Salsalate and adiponectin ameliorate hepatic steatosis by inhibition of the hepatokine fetuin-A

Effect of Intracerebroventricular Administration of Galanin-Like Peptide on Hepatokines in C57BL/6 J Mice

Galanin-like peptide (GALP) is a neuropeptide that was first isolated and identified from the porcine hypothalamus. Studies have described an anti-obesity effect of GALP. We previously found that intracerebroventricular administration of GALP in mice resulted in an increase in respiratory exchange rate 12 to 16 h later. GALP may also affect glucose metabolism, but the detailed mechanism has not been elucidated. In this study, we investigated the effects of GALP on glucose and lipid metabolism in the liver. Nine-week-old male C57BL / 6 J mice were administered a single intracerebroventricular dose of saline or GALP and dissected 16 h later. There were no significant between-group differences in body weight and blood glucose levels. With regard to gene and protein expression, G6Pase associated with hepatic gluconeogenesis was significantly reduced in the GALP group. In addition, the hepatokines selenoprotein P and fetuin-A, which induce insulin resistance in the liver, were significantly decreased in the GALP group. These results suggest that intracerebroventricular administration of GALP decreases the expression of key hepatokines, thereby enhancing glucose metabolism.

Insights into Prospects of Novel NSAID Prodrugs in the Management of Gastrointestinal Toxicity: A Perspective Review

Non-steroidal anti-inflammatory drugs (NSAIDs) have a long history in the healthcare system due to their therapeutic potential. These NSAIDs cause ulcerogenicity, stomach pains, gastrointestinal hemorrhage, mucosa bleeding, and pancreatitis when used moderately and consistently. With researchers, managing the aforementioned adverse effects therapeutically is getting increasingly difficult. One method for creating NSAID moieties with low penetration as well as ulcerogenic properties is the prodrug technique. During the oral consumption of NSAID-prodrugs, ulcerations, intestinal hemorrhage, and mucosa hemorrhage have significantly decreased. Considering this background, this review focussed on NSAID prodrugs as well as their justifications, the pathogenesis of NSAIDs inducing gastrointestinal toxicity, and the role of different antioxidants and spacer groups. Prodrug moieties have more advantages over parent medicines concerning both solubility and lipophilicity. In general, NSAID-class prodrugs can successfully treat both acute and long-term inflammation and aches without causing ulcerotoxicity and related gastrointestinal side effects, which reduces their burden from the pharmacoeconomic perspective.

Which Comes First, Nonalcoholic Fatty Liver Disease or Arterial Hypertension?

Non-alcoholic fatty liver disease (NAFLD) and arterial hypertension (AH) are widespread noncommunicable diseases in the global population. Since hypertension and NAFLD are diseases associated with metabolic syndrome, they are often comorbid. In fact, many contemporary published studies confirm the association of these diseases with each other, regardless of whether other metabolic factors, such as obesity, dyslipidemia, and type 2 diabetes mellites, are present. This narrative review considers the features of the association between NAFLD and AH, as well as possible pathophysiological mechanisms.

Porcine reproductive and respiratory syndrome virus regulates lipid droplet accumulation in lipid metabolic pathways to promote viral replication

Porcine reproductive and respiratory syndrome (PRRS) is a severe respiratory disease caused by porcine reproductive and respiratory syndrome virus (PRRSV) that can lead to the abortion of pregnant sows and decreased boar semen quality. However, the mechanisms of PRRSV replication in the host have not yet been fully elucidated. As lipid metabolism and lipid droplets (LDs) have been reported to play important roles in the replication of various viruses, we aimed to explore the mechanisms through which LDs affect PRRSV replication. Laser confocal and transmission electron microscopy revealed that PRRSV infection promoted intracellular LD accumulation, which was significantly reduced by treatment with the NF-κB signaling pathway inhibitors BAY11-7082 and metformin hydrochloride (MH). In addition, treatment with a DGAT1 inhibitor significantly reduced the protein expression of Phosphorylated NF-ΚB P65and PIκB and the transcription of IL-1β and IL-8 in the NF-κB signaling pathway. Furthermore, we showed that the reduction of the NF-κB signaling pathway and LDs significantly reduced PRRSV replication. Together, the findings of this study suggest a novel mechanism through which PRRSV regulates the NF-κB signaling pathway to increase LD accumulation and promote viral replication. Moreover, we demonstrated that both BAY11-7082 and MH can reduce PRRSV replication by reducing the NF-κB signaling pathway and LD accumulation. This study lays a theoretical foundation for research on the mechanism of PRRS prevention and control, as well as the research and development of antiviral drugs.

Proteomic profiling of protein expression changes after 3 months-exercise in ESRD patients on hemodialysis

The prevalence of chronic kidney disease (CKD) is steadily increasing, and it is a global health burden. Exercise has been suggested to improve physical activity and the quality of life in patients with CKD, eventually reducing mortality. This study investigated the change in physical performance after exercise in dialysis-dependent patients with CKD and analyzed differentially expressed proteins before and after the exercise. Plasma samples were collected at enrollment and after 3 months of exercise. Liquid chromatography with tandem mass spectrometry analysis and data-independent acquisition results were analyzed to determine the significantly regulated proteins. A total of 37 patients on dialysis were recruited, and 16 were randomized to exercise for 3 months. The hand grip strength and the walking speed significantly improved in the exercise group. Proteome analysis revealed 60 significantly expressed proteins after 3 months of exercise. In the protein functional analysis, the significantly expressed proteins were involved in the immune response. Also, some of the key significantly expressed proteins [(M Matrix metallopeptidase 9 (MMP-9), Activin A Receptor Type 1B (ACVR1B), Fetuin B (FETUB)] were validated via an enzyme-linked immunosorbent assay. Our results showed that exercise in dialysis-dependent patients with CKD could improve their physical performance. These results indicated that this beneficial effect of exercise in these populations could be associated with immune response.

Adenosine monophosphate activated protein kinase contributes to skeletal muscle health through the control of mitochondrial function

Skeletal muscle is one of the largest organs in the body and the largest protein repository. Mitochondria are the main energy-producing organelles in cells and play an important role in skeletal muscle health and function. They participate in several biological processes related to skeletal muscle metabolism, growth, and regeneration. Adenosine monophosphate-activated protein kinase (AMPK) is a metabolic sensor and regulator of systemic energy balance. AMPK is involved in the control of energy metabolism by regulating many downstream targets. In this review, we propose that AMPK directly controls several facets of mitochondrial function, which in turn controls skeletal muscle metabolism and health. This review is divided into four parts. First, we summarize the properties of AMPK signal transduction and its upstream activators. Second, we discuss the role of mitochondria in myogenesis, muscle atrophy, regeneration post-injury of skeletal muscle cells. Third, we elaborate the effects of AMPK on mitochondrial biogenesis, fusion, fission and mitochondrial autophagy, and discuss how AMPK regulates the metabolism of skeletal muscle by regulating mitochondrial function. Finally, we discuss the effects of AMPK activators on muscle disease status. This review thus represents a foundation for understanding this biological process of mitochondrial dynamics regulated by AMPK in the metabolism of skeletal muscle. A better understanding of the role of AMPK on mitochondrial dynamic is essential to improve mitochondrial function, and hence promote skeletal muscle health and function.

AMP activated kinase negatively regulates hepatic Fetuin-A via p38 MAPK-C/EBPβ/E3 Ubiquitin Ligase Signaling pathway

Fetuin-A (Fet-A) is a liver-secreted phosphorylated protein, known to impair insulin signaling, which has been shown to be associated with obesity, insulin resistance, and incident diabetes. Fet-A interacts with the insulin-stimulated insulin receptor (IR) and inhibits IR tyrosine kinase activity and glucose uptake. It has been shown that high glucose increases Fet-A expression through the ERK1/2 signaling pathway. However, factors that downregulate Fet-A expression and their potential mechanisms are unclear. We examined the effect of AMP-activated protein kinase (AMPK) on high-glucose induced Fet-A expression in HepG2 cells, Hep3B cells and primary rat hepatocytes. High glucose increased Fet-A and phosphorylated (Ser312) fetuin-A (pFet-A) expression, which are known to impair insulin signaling. AICAR-induced AMPK activation significantly down-regulated high glucose-induced Fet-A expression and secretion of pFet-A while treatment with Compound C (AMPK inhibitor), SB202190 (p38 MAPK inhibitor) or p38 MAPK siRNA transfection prevented AICAR-induced downregulation of Fet-A expression. In addition, activation of p38 MAPK, by anisomycin, decreased the hepatic expression of Fet-A. Further, we our studies have shown that short-term effect of AICAR-treatment on Fet-A expression was mediated by proteosomal degradation, and long-term treatment of AICAR was associated with decrease in hepatic expression of C/EBP beta, an important transcription factor involved in the regulation of Fet-A. Taken together, our studies implicate a critical role for AMPK-p38 MAPK-C/EBPb-ubiquitin-proteosomal axis in the regulation of the expression of hepatic Fet-A.

