hepatic inflammation; IL-6, CRP, TNFα, MCP-1, MIP-1β, eotaxin, VCAM-1. Biomarker assays were validated for accuracy and precision. Clinical performance was evaluated in a random sample of 52 patients with biopsy-proven NAFLD/NASH. Patients were categorized into three groups according to their fibrosis stage; advanced (F3-F4), mild (F1-2) and no (F0) fibrosis. Serum IL-6 was increased in patients with advanced fibrosis (2.71 pg/mL; 1.26 pg/mL; 1.39 pg/mL p<0.01) compared to patients with mild or no fibrosis respectively. While, there was no significant difference noted in CRP, TNFα, MCP-1, MIP-1β, eotaxin among the three groups, VCAM-1 levels were increased by 55% (p<0.01) and 40% (p<0.05) in the advanced cohort compared to the mild and no fibrosis groups respectively. VCAM-1 also displayed good clinical performance as a biomarker of advanced fibrosis with an area under the receiver operating curve of 0.87. The VCAM-1 assay demonstrated robust accuracy and precision, and VCAM-1 outperformed IL-6, CRP, TNFα, and the chemokines MCP-1, MIP-1β, and eotaxin as a biomarker of advanced fibrosis in NASH. Addition of biomarkers such as IL-6 and VCAM-1 to panels may yield increased sensitivity and specificity for staging of NASH.

Adipocytokines in Steatotic Liver Surgery/Transplantation

Because of the shortage of liver grafts available for transplantation, the restrictions on graft quality have been relaxed, and marginal grafts, such as steatotic livers, are now accepted. However, this policy change has not solved the problem, because steatotic liver grafts tolerate ischemia-reperfusion (I/R) injury poorly. Adipocytokines differentially modulate steatosis, inflammation, and fibrosis and are broadly present in hepatic resections and transplants. The potential use of adipocytokines as biomarkers of the severity of steatosis and liver damage to aid the identification of high-risk steatotic liver donors and to evaluate hepatic injury in the postoperative period are discussed. The hope of finding new therapeutic strategies aimed specifically at protecting steatotic livers undergoing surgery is a strong impetus for identifying the mechanisms responsible for hepatic failure after major surgical intervention. Hence, the most recently described roles of adipocytokines in steatotic livers subject to I/R injury are discussed, the conflicting results in the literature are summarized, and reasons are offered as to why strategic pharmacologic control of adipocytokines has yet to yield clinical benefits. After this, the next steps needed to transfer basic knowledge about adipocytokines into clinical practice to protect marginal livers subject to I/R injury are presented. Recent strategies based on adipocytokine regulation, which have shown efficacy in various pathologies, and hold promise for hepatic resection and transplantation are also outlined.

The incretin enhancer, sitagliptin, exacerbates expression of hepatic inflammatory markers in rats fed a high-cholesterol diet

OBJECTIVE

Hypercholesterolemia is associated with the development of a pro-inflammatory state and is a documented risk factor for progression to insulin resistance, nonalcoholic fatty liver and cardiovascular diseases. Sitagliptin is an incretin enhancer that improves glucose tolerance by inhibiting dipeptidyl peptidase-4, but it also has reported anti-inflammatory effects. The current study was thus undertaken to examine the interactions of dietary Cholesterol (Cho) and sitagliptin on markers of inflammation.

METHODS

Male Sprague-Dawley rats were provided diets high in Cho and gavaged with vehicle or an aqueous suspension of sitagliptin (100 mg/kg/day) from day 10 through day 35. Molecular methods were used to analyze the lipid profile and inflammatory markers in liver and serum samples. H&E-stained liver sections were used for histopathological evaluation. Hepatic influx of mononuclear cells and necrosis were assessed by immunohistochemistry.

RESULTS

Sitagliptin reduced triglyceride and Cho levels in serum of rats on the control diet but these effects were abrogated in rats on the high-Cho diet. Sitagliptin produced a significant increase in the expression of hepatic inflammatory markers (Tnfa, Il1b, and Mcp1) and a corresponding increase in serum TNFα and IL-1β in rats on the high-Cho diet, but it had no effect on rats on the control diet. Additionally, sitagliptin had no effect on liver morphology in rats on the control diet, but it produced hepatic histopathological changes indicative of necrosis and mononuclear cell infiltration in rats on the high-Cho diet. These mononuclear cells were identified as macrophages and T cells.

CONCLUSION

When provided in the context of a high-Cho diet, these findings reveal previously unrecognized hepato-inflammatory effects of sitagliptin that are accompanied by evidence of hepatic necrosis and mononuclear cell infiltration.

Liver Fat Is Associated With Markers of Inflammation and Oxidative Stress in Analysis of Data From the Framingham Heart Study

BACKGROUND & AIMS

Nonalcoholic fatty liver disease is an inflammatory condition that results in progressive liver disease. It is unknown if individuals with hepatic steatosis, but not known to have liver disease, have higher serum concentrations of markers of systemic inflammation and oxidative stress.

METHODS

We collected data from 2482 participants from the Framingham Heart Study (mean age, 51 ± 11 y; 51% women) who underwent computed tomography and measurement of 14 serum markers of systemic inflammation. Heavy alcohol users were excluded. The liver:phantom ratio (a continuous parameter of liver attenuation relative to a calibration phantom) was used to identify individuals with radiographic evidence of liver fat. Primary covariates included age, sex, smoking, alcohol, aspirin use, hypertension, dyslipidemia, diabetes, and cardiovascular disease. Body mass index and visceral fat were secondary covariates. We used multivariable linear regression models to assess the association between liver fat and systemic inflammatory markers.

RESULTS

In multivariable-adjusted models, liver fat was associated with the following inflammatory markers: high-sensitivity C-reactive protein (P < .001), urinary isoprostanes (P < .001), interleukin 6 (P < .001), intercellular adhesion molecule 1 (P < .001), and P-selectin (P = .002). Additional adjustment for body mass index or visceral fat attenuated the results slightly, although all associations remained statistically significant (P for all ≤ .01).

CONCLUSIONS

In a community-based cohort, individuals with hepatic steatosis without known liver disease had higher mean serum concentrations of systemic markers of inflammation. Studies are needed to determine whether treatment of hepatic steatosis reduces systemic inflammation.

Recent Insights into the Pathogenesis of Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is a burgeoning health problem worldwide and an important risk factor for both hepatic and cardiometabolic mortality. The rapidly increasing prevalence of this disease and of its aggressive form nonalcoholic steatohepatitis (NASH) will require novel therapeutic approaches based on a profound understanding of its pathogenesis to halt disease progression to advanced fibrosis or cirrhosis and cancer. The pathogenesis of NAFLD involves a complex interaction among environmental factors (i.e., Western diet), obesity, changes in microbiota, and predisposing genetic variants resulting in a disturbed lipid homeostasis and an excessive accumulation of triglycerides and other lipid species in hepatocytes. Insulin resistance is a central mechanism that leads to lipotoxicity, endoplasmic reticulum stress, disturbed autophagy, and, ultimately, hepatocyte injury and death that triggers hepatic inflammation, hepatic stellate cell activation, and progressive fibrogenesis, thus driving disease progression. In the present review, we summarize the currently available data on the pathogenesis of NAFLD, emphasizing the most recent advances. A better understanding of NAFLD/NASH pathogenesis is crucial for the design of new and efficient therapeutic interventions.

Liver macrophages regulate systemic metabolism through non-inflammatory factors

Liver macrophages (LMs) have been proposed to contribute to metabolic disease through secretion of inflammatory cytokines. However, anti-inflammatory drugs lead to only modest improvements in systemic metabolism. Here we show that LMs do not undergo a proinflammatory phenotypic switch in obesity-induced insulin resistance in flies, mice and humans. Instead, we find that LMs produce non-inflammatory factors, such as insulin-like growth factor-binding protein 7 (IGFBP7), that directly regulate liver metabolism. IGFBP7 binds to the insulin receptor and induces lipogenesis and gluconeogenesis via activation of extracellular-signal-regulated kinase (ERK) signalling. We further show that IGFBP7 is subject to RNA editing at a higher frequency in insulin-resistant than in insulin-sensitive obese patients (90% versus 30%, respectively), resulting in an IGFBP7 isoform with potentially higher capacity to bind to the insulin receptor. Our study demonstrates that LMs can contribute to insulin resistance independently of their inflammatory status and indicates that non-inflammatory factors produced by macrophages might represent new drug targets for the treatment of metabolic diseases.

A Regulatory Role of Apoptosis Antagonizing Transcription Factor in the Pathogenesis of Nonalcoholic Fatty Liver Disease and Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is increasing as a cause of liver-related mortality largely because of the growing burden of nonalcoholic steatohepatitis (NASH). The mechanisms of HCC development in nonalcoholic fatty liver disease (NAFLD) are incompletely understood. We initially identified apoptosis antagonizing transcription factor (AATF) to be associated with HCC in a mouse model of NASH that develops HCC without the addition of specific carcinogens. AATF, also called che-1, is a transcriptional factor that is highly conserved among eukaryotes. AATF is known to be a central mediator of the cellular responses as it promotes cell proliferation and survival by inducing cell cycle arrest, autophagy, DNA repair, and inhibition of apoptosis. However, the role of AATF in NASH and HCC remains unknown. Here, we provide evidence for AATF as a contributory factor for HCC in NAFLD. AATF overexpression was further verified in human NASH and HCC and multiple human HCC cell lines. Tumor necrosis factor-α (TNFα), known to be increased in NASH, induced AATF expression. Promoter analysis of AATF revealed a sterol regulatory element binding transcription factor 1-c (SREBP-1c) binding site; inhibition of SREBP-1 by using specific inhibitors as well as small interfering RNA decreased TNFα-induced AATF expression. AATF interacted with signal transducer and activator of transcription 3 to increase monocyte chemoattractant protein-1 expression. AATF knockdown decreased cell proliferation, migration, invasion, colony formation, and anchorage-dependent growth in HCC cell lines. Xenograft of QGY-7703 HCC cells with AATF stably knocked down into nonobese diabetic scid gamma mice demonstrated reduced tumorigenesis and metastases. Conclusion: AATF drives NAFLD and hepatocarcinogenesis, offering a potential target for therapeutic intervention.

