AMPK-Dependent Metabolic Regulation by PPAR Agonists

Fenofibrate reduces cardiac remodeling by mitochondrial dynamics preservation in a renovascular model of cardiac hypertrophy

Fenofibrate, a PPAR-α agonist clinically used to lower serum lipid levels, reduces cardiac remodeling and improves cardiac function. However, its mechanism of action is not completely elucidated. In this study we examined the effect of fenofibrate on mitochondria in a rat model of renovascular hypertension, focusing on mediators controlling mitochondrial dynamics and autophagy. Rats with two-kidney one-clip (2K1C) hypertension were treated with fenofibrate 150 mg/kg/day (2K1C-FFB) or vehicle (2K1C-VEH) for 8 weeks. Systolic blood pressure and cardiac functional were in-vivo assessed, while cardiomyocyte size and protein expression of mediators of cardiac hypertrophy and mitochondrial dynamics were ex-vivo examined by histological and Western blot analyses. Fenofibrate treatment counteracted the development of hypertension and the increase of left ventricular mass, relative wall thickness and cross-sectional area of cardiomyocytes. Furthermore, fenofibrate re-balanced the expression Mfn2, Drp1 and Parkin, regulators of fusion, fission, mitophagy respectively. Regarding autophagy, the LC3-II/LC3-I ratio was increased in 2K1C-VEH and 2K1C-FFB, whereas the autophagy was increased only in 2K1C-FFB. In cultured H9C2 cardiomyoblasts, fenofibrate reversed the Ang II-induced mRNA up-regulation of hypertrophy markers Nppa and Myh7, accumulation of reactive oxygen species and depolarization of the mitochondrial membrane exerting protection mediated by up-regulation of the Uncoupling protein 2. Our results indicate that fenofibrate acts directly on cardiomyocytes and counteracts the pressure overload-induced cardiac maladaptive remodeling. This study reveals a so far hidden mechanism involving mitochondrial dynamics in the beneficial effects of fenofibrate, support its repurposing for the treatment of cardiac hypertrophy and provide new potential targets for its pharmacological function.

Promotion of maturation of human pluripotent stem cell-derived cardiomyocytes via treatment with the peroxisome proliferator-activated receptor alpha agonist Fenofibrate

As research on in vitro cardiotoxicity assessment and cardiac disease modeling becomes more important, the demand for human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs) is increasing. However, it has been reported that differentiated hPSC-CMs are in a physiologically immature state compared to in vivo adult CMs. Since immaturity of hPSC-CMs can lead to poor drug response and loss of acquired heart disease modeling, various approaches have been attempted to promote maturation of CMs. Here, we confirm that peroxisome proliferator-activated receptor alpha (PPARα), one of the representative mechanisms of CM metabolism and cardioprotective effect also affects maturation of CMs. To upregulate PPARα expression, we treated hPSC-CMs with fenofibrate (Feno), a PPARα agonist used in clinical hyperlipidemia treatment, and demonstrated that the structure, mitochondria-mediated metabolism, and electrophysiology-based functions of hPSC-CMs were all mature. Furthermore, as a result of multi electrode array (MEA)-based cardiotoxicity evaluation between control and Feno groups according to treatment with arrhythmia-inducing drugs, drug response was similar in a dose-dependent manner. However, main parameters such as field potential duration, beat period, and spike amplitude were different between the 2 groups. Overall, these results emphasize that applying matured hPSC-CMs to the field of preclinical cardiotoxicity evaluation, which has become an essential procedure for new drug development, is necessary.

Salidroside inhibits insulin resistance and hepatic steatosis by downregulating miR-21 and subsequent activation of AMPK and upregulation of PPARα in the liver and muscles of high fat diet-fed rats

This study evaluated if salidroside (SAL) alleviates high-fat diet (HFD)-induced non-alcoholic fatty liver disease (NAFLD) by downregulating miR-21. Rats (n = 8/group) were treated for 12 weeks as normal diet (control/ND), ND + agmoir negative control (NC) (150 µg/kg), ND + SAL (300 mg/kg), HFD, HFD + SAL, HFD + compound C (an AMPK inhibitor) (200 ng/kg), HFD + SAL + NXT629 (a PPAR-α antagonist) (30 mg/kg), and HFD + SAL + miR-21 agomir (150 µg/kg). SAL improved glucose and insulin tolerance and preserved livers in HFD-fed rats. In ND and HFD-fed rats, SAL reduced levels of serum and hepatic lipids and the hepatic expression of SREBP1, SREBP2, fatty acid (FA) synthase, and HMGCOAR. It also activated hepatic Nrf2 and increased hepatic/muscular activity of AMPK and levels of PPARα. All effects afforded by SAL were prevented by CC, NXT629, and miR-21 agmoir. In conclusion, activation of AMPK and upregulation of PPARα mediate the anti-steatotic effect of SAL.

Harnessing peroxisome proliferator-activated receptor γ agonists to induce Heme Oxygenase-1: a promising approach for pulmonary inflammatory disorders

The activation of peroxisome proliferator-activated receptor (PPAR)-γ has been extensively shown to attenuate inflammatory responses in conditions such as asthma, acute lung injury, and acute respiratory distress syndrome, as demonstrated in animal studies. However, the precise molecular mechanisms underlying these inhibitory effects remain largely unknown. The upregulation of heme oxygenase-1 (HO-1) has been shown to confer protective effects, including antioxidant, antiapoptotic, and immunomodulatory effects in vitro and in vivo. PPARγ is highly expressed not only in adipose tissues but also in various other tissues, including the pulmonary system. Thiazolidinediones (TZDs) are highly selective agonists for PPARγ and are used as antihyperglycemic medications. These observations suggest that PPARγ agonists could modulate metabolism and inflammation. Several studies have indicated that PPARγ agonists may serve as potential therapeutic candidates in inflammation-related diseases by upregulating HO-1, which in turn modulates inflammatory responses. In the respiratory system, exposure to external insults triggers the expression of inflammatory molecules, such as cytokines, chemokines, adhesion molecules, matrix metalloproteinases, and reactive oxygen species, leading to the development of pulmonary inflammatory diseases. Previous studies have demonstrated that the upregulation of HO-1 protects tissues and cells from external insults, indicating that the induction of HO-1 by PPARγ agonists could exert protective effects by inhibiting inflammatory signaling pathways and attenuating the development of pulmonary inflammatory diseases. However, the mechanisms underlying TZD-induced HO-1 expression are not well understood. This review aimed to elucidate the molecular mechanisms through which PPARγ agonists induce the expression of HO-1 and explore how they protect against inflammatory and oxidative responses.