Role of Fetuin-A in the Pathogenesis of Psoriasis and Its Potential Clinical Applications

Fetuin-A is a plasma glycoprotein exhibiting multifaceted physiological and pathological functions. It has been determined to be involved in various essential biological functions, such as regulation of calcium metabolism, osteogenesis, and insulin signaling pathway. It also plays a crucial role in the pathogenesis of several disorders, including psoriasis. Psoriasis is a chronic systemic inflammatory disorder caused by a constellation of environmental, immunogenic, and genetic factors. It has been shown that dysregulation of cytokines mediated immune response is responsible for the development of psoriasis. Several recent publications suggest that dysregulation of fetuin-A correlates with psoriasis disease activities, revealing its putative role in the development of psoriasis. Furthermore, clinical application of fetuin-A as a diagnostic marker, prognostic predictor, and therapeutic target for different clinical conditions is in progress, and some are showing promising outcomes. This review primarily focuses on the current understanding of the role of fetuin-A in the pathogenesis of psoriasis and its potential clinical applications, with a brief highlight of psoriasis epidemiology and burden. The information was gathered systematically from various journals via electronic searches using various search engines: PubMed, Google Scholar, HINARI, and Cochrane Library from inception to 2022. The studies involved were restricted to English language. Conversely, articles written in other languages, studies done on fetuin B, or studies conducted on other dermatological diseases were excluded from the review article.

Hepatic PTEN Signaling Regulates Systemic Metabolic Homeostasis through Hepatokines-Mediated Liver-to-Peripheral Organs Crosstalk

Liver-derived circulating factors deeply affect the metabolism of distal organs. Herein, we took advantage of the hepatocyte-specific PTEN knockout mice (LPTENKO), a model of hepatic steatosis associated with increased muscle insulin sensitivity and decreased adiposity, to identify potential secreted hepatic factors improving metabolic homeostasis. Our results indicated that protein factors, rather than specific metabolites, released by PTEN-deficient hepatocytes trigger an improved muscle insulin sensitivity and a decreased adiposity in LPTENKO. In this regard, a proteomic analysis of conditioned media from PTEN-deficient primary hepatocytes identified seven hepatokines whose expression/secretion was deregulated. Distinct expression patterns of these hepatokines were observed in hepatic tissues from human/mouse with NAFLD. The expression of specific factors was regulated by the PTEN/PI3K, PPAR or AMPK signaling pathways and/or modulated by classical antidiabetic drugs. Finally, loss-of-function studies identified FGF21 and the triad AHSG, ANGPTL4 and LECT2 as key regulators of insulin sensitivity in muscle cells and in adipocytes biogenesis, respectively. These data indicate that hepatic PTEN deficiency and steatosis alter the expression/secretion of hepatokines regulating insulin sensitivity in muscles and the lipid metabolism in adipose tissue. These hepatokines could represent potential therapeutic targets to treat obesity and insulin resistance.

Fetuin-A to adiponectin ratio is an independent indicator of subclinical atherosclerosis in patients with newly diagnosed type 2 diabetes mellitus

AIMS

The purpose of this research was to explore the associations of fetuin-A, adiponectin, and fetuin-A/adiponectin ratio (F/A ratio) with subclinical atherosclerosis as evaluated by carotid intima-media thickness (CIMT) in cases with newly diagnosed type 2 diabetes mellitus (T2DM).

METHODS

A total of 283 newly diagnosed T2DM patients were enrolled in this study. Serum fetuin-A and adiponectin levels were determined with an ELISA method. Other clinical and biochemical parameters were also collected.

RESULTS

Significant linear increases in waist-to-hip ratio (WHR), systolic blood pressure (SBP), diastolic blood pressure, homoeostasis model assessment of insulin resistance, C-reactive protein (CRP) and F/A ratio, and a significant linear decrease in adiponectin with increasing tertiles of CIMT were observed (P for trends <0.05). However, no significant correlation between fetuin-A and CIMT was detected (P > 0.05). In multivariate logistic regression models, WHR, SBP and F/A ratio were independently correlated with higher CIMT. Receiver operating characteristic curve analysis indicated that F/A ratio had a better predictive power for higher CIMT than adiponectin and fetuin-A, with an area under the curve of 0.802, 0.713 and 0.646, respectively.

CONCLUSION

F/A ratio is an independent indicator of subclinical atherosclerosis in patients with newly diagnosed T2DM.

Hepatokines and Non-Alcoholic Fatty Liver Disease: Linking Liver Pathophysiology to Metabolism

The liver plays a key role in maintaining energy homeostasis by sensing and responding to changes in nutrient status under various metabolic conditions. Recently highlighted as a major endocrine organ, the contribution of the liver to systemic glucose and lipid metabolism is primarily attributed to signaling crosstalk between multiple organs via hepatic hormones, cytokines, and hepatokines. Hepatokines are hormone-like proteins secreted by hepatocytes, and a number of these have been associated with extra-hepatic metabolic regulation. Mounting evidence has revealed that the secretory profiles of hepatokines are significantly altered in non-alcoholic fatty liver disease (NAFLD), the most common hepatic manifestation, which frequently precedes other metabolic disorders, including insulin resistance and type 2 diabetes. Therefore, deciphering the mechanism of hepatokine-mediated inter-organ communication is essential for understanding the complex metabolic network between tissues, as well as for the identification of novel diagnostic and/or therapeutic targets in metabolic disease. In this review, we describe the hepatokine-driven inter-organ crosstalk in the context of liver pathophysiology, with a particular focus on NAFLD progression. Moreover, we summarize key hepatokines and their molecular mechanisms of metabolic control in non-hepatic tissues, discussing their potential as novel biomarkers and therapeutic targets in the treatment of metabolic diseases.

Patchouli alcohol ameliorates skeletal muscle insulin resistance and NAFLD via AMPK/SIRT1-mediated suppression of inflammation

Obesity-induced chronic low-grade inflammation and thus causes various metabolic diseases, such as insulin resistance and non-alcoholic fatty liver disease (NAFLD). Patchouli alcohol (PA), an active component extracted from patchouli, displayed anti-inflammatory effects on different cell types. However, the impact of PA on skeletal muscle insulin signaling and hepatic lipid metabolism remains unclear. This study aimed to investigate whether PA would affect insulin signaling impairment in myocytes and lipid metabolism in hepatocytes. Treatment with PA ameliorated palmitate-induced inflammation and aggravation of insulin signaling in C2C12 myocytes and lipid accumulation in HepG2 hepatocytes. Treatment of C2C12 myocytes and HepG2 cells with PA augmented AMP-activated protein kinase (AMPK) phosphorylation and Sirtuin 1 (SIRT1) expression in a dose-dependent manner. siRNA-mediated suppression of AMPK or SIRT1 mitigated the effects of PA on palmitate-induced inflammation and insulin resistance in C2C12 myocytes and lipid accumulation in HepG2 cells. Animal experiments demonstrated that PA administration increased AMPK phosphorylation and SIRT1 expression, and ameliorated inflammation, thereby attenuating skeletal muscle insulin resistance and hepatic steatosis in high-fat diet-fed mice. These results denote that PA alleviates skeletal muscle insulin resistance and hepatic steatosis through AMPK/SIRT1-dependent signaling. This study might provide a novel therapeutic approach for treating obesity-related insulin resistance and NAFLD.