Perilipin-2 promotes obesity and progressive fatty liver disease in mice through mechanistically distinct hepatocyte and extra-hepatocyte actions

KEY POINTS

Wild-type mice and mice with hepatocyte-specific or whole-body deletions of perilipin-2 (Plin2) were used to define hepatocyte and extra-hepatocyte effects of altered cellular lipid storage on obesity and non-alcoholic fatty liver disease (NAFLD) pathophysiology in a Western-diet (WD) model of these disorders. Extra-hepatocyte actions of Plin2 are responsible for obesity, adipose inflammation and glucose clearance abnormalities in WD-fed mice. Hepatocyte and extra-hepatic actions of Plin2 mediate fatty liver formation in WD-fed mice through distinct mechanisms. Hepatocyte-specific actions of Plin2 are primary mediators of immune cell infiltration and fibrotic injury in livers of obese mice.

ABSTRACT

Non-alcoholic fatty liver disease (NAFLD) is an obesity- and insulin resistance-related metabolic disorder with progressive pathology. Perilipin-2 (Plin2), a ubiquitously expressed cytoplasmic lipid droplet scaffolding protein, is hypothesized to contribute to NAFLD in humans and rodent models through effects on cellular lipid metabolism. In this study, we delineate hepatocyte-specific and extra-hepatocyte Plin2 mechanisms regulating the effects of obesity and insulin resistance on NAFLD pathophysiology in mice fed an obesogenic Western-style diet (WD). Total Plin2 deletion (Plin2-Null) fully protected WD-fed mice from obesity, insulin resistance, adipose inflammation, steatohepatitis (NASH) and liver fibrosis found in WT animals. Hepatocyte-specific Plin2 deletion (Plin2-HepKO) largely protected against NASH and fibrosis and partially protected against steatosis in WD-fed animals, but it did not protect against obesity, insulin resistance, or adipose inflammation. Significantly, total or hepatocyte-specific Plin2 deletion impaired WD-induced monocyte recruitment and pro-inflammatory macrophage polarization found in livers of WT mice. Analyses of the molecular and cellular processes mediating steatosis, inflammation and fibrosis identified differences in total and hepatocyte-specific actions of Plin2 on the mechanisms promoting NAFLD pathophysiology. Our results demonstrate that hepatocyte-specific actions of Plin2 are central to the initiation and pathological progression of NAFLD in obese and insulin-resistant mice through effects on immune cell recruitment and fibrogenesis. Conversely, extra-hepatocyte Plin2 actions promote NAFLD pathophysiology through effects on obesity, inflammation and insulin resistance. Our findings provide new insight into hepatocyte and extra-hepatocyte mechanisms underlying NAFLD development and progression.

Non-alcoholic fatty liver disease presence and severity are associated with aortic stiffness beyond abdominal obesity: The ELSA-Brasil

BACKGROUND AND AIMS

It is uncertain whether non-alcoholic fatty liver disease (NAFLD) is associated with aortic stiffness in a racial/ethnically diverse and admixed society. We addressed whether NAFLD presence and severity were associated with carotid-femoral pulse wave velocity (cf-PWV) in individuals free of cardiovascular disease.

METHODS

In 7196 individuals free of cardiovascular disease at the baseline Brazilian longitudinal study of adult health, we classified NAFLD presence and severity (mild, moderate and severe) by ultrasound hepatic attenuation. We measured cf-PWV using a non-invasive validated device (Complior SP, Artech Medicale France). We compared cf-PWV of NAFLD individuals to those without by analysis of covariance adjusted for demographics, life style, waist circumference, and arterial pressure. We also analyzed the cf-PWV trend from no-NAFLD to severe NAFLD.

RESULTS

In unadjusted analysis, from no-NAFLD to severe NAFLD, there were slightly older individuals, lower frequency of smokers, more prevalent diabetes and hypertension. In adjusted analysis, there was slightly higher cf-PWV (m/s) (95%CI) in NAFLD vs. no-NAFLD, respectively 9.32 (9.22, 9.41) and 9.24 (9.15, 9.33) (p = 0.037). Across NAFLD severity spectrum, adjusted cf-PWV increased from 9.24 (9.15, 9.33) in no-NAFLD to 9.69 (9.46, 9.93) in severe NAFLD (p for trend association = 0.001). In sensitivity analysis, diabetes adjustment nullified the association of binary NAFLD with cf-PWV, but not that of increasingly severe NAFLD.

CONCLUSIONS

In racial/ethnically diverse individuals free of cardiovascular disease, NAFLD is associated with aortic stiffness beyond abdominal obesity. The specific NAFLD impact on CVD worldwide is potentially relevant.

Interplay between early-life malnutrition, epigenetic modulation of the immune function and liver diseases

Early-life nutrition plays a critical role in fetal growth and development. Food intake absence and excess are the two main types of energy malnutrition that predispose to the appearance of diseases in adulthood, according to the hypothesis of 'developmental origins of health and disease'. Epidemiological data have shown an association between early-life malnutrition and the metabolic syndrome in later life. Evidence has also demonstrated that nutrition during this period of life can affect the development of the immune system through epigenetic mechanisms. Thus, epigenetics has an essential role in the complex interplay between environmental factors and genetics. Altogether, this leads to the inflammatory response that is commonly seen in non-alcoholic fatty liver disease (NAFLD), the hepatic manifestation of the metabolic syndrome. In conjunction, DNA methylation, covalent modification of histones and the expression of non-coding RNA are the epigenetic phenomena that affect inflammatory processes in the context of NAFLD. Here, we highlight current understanding of the mechanisms underlying developmental programming of NAFLD linked to epigenetic modulation of the immune system and environmental factors, such as malnutrition.

Influence of total polar compounds on lipid metabolism, oxidative stress and cytotoxicity in HepG2 cells

BACKGROUND

Recently, the harmful effects of frying oil on health have been gradually realized. However, as main components of frying oils, biochemical effects of total polar compounds (TPC) on a cellular level were underestimated.

METHODS

The effects of total polar compounds (TPC) in the frying oil on the lipid metabolism, oxidative stress and cytotoxicity of HepG2 cells were investigated through a series of biochemical methods, such as oil red staining, real-time polymerase chain reaction (RT-PCR), cell apoptosis and cell arrest.

RESULTS

Herein, we found that the survival rate of HepG2 cells treated with TPC decreased in a time and dose dependent manner, and thereby presented significant lipid deposition over the concentration of 0.5 mg/mL. TPC were also found to suppress the expression levels of PPARα, CPT1 and ACOX, elevate the expression level of MTP and cause the disorder of lipid metabolism. TPC ranged from 0 to 2 mg/mL could significantly elevate the amounts of reactive oxygen species (ROS) in HepG2 cells, and simultaneously increase the malondialdehyde (MDA) content from 21.21 ± 2.62 to 65.71 ± 4.20 μmol/mg of protein (p < 0.05) at 24 h. On the contrary, antioxidant enzymes superoxide dismutase (SOD), glutathione (GSH), and catalase (CAT) respectively decreased by 0.52-, 0.56- and 0.28-fold, when HepG2 cells were exposed to 2 mg/mL TPC for 24 h. In addition, TPC could at least partially induce the apoptosis of HepG2 cells, and the transition from G0/G1 to G2 phase in HepG2 cells was impeded.

CONCLUSIONS

TPC could progressively cause lipid deposition, oxidative stress and cytotoxicity, providing the theoretical support for the detrimental health effects of TPC.

A comparative analysis of hepatic pathological phenotypes in C57BL/6J and C57BL/6N mouse strains in non-alcoholic steatohepatitis models

C57BL/6J (BL6J) and C57BL/6N (BL6N) inbred substrains are most widely used to understand the pathological roles of target molecules in a variety of diseases, including non-alcoholic steatohepatitis (NASH), based on transgenic mouse technologies. There are notable differences in the metabolic phenotypes, including glucose tolerance, between the BL6J and BL6N substrains, but the phenotypic differences in NASH are still unknown. We performed a comparative analysis of the two mouse substrains to identify the pathological phenotypic differences in NASH models. In the CCl₄-induced NASH model, the BL6J mice exhibited a more severe degree of oxidative stress and fibrosis in the liver than the BL6N mice. In contrast, in the high-fat diet-induced NASH model, more accumulation of hepatic triglycerides but less weight gain and liver injury were noted in the BL6J mice than in the BL6N mice. Our findings strongly suggest caution be exercised with the use of unmatched mixed genetic background C57BL6 mice for studies related to NASH, especially when generating conditional knockout C57BL6 mice.