An Overview of the Role of Peroxisome Proliferator-activated Receptors in Liver Diseases

Peroxisome proliferator-activated receptors (PPARs) are a superfamily of nuclear transcription receptors, consisting of PPARα, PPARγ, and PPARβ/δ, which are highly expressed in the liver. They control and modulate the expression of a large number of genes involved in metabolism and energy homeostasis, oxidative stress, inflammation, and even apoptosis in the liver. Therefore, they have critical roles in the pathophysiology of hepatic diseases. This review provides a general insight into the role of PPARs in liver diseases and some of their agonists in the clinic.

A cholinergic circuit that relieves pain despite opioid tolerance

Chronic pain is a tremendous burden for afflicted individuals and society. Although opioids effectively relieve pain, significant adverse outcomes limit their utility and efficacy. To investigate alternate pain control mechanisms, we explored cholinergic signaling in the ventrolateral periaqueductal gray (vlPAG), a critical nexus for descending pain modulation. Biosensor assays revealed that pain states decreased acetylcholine release in vlPAG. Activation of cholinergic projections from the pedunculopontine tegmentum to vlPAG relieved pain, even in opioid-tolerant conditions, through ⍺7 nicotinic acetylcholine receptors (nAChRs). Activating ⍺7 nAChRs with agonists or stimulating endogenous acetylcholine inhibited vlPAG neuronal activity through Ca2+ and peroxisome proliferator-activated receptor α (PPAR⍺)-dependent signaling. In vivo 2-photon imaging revealed that chronic pain induces aberrant excitability of vlPAG neuronal ensembles and that ⍺7 nAChR-mediated inhibition of these cells relieves pain, even after opioid tolerance. Finally, pain relief through these cholinergic mechanisms was not associated with tolerance, reward, or withdrawal symptoms, highlighting its potential clinical relevance.

Lonicera Caerulea Juice Alleviates Alcoholic Liver Disease by Regulating Intestinal Flora and the FXR-FGF15 Signaling Pathway

Alcoholic liver disease (ALD) is a growing public health issue with high financial, social, and medical costs. Lonicera caerulea, which is rich in polyphenolic compounds, has been shown to exert anti-oxidative and anti-inflammatory effects. This study aimed to explore the effects and mechanisms of concentrated Lonicera caerulea juice (LCJ) on ALD in mice. ALD was established in mice via gradient alcohol feeding for 30 days. The mice in the experimental group were given LCJ by gavage. The reduction of aspartate transaminase (AST) and alanine transaminase (ALT) in the serum of mice indicated that LCJ has a liver-protective effect. LCJ improved the expression of AMPK, PPARα, and CPT1b in ALD mice to reduce the liver lipid content. Additionally, LCJ increased the expression of farnesoid X receptor (FXR), fibroblast growth factor 15 (FGF15), and fibroblast growth factor receptor 4 (FGFR4), which lowers the expression of cytochrome P450 7A1 (CYP7A1) and lessens bile acid deposition in the liver. In mice, LCJ improved the intestinal barrier by upregulating the expression of mucins and tight junction proteins in the small intestine. Moreover, it accelerated the restoration of microbial homeostasis in both the large and small intestines and increased short-chain fatty acids in the cecum. In conclusion, LCJ alleviates ALD by reducing liver and serum lipid accumulation and modulating the FXR-FGF15 signaling pathway mediated by gut microbes.

Quantitative Proteomic Analysis of Tibetan Pig Livers at Different Altitudes

In this study, the differences in protein profiles between the livers of Shannan Tibetan pigs (SNT), Linzhi Tibetan pigs (LZT) and Jiuzhaigou Tibetan pigs (JZT) were comparatively analyzed by tandem mass spectrometry-labeling quantitative proteomics. A total of 6804 proteins were identified: 6471 were quantified and 1095 were screened as differentially expressed proteins (DEPs). Bioinformatics analysis results show that, compared with JZT livers, up-regulated DEPs in SNT and LZT livers mainly promoted hepatic detoxification through steroid hormone biosynthesis and participated in lipid metabolism to maintain body energy homeostasis, immune response and immune regulation, while down-regulated DEPs were mainly involved in lipid metabolism and immune regulation. Three proteases closely related to hepatic fatty acid oxidation were down-regulated in enzymatic activity, indicating higher levels of lipid oxidation in SNT and LZT livers than in JZT livers. Down-regulation of the expression of ten immunoglobulins suggests that JZT are more susceptible to autoimmune diseases. It is highly likely that these differences in lipid metabolism and immune-related proteins are in response to the ecological environment at different altitudes, and the findings contribute to the understanding of the potential molecular link between Tibetan pig livers and the environment.

Network Pharmacological Analysis of a New Herbal Combination Targeting Hyperlipidemia and Efficacy Validation In Vitro

The network pharmacology (NP) approach is a valuable novel methodology for understanding the complex pharmacological mechanisms of medicinal herbs. In addition, various in silico analysis techniques combined with the NP can improve the understanding of various issues used in natural product research. This study assessed the therapeutic effects of Arum ternata (AT), Poria cocos (PC), and Zingiber officinale (ZO) on hyperlipidemia after network pharmacologic analysis. A protein-protein interaction (PPI) network of forty-one key targets was analyzed to discover core functional clusters of the herbal compounds. The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway and gene ontology (GO) term enrichment analysis identified significant categories of hypolipidemic mechanisms. The STITCH database indicated a high connection with several statin drugs, deduced by the similarity in targets. AT, PC, and ZO regulated the genes related to the energy metabolism and lipogenesis in HepG2 cells loaded with free fatty acids (FFAs). Furthermore, the mixture of three herbs had a combinational effect. The herbal combination exerted superior efficacy compared to a single herb, particularly in regulating acetyl-CoA carboxylase (ACC) and carnitine palmitoyltransferase 1 (CPT-1). In conclusion, the network pharmacologic approach was used to assess potential targets of the herbal combination for treatment. Experimental data from FFA-induced HepG2 cells suggested that the combination of AT, PC, and ZO might attenuate hyperlipidemia and its associated hepatic steatosis.