Molecular mechanism of DLBS3733, a bioactive fraction of Lagerstroemia speciosa (L.) Pers., on ameliorating hepatic lipid accumulation in HepG2 cells

ETHNOPHARMACOLOGICAL RELEVANCE

Lagerstroemia speciosa (L.) Pers., commonly known as banaba and locally known as bungur, is widely used in Indonesia and other countries as a folk remedy for various chronic diseases such as diabetes mellitus and hypertension. L. speciosa (L.) Pers. has been used and evaluated on conditions associated to liver diseases by altering cholesterol absorption, lipid metabolism, as well as the related gene expressions.

AIM OF THE STUDY

The aim of this study is to evaluate the effect of DLBS3733, a standardized bioactive fraction of Lagerstroemia speciosa (L.) Pers. leaves, on ameliorating hepatic steatosis induced by oleic acid, and elucidate its mechanism of action to ameliorate lipid accumulation in HepG2 cells.

MATERIALS AND METHODS

Effects of DLBS3733 on expression of genes and proteins associated with lipid metabolism were evaluated in HepG2 cells in this study. Genes associated with lipid metabolism were evaluated using PCR, while the protein levels were revealed using western blot and ELISA. Cellular lipid accumulations and triglyceride (TG) synthesis were measured using ELISA, and antioxidant assay was conducted using DPPH assay.

RESULTS

DLBS3733 significantly reduced lipid accumulation and TG synthesis by 51% and 32% (p < 0.01), respectively, through the significant increment of adiponectin expression by 58% (p < 0.01). Subsequently, adiponectin enhanced PPARα expression and AMPK phosphorylation which further regulate the downstream signaling pathway of lipogenesis and lipolysis. Moreover, 2.5 µg/mL DLBS3733 was found to significantly downregulate the expression of HMGCR, ACC and SREBP by 66%, 61% and 36%, respectively (p < 0.01), as well as significantly upregulate CPT-1 by 300% at the protein level (P < 0.05). DLBS3733 was also found to possess high antioxidant activity, where the highest concentration exhibited DPPH inhibition activity by up to 93% (P < 0.01).

CONCLUSIONS

We propose that DLBS3733 may provide a prevention on hepatic steatosis through its activity as anti-lipogenesis, anti-cholesterologenesis and pro-lipolysis in HepG2 cells. This is the first report that revealed the molecular mechanism of L. speciosa (L.) Pers. as a potential treatment of hepatic steatosis-related diseases.

Links between metabolic syndrome and metabolic dysfunction-associated fatty liver disease

Metabolic dysfunction-associated fatty liver disease (MAFLD) is a chronic condition characterized by hepatic fat accumulation combined with underlying metabolic dysregulation. Having evolved from the previous term of nonalcoholic fatty liver disease (NAFLD), the term MAFLD more closely implicates the presence of overweight/obesity, type 2 diabetes, or metabolic dysregulation as essential pathogenic factors, leading to better identification of individuals with this metabolic liver disease. Low-grade inflammation, increased oxidative stress, mitochondrial dysfunction, and intestinal dysbiosis are also involved in its pathogenesis. MAFLD is not only associated with liver-related complications, but also with adverse cardiometabolic outcomes. Further studies are needed to assess whether the newly proposed definition of MAFLD is more accurate than the NAFLD in predicting the adverse liver-related and extrahepatic outcomes.

Liver inflammation at the time of spinal cord injury enhances intraspinal pathology, liver injury, metabolic syndrome and locomotor deficits

The current high obesity rates mean that neurological injuries are increasingly sustained on a background of systemic pathology, including liver inflammation, which likely has a negative impact on outcomes. Because obesity involves complex pathology, the effect of hepatic inflammation alone on neurological recovery is unknown. Thus, here we used a gain-of-function model to test if liver inflammation worsens outcome from spinal cord injury (SCI) in rats. Results show liver inflammation concomitant with SCI exacerbated intraspinal pathology and impaired locomotor recovery. Hepatic inflammation also potentiated SCI-induced non-alcoholic steatohepatitis (NASH), endotoxemia and insulin resistance. Circulating and cerebrospinal levels of the liver-derived protein Fetuin-A were higher in SCI rats with liver inflammation, and, when microinjected into intact spinal cords, Fetuin-A caused macrophage activation and neuron loss. Thus, liver inflammation functions as a disease modifying factor to impair recovery from SCI, and Fetuin-A is a potential neuropathological mediator. Since SCI alone induces acute liver inflammation, the liver may be a novel clinical target for improving recovery from SCI.

Positive Correlation between Circulating Fetuin-A and Severity of Coronary Artery Disease in Men

OBJECTIVE

Fetuin-A serves a dual function; its high levels are associated with metabolic syndrome, type 2 diabetes, obesity, insulin resistance, and nonalcoholic fatty liver disease, and on the other hand, it serves as a potent inhibitor of ectopic vascular calcification. Due to the opposing findings, the aim of the current study was to investigate serum fetuin-A levels in men with coronary artery disease (CAD).

METHODS

In the case-control study, anthropometric and biochemical parameters were determined in 83 men (43 CAD patients and 40 control subjects). At last, the serum fetuin-A levels were measured using the fetuin-A human enzyme-linked immunosorbent assay (ELISA) kit.

RESULTS

A significant difference was detected among the two groups for triglyceride and cholesterol levels (P=0.003 and P=0.002, respectively). The mean fetuin-A levels were determined 230.57 ± 63.76 and 286.35 ± 64.07 μg/ml for the control group and the CAD patients, respectively (P<0.001). Fetuin- A was significantly correlated to the severity of CAD (r 0.393, P<0.001) and associated with the risk of CAD in subjects (OR [CI] = 1. 144 [1.060-1. 235]; p = 0.001). A cut-off value of 237.4 μg/ml had good sensitivity (76.7%) and specificity (65.0%) for differentiating between two groups [area under curve (AUC) = 0.732 (CI=0.621-0.842); p < 0.001].

CONCLUSION

Our results indicated that fetuin-A levels were positively correlated to the severity of CAD. The findings suggest that there is a possible link between pathogenic mechanisms of atherosclerosis and fetuin-A; however, more investigations are needed in this regard.

Non-alcoholic fatty liver disease: a metabolic burden promoting atherosclerosis

Non-alcoholic fatty liver disease (NAFLD) has become the fastest growing chronic liver disease, with a prevalence of up to 25% worldwide. Individuals with NAFLD have a high risk of disease progression to cirrhosis, hepatocellular carcinoma (HCC), and liver failure. With the exception of intrahepatic burden, cardiovascular disease (CVD) and especially atherosclerosis (AS) are common complications of NAFLD. Furthermore, CVD is a major cause of death in NAFLD patients. Additionally, AS is a metabolic disorder highly associated with NAFLD, and individual NAFLD pathologies can greatly increase the risk of AS. It is increasingly clear that AS-associated endothelial cell damage, inflammatory cell activation, and smooth muscle cell proliferation are extensively impacted by NAFLD-induced systematic dyslipidemia, inflammation, oxidative stress, the production of hepatokines, and coagulations. In clinical trials, drug candidates for NAFLD management have displayed promising effects for the treatment of AS. In this review, we summarize the key molecular events and cellular factors contributing to the metabolic burden induced by NAFLD on AS, and discuss therapeutic strategies for the improvement of AS in individuals with NAFLD.

Adiponectin in Chronic Kidney Disease

Adiponectin is the adipokine associated with insulin sensitization, reducing liver gluconeogenesis, and increasing fatty acid oxidation and glucose uptake. Adiponectin is present in the kidneys, mainly in the arterial endothelium and smooth muscle cells, as well as in the capillary endothelium, and might be considered as a marker of many negative factors in chronic kidney disease. The last few years have brought a rising body of evidence that adiponectin is a multipotential protein with anti-inflammatory, metabolic, anti-atherogenic, and reactive oxygen species (ROS) protective actions. Similarly, adiponectin has shown many positive and direct actions in kidney diseases, and among many kidney cells. Data from large cross-sectional and cohort studies showed a positive correlation between serum adiponectin and mortality in chronic kidney disease. This suggests a complex interaction between local adiponectin action, comorbidities, and uremic milieu. In this review we discuss the role of adiponectin in chronic kidney disease.