Effects of palmitate and astaxanthin on cell viability and proinflammatory characteristics of mesenchymal stem cells

Mesenchymal stem cells (MSCs) have broad immunomodulatory activities. These cells are a stable source of cytokine production such as interleukin-6 (IL6), monocyte chemoattractant protein-1 (MCP-1/CCL2) and vascular endothelial growth factor (VEGF). Fatty acid elevation in chronic metabolic diseases alters the microenvironment of MSCs and thereby, might affect their survival and cytokine production. In the present study, we investigated the effects of palmitate, the most abundant saturated free fatty acid (FFA) in plasma, and astaxanthin, a potent antioxidant, on cell viability and apoptosis in human bone marrow-driven mesenchymal stem cells. We also elucidated how palmitate and astaxanthin influence the inflammation in MSCs. Human mesenchymal stem cells were collected from an aspirate of the femurs and tibias marrow compartment. The effect of palmitate on cell viability, caspase activity and pro-inflammatory cytokines expression and secretion were evaluated. In addition, activation of the MAP kinases and NF-kB signaling pathways were investigated. The results showed that astaxanthin protected MSCs from palmitate-induced cell death. We found that palmitate significantly enhanced IL-6, VEGF and MCP-1 expression, and secretion in MSC cells. Increased cytokine expression was parallel to the enhanced phosphorylation of P38, ERK and IKKα-IKKβ. In addition, pretreatment with JNK, ERK, P38, and NF-kB inhibitors could correspondingly attenuate palmitate-induced expression of VEGF, IL-6, and MCP-1. Our results demonstrated that fatty acid exposure causes inflammatory responses in MSCs that can be alleviated favorably by astaxanthin treatment.

Chronic intake of moderate fat-enriched diet induces fatty liver and low-grade inflammation without obesity in rabbits

Non-Alcoholic Fatty Liver Disease (NAFLD) is the cause of chronic liver disease. Even though NAFLD is strongly associated with obesity and metabolic syndrome, there is a proportion of patients who develop this condition in the absence of obesity and the underlying mechanisms are poorly understood. We investigated early events in the pathogenesis of non-obese NAFLD, analyzing the impact of the chronic intake of a moderate fat-enriched diet on hepatic lipid accumulation and their relationship with inflammation. Rabbits fed with a moderate Fatty-Acid- Enriched Diet 3% palmitic acid (FAED), were evaluated for body weight, biochemical parameters, and liver function. Liver samples were analyzed by histology and RT-qPCR to measure lipid accumulation, the expression of inflammation-related genes IL-1β, IL-6, IL-10, IL-13, IL-18, COX-2, TNF-α, and TLR-4. Chronic consumption by 6-months of FAED did not generate metabolic changes, but it induced fatty liver. We also observed the development of low-grade inflammation characterized by the up regulation of TNF-α, IL-13 and IL-18. The consumption by 12-months of FAED caused the overexpression of IL-6, IL-10, IL-13, COX-2, and TLR-4. We show that hepatic steatosis is an early consequence of fat-enriched diets, and that it is accompanied by an immune response that exerts protective effects that prevent the development of metabolic disorders, such as overweight/obesity and metabolic syndrome. However, the excessive intake of fatty acids renders these mechanisms less efficient for delaying the start of metabolic alterations. Rabbits fed with FAED can be used as a model of NAFLD in non-obese and obese groups, especially at early stages of the disease.

Hepatic Fat Content and Liver Enzymes Are Associated with Circulating Free and Protein-Bound Advanced Glycation End Products, Which Are Associated with Low-Grade Inflammation: The CODAM Study

Advanced glycation end products (AGEs) accumulate in fatty livers and may contribute to low-grade inflammation (LGI), potentially via their receptor, RAGE. It is unknown if the AGE accumulation in fatty livers results in elevated circulating AGEs. In a cohort study, we investigated the association of liver fat and hepatocellular damage with circulating AGEs and soluble RAGE (sRAGE) and subsequently the association of circulating AGEs and sRAGE with LGI. Cross-sectional associations of liver fat percentage (eLF%; ln-transformed) and liver enzymes (LE score; standardized) with circulating AGEs (free CML, CEL, and MG-H1 in nM and protein-bound CML, CEL, and pentosidine in nmol/mmol lysine; ln-transformed) and sRAGE (pg/ml, ln-transformed) and additionally of AGEs and sRAGE with LGI (standardized) were determined by multiple linear regression. eLF% was positively associated with circulating free CEL (β = 0.090; 95% CI 0.041; 0.139) but inversely with protein-bound CML (β = -0.071; 95% CI -0.108; -0.034). Similarly, the LE score was positively associated with free CML (β = 0.044; 95% CI 0.012; 0.076) and CEL (β = 0.040; 95% CI 0.009; 0.072) but inversely with protein-bound CML (β = -0.037; 95% CI -0.060; -0.013). Free CML (β = 0.297; 95% CI 0.049; 0.545) was positively associated with LGI, while protein-bound CML (β = -0.547; 95% CI -0.888; -0.207) was inversely associated, although this association was absent after adjustment for BMI. eLF% and LE score were not associated with sRAGE and sRAGE not with LGI after adjustment for BMI. Liver fat and enzymes were positively associated with circulating free AGEs, which were associated with LGI. In contrast, inverse relations were observed of liver fat and enzymes with circulating protein-bound AGEs and of protein-bound AGEs with LGI. These data suggest that hepatic steatosis and inflammation affect the formation and degradation of hepatic protein-bound AGEs resulting in elevated circulating free AGE levels. These alterations in AGE levels might influence LGI, but this is likely independent of RAGE.

Gut Dysfunction and Non-alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) has emerged as one of the leading liver diseases worldwide. NAFLD is characterized by hepatic steatosis and may progress to an inflammatory condition termed non-alcoholic steatohepatitis (NASH), liver cirrhosis, and hepatocellular carcinoma. It became evident in the last years that NAFLD pathophysiology is complex and involves diverse immunological and metabolic pathways. An association between intestinal signals (e.g., derived from the gut microbiota) and the development of obesity and its metabolic consequences such as NAFLD are increasingly recognized. Pre-clinical studies have shown that germ-free mice are protected against obesity and hepatic steatosis. Several human studies from the past years have demonstrated that NAFLD contains a disease-specific gut microbiome signature. Controlled studies propose that certain bacteria with rather pro-inflammatory features such as Proteobacteria or Escherichia coli are dominantly present in these patients. In contrast, rather protective bacteria such as Faecalibacterium prausnitzii are decreased in NAFLD patients. Furthermore, various bacterial metabolites and microbiota-generated secondary bile acids are involved in NAFLD-associated metabolic dysfunction. Although these findings are exciting, research currently lack evidence that interference at the level of the gut microbiome is beneficial for these diseases. Further preclinical and clinical studies are needed to advance this aspect of NAFLD research and to support the notion that the intestinal microbiota is indeed of major relevance in this disorder.

Erythrocyte membrane fatty acid profile & serum cytokine levels in patients with non-alcoholic fatty liver disease

Background & objectives

Fatty acids may affect the expression of genes, and this process is influenced by sex hormones. Cytokines are involved in the pathogenesis of non-alcoholic fatty liver disease (NAFLD), so this study was aimed to assess the association of erythrocyte membrane fatty acids with three cytokines and markers of hepatic injury in NAFLD patients and to explore whether these associations were the same in both sexes.

Methods

In this cross-sectional study, 62 consecutive patients (32 men and 30 women) with NAFLD during the study period. Tumour necrosis factor-α (TNF-α), interleukin 6 (IL-6), monocyte chemoattractant protein-1 (MCP-1), aspartate aminotransferase and alanine aminotransferase were measured in a fasting serum sample, and Fibroscan was conducted for each individual. Gas chromatography was used to measure erythrocyte membrane fatty acids. Univariate and multiple linear regressions were used to analyze data.

Results

In men, IL-6 had a significant (P <0.05) positive association with total ω-3 polyunsaturated fatty acids (PUFAs). In women, TNF-α had a significant positive association with total ω-3 (P <0.05) and ω-6 (P <0.01) PUFAs, IL-6 had a significant (P <0.05) positive association with total monounsaturated fatty acids and MCP-1 had a significant positive association with total trans-fatty acids (P <0.05). No significant associations were observed between erythrocyte membrane fatty acids and liver enzymes or Fibroscan report in both sexes. In this study, women were significantly older than men [51 (42.75-55) vs 35.5 (29-52), P <0.01], so the associations were adjusted for age and other confounders.

Interpretation & conclusions

Erythrocyte membrane fatty acid profile was not associated with serum liver enzymes or Fibroscan reports in NAFLD patients, but it had significant associations with serum TNF-α, IL-6 and MCP-1 and these associations were probably sex dependent.

Wuzhi capsule (Schisandra Sphenanthera extract) attenuates liver steatosis and inflammation during non-alcoholic fatty liver disease development

OBJECTIVE

Wuzhi (WZ) capsule contains an ethanol extract of Schisandra sphenanthera. The efficacy of WZ in treating non-alcoholic fatty liver disease (NAFLD) has not yet been elucidated. The present study assessed the effects of WZ on NAFLD.