AMPK inhibits liver gluconeogenesis: fact or fiction?

Is there a role for AMPK in the control of hepatic gluconeogenesis and could targeting AMPK in liver be a viable strategy for treating type 2 diabetes? These are frequently asked questions this review tries to answer. After describing properties of AMPK and different small-molecule AMPK activators, we briefly review the various mechanisms for controlling hepatic glucose production, mainly via gluconeogenesis. The different experimental and genetic models that have been used to draw conclusions about the role of AMPK in the control of liver gluconeogenesis are critically discussed. The effects of several anti-diabetic drugs, particularly metformin, on hepatic gluconeogenesis are also considered. We conclude that the main effect of AMPK activation pertinent to the control of hepatic gluconeogenesis is to antagonize glucagon signalling in the short-term and, in the long-term, to improve insulin sensitivity by reducing hepatic lipid content.

Lipocalin-Type Prostaglandin D2 Synthase Protein- A Central Player in Metabolism

Lipocalin-type prostaglandin D synthase was previously known as β-trace protein (BTP), a low-molecular-weight glycoprotein that is heavily expressed in human cerebrospinal fluid. Nevertheless, it is also seen to be expressed in numerous other tissues including the kidney, liver, lung, heart, adipose, muscle, and pancreas. Functionally, L-PGDS behaves like a lipocalin type protein where it helps in binding and transportation of small lipophilic substances, such as steroids, retinoids, and other lipophilic ligands. Enzymatically, L-PGDS functions as a prostaglandin synthase where it helps in the production of PGD₂ by catalyzing the isomerization of PGH₂, a common precursor of the two series of prostaglandins. PGD₂ regulates its physiological function through two individual receptors named DP1 and DP2. L-PGDS has been a central player in many diseases, its role in metabolism including diabetes, fatty liver disease, and obesity has gathered a large attention. In this review, we summarize the current state of knowledge about L-PGDS and it's signaling in adipose, hepatic, skeletal muscle, and pancreas tissues, which are core targets for metabolic studies. Modulation of L-PGDS signaling can be considered as a potential future therapeutic target for the treatment of insulin resistance as well as fatty liver disease.

Systemic Ketone Replacement Does Not Improve Survival or Cancer Cachexia in Mice With Lung Cancer

Cachexia is a debilitating comorbidity affecting many lung cancer patients. We have previously found that cachectic mice with lung cancer have reduced serum ketone body levels due to low PPARα activity in the liver. Restoring hepatic PPARα activity with fenofibrate increased circulating ketones and delayed muscle and white adipose tissue wasting. We hypothesized that the loss of circulating ketones plays a pathophysiologic role in cachexia and performed two dietary intervention studies to test this hypothesis. In the first study, male and female mice were randomized to consume either a very low carbohydrate, ketogenic diet (KD) or normal chow (NC) after undergoing tumor induction. The KD successfully restored serum ketone levels and decreased blood glucose in cachectic mice but did not improve body weight maintenance or survival. In fact, there was a trend for the KD to worsen survival in male but not in female mice. In the second study, we compounded a ketone ester supplement into the NC diet (KE) and randomized tumor-bearing mice to KE or NC after tumor induction. We confirmed that KE was able to acutely and chronically increase ketone body abundance in the serum compared to NC. However, the restoration of ketones in the circulation was not able to improve body weight maintenance or survival in male or female mice with lung cancer. Finally, we investigated PPARα activity in the liver of mice fed KE and NC and found that animals fed a ketone ester supplement showed a significant increase in mRNA expression of several PPARα targets. These data negate our initial hypothesis and suggest that restoring ketone body availability in the circulation of mice with lung cancer does not alter cachexia development or improve survival, despite increasing hepatic PPARα activity.

Identification of Structural and Molecular Signatures Mediating Adaptive Changes in the Mouse Kidney in Response to Pregnancy

Pregnancy is characterized by adaptations in the function of several maternal body systems that ensure the development of the fetus whilst maintaining health of the mother. The renal system is responsible for water and electrolyte balance, as well as waste removal. Thus, it is imperative that structural and functional changes occur in the kidney during pregnancy. However, our knowledge of the precise morphological and molecular mechanisms occurring in the kidney during pregnancy is still very limited. Here, we investigated the changes occurring in the mouse kidney during pregnancy by performing an integrated analysis involving histology, gene and protein expression assays, mass spectrometry profiling and bioinformatics. Data from non-pregnant and pregnant mice were used to identify critical signalling pathways mediating changes in the maternal kidneys. We observed an expansion of renal medulla due to proliferation and infiltration of interstitial cellular constituents, as well as alterations in the activity of key cellular signalling pathways (e.g., AKT, AMPK and MAPKs) and genes involved in cell growth/metabolism (e.g., Cdc6, Foxm1 and Rb1) in the kidneys during pregnancy. We also generated plasma and urine proteomic profiles, identifying unique proteins in pregnancy. These proteins could be used to monitor and study potential mechanisms of renal adaptations during pregnancy and disease.