Therapeutic Effects of Morinda citrifolia Linn. (Noni) Aqueous Fruit Extract on the Glucose and Lipid Metabolism in High-Fat/High-Fructose-Fed Swiss Mice

The aim of this study was to evaluate the therapeutic effects of two different doses (250 and 500 mg/kg) of Morinda citrifolia fruit aqueous extract (AE) in high-fat/high-fructose-fed Swiss mice. The food intake, body weight, serum biochemical, oral glucose tolerance test (OGTT), and enzyme-linked immunosorbent assay (ELISA), as well as histological analyses of the liver, pancreatic, and epididymal adipose tissue, were used to determine the biochemical and histological parameters. The chemical profile of the extract was determined by ultra-fast liquid chromatography–diode array detector–tandem mass spectrometry (UFLC–DAD–MS), and quantitative real-time PCR (qRT-PCR) was used to evaluate the gene expressions involved in the lipid and glucose metabolism, such as peroxisome proliferative-activated receptors-γ (PPAR-γ), -α (PPAR-α), fatty acid synthase (FAS), glucose-6-phosphatase (G6P), sterol regulatory binding protein-1c (SREBP-1c), carbohydrate-responsive element-binding protein (ChREBP), and fetuin-A. Seventeen compounds were tentatively identified, including iridoids, noniosides, and the flavonoid rutin. The higher dose of AE (AE 500 mg/kg) was demonstrated to improve the glucose tolerance; however, both doses did not have effects on the other metabolic and histological parameters. AE at 500 mg/kg downregulated the PPAR-γ, SREBP-1c, and fetuin-A mRNA in the liver and upregulated the PPAR-α mRNA in white adipose tissue, suggesting that the hypoglycemic effects could be associated with the expression of genes involved in de novo lipogenesis.

ssRNA Virus and Host Lipid Rearrangements: Is There a Role for Lipid Droplets in SARS-CoV-2 Infection?

Since its appearance, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has immediately alarmed the World Health Organization for its very high contagiousness and the complexity of patient clinical profiles. The worldwide scientific community is today gathered in a massive effort in order to develop safe vaccines and effective therapies in the shortest possible time. Every day, new pieces of SARS-CoV-2 infective puzzle are disclosed. Based on knowledge gained with other related coronaviruses and, more in general, on single-strand RNA viruses, we highlight underexplored molecular routes in which lipids and lipid droplets (LDs) might serve essential functions in viral infections. In fact, both lipid homeostasis and the pathways connected to lipids seem to be fundamental in all phases of the coronavirus infection. This review aims at describing potential roles for lipid and LDs in host-virus interactions and suggesting LDs as new and central cellular organelles to be investigated as potential targets against SARS-CoV-2 infection.

Nuclear factor-κB subunit p65 is involved in lipopolysaccharide-induced lipid accumulation via regulating DGAT1b in Ctenopharyngodon idellus kidney cells

Lipopolysaccharide (LPS) can promote the accumulation of triglycerides (TGs) in CIK (Ctenopharyngodon idellus kidney) cells, but the underlying mechanism is unclear. In this study, two genes involved TG synthesis, DGAT1a and DGAT1b, were isolated and characterized from grass carp Ctenopharyngodon idella, which encode peptides of 498 and 501 amino acids, respectively. Phylogenetic and synteny analyses indicated that DGAT1a and DGAT1b could have originated from the teleost-specific genome duplication event. Analysis of the exon-intron structures clarified that genomic structures of all DGAT1 proteins are conserved in vertebrates. DGAT1a mRNA was highly expressed in gut, adipose tissue and heart, while DGAT1b mRNA was highly expressed in liver and kidney. After LPS treatment, only expression of DGAT1b was up-regulated and knockdown of DGAT1b reduced the content of TG, suggesting that DGAT1b is involved in LPS-induced lipid accumulation. To explore the mechanism underlying the transcriptional regulation of DGAT1b in response to LPS, we cloned DGAT1b promoter sequence. Its promoter sequence consists of IRF7, RelA (p65) and RelB binding elements. Dual luciferase assay and q-PCR suggested that the promoter of DGAT1b can be activated by the overexpression of p65, but cannot be triggered by IRF7 and RelB. Mutational analysis shows that the potential p65 binding sites may locate in the region -111/-100 bp of the DGAT1b promoter. These results indicated that DGAT1b is the target gene of NF-κB p65. Finally, inhibiting p65 effectively decreased LPS-induced lipid accumulation. Taken together, we demonstrate that NF-κB p65 takes part in the lipid accumulation by regulating DGAT1b-induced TG synthesis in LPS signalling in CIK cells. The finding that NF-κB p65 links LPS signalling and TG synthesis adds to our growing appreciation of the interplay between immunity and lipid metabolism in fish.

The Role of Exercise in the Interplay between Myokines, Hepatokines, Osteokines, Adipokines, and Modulation of Inflammation for Energy Substrate Redistribution and Fat Mass Loss: A Review

Exercise is an effective strategy for preventing and treating obesity and its related cardiometabolic disorders, resulting in significant loss of body fat mass, white adipose tissue browning, redistribution of energy substrates, optimization of global energy expenditure, enhancement of hypothalamic circuits that control appetite-satiety and energy expenditure, and decreased systemic inflammation and insulin resistance. Novel exercise-inducible soluble factors, including myokines, hepatokines, and osteokines, and immune cytokines and adipokines are hypothesized to play an important role in the body's response to exercise. To our knowledge, no review has provided a comprehensive integrative overview of these novel molecular players and the mechanisms involved in the redistribution of metabolic fuel during and after exercise, the loss of weight and fat mass, and reduced inflammation. In this review, we explain the potential role of these exercise-inducible factors, namely myokines, such as irisin, IL-6, IL-15, METRNL, BAIBA, and myostatin, and hepatokines, in particular selenoprotein P, fetuin A, FGF21, ANGPTL4, and follistatin. We also describe the function of osteokines, specifically osteocalcin, and of adipokines such as leptin, adiponectin, and resistin. We also emphasize an integrative overview of the pleiotropic mechanisms, the metabolic pathways, and the inter-organ crosstalk involved in energy expenditure, fat mass loss, reduced inflammation, and healthy weight induced by exercise.

Metabolic Inflammation-A Role for Hepatic Inflammatory Pathways as Drivers of Comorbidities in Nonalcoholic Fatty Liver Disease?

Nonalcoholic fatty liver disease (NAFLD) is a global and growing health concern. Emerging evidence points toward metabolic inflammation as a key process in the fatty liver that contributes to multiorgan morbidity. Key extrahepatic comorbidities that are influenced by NAFLD are type 2 diabetes, cardiovascular disease, and impaired neurocognitive function. Importantly, the presence of nonalcoholic steatohepatitis and advanced hepatic fibrosis increase the risk for systemic comorbidity in NAFLD. Although the precise nature of the crosstalk between the liver and other organs has not yet been fully elucidated, there is emerging evidence that metabolic inflammation-in part, emanating from the fatty liver-is the engine that drives cellular dysfunction, cell death, and deleterious remodeling within various body tissues. This review describes several inflammatory pathways and mediators that have been implicated as links between NAFLD and type 2 diabetes, cardiovascular disease, and neurocognitive decline.

Acute Hyperenergetic, High-Fat Feeding Increases Circulating FGF21, LECT2, and Fetuin-A in Healthy Men

BACKGROUND

Hepatokines such as fibroblast growth factor 21 (FGF21), leukocyte cell-derived chemotaxin 2 (LECT2), fetuin-A, fetuin-B, and selenoprotein P (SeP) are liver-derived proteins that are modulated by chronic energy status and metabolic disease. Emerging data from rodent and cell models indicate that hepatokines may be sensitive to acute nutritional manipulation; however, data in humans are lacking.

OBJECTIVE

The aim was to investigate the influence of hyperenergetic, high-fat feeding on circulating hepatokine concentrations, including the time course of responses.