MATERIAL AND METHODS

A C57BL/6 male mouse model of NAFLD was established by feeding the animals a methionine-choline-deficient (MCD) diet. Mice fed the basal diet were used as controls. Both groups were randomly administered WZ or vehicle by gavage for 5 weeks. Body weight change, liver/body weight ratio, metabolic parameters, and histological changes were assessed. Serum levels of IL-1β, IL-6, IL-10, and TNF-α were analysed by ELISA; mRNA expression of these genes in the liver was studied by real-time PCR. Western blotting was used to analyse the protein levels of PPAR-α, PPAR-γ, MCAD, LCAD, and p65 in the liver.

RESULTS

After 5 weeks of the MCD diet, the liver/body weight ratio of WZ mice was higher than that of control mice. Liver histology revealed significantly less steatosis, inflammation, and necrosis, which was confirmed by decreased intrahepatic triglycerides and serum ALT in WZ-treated mice. WZ also reduced the liver mRNA expression of IL-1β, IL-6, and TNF-α and the serum levels of IL-1β and IL-6. Sensitivity to steatohepatitis due to WZ administration correlated significantly with alterations in the expression of PPAR-α/γ, as well as the NF-κB signalling pathway.

CONCLUSIONS

WZ plays a protective role against MCD-induced steatohepatitis. The underlying mechanism likely involves the upregulation of PPAR-α/γ and downregulation of the NF-κB signalling pathway. Based on its beneficial effects on the liver, WZ is a promising therapeutic for NAFLD patients.

Are Vaspin and Omentin-1 Related to Insulin Resistance, Blood Pressure and Inflammation in NAFLD Patients?

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD), the hepatic manifestation of insulin resistance, is the most common cause of chronic liver. The present study aimed to investigate the roles of vaspin and omentin-1 in the NAFLD-related pathology including IR, inflammation and elevated blood pressure.

METHODS

This cross-sectional study was conducted among 83 NAFLD patients in Jahrom, Iran. Plasma levels of omentin-1, vaspin, hs-CRP and IL-6 were measured. Anthropometric indices, lipid profiles, liver enzymes as well as abdominal ultrasonography were assessed.

RESULTS

Partial correlations controlling for age and sex showed significant positive correlation between vaspin and fasting blood sugar (FBS), insulin, HOMA-IR, and hs-CRP. It has been observed that omentin negatively correlated with glucose levels. Moreover, a marginally significant association has been found between omentin levels and systolic blood pressure (SBP).

CONCLUSIONS

This study shows that vaspin and omentin-1 are associated with inflammation, insulin resistance and serum glucose levels in patients with NAFLD.

TRUSS Exacerbates NAFLD Development by Promoting IκBα Degradation in Mice

There is no effective treatment method for nonalcoholic fatty liver disease (NAFLD), the most common liver disease. The exact mechanism underlying the pathogenesis of NAFLD remains to be elucidated. Here, we report that tumor necrosis factor receptor-associated ubiquitous scaffolding and signaling protein (TRUSS) acts as a positive regulator of NAFLD and in a variety of metabolic disorders. TRUSS expression was increased in the human liver specimens with NAFLD or nonalcoholic steatohepatitis, and in the livers of high-fat diet (HFD)-induced and genetically obese mice. Conditional knockout of TRUSS in hepatocytes significantly ameliorated hepatic steatosis, insulin resistance, glucose intolerance, and inflammatory responses in mice after HFD challenge or in spontaneous obese mice with normal chow feeding. All of these HFD-induced pathological phenotypes were exacerbated in mice overexpressing TRUSS in hepatocytes. We show that TRUSS physically interacts with the inhibitor of nuclear factor κB α (IκBα) and promotes the ubiquitination and degradation of IκBα, which leads to aberrant activation of nuclear factor κB (NF-κB). Overexpressing IκBα^S32A/S36A , a phosphorylation-resistant mutant of IκBα, in the hepatocyte-specific TRUSS overexpressing mice almost abolished HFD-induced NAFLD and metabolic disorders. Conclusion: Hepatocyte TRUSS promotes pathological stimuli-induced NAFLD and metabolic disorders, through activation of NF-κB by promoting ubiquitination and degradation of IκBα. Our findings may provide a strategy for the prevention and treatment of NAFLD by targeting TRUSS.

Glutathione S-transferase P deficiency induces glucose intolerance via JNK-dependent enhancement of hepatic gluconeogenesis

Hepatic glutathione S-transferases (GSTs) are dysregulated in human obesity, nonalcoholic fatty liver disease, and diabetes. The multifunctional GST pi-isoform (GSTP) catalyzes the conjugation of glutathione with acrolein and inhibits c-Jun NH₂-terminal kinase (JNK) activation. Herein, we tested whether GSTP deficiency disturbs glucose homeostasis in mice. Hepatic GST proteins were downregulated by short-term high-fat diet in wild-type (WT) mice concomitant with increased glucose intolerance, JNK activation, and cytokine mRNAs in the liver. Genetic deletion of GSTP did not affect body composition, fasting blood glucose levels, or insulin levels in mice maintained on a normal chow diet; however, compared with WT mice, the GSTP-null mice were glucose intolerant. In GSTP-null mice, pyruvate intolerance, reflecting increased hepatic gluconeogenesis, was accompanied by elevated levels of activated JNK, cytokine mRNAs, and glucose-6-phosphatase proteins in the liver. Treatment of GSTP-null mice with the JNK inhibitor 1,9-pyrazoloanthrone (SP600125) significantly attenuated pyruvate-induced hepatic gluconeogenesis and significantly altered correlations between hepatic cytokine mRNAs and metabolic outcomes in GSTP-null mice. Collectively, these findings suggest that hepatic GSTP plays a pivotal role in glucose handling by regulating JNK-dependent control of hepatic gluconeogenesis. Thus, hepatic GSTP-JNK dysregulation may be a target of new therapeutic interventions during early stages of glucose intolerance to prevent the worsening metabolic derangements associated with human obesity and its relentless progression to diabetes.

Association of non-alcoholic fatty liver disease with cardiovascular disease and subclinical atherosclerosis

Non-alcoholic fatty liver disease (NAFLD) refers to fatty infiltration of liver in the absence of significant alcohol intake, use of steatogenic medication, or hereditary disorders. It is a common cause of chronic liver disease with a worldwide estimated prevalence ranging from 6.3% to 33%. The NAFLD is considered a hepatic manifestation of the metabolic syndrome. Insulin resistance and increased oxidative stress are central to pathogenesis of NAFLD, and risk factors include metabolic syndrome, diabetes mellitus, obesity, lack of physical activity, smoking, and high fat diet. NAFLD is associated with higher mortality as compared to the general population with cardiovascular disease being the most common cause of death. The NAFLD is associated with a higher prevalence of subclinical atherosclerosis as evidenced by odds of higher coronary artery calcification, higher average and maximum carotid intima-media thickness. It is also associated with stiff arteries as evidenced by higher cardio-ankle vascular index and higher brachial-ankle pulse wave velocity. Increasing evidence has linked NAFLD with atherosclerotic cardiovascular diseases. The NAFLD is associated with a higher prevalence of coronary artery disease (CAD), more severe CAD, poor coronary collateral development, and higher incidence of coronary events. The NAFLD is also associated with ischemic stroke. Studies have shown that the association between NAFLD and atherosclerotic cardiovascular diseases is independent of shared risk factors.

Serum Interleukin-8, Osteopontin, and Monocyte Chemoattractant Protein 1 Are Associated With Hepatic Fibrosis in Patients With Nonalcoholic Fatty Liver Disease

The severity of hepatic fibrosis is the primary predictor of liver‐related morbidity and mortality in patients with nonalcoholic fatty liver disease (NAFLD). Unfortunately, noninvasive serum biomarkers for NAFLD‐associated fibrosis are limited. We analyzed baseline serum samples for 24 cytokines of 97 patients with biopsy‐proven NAFLD. These patients were prospectively enrolled in a clinical study (ClinicalTrials.gov NCT00794716) to identify cytokines associated with liver fibrosis in patients with nonalcoholic steatohepatitis. Patients were stratified according to severity of hepatic fibrosis (mild, stage 0‐1, n = 37; moderate, stage 2, n = 40; and advanced, stage 3‐4, n = 20) while controlling for age, race, sex, body mass index, and diabetes mellitus. Interleukin‐8 (IL‐8), osteopontin (OPN), and monocyte chemoattractant protein 1 (MCP1) were associated with liver fibrosis (P < 0.001, P = 0.005, P = 0.016, respectively). After controlling for steatosis, lobular inflammation, hepatocyte ballooning, age, sex, body mass index, diabetes mellitus, hypertension, and metabolic syndrome status, IL‐8 remained strongly associated with fibrosis (P = 0.001). Furthermore, IL‐8 was also a strong predictor of increased fibrotic liver injury compared to established markers of hepatic fibrosis. Hepatic gene expression from 72 patients with NAFLD (n = 40 mild fibrosis; n = 32 advanced fibrosis) from the Duke University Health System NAFLD Clinical Database and Biorepository revealed IL‐8, MCP1, and OPN gene expression to be increased and differentially expressed in patients with advanced hepatic fibrosis. Thus, serum IL‐8, MCP1, and OPN may reflect up‐regulated gene expression during liver fibrosis in NAFLD. Conclusion: Serum IL‐8, MCP1, and OPN may serve as a test for advanced hepatic fibrosis in NAFLD and thus reveal novel targets for antifibrotic therapies. The increased serum IL‐8, MCP1, and OPN that correspond with associated hepatic gene expression lend strength to such analytes as ideal surrogate serum biomarkers for severity of hepatic fibrosis.