Effects of 1,3,7-tribromodibenzo-p-dioxin, a natural dioxin on chicken embryos: Comparison with effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin

Several naturally occurring dioxins, including 1,3,7-tribromodibenzo-p-dioxin (1,3,7-TriBDD), synthesized by red algae, have been detected in the marine environment. As 1,3,7-TriBDD is accumulated in mussels and fish, predators, such as marine birds, are exposed to this congener, similar to anthropogenic dioxins (including 2,3,7,8-tetrachlorodibenzo-p-dioxin TCDD). However, little is known about the impact of 1,3,7-TriBDD exposure on the bird health. To understand the effects of 1,3,7-TriBDD on birds, the phenotypic effects and hepatic transcriptome were investigated in chicken (Gallus gallus) embryos treated with 27 μM (2.9 ng/g egg) and 137 μM (14.4 ng/g egg) 1,3,7-TriBDD. The blood glucose levels in the 1,3,7-TriBDD-treated groups were lower than those in the control group. The transcriptome analysis of 6520 sequences in the 27 and 137 μM 1,3,7-TriBDD-treated groups identified 733 and 596 differentially expressed genes (DEGs). Cytochrome P450 1A4 and 1A5 were also identified as DEGs, suggesting that the aryl hydrocarbon receptor is activated by this congener. Pathway and network analyses with DEGs suggested that 1,3,7-TriBDD may induce carcinogenic effects and metabolic alterations. These results were similar to the effects on TCDD-treated embryos. Nevertheless, the overall transcriptome results suggested that compared with TCDD, 1,3,7-TriBDD has a unique impact on insulin- and peroxisome-signaling pathways in chicken embryos. Differences in altered transcriptome profiles between 1,3,7-TriBDD- and TCDD-treated embryos may lead to different phenotypic effects: less severe effects of 1,3,7-TriBDD and more fatal effects of TCDD. Collectively, these findings warrant the further assessment of the hazard and risk of 1,3,7-TriBDD on marine animals, considering increased exposure due to climate change.

Cevimeline co-treatment attenuates olanzapine-induced metabolic disorders via modulating hepatic M3 muscarinic receptor: AMPKα signalling pathway in female rats

BACKGROUND

Olanzapine is one of the most commonly used antipsychotic drugs; however, its metabolic disorders are the main obstacle in the clinic. Olanzapine is a potent antagonist of the M3 acetylcholine muscarinic receptor (M3R), while the downregulated hepatic M3R-AMPKα signalling pathway is involved in metabolic disorders.

AIM

This study investigated the effects of chronic co-treatment with cevimeline (an agonist of M3Rs) in attenuating olanzapine-induced metabolic disorders and the underlying mechanisms.

METHODS

Forty-eight adult female Sprague-Dawley rats were treated orally with olanzapine (2 mg/kg, 3 times/day (t.i.d.)) and/or cevimeline (9 mg/kg, t.i.d.), or control (vehicle) for 9 weeks.

RESULTS

Cevimeline co-treatment significantly attenuated olanzapine-induced body weight gain and glucolipid metabolic disorders. Importantly, cevimeline co-treatment attenuated olanzapine-induced upregulation of M3Rs, while the co-treatment improved olanzapine-induced downregulation of AMPKα in the liver. Cevimeline co-treatment attenuated olanzapine-induced dyslipidaemia by modulating the hepatic M3R-AMPKα downstream pathways. Cevimeline co-treatment also improved lower activated AKT-GSK3β signalling to reverse impairment of glucose metabolism and insulin resistance caused by chronic olanzapine treatment.

CONCLUSION

These results not only support the important role of M3R antagonism and its related AMPKα and downstream pathways in antipsychotic-induced metabolic disorders but also indicate that these pathways might be promising targets for pharmacological intervention to control these side effects caused by antipsychotic therapy.

Identifying the Metabolic Signatures of PPARD-Overexpressing Gastric Tumors

Peroxisome proliferator-activated receptor delta (PPARD) is a nuclear receptor known to play an essential role in regulation of cell metabolism, cell proliferation, inflammation, and tumorigenesis in normal and cancer cells. Recently, we found that a newly generated villin-PPARD mouse model, in which PPARD is overexpressed in villin-positive gastric progenitor cells, demonstrated spontaneous development of large, invasive gastric tumors as the mice aged. However, the role of PPARD in regulation of downstream metabolism in normal gastric and tumor cells is elusive. The aim of the present study was to find PPARD-regulated downstream metabolic changes and to determine the potential significance of those changes to gastric tumorigenesis in mice. Hyperpolarized [1-13C] pyruvate magnetic resonance spectroscopy, nuclear magnetic resonance spectroscopy, and liquid chromatography-mass spectrometry were employed for metabolic profiling to determine the PPARD-regulated metabolite changes in PPARD mice at different ages during the development of gastric cancer, and the changes were compared to corresponding wild-type mice. Nuclear magnetic resonance spectroscopy-based metabolomic screening results showed higher levels of inosine monophosphate (p = 0.0054), uracil (p = 0.0205), phenylalanine (p = 0.017), glycine (p = 0.014), and isocitrate (p = 0.029) and lower levels of inosine (p = 0.0188) in 55-week-old PPARD mice than in 55-week-old wild-type mice. As the PPARD mice aged from 10 weeks to 35 weeks and 55 weeks, we observed significant changes in levels of the metabolites inosine monophosphate (p = 0.0054), adenosine monophosphate (p = 0.009), UDP-glucose (p = 0.0006), and oxypurinol (p = 0.039). Hyperpolarized [1-13C] pyruvate magnetic resonance spectroscopy performed to measure lactate flux in live 10-week-old PPARD mice with no gastric tumors and 35-week-old PPARD mice with gastric tumors did not reveal a significant difference in the ratio of lactate to total pyruvate plus lactate, indicating that this PPARD-induced spontaneous gastric tumor development does not require glycolysis as the main source of fuel for tumorigenesis. Liquid chromatography-mass spectrometry-based measurement of fatty acid levels showed lower linoleic acid, palmitic acid, oleic acid, and steric acid levels in 55-week-old PPARD mice than in 10-week-old PPARD mice, supporting fatty acid oxidation as a bioenergy source for PPARD-expressing gastric tumors.

A Novel Multidrug Combination Mitigates Rat Liver Steatosis Through Activating AMPK Pathway During Normothermic Machine Perfusion

BACKGROUND

Hepatic steatosis is now the leading cause of liver discards in deceased donors. Previous studies [Yarmush formula (Y) defatting] have successfully reduced the fat content by treating rat steatotic livers on extracorporeal normothermic machine perfusion (NMP) with a multidrug combination including the GW compounds that were linked to an increased risk of carcinogenesis.

METHODS

We developed a novel multidrug combination by replacing the GW compounds with 2 polyphenols, epigallocatechin-3-gallate (E) and resveratrol (R). Sixteen rat livers were placed on NMP and assigned to control, Y defatting, Y + E + R defatting, or Y'-GW + E + R defatting groups (Y'-GW = 90% dose-reduced Y defatting, n = 4/group).