METHODS

In a randomized, crossover design, 12 healthy men [mean ± SD: age, 24 ± 4 y; BMI (kg/m2), 24.1 ± 1.5] consumed a 7-d hyperenergetic, high-fat diet [HE-HFD; +50% energy, 65% total energy as fat (32% saturated, 26% monounsaturated, 8% polyunsaturated)] and control diet (36% total energy as fat), separated by 3 wk. Whole-body insulin sensitivity was assessed before and after each diet using oral-glucose-tolerance tests. Fasting plasma concentrations of FGF21 (primary outcome), LECT2, fetuin-A, fetuin-B, SeP, and related metabolites were measured after 1, 3, and 7 d of each diet. Hepatokine responses were analyzed using 2-factor repeated-measures ANOVA and subsequent pairwise comparisons.

RESULTS

Compared with the control, the HE-HFD increased circulating FGF21 at 1 d (105%) and 3 d (121%; P ≤ 0.040), LECT2 at 3 d (17%) and 7 d (32%; P ≤ 0.004), and fetuin-A at 7 d (7%; P = 0.028). Plasma fetuin-B and SeP did not respond to the HE-HFD. Whole-body insulin sensitivity was reduced after the HE-HFD by 31% (P = 0.021).

CONCLUSIONS

Acute high-fat overfeeding augments circulating concentrations of FGF21, LECT2, and fetuin-A in healthy men. Notably, the time course of response varies between proteins and is transient for FGF21. These findings provide further insight into the nutritional regulation of hepatokines in humans and their interaction with metabolic homeostasis. This study was registered at clinicaltrials.gov as NCT03369145.

Fetuin-A and Fetuin-B in Non-Alcoholic Fatty Liver Disease: A Meta-Analysis and Meta-Regression

The magnitude of the effect of fetuin-A and fetuin-B on non-alcoholic fatty liver disease (NAFLD) remains undefined. Therefore, the aim of this study was to synthesize previous findings to obtain a reliable estimation of this relationship. This study was registered in PROSPERO with the number CRD42019126314. Studies published not later than March 2019, examining the relationship between fetuin-A, fetuin-B, and NAFLD, were identified by a systematic search in the electronic databases of the Web of Science, PubMed, Embase, and Cochrane Library. Pooled estimates of standardized mean difference (SMD), calculated using the random-effects model in a meta-analysis, were applied to estimate the strength of the association between fetuin-A, fetuin-B, and NAFLD. Thirty publications were identified and analyzed based on specified inclusion criteria. Collectively, they consisted of 3800 NAFLD participants and 3614 controls. Compared with the controls, significant higher values of the fetuin-A (SMD = 0.83, 95% CI: 0.59 to 1.07, Z = 6.82, p < 0.001) and fetuin-B (SMD = 0.18, 95% CI: 0.02 to 0.33, Z = 2.27, p = 0.023) were observed in NAFLD patients. Meanwhile, in the subgroup analysis, the effect value of fetuin-A in the NASH group was significantly higher than that in the NAFL group (p = 0.036). The findings of this study suggest that elevated fetuin-A and fetuin-B may independently indicate the occurrence of NAFLD. Nevertheless, further research is needed to confirm these results.

Fetuin-a to adiponectin ratio is a sensitive indicator for evaluating metabolic syndrome in the elderly

Background

Fetuin-A and adiponectin present significant associations, supported by recent evidence, with metabolic syndrome (MS) featuring hyperglycemia, central obesity and insulin resistance as the main components, but their biological functions are opposite. The aim of this study was to verify whether fetuin-A/adiponectin ratio (F/A ratio) is a more sensitive indicator for evaluation of MS than either fetuin-A or adiponectin.

Methods

In this cross-sectional study, 465 elderly subjects were selected from the physical examination database. Serum levels of fetuin-A and adiponectin were measured using an enzyme-linked immunosorbent assay (ELISA) method. Spearman’s rank correlation coefficient, linear regression and logistic regression analysis were adopted to estimate the correlations of fetuin-A, adiponectin and F/A ratio with MS and its components, and receiver operating characteristic (ROC) curve analysis was performed to evaluate the predictive values of the aforesaid indices.

Results

Compared with fetuin-A or adiponectin, F/A ratio was significantly associated with all the components of MS, and this correlation was significant even after adjusting potential confounding factors (P < 0.05). Logistic regression analysis indicated that F/A ratio presented a stronger correlation with incident MS (adjusted OR: 1.466; 95% CI: 1.189–1.808) than fetuin-A (adjusted OR: 1.100; 95% CI: 1.020–1.186) and adiponectin (adjusted OR: 0.760; 95% CI: 0.664–0.871) alone. ROC analysis revealed that F/A ratio achieved a larger area under curve (AUC) than fetuin-A and adiponectin, with their AUC values of 0.755, 0.709 and 0.708, respectively.

Conclusion

F/A ratio is a more sensitive index for evaluating MS than either fetuin-A or adiponectin in the elderly.

Fetuin-A in Metabolic syndrome: A systematic review and meta-analysis

Objective

Fetuin-A has been associated with the progression of metabolic syndrome, but previous studies found inconsistent results on the relationship between metabolic syndrome and the concentration of fetuin-A. The aim of this study was to perform a meta-analysis to summarize previous findings on this relationship.

Method

This study was registered with the International Prospective Register of Systematic Reviews PROSPERO (CRD42019129566). Studies examining the relationship between metabolic syndrome and the concentration of circulating fetuin-A were identified using a systematic search in the electronic databases of Embase, PubMed, Web of Science, and Cochrane Library before March 2019. A random effects model was used to summarize the effect size of the association in terms of the standardized mean difference (SMD).

Results

Fourteen eligible studies compared fetuin-A concentrations between 4,551 metabolic syndrome patients and 8,805 controls. The circulating fetuin-A concentration was significantly higher in the metabolic syndrome patients than in the controls (SMD = 0.65, 95% confidence interval (CI): 0.48 to 0.83, Z = 7.18, p<0.001). Besides, circulating fetuin-A was a risk factor for metabolic syndrome (odds ratio 1.23, 95% CI: 1.08 to 1.40).

Conclusion

These findings suggest that fetuin-A may be an important indicator for metabolic syndrome, in which case this may lead to new perspectives in early diagnosis, identification of novel biomarkers, and providing novel targets for pharmacological interventions.

Pathophysiological Implication of Fetuin-A Glycoprotein in the Development of Metabolic Disorders: A Concise Review

Alpha 2-Heremans-Schmid glycoprotein, also known as fetuin-A (Fet-A), is a multifunctional plasma glycoprotein that has been identified in both animal and human beings. The protein is a hepatokine predominantly synthesized in the liver, which is considered as an important component of diverse normal and pathological processes, including bone metabolism regulation, vascular calcification, insulin resistance, and protease activity control. Epidemiological studies have already consistently demonstrated significant elevated circulating Fet-A in the course of obesity and related complications, such as type 2 diabetes mellitus, metabolic syndrome, and nonalcoholic fatty liver disorder (NAFLD). Moreover, Fet-A has been strongly correlated with many parameters related to metabolic homeostasis dysregulation, such as insulin sensitivity, glucose tolerance, circulating lipid levels (non-esterified free fatty acids and triglycerides), and circulating levels of both pro- and anti-inflammatory factors (C-reactive protein, tumor necrosis factor-α (TNF-α), and interleukin (IL)-6). Metabolic-interfering effects of Fet-A have thus been shown to highly exacerbate insulin resistance (IR) through blocking insulin-stimulated glucose transporter 4 (GLUT-4) translocation and protein kinase B (Akt) activation. Furthermore, the protein appeared to interfere with downstream phosphorylation events in insulin receptor and insulin receptor substrate signaling. The emerging importance of Fet-A for both diagnosis and therapeutics has therefore come to the attention of researchers and the pharmaceutical industry, in the prospect of developing new therapeutic strategies and diagnosis methods for metabolic disorders.