Inhibition of CCL19 benefits non‑alcoholic fatty liver disease by inhibiting TLR4/NF‑κB‑p65 signaling

Non‑alcoholic fatty liver disease (NAFLD), which affects approximately one‑third of the general population, has become a global health problem. Thus, more effective treatments for NAFLD are urgently required. In the present study, high levels of C‑C motif ligand 19 (CCL19), signaling pathways such as Toll‑like receptor 4 (TLR4)/nuclear factor‑κB (NF‑κB), and proinflammatory factors including interleukin‑6 (IL‑6) and tumor necrosis factor‑α (TNF‑α) were detected in NAFLD patients, thereby indicating that there may be an association between CCL19 and these factors in NAFLD progression. Using a high‑fat diet (HFD), the present study generated a Sprague‑Dawley rat model of NAFLD, which displayed dyslipidemia with increased levels of plasma aspartate aminotransferase, alanine aminotransferase, total cholesterol and triglyceride. Dyslipidemia, liver histopathology and gene expression analyses indicated that the NAFLD model was successfully induced by HFD, and metformin and berberine (BBR) were effective treatments for NAFLD. HFD‑induced CCL19 levels and associated factors were markedly reduced by the two drug treatments. In addition, metformin or BBR alone significantly promoted adenosine monophosphate‑activated protein kinase (AMPK) phosphorylation, which was inhibited by HFD. These results demonstrated that metformin and BBR could improve NAFLD, which may be via the activation of AMPK signaling, and the high expression of CCL19 in NAFLD was significantly reduced by metformin and BBR. It could be inferred that inhibition of CCL19 may be an effective treatment for NAFLD.

Catalase and nonalcoholic fatty liver disease

Obesity and insulin resistance are considered the main causes of nonalcoholic fatty liver disease (NAFLD), and oxidative stress accelerates the progression of NAFLD. Free fatty acids, which are elevated in the liver by obesity or insulin resistance, lead to incomplete oxidation in the mitochondria, peroxisomes, and microsomes, leading to the production of reactive oxygen species (ROS). Among the ROS generated, H₂O₂ is mainly produced in peroxisomes and decomposed by catalase. However, when the H₂O₂ concentration increases because of decreased expression or activity of catalase, it migrates to cytosol and other organelles, causing cell injury and participating in the Fenton reaction, resulting in serious oxidative stress. To date, numerous studies have been shown to inhibit the pathogenesis of NAFLD, but treatment for this disease mainly depends on weight loss and exercise. Various molecules such as vitamin E, metformin, liraglutide, and resveratrol have been proposed as therapeutic agents, but further verification of the dose setting, clinical application, and side effects is needed. Reducing oxidative stress may be a fundamental method for improving not only the progression of NAFLD but also obesity and insulin resistance. However, the relationship between NAFLD progression and antioxidants, particularly catalase, which is most commonly expressed in the liver, remains unclear. Therefore, this review summarizes the role of catalase, focusing on its potential therapeutic effects in NAFLD progression.

Exposure to environmental level phenanthrene induces a NASH-like phenotype in new born rat

More and more evidence indicates that persistent organic pollutants (POPs) are a risk factor for non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH). Phenanthrene (Phe) is a kind of POP which existed extensively in the environment, but whose toxicity on mammals has so far received less focus. Subcutaneously injection of Phe (0.5, 5, 50 μg/kg) for 21 days induced significant NAFLD/NASH symptoms in new born rats. Exposure to environmental levels of Phe decreased body weight and liver-somatic index; impaired histology of liver; influenced the peroxisome proliferator-activated receptor gamma (PPARγ) signaling and lipid metabolism in liver; stimulated oxidative stress in the rats' liver; induced the variation of NFκB pathway and liver inflammatory response; and caused liver fibrosis via transforming growth factor β1 (tgfβ1). We speculated that the subcutaneously injected Phe was transferred to the liver through blood circulation, which may have induced the elevation of PPARγ directly or indirectly, leading to liver steatosis. Excess lipid, acting as the first hit, stimulated the second hit factors - oxidative stress, inflammatory response and lipid peroxidation, and finally resulted in steatohepatitis and liver fibrosis.

Serum levels of immunoglobulins in an adult population and their relationship with nonalcoholic fatty liver disease

OBJECTIVES

Few studies have reported the association between nonalcoholic fatty liver disease (NAFLD) and immunoglobulins. In this study, we aimed to investigate the relationship between serum immunoglobulin levels and NAFLD in a Chinese adult population.

METHODS

We performed a cross-sectional study including 11 261 Chinese adults. NAFLD was diagnosed based on the Chinese Guidelines for the diagnosis and treatment of fatty liver diseases and an alcohol intake of <70 g/week in women and <140 g/week in men, and serum immunoglobulin (Ig) levels were determined using immune nephelometry. Multiple logistic regression analysis was done to assess relationships between concentrations of serum immunoglobulins and NAFLD.

RESULTS

Of the 11 261 adults recruited from January 2010 to December 2015, the prevalence of NAFLD was 40.8% (n = 4598). The geometric mean levels of IgG, IgM, IgE and IgA were 1177.49 mg/dL (95% confidence interval [CI] 1173.07-1181.93), 93.56 mg/dL (95% CI 92.70-94.42), 30.70 IU/mL (95% CI 29.92-31.49) and 216.64 mg/dL (95% CI 214.95-218.34), respectively. Compared with the lowest quintile, the multivariable adjusted odds ratio (95% CI) of NAFLD for the highest quintile of IgG, IgM, IgE, and IgA were 0.78 (0.66-0.92), 0.71 (0.60-0.84), 0.98 (0.84-1.15) and 1.41 (1.21-1.66), respectively.

CONCLUSION

Increased IgA and decreased IgG and IgM levels are independently associated with NAFLD prevalence. Further research is needed to explore the causal association between serum immunoglobulins and NAFLD.

miR-122 inhibition in a human liver organoid model leads to liver inflammation, necrosis, steatofibrosis and dysregulated insulin signaling

To investigate the role of miR-122 in the development and regression of non-alcoholic fatty liver disease (NAFLD) in vitro, we used multicellular 3D human liver organoids developed in our laboratory. These organoids consist of primary human hepatocytes, Kupffer cells, quiescent stellate cells and liver sinusoidal endothelial cells. They remain viable and functional for 4 weeks expressing typical markers of liver function such as synthesis of albumin, urea, and alpha-1 p450 drug metabolism. Before mixing, hepatic cells were transduced with lentivirus to inhibit miR122 expression (ABM, CA). Immediately after the organoids were fully formed (day 4) or after 1 or 2 weeks of additional incubation (days 11 or 18), the organoids were analyzed using fluorescent live/dead staining and ATP production; total RNA was extracted for qPCR gene expression profiling. Our results show that miR-122 inhibition in liver organoids leads to inflammation, necrosis, steatosis and fibrosis. This was associated with increase in inflammatory cytokines (IL6, TNF), chemokines (CCL2, CCL3) and increase in a subset of Matrix Metaloproteinases (MMP8, MMP9). An altered expression of key genes in lipid metabolism (i.e LPL, LDLR) and insulin signaling (i.e GLUT4, IRS1) was also identified. Conclusion: Our results highlight the role of miR-122 inhibition in liver inflammation, steatofibrosis and dysregulation of insulin signaling. Patients with NAFLD are known to have altered levels of miR-122, therefore we suggest that miR-122 mimics could play a useful role in reversing liver steatofibrosis and insulin resistance seen in patients with NAFLD.

Effects and mechanisms of caffeine to improve immunological and metabolic abnormalities in diet-induced obese rats

In obesity, there are no effective therapies for parallel immune and metabolic abnormalities, including systemic/tissue insulin-resistance/inflammation, adiposity and hepatic steatosis. Caffeine has anti-inflammation, antihepatic steatosis, and anti-insulin resistance effects. In this study, we evaluated the effects and molecular mechanisms of 6 wk of caffeine treatment (HFD-caf) on immunological and metabolic abnormalities of high-fat diet (HFD)-induced obese rats. Compared with HFD vehicle (HFD-V) rats, in HFD-caf rats the suppressed circulating immune cell inflammatory [TNFα, MCP-1, IL-6, intercellular adhesion molecule 1 (ICAM-1), and nitrite] profiles were accompanied by decreased liver, white adipose tissue (WAT), and muscle macrophages and their intracellular cytokine levels. Metabolically, the increase in metabolic rates reduced lipid accumulation in various tissues, resulting in reduced adiposity, lower fat mass, decreased body weight, amelioration of hepatic steatosis, and improved systemic/muscle insulin resistance. Further mechanistic approaches revealed an upregulation of tissue lipogenic [(SREBP1c, fatty acid synthase, acetyl-CoA carboxylase)/insulin-sensitizing (GLUT4 and p-IRS1)] markers in HFD-caf rats. Significantly, ex vivo experiments revealed that the cytokine release by the cocultured peripheral blood mononuclear cell (monocyte) and WAT (adipocyte), which are known to stimulate macrophage migration and hepatocyte lipogenesis, were lower in HFD-V groups than HFD-caf groups. Caffeine treatment simultaneously ameliorates immune and metabolic pathogenic signals present in tissue to normalize immunolgical and metabolic abnormalities found in HFD-induced obese rats.