RESULTS

All livers in defatting groups had significant decreases in hepatic triglyceride content at the end of the experiment. However, livers treated with our novel Y'-GW + E + R combination had evidence of increased metabolism and less hepatocyte damage and carcinogenic potential. Our Y'-GW + E + R combination had increased phosphorylation of AMP-activated protein kinase (P = 0.019) and acetyl-CoA carboxylase (P = 0.023) compared with control; these were not increased in Y + E + R group and actually decreased in the Y group. Furthermore, the Y'-GW + E + R group had less evidence of carcinogenic potential with no increase in AKT phosphorylation compared with control (P = 0.089); the Y (P = 0.031) and Y + E + R (P = 0.035) groups had striking increases in AKT phosphorylation. Finally, our Y'-GW + E + R showed less evidence of hepatocyte damage with significantly lower perfusate alanine aminotransferase (P = 0.007) and aspartate aminotransferase (P = 0.014) levels.

CONCLUSIONS

We have developed a novel multidrug combination demonstrating promising defatting efficacy via activation of the AMP-activated protein kinase pathway with an optimized safety profile and reduced hepatotoxicity during ex vivo NMP.

The adiponectin signalling pathway - A therapeutic target for the cardiac complications of type 2 diabetes?

Diabetes is associated with an increased risk of heart failure (HF). This is commonly termed diabetic cardiomyopathy and is often characterised by increased cardiac fibrosis, pathological hypertrophy, increased oxidative and endoplasmic reticulum stress as well as diastolic dysfunction. Adiponectin is a cardioprotective adipokine that is downregulated in settings of type 2 diabetes (T2D) and obesity. Furthermore, both adiponectin receptors (AdipoR1 and R2) are also downregulated in these settings which further results in impaired cardiac adiponectin signalling and reduced cardioprotection. In many cardiac pathologies, adiponectin signalling has been shown to protect against cardiac remodelling and lipotoxicity, however its cardioprotective actions in T2D-induced cardiomyopathy remain unresolved. Diabetic cardiomyopathy has historically lacked effective treatment options. In this review, we summarise the current evidence for links between the suppressed adiponectin signalling pathway and cardiac dysfunction, in diabetes. We describe adiponectin receptor-mediated signalling pathways that are normally associated with cardioprotection, as well as current and potential future therapeutic approaches that could target this pathway as possible interventions for diabetic cardiomyopathy.

Analysis of miRNAs Profiles in Serum of Patients With Steatosis and Steatohepatitis

Non-alcoholic fatty liver disease (NAFLD) is emerging as one of the most common chronic liver diseases worldwide, affecting 25% of the world population. In recent years, there has been increasing evidence for the involvement of microRNAs in the epigenetic regulation of genes taking part in the development of steatosis and steatohepatitis—two main stages of NAFLD pathogenesis. In the present study, miRNA profiles were studied in groups of patients with steatosis and steatohepatitis to compare the characteristics of RNA-dependent epigenetic regulation of the stages of NAFLD development. According to the results of miRNA screening, 23 miRNAs were differentially expressed serum in a group of patients with steatohepatitis and 2 in a group of patients with steatosis. MiR-195-5p and miR-16-5p are common differentially expressed miRNAs for both steatosis and steatohepatitis. We analyzed the obtained results: the search for target genes for the differentially expressed miRNAs in our study and the subsequent gene set enrichment analysis performed on KEGG and REACTOME databases revealed which metabolic pathways undergo changes in RNA-dependent epigenetic regulation in steatosis and steatohepatitis. New findings within the framework of this study are the dysregulation of neurohumoral pathways in the pathogenesis of NAFLD as an object of changes in RNA-dependent epigenetic regulation. The miRNAs differentially expressed in our study were found to target 7% of genes in the classic pathogenesis of NAFLD in the group of patients with steatosis and 50% in the group of patients with steatohepatitis. The effects of these microRNAs on genes for the pathogenesis of NAFLD were analyzed in detail. MiR-374a-5p, miR-1-3p and miR-23a-3p do not target genes directly involved in the pathogenesis of NAFLD. The differentially expressed miRNAs found in this study target genes largely responsible for mitochondrial function. The role of miR-423-5p, miR-143-5p and miR-200c-3 in regulating apoptotic processes in the liver and hepatocarcinogenesis is of interest for future experimental studies. These miR-374a, miR-143, miR-1, miR-23a, and miR-423 have potential for steatohepatitis diagnosis and are poorly studied in the context of NAFLD. Thus, this work opens up prospects for further studies of microRNAs as diagnostic and therapeutic biomarkers for NAFLD.

Targeting autophagy in ischemic stroke: From molecular mechanisms to clinical therapeutics

Stroke constitutes the second leading cause of death and a major cause of disability worldwide. Stroke is normally classified as either ischemic or hemorrhagic stroke (HS) although 87% of cases belong to ischemic nature. Approximately 700,000 individuals suffer an ischemic stroke (IS) in the US each year. Recent evidence has denoted a rather pivotal role for defective macroautophagy/autophagy in the pathogenesis of IS. Cellular response to stroke includes autophagy as an adaptive mechanism that alleviates cellular stresses by removing long-lived or damaged organelles, protein aggregates, and surplus cellular components via the autophagosome-lysosomal degradation process. In this context, autophagy functions as an essential cellular process to maintain cellular homeostasis and organismal survival. However, unchecked or excessive induction of autophagy has been perceived to be detrimental and its contribution to neuronal cell death remains largely unknown. In this review, we will summarize the role of autophagy in IS, and discuss potential strategies, particularly, employment of natural compounds for IS treatment through manipulation of autophagy.