Protectin DX ameliorates palmitate-induced hepatic insulin resistance through AMPK/SIRT1-mediated modulation of fetuin-A and SeP expression

The role as well as the molecular mechanisms of protectin DX (PDX) in the prevention of hepatic insulin resistance, a hallmark of type 2 diabetes, remains unknown. Therefore, the present study was designed to explore the direct impact of PDX on insulin resistance and to investigate the expression of fetuin-A and selenoprotein P (SeP), hepatokines that are involved in insulin signalling, in hepatocytes. Human serum levels of PDX as well as fetuin-A and SeP were determined by high-performance liquid chromatography (HPLC). Human primary hepatocytes were treated with palmitate and PDX. NF-κB phosphorylation as well as expression of insulin signalling associated genes and hepatokines were determined by Western blotting analysis. FOXO1 binding levels were measured by quantitative real-time PCR. Selected genes from candidate pathways were evaluated by small interfering (si) RNA-mediated gene suppression. Serum PDX levels were significantly (P < 0.05) downregulated, whereas serum fetuin-A and SeP levels were increased (P < 0.05) in obese subjects compared with healthy subjects. In in vitro experiments, PDX treatment increased AMP-activated protein kinase (AMPK) phosphorylation and SIRT1 expression and attenuated palmitate-induced fetuin-A and SeP expression and insulin resistance in hepatocytes. AMPK or SIRT1 siRNA mitigated the suppressive effects of PDX on palmitate-induced fetuin-A through NF-κB and SeP expression linked to FOXO1 and insulin resistance. Recombinant fetuin-A and SeP reversed the suppressive effects of fetuin-A and SeP expression on palmitate-mediated impairment of insulin signalling. The current finding provides novel insight into the underlying mechanism linking hepatokines to the pathogenesis of hepatic insulin resistance.

Crosstalk between nonalcoholic fatty liver disease and cardiometabolic syndrome

Nonalcoholic fatty liver disease (NAFLD) is a chronic condition characterized by fat accumulation combined with low-grade inflammation in the liver. A large body of clinical and experimental data shows that increased flux of free fatty acids from increased visceral adipose tissue and de novo lipogenesis can lead to NAFLD and insulin resistance. Thus, individuals with obesity, insulin resistance, and dyslipidaemia are at the greatest risk of developing NAFLD. Conversely, NAFLD is a phenotype of cardiometabolic syndrome. Notably, researchers have discovered a close association between NAFLD and impaired glucose metabolism and focused on the role of NAFLD in the development of type 2 diabetes. Moreover, recent studies provide substantial evidence for an association between NAFLD and atherosclerosis and cardiometabolic disorders. Even if NAFLD can progress into severe liver disorders including nonalcoholic steatohepatitis (NASH) and cirrhosis, the majority of subjects with NAFLD die from cardiovascular disease eventually. In this review, we propose a potential pathological link between NAFLD/NASH and cardiometabolic syndrome. The potential factors that can play a pivotal role in this link, such as inflammation, insulin resistance, alteration in lipid metabolism, oxidative stress, genetic predisposition, and gut microbiota are discussed.

Effects of aerobic versus resistance training on serum fetuin-A, fetuin-B, and fibroblast growth factor-21 levels in male diabetic patients

The aim of this study was to compare the effects of 8 weeks of aerobic versus resistance training programs on serum fetuin-A, fetuin-B, and fibroblast growth factor-21 (FGF-21) levels in males with type 2 diabetes mellitus. Participants (n = 34) were randomly assigned to a resistance training group (RTG; n = 12), an aerobic training group (ATG; n = 11), or a control group (n = 11). The ATG completed 30-45 min of aerobic running training at 65%-75% of the maximum heart rate. The RTG completed three sets of 10 repetitions maximum of leg press, bench press, knee extension, seated cable row, knee flexion, military press, and calf rise. Blood samples were taken before and after the training period to assess dependent variables. After 8 weeks, both the ATG and the RTG reduced fetuin-A (p < 0.05) and fetuin-B (p < 0.05), but increased FGF-21 (p < 0.05). Moreover, the RTG showed greater decrease than the ATG in fetuin-A (-18.3% vs. -7.9%), fetuin-B (-29.2% vs. -11.45%), and a lower increase in FGF-21 (42.2% vs. 25.1%), respectively. Aerobic and resistance exercise training significantly decreased serum fetuin-A, and fetuin-B, and increased FGF-21 levels in males with type 2 diabetes mellitus. However, more significant alterations in serum factors were observed from resistance training. Thus, resistance training may be considered a more suitable training strategy.

Effects of exercise training on Fetuin-a in obese, type 2 diabetes and cardiovascular disease in adults and elderly: a systematic review and Meta-analysis

Background

Elevated levels of fetuin-A are associated with increased risks of metabolic syndrome, type 2 diabetes and nonalcoholic fatty liver disease. This meta-analysis investigated whether exercise interventions can reduce fetuin-A in adults.

Methods

We searched clinical trials that objectively assessed fetuin-A and included study arms with exercise intervention. The pre-intervention and post-intervention data were used for meta-analysis. The effect sizes were calculated as standardized mean differences or changes in fetuin-A and expressed as Hedges’ g using random-effects models.

Results

The overall Hedges’ g for fetuin-A in all included interventions was − 0.640 (95%CI − 1.129 to − 0.151; n = 9), but this effect was not observed in obese (g = − 0.096; 95%CI, − 0.328 to 0.135) and type 2 diabetes/dysglycemia (g = − 0.56; 95%CI, − 1.348 to 0.236) individuals. Additionally, the random-effects meta-regression analysis showed that there was not a greater decrease in fetuin-A in individuals who achieved greater body mass index reductions (regression coefficient = 0.065; 95%CI, − 0.185 to 0.315).

Conclusion

Supervised exercise is associated with reductions in fetuin-A levels in adults and elderly. However, the results of the present meta-analysis should be interpreted with caution because of the variety of type of exercises and individual obesity related-disorders involve. Therefore, additional high-quality randomized controlled trials describing the effect of supervised exercise interventions on fetuin-A in adults are still needed. 

Electronic supplementary material

The online version of this article (10.1186/s12944-019-0962-2) contains supplementary material, which is available to authorized users.

Maresin 1 attenuates NAFLD by suppression of endoplasmic reticulum stress via AMPK-SERCA2b pathway

Maresin 1 (MAR1), which is derived from docosahexaenoic acid biosynthesized by macrophages, has been reported to improve insulin resistance. Recently, it has been documented that MAR1 could ameliorate inflammation and insulin resistance in obese mice. These findings led us to investigate the effects of MAR1 on hepatic lipid metabolism. We found that MAR1 could stimulate AMP-activated protein kinase (AMPK), thereby augmenting sarcoendoplasmic reticulum Ca²⁺-ATPase 2b (SERCA2b) expression. This stimulation suppressed lipid accumulation by attenuating the endoplasmic reticulum (ER) stress in hepatocytes under hyperlipidemic conditions. Attenuation was mitigated by knockdown of AMPK or thapsigargin, a SERCA2b inhibitor. We also demonstrated that MAR1 administration resulted in increased hepatic AMPK phosphorylation and Serca2b mRNA expression, whereas hepatic ER stress was reduced in high-fat diet (HFD)-fed mice. Moreover, MAR1 treatment suppressed hepatic lipid synthesis, thereby attenuating hepatic steatosis in HFD-fed mice. In conclusion, our results suggest that MAR1 ameliorates hepatic steatosis via AMPK/SERCA2b-mediated suppression of ER stress. Therefore, MAR1 may be an effective therapeutic strategy for treating non-alcoholic fatty liver disease (NAFLD) via regulation of ER stress-induced hepatic lipogenesis.

The association between circulating fetuin-A levels and type 2 diabetes mellitus risk: systematic review and meta-analysis of observational studies

BACKGROUND AND OBJECTIVE

Fetuin-A is a liver-derived circulating protein that is associated with insulin resistance and diabetes. The objective of this systematic review and meta-analysis of published observational studies was to investigate mean levels of fetuin-A in T2D patients and the relationship between blood fetuin-A levels and T2D risk.

MATERIALS AND METHODS

PubMed, Embase, Google Scholar, Web of Science, and The Cochrane Library were systematically searched for potential relevant studies up to 1 December 2016. Natural logarithm-transformed estimate risks, standard mean differences on the basis of Hedges's adjusted g, and 95% confidence intervals (CIs) were calculated for all eligible studies and were combined to measure the pooled data using random-effects model.

RESULTS

A total of 32 studies including 27 case-control and 5 cohort studies were included in the current study. Fetuin-A levels in T2D patients were significantly higher than control groups [Hedges' g = 1.73, 95% CI (1.25-2.22), P < 0.001], with significant heterogeneity across studies (P < 0.001, I ² = 98.46%). Findings from meta-analyses of cohort studies showed a statistically significant association between fetuin-A levels and T2D risk [rate ratio = 1.62, 95% CI (1.26-2.08), P < 0.001], with no significant heterogeneity (P = 0.10, I ² = 46.06%).