Hepatocyte nuclear receptor SHP suppresses inflammation and fibrosis in a mouse model of nonalcoholic steatohepatitis

Nonalcoholic fatty liver disease (NAFLD) is a burgeoning health problem worldwide, ranging from nonalcoholic fatty liver (NAFL, steatosis without hepatocellular injury) to the more aggressive nonalcoholic steatohepatitis (NASH, steatosis with ballooning, inflammation, or fibrosis). Although many studies have greatly contributed to the elucidation of NAFLD pathogenesis, the disease progression from NAFL to NASH remains incompletely understood. Nuclear receptor small heterodimer partner (Nr0b2, SHP) is a transcriptional regulator critical for the regulation of bile acid, glucose, and lipid metabolism. Here, we show that SHP levels are decreased in the livers of patients with NASH and in diet-induced mouse NASH. Exposing primary mouse hepatocytes to palmitic acid and lipopolysaccharide in vitro, we demonstrated that the suppression of Shp expression in hepatocytes is due to c-Jun N-terminal kinase (JNK) activation, which stimulates c-Jun-mediated transcriptional repression of Shp Interestingly, in vivo induction of hepatocyte-specific SHP in steatotic mouse liver ameliorated NASH progression by attenuating liver inflammation and fibrosis, but not steatosis. Moreover, a key mechanism linking the anti-inflammatory role of hepatocyte-specific SHP expression to inflammation involved SHP-induced suppression of NF-κB p65-mediated induction of chemokine (C-C motif) ligand 2 (CCL2), which activates macrophage proinflammatory polarization and migration. In summary, our results indicate that a JNK/SHP/NF-κB/CCL2 regulatory network controls communications between hepatocytes and macrophages and contributes to the disease progression from NAFL to NASH. Our findings may benefit the development of new management or prevention strategies for NASH.

CC chemokine receptor 2 promotes recruitment of myeloid cells associated with insulin resistance in nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is a common disease, closely associated with obesity and insulin resistance. We investigated the presence of a subset of myeloid cells associated with metabolic disturbance in the liver of patients with NAFLD and a murine model of obesity-induced liver disease. Gene and protein expression in liver and serum was investigated with RT-PCR or ELISA and correlated to clinical disease. Liver-infiltrating immune cells were isolated from normal or diseased human liver for flow cytometric analysis. In animal experiments, mice were fed a high-fat diet (60% of calories from fat) for 16 wk, or high-fat diet with 30% fructose for 32 wk to induce steatohepatitis and fibrosis. A small molecule inhibitor of CC chemokine receptor 2 (CCR2), CCX872, was administered to some mice. A subset of CD11c⁺CD206⁺ immune cells was enriched in human liver tissue, and greater infiltration was observed in NAFLD. The presence of CD11c⁺CD206⁺ myeloid cells correlated with systemic insulin resistance. CD11c⁺CD206⁺ cells expressed high levels of CCR2, and liver CC chemokine ligand 2 (CCL2) expression was increased in nonalcoholic steatohepatitis and correlated with disease activity. In mice, CCR2 inhibition reduced infiltration of liver CD11b⁺CD11c⁺F4/80⁺ monocytes, which are functional homologs of human CD11c⁺CD206⁺ cells, and improved liver injury and glycemic control. A role for CCR2/CCL2 in human NAFLD has long been postulated. These data confirm a role for this chemokine/receptor axis, through mediating adipose and hepatic infiltration of myeloid cells. Inhibition of CCR2 improved hepatic inflammation and fibrosis in murine models of NAFLD. These data confirm the rationale for targeting CCR2 to treat NAFLD. NEW & NOTEWORTHY These data show for the first time that CD11c⁺CD206⁺ myeloid cells, previously associated with human adipose tissue inflammation, infiltrate into liver tissue in nonalcoholic fatty liver disease. These cells express CCR2. Inhibition of CCR2 in mice inhibits hepatic inflammation caused by a murine homolog of these myeloid cells and improves experimental liver disease.

Zinc regulates vascular endothelial cell activity through zinc-sensing receptor ZnR/GPR39

Zn2+ is an essential element for cell survival/growth, and its deficiency is linked to many disorders. Extracellular Zn2+ concentration changes participate in modulating fundamental cellular processes such as proliferation, secretion, ion transport, and cell signal transduction in a mechanism that is not well understood. Here, we hypothesize that the Zn2+-sensing receptor ZnR/G protein-coupled receptor 39 (GPR39), found in tissues where dynamic Zn2+ homeostasis takes place, enables extracellular Zn2+ to trigger intracellular signaling pathways regulating key cell functions in vascular cells. Thus, we investigated how extracellular Zn2+ regulates cell viability, proliferation, motility, angiogenesis, vascular tone, and inflammation through ZnR/GPR39 in endothelial cells. Knockdown of GPR39 through siRNA largely abolished Zn2+-triggered cellular activity changes, Ca2+ responses, as well as the downstream activation of Gαq-PLC pathways. Extracellular Zn2+ promoted vascular cell survival/growth through activation of cAMP and Akt as well as overexpressing of platelet-derived growth factor-α receptor and vascular endothelial growth factor A. It also enhanced cell adhesion and mobility, endothelial tubule formation, and cytoskeletal reorganization. Such effects from extracellular Zn2+ were not observed in GPR39-/- endothelial cells. Zn2+ also regulated inflammation-related key molecules such as heme oxygenase-1, selectin L, IL-10, and platelet endothelial cell adhesion molecule 1, as well as vascular tone-related prostaglandin I2 synthase and nitric oxide synthase-3. In sum, extracellular Zn2+ regulates endothelial cell activity in a ZnR/GPR39-dependent manner and through the downstream Gαq-PLC pathways. Thus, ZnR/GPR39 may be a therapeutic target for regulating endothelial activity.

Sex disparity in viral load, inflammation and liver damage in transgenic mice carrying full hepatitis B virus genome with the W4P mutation in the preS1 region

AIM

To study sex disparity in susceptibility to hepatocellular carcinoma (HCC), we created a transgenic mouse model that expressed the full hepatitis B virus (HBV) genome with the W4P mutation.

METHODS

Transgenic mice were generated by transferring the pHY92-1.1x-HBV-full genome plasmid (genotype A2) into C57Bl/6N mice. We compared serum levels of hepatitis B surface antigen (HBsAg), interleukin (IL)-6, and the liver enzymes alanine aminotransferase (ALT) and aspartate transaminase (AST), as well as liver histopathological features in male and female transgenic (W4P TG) mice and in nontransgenic littermates of 10 mo of age.

RESULTS

W4P TG males exhibited more pronounced hepatomegaly, significantly increased granule generation in liver tissue, elevated HBsAg expression in the liver and serum, and higher serum ALT and IL-6 levels compared to W4P TG females or littermate control groups.

CONCLUSION

Together, our data indicate that the W4P mutation in preS1 may contribute to sex disparity in susceptibility to HCC by causing increased HBV virion replication and enhanced IL-6-mediated inflammation in male individuals. Additionally, our transgenic mouse model that expresses full HBV genome with the W4P mutation in preS1 could be effectively used for the studies of the progression of liver diseases, including HCC.

Cenicriviroc for the treatment of non-alcoholic steatohepatitis and liver fibrosis

INTRODUCTION

Nonalcoholic fatty liver disease (NAFLD) has an increasing prevalence worldwide. At present, no specific pharmacotherapy is approved for NAFLD. Simple steatosis and nonalcoholic steatohepatitis (NASH) can progress to liver fibrosis that is associated with mortality in NAFLD. The recruitment of inflammatory monocytes and macrophages via chemokine receptor CCR2 as well as of lymphocytes and hepatic stellate cells via CCR5 promote the progression of NASH to fibrosis. Areas covered: I summarize preclinical and clinical data on the efficacy and safety of the dual CCR2/CCR5 inhibitor cenicriviroc (CVC, also TBR-652 or TAK-652) for the treatment of NASH and fibrosis. In animal models of liver diseases, CVC potently inhibits macrophage accumulation in the liver and ameliorates fibrosis. In a phase 2b clinical trial (CENTAUR) on 289 patients with NASH and fibrosis, CVC consistently demonstrated liver fibrosis improvement after 1 year of therapy and had an excellent safety profile, leading to the implementation of a phase 3 trial (AURORA). Expert opinion: Preclinical and clinical data support the development of CVC as a safe and potent antifibrotic agent. However, open questions around CVC are the durability of antifibrotic responses, divergent effects on NASH versus fibrosis, potential long-term concerns and the expected path to approval.

Reactive hyperemia index (RHI) and cognitive performance indexes are associated with histologic markers of liver disease in subjects with non-alcoholic fatty liver disease (NAFLD): a case control study

Background

No study evaluated vascular health markers in subjects with non-alcoholic fatty liver disease (NAFLD) through a combined analysis of reactive hyperemia peripheral arterial tonometry (RH-PAT) and arterial stiffness indexes.

Aim of the study

We aimed to assess whether NAFLD and its histological severity are associated with impairment of arterial stiffness and RH-PAT indexes in a mixed cohort of patients with biopsy-proven NAFLD.

Materials and methods

The Kleiner classification was used to grade NAFLD grade. Pulse wave velocity (PWV) and augmentation index (Aix) were used as markers of arterial stiffness, whereas endothelial function was assessed using reactive hyperemia index (RHI). The mini-mental state examination (MMSE) was administered to test cognitive performance.