Magnolia officinalis Ameliorates Dehydroepiandrosterone-Induced Polycystic Ovary Syndrome in Rats

Background: Polycystic ovary syndrome (PCOS) is a prevalent reproductive and metabolic disorder. Insulin resistance (IR) is highly associated with PCOS and aggravates its symptoms. Thiazolidinediones (TZDs), as insulin sensitizing agents, are PPARγ agonists that improve many of the symptoms of PCOS. The Magnolia officinalis extract (MOE) is a natural peroxisome proliferator activated receptor gamma (PPARγ) agonist that improves insulin sensitivity in experimental models. Objectives: Using a dehydroepiandrosterone (DHEA)-induced rat model of PCOS and IR, this study aimed to explore both the potential beneficial effects and the molecular mechanisms of action of MOE. Methods: Post-pubertal female Sprague Dawley rats were subcutaneously injected daily with DHEA (6 mg/100 g body weight) dissolved in sesame oil for 28 days (n = 30). Age- and weight-matched control rats received only sesame oil (n = 12). Afterward, 16 of the DHEA-injected rats, along with five control rats, were sacrificed for blood and tissue collection. The 14 remaining DHEA-injected rats received either treatment of 30 days of oral MOE (500 mg/kg) dissolved in dimethyl sulfoxide (DMSO) (n = 7), or oral DMSO only (n = 7). Meanwhile, the remaining control rats (n = 7) continued to receive daily oral DMSO for 30 days. At the end of the treatments, the rats were sacrificed for blood and tissue collection. Results: After 28 days, the DHEA-treated rats exhibited an increase in body weight as compared to controls (P < 0.05). DHEA injection induced a PCOS phenotype as evident by a statistically significant (P < 0.05) elevated serum luteinizing hormone (LH), and an increased number of cystically dilated follicles with thicker granulosa compared to controls. PCOS rats showed a statistically significant rise in fasting insulin with an increased homeostatic model assessment index of insulin resistance (HOMA-IR) as compared to controls (P < 0.05). Compared to the control group, PCOS rats had a statistically significant lower ovarian protein expression of PPARγ, insulin receptor substrate 1 (IRS1), and protein kinase B (Akt) by Western Blot (P < 0.05). Conversely, the PCOS group showed an increased mammalian target of rapamycin (mTOR) pathway activity as evident by an increase in the fraction of phosphorylated mTOR to total mTOR compared to the control group (P < 0.05). When treated for 30 days with oral MOE (500 mg/kg), the PCOS rats showed a statistically significant decrease in body weight and serum LH levels as compared to the non-treated PCOS rats (P < 0.05). The number of cystically dilated follicles in the MOE-treated PCOS rats was significantly reduced compared to the non-treated PCOS rats. In the MOE-treated PCOS rats, the ovarian protein expression of PPARγ, IRS1, and Akt was significantly increased, while the p-mTOR/mTOR expression was decreased compared to the non-treated PCOS group (P < 0.05). Conclusions: According to our results, the MOE ameliorated the DHEA-induced PCOS phenotype histologically, hormonally, and metabolically. Fundamentally, this explores the elusive pathophysiologic association between IR and PCOS by targeting pathways common to both disorders.

Syringaldehyde promoting intestinal motility with suppressing α-amylase hinders starch digestion in diabetic mice

The antihyperglycemic potential of syringaldehyde has been previously investigated; however, the underlying mechanism remains unclear. In this study, we performed a postprandial glucose test (in vivo) including oral glucose tolerance test (OGTT) and oral starch tolerance test (OSTT) in fructose-induced diabetic mice on a high-fat diet for mimicking type 2 diabetes to explore the hypoglycemic efficacy of syringaldehyde and the underlined molecular involvement of syringaldehyde in a glucose-lowering effect. The results revealed that syringaldehyde dose-dependently suppressed blood glucose in both the OSTT and OGTT when referenced to acarbose and metformin, respectively. Surprisingly, syringaldehyde triggered jejunum motility (ex vivo) via activation of the muscarinic-type acetylcholine receptor. By performing virtual screening with molecular docking, the data showed that syringaldehyde nicely interacted with glucagon-like peptide 1 receptor (GLP-1R), peroxisome proliferator-activated receptor (PPAR), dipeptidyl peptidase-IV (DPP-4), acetylcholine M2 receptor, and acetylcholinesterase. These results showed that syringaldehyde can potentiate intestinal contractility to abolish the α-amylase reaction when concurrently reducing retention time and glucose absorption to achieve a glucose-lowering effect in diabetic mice, suggesting its potential therapeutic benefits with improvement for use as a prophylactic and treatment.

Fenofibrate, a PPARα agonist, reduces hepatic fat accumulation through the upregulation of TFEB-mediated lipophagy

BACKGROUND

Recent studies have shown that dysregulation of autophagy is involved in the development of nonalcoholic fatty liver disease (NAFLD). Transcription factors E3 (TFE3) and EB (TFEB) are master regulators of the transcriptional response of basic cellular processes such as lysosomal biogenesis and autophagy. Here, we investigated the role of fenofibrate, a PPARα agonist, in promotion of intracellular lipid clearance by upregulation of TFEB/TFE3.

METHODS

We investigated whether the effects of fenofibrate on livers were dependent on TFEB in high fat diet (HFD)-fed mice and in vivo Tfeb knockdown mice. These mice were analyzed for characteristics of obesity and diabetes; the effects of fenofibrate on hepatic fat content, glucose sensitivity, insulin resistance, and autophagy functional dependence on TFEB were investigated. HepG2, Hep3B, TSC2^+/+ and tsc2^-/- MEFs, tfeb wild type- and tfeb knockout-HeLa cells were used for in vitro experiments.

RESULTS

Fenofibrate treatment activated autophagy and TFEB/TFE3 and reduced hepatic fat accumulation in an mTOR-independent manner. Knockdown of TFEB offset the effects of fenofibrate on autophagy and hepatic fat accumulation. In addition, fenofibrate treatment induced lysosomal Ca²⁺ release through mucolipin 1, activated calcineurin and the CaMKKβ-AMPK-ULK1 pathway, subsequently promoted TFEB and TFE3 dephosphorylation and nuclear translocation. Treatment with calcium chelator or knockdown of mucolipin 1 in hepatocytes offset the effects of fenofibrate treatment on autophagy and hepatic fat accumulation.

CONCLUSION

Activation of PPARα ameliorates hepatic fat accumulation via activation of TFEB and lipophagy induction. Lysosomal calcium signaling appears to play a critical role in this process. In addition, activation of TFEB by modulating nuclear receptors including PPARα with currently available drugs or new molecules might be a therapeutic target for treatment of NAFLD and other cardiometabolic diseases.