CONCLUSION

We found a significant relationship between the fetuin-A levels with T2D risk. Although fetuin-A may be as a potential screening and prediction biomarker or a therapeutic target in T2D patients, further studies are required in this regard.

Serum fetuin A level is associated with nonalcoholic fatty liver disease in Chinese population

Objective

To investigate the association between serum fetuin A concentration and non-alcoholic fatty liver disease (NAFLD) in Chinese population.

Methods

This case-control study enrolled 79 NAFLD cases and 79 non-NAFLD controls. All subjects were selected from Chinese population who received annual health examination in the First Affiliated Hospital of Zhejiang University in 2016. NAFLD was diagnosed mainly based on abdominal ultrasonography. The severity of NAFLD was categorized by serum level of alanine aminotransferase. Serum fetuin A was measured by ELISA.

Results

Serum fetuin A level in NAFLD patients was significantly lower than that in controls (0.27±0.17 vs. 0.32±0.12g/L, P < 0.05). Compared with controls, mild NAFLD (0.24±0.16 g/L, P < 0.05) and moderate NAFLD (0.25±0.17 g/L, P < 0.05) had significantly lower concentration of Fetuin A, while Fetuin A level tended to slightly increase with the severity of NAFLD. The prevalence rate of NAFLD decreased (75 %, 40 %, and 36 %), as Fetuin A level elevated. ROC curve of Fetuin A was developed to predict the presence of NAFLD. Area under ROC was 0.656.

Conclusion

Serum level of Fetuin A was lower in NAFLD patients than controls, while Fetuin A level increased with the severity of NAFLD, indicating a potential predicting role of Fetuin A in the development of NAFLD.

Effect of Diabetea tea ™ consumption on inflammatory cytokines and metabolic biomarkers in type 2 diabetes patients

ETHNOPHARMACOLOGICAL RELEVANCE

Diabetea tea™ (DT) is an anti-diabetic alternative medicine in some Asian countries. The main constituent of DT is black tea originating from Camellia sinensis that is supplemented by 12 other medicinal plants. Black tea contains a large amount of the flavonoids catechins especially epigallocatechin gallate (EGCG) which has anti-inflammatory and antioxidative capacity. This study was undertaken to evaluate the possible effects of DT intake on inflammatory cytokines, regulatory T cells (Tregs) and metabolic biomarkers in T2DM.

MATERIALS AND METHODS

The study included 50 patients with T2DM. The patients had received 3 cups (600ml) of DT extract or placebo (PL) extract per day during a period of 12 weeks. Intracellular cytokine expression in peripheral blood mononuclear cell (PBMC) as well as the glycemic and lipid profiles were measured at baseline and after the treatment period. The active constituents of the medicinal plants included in DT were investigated by gas chromatography-mass spectrometry (GC/MS).

RESULTS

Ingestion of DT suppressed CD4+ T cell expression of IL-1β and Il-8 (p<0.05) and up-regulated the expression of IL-10 and the Treg/IL-17 ratio (p<0.05) which was not shown in PL. A significant decrease in HbA1c and LDL was observed at the end of the study period (p<0.05) in DT. The GC/MS analyses of DT indicated the presence of lupeol, β-Amyrin and β-sitosterol. Also analyses of individual herbs showed the presence of higher levels of lupeol and β-Amyrin in Nuga Ficus bengalensis and β-sitosterol in the Attikka Ficus racemosa, indicating that the active ingredients of DT are concentrated in these two herbs.

CONCLUSION

The present study provides evidence that DT has hypoglycemic and antihyperlipidemic properties. Interestingly, DT has anti-inflammatory effects. These properties are attributed to the flavonoids, triterpenes and phytosterol contents of the tea. We suggest that DT protects against diabetes complications in the long term.

Metabolic Adaptation in Obesity and Type II Diabetes: Myokines, Adipokines and Hepatokines

Obesity and type II diabetes are characterized by insulin resistance in peripheral tissues. A high caloric intake combined with a sedentary lifestyle is the leading cause of these conditions. Whole-body insulin resistance and its improvement are the result of the combined actions of each insulin-sensitive organ. Among the fundamental molecular mechanisms by which each organ is able to communicate and engage in cross-talk are cytokines or peptides which stem from secretory organs. Recently, it was reported that several cytokines or peptides are secreted from muscle (myokines), adipose tissue (adipokines) and liver (hepatokines) in response to certain nutrition and/or physical activity conditions. Cytokines exert autocrine, paracrine or endocrine effects for the maintenance of energy homeostasis. The present review is focused on the relationship and cross-talk amongst muscle, adipose tissue and the liver as secretory organs in metabolic diseases.

Recent advances in understanding the role of adipocytokines during non-alcoholic fatty liver disease pathogenesis and their link with hepatokines

Non-alcoholic fatty liver disease (NAFLD) is currently considered the main cause of chronic liver disease worldwide. Mechanisms leading to the development and progression of this disease are topics of great interest for researchers and clinicians. The current multi-hit hypothesis has thrown the crosstalk between liver and adipose tissue into sharp focus. It is well known that adipose tissue produces circulating factors, known as adipocytokines, which exert several effects on liver cells, promoting the onset of NAFLD and its progression to non-alcoholic steatohepatitis in obese subjects. In a similar way, hepatocytes may also respond to obesogenic stimuli by producing and releasing hepatokines into the circulation. Here, the authors provide an overview of recent advances in our understanding of the role of the most relevant adipocytokines and hepatokines in NAFLD pathogenesis, highlighting their possible molecular and functional interactions.

Treatment of nonalcoholic fatty liver disease: role of AMPK

Nonalcoholic fatty liver disease (NAFLD) is a growing worldwide epidemic and an important risk factor for the development of insulin resistance, type 2 diabetes, nonalcoholic steatohepatitis (NASH), and hepatic cellular carcinoma (HCC). Despite the prevalence of NAFLD, lifestyle interventions involving exercise and weight loss are the only accepted treatments for this disease. Over the last decade, numerous experimental compounds have been shown to improve NAFLD in preclinical animal models, and many of these therapeutics have been shown to increase the activity of the cellular energy sensor AMP-activated protein kinase (AMPK). Because AMPK activity is reduced by inflammation, obesity, and diabetes, increasing AMPK activity has been viewed as a viable therapeutic strategy to improve NAFLD. In this review, we propose three primary mechanisms by which AMPK activation may improve NAFLD. In addition, we examine the mechanisms by which AMPK is activated. Finally, we identify 27 studies that have used AMPK activators to reduce NAFLD. Future considerations for studies examining the relationship between AMPK and NAFLD are highlighted.

Implication of hepatokines in metabolic disorders and cardiovascular diseases

The liver is a central regulator of systemic energy homeostasis and has a pivotal role in glucose and lipid metabolism. Impaired gluconeogenesis and dyslipidemia are often observed in patients with nonalcoholic fatty liver disease (NAFLD). The liver is now recognized to be an endocrine organ that secretes hepatokines, which are proteins that regulate systemic metabolism and energy homeostasis. Hepatokines are known to contribute to the pathogenesis of metabolic syndrome, NAFLD, type 2 diabetes (T2DM), and cardiovascular diseases (CVDs). In this review, we focus on the roles of two major hepatokines, fetuin-A and fibroblast growth factor 21 (FGF21), as well as recently-redefined hepatokines, such as selenoprotein P, angiopoietin-like protein 4 (ANGPTL4), and leukocyte cell-derived chemotaxin 2 (LECT2). We also assess the biology and molecular mechanisms of hepatokines in the context of their potential as therapeutic targets for metabolic disorders and cardiovascular diseases.