Results

80 consecutive patients with biopsy-proven NAFLD and 83 controls without fatty liver disease. NAFLD subjects showed significantly lower mean RHI, higher mean arterial stiffness indexes and lower mean MMSE score. Multivariable analysis after correction for BMI, dyslipidaemia, hypertension, sex, diabetes, age and cardiovascular disease showed that BMI, diastolic blood pressure and RHI are significantly associated to NAFLD. Simple linear regression analysis showed among non-alcoholic steatohepatitis (NASH) subjects a significant negative relationship between ballooning grade and MMSE and a significant positive association between Kleiner steatosis grade and augmentation index.

Conclusions

Future research will be addressed to evaluate the relationship between inflammatory markers and arterial stiffness and endothelial function indexes in NAFLD subjects. These study will evaluate association between cardiovascular event incidence and arterial stiffness, endothelial and cognitive markers, and they will address the beneficial effects of cardiovascular drugs such as statins and ACE inhibitors on these surrogate markers in NAFLD subjects.

Lactoferrin attenuates high-fat diet-induced hepatic steatosis and lipid metabolic dysfunctions by suppressing hepatic lipogenesis and down-regulating inflammation in C57BL/6J mice

Lactoferrin was reported to exert modulatory effects on lipid metabolism, but the regulatory mechanisms remain unclear.

Dietary fat stimulates development of NAFLD more potently than dietary fructose in Sprague-Dawley rats

BACKGROUND

In humans and animal models, excessive intake of dietary fat, fructose and cholesterol has been linked to the development of non-alcoholic fatty liver disease (NAFLD). However, the individual roles of the dietary components remain unclear. To investigate this further, we compared the effects of a high-fat diet, a high-fructose diet and a combination diet with added cholesterol on the development of NAFLD in rats.

METHODS

Forty male Sprague-Dawley rats were randomized into four groups receiving either a control-diet (Control: 10% fat); a high-fat diet (HFD: 60% fat, 20% carbohydrate), a high-fructose diet [HFr: 10% fat, 70% carbohydrate (mainly fructose)] or a high-fat/high-fructose/high-cholesterol-diet (NASH: 40% fat, 40% carbohydrate (mainly fructose), 2% cholesterol) for 16 weeks.

RESULTS

After 16 weeks, liver histology revealed extensive steatosis and inflammation in both NASH- and HFD-fed rats, while hepatic changes in HFr-rats were much more subtle. These findings were corroborated by significantly elevated hepatic triglyceride content in both NASH- (p < 0.01) and HFD-fed rats (p < 0.0001), elevated hepatic cholesterol levels in NASH-fed rats (p < 0.0001), but no changes in HFr-fed rats, compared to Control. On the contrary, only HFr-fed rats developed dyslipidemia as characterized by higher levels of plasma triglycerides compared to all other groups (p < 0.0001). Hepatic dysfunction and inflammation was confirmed in HFD-fed rats by elevated levels of hepatic MCP-1 (p < 0.0001), TNF-alpha (p < 0.001) and plasma β-hydroxybutyrate (p < 0.0001), and in NASH-fed rats by elevated levels of hepatic MCP-1 (p < 0.01), increased hepatic macrophage infiltration (p < 0.001), and higher plasma levels of alanine aminotransferase (p < 0.0001) aspartate aminotransferase (p < 0.05), haptoglobin (p < 0.001) and TIMP-1 (p < 0.01) compared to Control.

CONCLUSION

These findings show that dietary fat and cholesterol are the primary drivers of NAFLD development and progression in rats, while fructose mostly exerts its effect on the circulating lipid pool.

Prostaglandin I2 suppresses the development of diet-induced nonalcoholic steatohepatitis in mice

Nonalcoholic steatohepatitis (NASH) is a hepatic manifestation of metabolic syndrome. Although the prostaglandin (PG)I₂ receptor IP is expressed broadly in the liver, the role of PGI₂-IP signaling in the development of NASH remains to be determined. Here, we investigated the role of the PGI₂-IP system in the development of steatohepatitis using mice lacking the PGI₂ receptor IP [IP-knockout (IP-KO) mice] and beraprost (BPS), a specific IP agonist. IP-KO and wild-type (WT) mice were fed a methionine- and choline-deficient diet (MCDD) for 2, 5, or 10 wk. BPS was administered orally to mice every day during the experimental periods. The effect of BPS on the expression of chemokine and inflammatory cytokines was examined also in cultured Kupffer cells. WT mice fed MCDD developed steatohepatitis at 10 wk. IP-KO mice developed steatohepatitis at 5 wk with augmented histologic derangements accompanied by increased hepatic monocyte chemoattractant protein-1 (MCP-1) and TNF-α concentrations. After 10 wk of MCDD, IP-KO mice had greater hepatic iron deposition with prominent oxidative stress, resulting in hepatocyte damage. In WT mice, BPS improved histologic and biochemical parameters of steatohepatitis, accompanied by reduced hepatic concentration of MCP-1 and TNF-α. Accordingly, BPS suppressed the LPS-stimulated Mcp-1 and Tnf-α mRNA expression in cultured Kupffer cells prepared from WT mice. PGI₂-IP signaling plays a crucial role in the development and progression of steatohepatitis by modulating the inflammatory response, leading to augmented oxidative stress. We suggest that the PGI₂-IP system is an attractive therapeutic target for treating patients with NASH.-Kumei, S., Yuhki, K.-I., Kojima, F., Kashiwagi, H., Imamichi, Y., Okumura, T., Narumiya, S., Ushikubi, F. Prostaglandin I₂ suppresses the development of diet-induced nonalcoholic steatohepatitis in mice.

Hepatic recruitment of CD11b+Ly6C+ inflammatory monocytes promotes hepatic ischemia/reperfusion injury

Monocytes infiltrate damaged liver tissue during noninfectious liver injury and often have dual roles, perpetuating inflammation and promoting resolution of inflammation and fibrosis. However, how monocyte subsets distribute and are differentially recruited in the liver remain unclear. In the current study, the subpopulations of infiltrating monocytes were examined following liver ischemia/reperfusion (I/R) injury in mice using flow cytometry. CD11b⁺Ly6C high (Ly6C^hi) cells (inflammatory monocytes) and CD11b⁺Ly6C low cells (reparative monocytes) were recruited into the liver following I/R injury. Treatment with clodronate-loaded liposomes, which transiently deplete systemic macrophages, alleviated hepatic damage. Mice genetically deficient in C-C motif chemokine ligand 2 (CCL2), or its receptor C-C chemokine receptor 2 (CCR2), exhibited diminished hepatic damage compared with wild-type mice following I/R, by controlling intrahepatic inflammatory Ly6C^hi monocyte accumulation. In addition, the CCR2 specific inhibitor RS504393 alleviated hepatic I/R injury. The results suggest that the CCR2/ CCL2 axis an important role in monocyte infiltration and may represent a novel target for the treatment of liver I/R injury.

Transcriptomics, metabolomics and histology indicate that high-carbohydrate diet negatively affects the liver health of blunt snout bream (Megalobrama amblycephala)

Background

Global trend of the introduction of high levels of relatively cheap carbohydrates to reduce the amount of costly protein in the aquatic animal feed production has affected the aquaculture of an economically important cyprinid fish, blunt snout bream (Megalobrama amblycephala). This dietary shift has resulted in increased prevalence of metabolic disorders, often causing economic losses. High dietary intake of carbohydrates, associated with obesity, is one of the major causes of non-alcoholic fatty liver disease (NAFLD) in humans.

Results

We have conducted an eight-week feeding trial to better understand how a high-carbohydrate diet (HCBD) affects the liver health in this fish. Hepatosomatic index and lipid content were significantly (P < 0.05) higher in the HCBD group. Histology results also suggested pathological changes in the livers of HCBD group, with excessive lipid accumulation and indication of liver damage. Metabolomics and serum biochemistry analyses showed that a number of metabolites indicative of liver damage were increased in the HCBD group. This group also exhibited low levels of betaine, which is a metabolite crucial for maintaining the healthy liver functions. Transcriptomic and qPCR analyses indicated that HCBD had a strong impact on the expression of a large number of genes associated with the NAFLD and insulin signalling pathways, which may lead to the development of insulin resistance in hepatocytes, pathological liver changes, and eventually the NAFLD.

Conclusions

Transcriptomics, metabolomics and histology results all indicate early symptoms of liver damage. However whether these would actually lead to the development of NAFLD after a longer period of time, remains inconclusive. Additionally, a very high number of upregulated genes in the HCBD group associated with several neurodegenerative diseases is a strong indication of neurodegenerative changes caused by the high-carbohydrate diet in blunt snout bream. This suggests that fish might present a good model to study neurodegenerative changes associated with high-carbohydrate diet in humans.

Electronic supplementary material

The online version of this article (10.1186/s12864-017-4246-9) contains supplementary material, which is available to authorized users.