Alcoholic and Non-Alcoholic Liver Diseases: Promising Molecular Drug Targets and their Clinical Development

Alcoholic and non-alcoholic fatty liver diseases have become a serious concern worldwide. Both these liver diseases have an identical pathology, starting from simple steatosis to cirrhosis and, ultimately to hepatocellular carcinoma. Treatment options for alcoholic liver disease (ALD) are still the same as they were 50 years ago which include corticosteroids, pentoxifylline, antioxidants, nutritional support and abstinence; and for non-alcoholic fatty liver disease (NAFLD), weight loss, insulin sensitizers, lipid-lowering agents and anti-oxidants are the only treatment options. Despite broad research in understanding the disease pathophysiology, limited treatments are available for clinical use. Some therapeutic strategies based on targeting a specific molecule have been developed to lessen the consequences of disease and are under clinical investigation. Therefore, focus on multiple molecular targets will help develop an efficient therapeutic strategy. This review comprises a brief overview of the pathogenesis of ALD and NAFLD; recent molecular drug targets explored for ALD and NAFLD that may prove to be effective for multiple therapeutic regimens and also the clinical status of these promising drug targets for liver diseases.

Fabrication of All-Trans Retinoic Acid loaded Chitosan/Tripolyphosphate Lipid Hybrid Nanoparticles as a Novel Oral Delivery Approach for Management of Diabetic Nephropathy in Rats

The present study aims to formulate all-trans retinoic acid (ATRA) loaded chitosan/tripolyphosphate lipid hybrid nanoparticles (CTLHNs) for enhancing its solubility and oral delivery. This is to improve ATRA therapeutic effect on diabetic nephropathy (DN). CTLHNs were prepared by o/w homogenization, employing stearic acid, to form lipid nanoparticles coated with chitosan that is stabilized against acidic pH via sodium tripolyphosphate crosslinking. Chitosan coated (F7) and naked lipid nanoparticles (F6) were also prepared for comparison with CTLHNs. In vitro characterization for the prepared formulations was performed comprising entrapment efficiency, particle size, zeta potential, transmission electron microscopy, FT-IR spectroscopy and x-ray diffraction. Stability of chitosan coat in GI fluid revealed that CTLHNs were more stable than F7. In vitro release indicated an enhanced release of ATRA from the developed formulations. In vitro mucoadhesion study proved a notable mucoadhesive property for CTLHNs. In DN rat model, serum levels of creatinine and urea were elevated, over expression of tumor necrosis factor alpha (TNF-α), granulocyte macrophage colony-stimulating factor (GM-CSF), vascular endothelial growth factor (VEGF) and intercellular adhesion molecule-1 (ICAM-1) were observed. In addition, adenosine monophosphate activated protein kinase (AMPK) and liver kinase B1 (LKB1) expressions were decreased in DN rats. Treatment with free ATRA and the selected formulations led to a significant amelioration of DN by reducing of creatinine, urea, TNF-α, ICAM-1, GM-CSF, VEGF levels as well as elevating AMPK and LKB1 levels. The order of activity was: CTLHNs > F7 > F6 > free ATRA, as proved by histopathological examination.

Cardiovascular protection effect of chlorogenic acid: focus on the molecular mechanism

Vascular endothelial cells have a variety of functions such as the control of blood coagulation, vascular permeability, and tone regulation, as well as quiesce of immune cells. Endothelial dysfunction is a cardiovascular events predictor, which is considered the initial stage in atherosclerosis development. It is characterized by alterations in endothelium functions due to imbalanced vasodilators and vasoconstrictors, procoagulant and anticoagulant mediators, as well as growth inhibitor and promotor substances. Chlorogenic acid (CGA) is the primary polyphenol in coffee and some fruits. It has many health-promoting properties, especially in the cardiovascular system. Many studies investigated the efficacy and mechanism of this compound in vascular health. CGA has several vascular benefits such as anti-atherosclerosis, anti-thrombosis, and anti-hypertensive. This review focuses on the molecular mechanism of CGA in vascular health.

α-Amyrin induces GLUT4 translocation mediated by AMPK and PPARδ/γ in C2C12 myoblasts

α-Amyrin, a natural pentacyclic triterpene, has an antihyperglycemic effect in mice and dual PPARδ/γ action in 3T3-L1 adipocytes, and potential in the control of type 2 diabetes (T2D). About 80% of glucose uptake occurs in skeletal muscle cells, playing a significant role in insulin resistance (IR) and T2D. Peroxisome-proliferator activated receptors (PPARs), in particular PPARδ and PPARγ, are involved in the regulation of lipids and carbohydrates and, along with adenosine-monophosphate (AMP) - activated protein kinase (AMPK) and protein kinase B (Akt), are implicated in translocation of glucose transporter 4 (GLUT4); however, it is still unknown whether α-amyrin can affect these pathways in skeletal muscle cells. Our objective was to determine the action of α-amyrin in PPARδ, PPARγ, AMPK, and Akt in C2C12 myoblasts. The expression of PPARδ, PPARγ, fatty acid transporter protein (FATP), and GLUT4 was quantified using reverse transcription quantitative PCR and Western blot. α-Amyrin increased these markers along with phospho-AMPK (p-AMPK) but not p-Akt. Molecular docking showed that α-amyrin acts as an AMPK-allosteric activator, and may be related to GLUT4 translocation, as evidenced by confocal microscopy. These data support that α-amyrin could have an insulin-mimetic action in C2C12 myoblasts and should be considered as a bioactive molecule for new multitarget drugs with utility in T2D and other metabolic diseases.

PPARs in liver physiology

Peroxisome proliferator-activated receptors (PPARs) are nuclear receptors and transcriptional modulators with crucial functions in hepatic and whole-body energy homeostasis. Besides their well-documented roles in lipid and glucose metabolism, emerging evidence also implicate PPARs in the control of other processes such as inflammatory responses. Recent technological advances, such as single-cell RNA sequencing, have allowed to unravel an unexpected complexity in the regulation of PPAR expression, activity and downstream signaling. Here we provide an overview of the latest advances in the study of PPARs in liver physiology, with a specific focus on formerly neglected aspects of PPAR regulation, such as tissular zonation, cellular heterogeneity, circadian rhythms, sexual dimorphism and species-specific features.