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The roles of hepatokines such as fetuin-A, FGF21, selenoprotein P, ANGPTL4, and LECT2

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The molecular mechanisms of hepatokines in metabolic disorders and CVD

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Hepatokines as therapeutic strategies for metabolic disorders and CVD

The Impact of Organokines on Insulin Resistance, Inflammation, and Atherosclerosis

Immoderate energy intake, a sedentary lifestyle, and aging have contributed to the increased prevalence of obesity, sarcopenia, metabolic syndrome, type 2 diabetes, and cardiovascular disease. There is an urgent need for the development of novel pharmacological interventions that can target excessive fat accumulation and decreased muscle mass and/or strength. Adipokines, bioactive molecules derived from adipose tissue, are involved in the regulation of appetite and satiety, inflammation, energy expenditure, insulin resistance and secretion, glucose and lipid metabolism, and atherosclerosis. Recently, there is emerging evidence that skeletal muscle and the liver also function as endocrine organs that secrete myokines and hepatokines, respectively. Novel discoveries and research into these organokines (adipokines, myokines, and hepatokines) may lead to the development of promising biomarkers and therapeutics for cardiometabolic disease. In this review, I summarize recent data on these organokines and focus on the role of adipokines, myokines, and hepatokines in the regulation of insulin resistance, inflammation, and atherosclerosis.

Salsalate attenuates diet induced non-alcoholic steatohepatitis in mice by decreasing lipogenic and inflammatory processes

BACKGROUND AND PURPOSE

Salsalate (salicylsalicylic acid) is an anti-inflammatory drug that was recently found to exert beneficial metabolic effects on glucose and lipid metabolism. Although its utility in the prevention and management of a wide range of vascular disorders, including type 2 diabetes and metabolic syndrome has been suggested before, the potential of salsalate to protect against non-alcoholic steatohepatitis (NASH) remains unclear. The aim of the present study was therefore to ascertain the effects of salsalate on the development of NASH.

EXPERIMENTAL APPROACH

Transgenic APOE*3Leiden.CETP mice were fed a high-fat and high-cholesterol diet with or without salsalate for 12 and 20 weeks. The effects on body weight, plasma biochemical variables, liver histology and hepatic gene expression were assessed.

KEY RESULTS

Salsalate prevented weight gain, improved dyslipidemia and insulin resistance and ameliorated diet-induced NASH, as shown by decreased hepatic microvesicular and macrovesicular steatosis, reduced hepatic inflammation and reduced development of fibrosis. Salsalate affected lipid metabolism by increasing β-oxidation and decreasing lipogenesis, as shown by the activation of PPAR-α, PPAR-γ co-activator 1β, RXR-α and inhibition of genes controlled by the transcription factor MLXIPL/ChREBP. Inflammation was reduced by down-regulation of the NF-κB pathway, and fibrosis development was prevented by down-regulation of TGF-β signalling.

CONCLUSIONS AND IMPLICATIONS

Salsalate exerted a preventive effect on the development of NASH and progression to fibrosis. These data suggest a clinical application of salsalate in preventing NASH.

Endocrine causes of nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease in the industrialized world. The prevalence of NAFLD is increasing, becoming a substantial public health burden. NAFLD includes a broad spectrum of disorders, from simple conditions such as steatosis to severe manifestations such as fibrosis and cirrhosis. The relationship of NAFLD with metabolic alterations such as type 2 diabetes is well described and related to insulin resistance, with NAFLD being recognized as the hepatic manifestation of metabolic syndrome. However, NAFLD may also coincide with endocrine diseases such as polycystic ovary syndrome, hypothyroidism, growth hormone deficiency or hypercortisolism. It is therefore essential to remember, when discovering altered liver enzymes or hepatic steatosis on radiological exams, that endocrine diseases can cause NAFLD. Indeed, the overall prognosis of NAFLD may be modified by treatment of the underlying endocrine pathology. In this review, we will discuss endocrine diseases that can cause NALFD. Underlying pathophysiological mechanisms will be presented and specific treatments will be reviewed.

Exercise-induced lowering of fetuin-A may increase hepatic insulin sensitivity

INTRODUCTION

Fetuin-A is a novel hepatokine, and there is preliminary evidence that it may contribute to the pathogenesis of type 2 diabetes. Exercise reduces fetuin-A, but the specific metabolic effects particularly as they relate to the regulation of insulin resistance are unknown. This led us to examine the effect of exercise training on circulating fetuin-A in relation to skeletal muscle and/or hepatic insulin resistance in obese adults.

METHODS

Twenty older adults (66.3 ± 0.9 yr; body mass index, 34.1 ± 1.2 kg · m(-1)) participated in this prospective 12-wk study and underwent supervised exercise training (5 d · wk(-1), 60 min · d(-1) at approximately 85% HRmax). Insulin resistance was assessed using the euglycemic-hyperinsulinemic clamp (40 mU · m(-2) · min(-1)) with isotope dilution ([6,6-H2]-glucose). Skeletal muscle insulin sensitivity (rate of glucose disposal), hepatic insulin resistance (rate of glucose appearance × fasting insulin), metabolic flexibility (respiratory quotient clamp - respiratory quotient fasting), fetuin-A, high-molecular weight adiponectin, high-sensitivity C-reactive protein, leptin, and body fat (dual energy x-ray absorptiometry) were measured before and after the intervention.

RESULTS

Exercise reduced body fat, high-sensitivity C-reactive protein, leptin and hepatic as well as skeletal muscle insulin resistance (each, P < 0.05). Fetuin-A was decreased by approximately 8% (pre, 1.01 ± 0.08, vs post, 0.89 ± 0.06 g · L(-1); P < 0.05) after the intervention, and lower fetuin-A after exercise correlated with lower hepatic insulin resistance (r = -0.46, P < 0.01), increased metabolic flexibility (r = -0.70, P < 0.01) and high-molecular weight adiponectin (r = -0.57, P < 0.01).

CONCLUSIONS

Fetuin-A may contribute to exercise training-induced improvements in hepatic insulin resistance, CHO utilization, and inflammation in older obese adults. Further work is required to determine the cellular mechanism(s) of action for fetuin-A because this hepatokine is related to type 2 diabetes risk.

Mechanistic link between nonalcoholic fatty liver disease and cardiometabolic disorders

Nonalcoholic fatty liver disease (NAFLD) is a chronic condition characterized by fat accumulation combined with low-grade inflammation in the liver. A large body of clinical and experimental data shows that increased flux of free fatty acids from increased visceral adipose tissue can lead to NAFLD related with insulin resistance. Thus, individuals with obesity, insulin resistance, and dyslipidemia are at the greatest risk of developing NAFLD. Conversely, NAFLD is one of the phenotypes of insulin resistance or metabolic syndrome. Many researchers have discovered a close association between NAFLD and insulin resistance, and focused on the role of NAFLD in the development of type 2 diabetes. Further, substantial evidence has suggested the association between NAFLD and cardiovascular disease (CVD). In the current review, we provide a plausible mechanistic link between NAFLD and CVD and the potential of the former as a therapeutic target based on pathophysiology. We also discuss in detail about the role of insulin resistance, oxidative stress, low-grade inflammation, abnormal lipid metabolism, gut microbiota, changes of biomarkers, and genetic predisposition in the pathological linking between NAFLD and cardiometabolic disorders.

Metformin and salicylate synergistically activate liver AMPK, inhibit lipogenesis and improve insulin sensitivity

Metformin is the mainstay therapy for type 2 diabetes (T2D) and many patients also take salicylate-based drugs [i.e., aspirin (ASA)] for cardioprotection. Metformin and salicylate both increase AMP-activated protein kinase (AMPK) activity but by distinct mechanisms, with metformin altering cellular adenylate charge (increasing AMP) and salicylate interacting directly at the AMPK β1 drug-binding site. AMPK activation by both drugs results in phosphorylation of ACC (acetyl-CoA carboxylase; P-ACC) and inhibition of acetyl-CoA carboxylase (ACC), the rate limiting enzyme controlling fatty acid synthesis (lipogenesis). We find doses of metformin and salicylate used clinically synergistically activate AMPK in vitro and in vivo, resulting in reduced liver lipogenesis, lower liver lipid levels and improved insulin sensitivity in mice. Synergism occurs in cell-free assays and is specific for the AMPK β1 subunit. These effects are also observed in primary human hepatocytes and patients with dysglycaemia exhibit additional improvements in a marker of insulin resistance (proinsulin) when treated with ASA and metformin compared with either drug alone. These data indicate that metformin-salicylate combination therapy may be efficacious for the treatment of non-alcoholic fatty liver disease (NAFLD) and T2D.