Nonalcoholic Fatty Liver Disease Is Exacerbated in High-Fat Diet-Fed Gnotobiotic Mice by Colonization with the Gut Microbiota from Patients with Nonalcoholic Steatohepatitis

Nonalcoholic fatty liver disease (NAFLD) is a serious liver disorder associated with the accumulation of fat and inflammation. The objective of this study was to determine the gut microbiota composition that might influence the progression of NAFLD. Germ-free mice were inoculated with feces from patients with nonalcoholic steatohepatitis (NASH) or from healthy persons (HL) and then fed a standard diet (STD) or high-fat diet (HFD). We found that the epididymal fat weight, hepatic steatosis, multifocal necrosis, and inflammatory cell infiltration significantly increased in the NASH-HFD group. These findings were consistent with markedly elevated serum levels of alanine transaminase, aspartate transaminase, endotoxin, interleukin 6 (IL-6), monocyte chemotactic protein 1 (Mcp1), and hepatic triglycerides. In addition, the mRNA expression levels of Toll-like receptor 2 (Tlr2), Toll-like receptor 4 (Tlr4), tumor necrosis factor alpha (Tnf-α), Mcp1, and peroxisome proliferator-activated receptor gamma (Ppar-γ) significantly increased. Only abundant lipid accumulation and a few inflammatory reactions were observed in group HL-HFD. Relative abundance of Bacteroidetes and Firmicutes shifted in the HFD-fed mice. Furthermore, the relative abundance of Streptococcaceae was the highest in group NASH-HFD. Nevertheless, obesity-related Lactobacillaceae were significantly upregulated in HL-HFD mice. Our results revealed that the gut microbiota from NASH Patients aggravated hepatic steatosis and inflammation. These findings might partially explain the NAFLD progress distinctly was related to different compositions of gut microbiota.

Nonalcoholic fatty liver disease and the risk of clinical cardiovascular events: A systematic review and meta-analysis

OBJECTIVE

Numerous studies have assessed the association between Nonalcoholic fatty liver disease (NAFLD) and cardiovascular disease (CVD). However, results have been conflicting due to variability in definitions of NAFLD and ascertainment of CVD, often combining clinical and surrogate endpoints. We therefore systematically reviewed published literature to assess the association between NAFLD and clinical cardiovascular events (CVE) and performed a meta-analysis.

METHODS

We searched PubMed, Medline, Cochrane, CINAHL, and Web of Science databases using terms "nonalcoholic fatty liver disease", "nonalcoholic steatohepatitis", "cardiovascular disease", and their combinations to identify prospective studies published from inception through March 2016. Data from selected studies was extracted and meta-analysis was then performed using random effects model.

RESULTS

A total of six studies with 25,837 patients (NAFLD: 5953; controls: 19,884) were included in the final analysis. Patients with NAFLD had a significantly higher risk of clinical CVE compared to controls (RR: 1.77; 95% CI: 1.26-2.48, p<0.001). Exclusion sensitivity analysis did not alter the above results. The association remained consistent for subgroups with clinical coronary artery disease (RR: 2.26; 95% CI: 1.04-4.92, p<0.001) and ischemic stroke (RR: 2.09; 95% CI: 1.46-2.98, p<0.001). The risk of cardiovascular mortality was also increased in the NAFLD group (RR 1.46, 95% CI 1.31-1.64, p<0.001).

CONCLUSION

NAFLD patients have a significantly higher risk for clinical CVE compared to those without. These results need to be confirmed in large prospective studies.

Hepatic steatosis progresses faster in HIV mono-infected than HIV/HCV co-infected patients and is associated with liver fibrosis

BACKGROUND & AIMS

Hepatic steatosis (HS) seems common in patients infected with human immunodeficiency virus (HIV). However, the relative effect of HIV, as well as hepatitis C virus (HCV) in those co-infected, and the influence of HS on liver fibrosis progression are unclear.

METHODS

The LIVEr disease in HIV (LIVEHIV) is a Canadian prospective cohort study using transient elastography and associated controlled attenuation parameter (CAP) to screen for HS and liver fibrosis, in unselected HIV-infected adults. HS progression was defined as development of any grade HS (CAP ⩾248dB/m), or transition to severe HS (CAP >292dB/m), for those with any grade HS at baseline. Fibrosis progression was defined as development of significant liver fibrosis (liver stiffness measurement [LSM] >7.1kPa), or transition to cirrhosis (LSM >12.5kPa) for those with significant liver fibrosis at baseline. Cox regression analysis was used to assess predictors of HS and fibrosis progression.

RESULTS

A prospective cohort study was conducted, which included 726 HIV-infected patients (22.7% HCV co-infected). Prevalence of any grade HS did not differ between HIV mono-infected and HIV/HCV co-infected patients (36.1% vs. 38.6%, respectively). 313 patients were followed for a median of 15.4 (interquartile range 8.5-23.0) months. The rate of HS progression was 37.8 (95% confidence interval [CI] 29.2-49.0) and 21.9 (95% CI 15.6-30.7) per 100 person-years in HIV mono-infection and HIV/HCV co-infection, respectively. HCV co-infection was an independent negative predictor of HS progression (adjusted hazard ratio [aHR] 0.50, 95% CI 0.28-0.89). HS predicted liver fibrosis progression in HIV mono-infection (aHR 4.18, 95% CI 1.21-14.5), but not in HIV/HCV co-infection.

CONCLUSION

HS progresses faster and is associated with liver fibrosis progression in HIV mono-infection but not in HIV/HCV co-infection. Lay summary: Fatty liver is the most frequent liver disease in Western countries. People living with HIV seem at high risk of fatty liver due to frequent metabolic disorders and the long-term effects of antiretroviral therapy. However, due to the invasiveness of liver biopsy, the traditional method of diagnosing fatty liver, there are few data regarding its frequency in people living with HIV. In this study, we used a non-invasive diagnostic tool to analyze the epidemiology of fatty liver in 726 HIV+ patients. We found that fatty liver affects over one-third of people living with HIV. When followed over time, we found that HIV+ patients without HCV co-infection develop fatty liver more frequently than those co-infected with HCV.

Effects of Oral Administration of Silymarin in a Juvenile Murine Model of Non-alcoholic Steatohepatitis

The increasing prevalence of non-alcoholic fatty liver disease (NAFLD) in adolescents is challenging the global care system. No therapeutic strategies have been defined so far, and changes in the lifestyle remain the only alternative. In this study, we assessed the protective effects of silymarin in a juvenile non-alcoholic steatohepatitis (NASH) model and the in vitro effects on fat-laden human hepatocytes. C57Bl/6 mice were exposed to HFHC diet immediately after weaning. After eight weeks, animals showed histological signs of NASH. Silymarin was added to the HFHC diet, the treatment continued for additional 12 weeks and the effects on BMI, hepatomegaly, visceral fat, lipid profile, transaminases, HOMA-IR, steatosis, inflammation, fibrosis, oxidative stress, and apoptosis were determined. The switch from HFHC to control diet was used to mimic life style changes. In vitro experiments were performed in parallel in human hepatocytes. HFHC diet supplemented with silymarin showed a significant improvement in glycemia, visceral fat, lipid profile, and liver fibrosis. Moreover, it reduced (both in vitro and in vivo) ALT, hepatic inflammation, oxidative stress, and apoptosis. Lifestyle changes restored the control group parameters. The data presented show the beneficial effects of the oral administration of silymarin in the absence of changes in the dietary habits in a juvenile model of NASH.

CD44 is a key player in non-alcoholic steatohepatitis

BACKGROUND & AIMS

Cluster of differentiation (CD)44 regulates adipose tissue inflammation in obesity and hepatic leukocyte recruitment in a lithogenic context. However, its role in hepatic inflammation in a mouse model of steatohepatitis and its relevance in humans have not yet been investigated. We aimed to evaluated the contribution of CD44 to non-alcoholic steatohepatitis (NASH) development and liver injury in mouse models and in patients at various stages of non-alcoholic fatty liver disease (NAFLD) progression.

METHODS

The role of CD44 was evaluated in CD44^-/- mice and after injections of an αCD44 antibody in wild-type mice challenged with a methionine- and choline-deficient diet (MCDD). In obese patients, hepatic CD44 (n=30 and 5 NASH patients with a second liver biopsy after bariatric surgery) and serum sCD44 (n=64) were evaluated.

RESULTS

Liver inflammation (including inflammatory foci number, macrophage and neutrophil infiltration and CCL2/CCR2 levels), liver injury and fibrosis strongly decreased in CD44^-/- mice compared to wild-type mice on MCDD. CD44 deficiency enhanced the M2 polarization and strongly decreased the activation of macrophages by lipopolysaccharide (LPS), hepatocyte damage-associated molecular patterns (DAMPs) and saturated fatty acids. Neutralization of CD44 in mice with steatohepatitis strongly decreased the macrophage infiltration and chemokine ligand (CCL)2 expression with a partial correction of liver inflammation and injury. In obese patients, hepatic CD44 was strongly upregulated in NASH patients (p=0.0008) and correlated with NAFLD activity score (NAS) (p=0.001), ballooning (p=0.003), alanine transaminase (p=0.005) and hepatic CCL2 (p<0.001) and macrophage marker CD68 (p<0.001) expression. Correction of NASH was associated with a strong decrease in liver CD44⁺ cells. Finally, the soluble form of CD44 increased with severe steatosis (p=0.0005) and NASH (p=0.007).

CONCLUSION

Human and experimental data suggest that CD44 is a marker and key player of hepatic inflammation and its targeting partially corrects NASH.

LAY SUMMARY

Human and experimental data suggest that CD44, a cellular protein mainly expressed in immune cells, is a marker and key player of non-alcoholic steatohepatitis (NASH). Indeed, CD44 enhances the non-alcoholic fatty liver (NAFL) (hepatic steatosis) to NASH progression by regulating hepatic macrophage polarization (pro-inflammatory phenotype) and infiltration (macrophage motility and the MCP1/CCL2/CCR2 system). Targeting CD44 partially corrects NASH, making it a potential therapeutic strategy.