Enhanced cardiac hypoxic injury in atherogenic dyslipidaemia results from alterations in the energy metabolism pattern

OBJECTIVE

Dyslipidaemia is a major risk factor for myocardial infarction that is known to correlate with atherosclerosis in the coronary arteries. We sought to clarify whether metabolic alterations induced by dyslipidaemia in cardiomyocytes collectively constitute an alternative pathway that escalates myocardial injury.

METHODS

Dyslipidaemic apolipoprotein E and low-density lipoprotein receptor (ApoE/LDLR) double knockout (ApoE^-/-/LDLR^-/-) and wild-type C57BL/6 (WT) mice aged six months old were studied. Cardiac injury under reduced oxygen supply was evaluated by 5 min exposure to 5% oxygen in the breathing air under electrocardiogram (ECG) recording and with the assessment of troponin I release. To address the mechanisms LC/MS was used to analyse the cardiac proteome pattern or in vivo metabolism of stable isotope-labelled substrates and HPLC was applied to measure concentrations of cardiac high-energy phosphates. Furthermore, the effect of blocking fatty acid use with ranolazine on the substrate preference and cardiac hypoxic damage was studied in ApoE^-/-/LDLR^-/- mice.

RESULTS

Hypoxia induced profound changes in ECG ST-segment and troponin I leakage in ApoE^-/-/LDLR^-/- mice but not in WT mice. The evaluation of the cardiac proteomic pattern revealed that ApoE^-/-/LDLR^-/- as compared with WT mice were characterised by coordinated increased expression of mitochondrial proteins, including enzymes of fatty acids' and branched-chain amino acids' oxidation, accompanied by decreased expression levels of glycolytic enzymes. These findings correlated with in vivo analysis, revealing a reduction in the entry of glucose and enhanced entry of leucine into the cardiac Krebs cycle, with the cardiac high-energy phosphates pool maintained. These changes were accompanied by the activation of molecular targets controlling mitochondrial metabolism. Ranolazine reversed the oxidative metabolic shift in ApoE^-/-/LDLR^-/- mice and reduced cardiac damage induced by hypoxia.

CONCLUSIONS

We suggest a novel mechanism for myocardial injury in dyslipidaemia that is consequent to an increased reliance on oxidative metabolism in the heart. The alterations in the metabolic pattern that we identified constitute an adaptive mechanism that facilitates maintenance of metabolic equilibrium and cardiac function under normoxia. However, this adaptation could account for myocardial injury even in a mild reduction of oxygen supply.

Design, synthesis and in vitro antiproliferative activity of new thiazolidinedione-1,3,4-oxadiazole hybrids as thymidylate synthase inhibitors

Thymidylate synthase (TS) has been an attention-grabbing area of research for the treatment of cancers due to their role in DNA biosynthesis. In the present study, we have synthesised a library of thiazolidinedione-1,3,4-oxadiazole hybrids as TS inhibitors. All the synthesised hybrids followed Lipinski and Veber rules which indicated good drug likeness properties upon oral administration. Among the synthesised hybrids, compound 9 and 10 displayed 4.5 and 4.4 folds activity of 5-Fluorouracil, respectively against MCF-7 cell line whereas 3.1 and 2.5 folds cytotoxicity against HCT-116 cell line. Furthermore, compound 9 and 10 also inhibited TS enzyme with IC50 = 1.67 and 2.21 µM, respectively. Finally, the docking studies of 9 and 10 were found to be consistent with in vitro TS results. From these studies, compound 9 and 10 has the potential to be developed as TS inhibitors.

Critical Role for AMPK in Metabolic Disease-Induced Chronic Kidney Disease

Chronic kidney disease (CKD) is prevalent in 9.1% of the global population and is a significant public health problem associated with increased morbidity and mortality. CKD is associated with highly prevalent physiological and metabolic disturbances such as hypertension, obesity, insulin resistance, cardiovascular disease, and aging, which are also risk factors for CKD pathogenesis and progression. Podocytes and proximal tubular cells of the kidney strongly express AMP-activated protein kinase (AMPK). AMPK plays essential roles in glucose and lipid metabolism, cell survival, growth, and inflammation. Thus, metabolic disease-induced renal diseases like obesity-related and diabetic chronic kidney disease demonstrate dysregulated AMPK in the kidney. Activating AMPK ameliorates the pathological and phenotypical features of both diseases. As a metabolic sensor, AMPK regulates active tubular transport and helps renal cells to survive low energy states. AMPK also exerts a key role in mitochondrial homeostasis and is known to regulate autophagy in mammalian cells. While the nutrient-sensing role of AMPK is critical in determining the fate of renal cells, the role of AMPK in kidney autophagy and mitochondrial quality control leading to pathology in metabolic disease-related CKD is not very clear and needs further investigation. This review highlights the crucial role of AMPK in renal cell dysfunction associated with metabolic diseases and aims to expand therapeutic strategies by understanding the molecular and cellular processes underlying CKD.

Time-restricted feeding for the prevention of cardiometabolic diseases in high-stress occupations: a mechanistic review

Factors such as shift work, poor diet, lack of physical activity, and irregular sleep patterns put men and women employed in high-stress occupations (e.g., firefighters, police officers) at risk for cardiometabolic diseases. Time-restricted feeding (TRF) is a new approach to combatting many of these diseases; it places an emphasis on when meals are consumed, rather than calorie content. By only manipulating the eating "window," and without changing the food composition of the diet, research in rodent models has shown promising results that have health implications in people, such as obesity prevention, improved insulin sensitivity, and decreased oxidative stress, inflammation, and cholesterol synthesis. Human trials remain limited and the current data are mixed with regard to TRF and improving health. Present findings suggest the timing of the feeding-fasting window, with feeding taking place in the waking hours and fasting in the evening hours, might offer the greatest benefit for improving cardiometabolic markers. Although additional human trials are needed, TRF might reset and synchronize metabolic "clocks" found throughout the body that are disturbed with obesity, shift work, and frequent eating. Therefore, TRF might offer an effective feeding-fasting paradigm with significant clinical implications for the management and treatment of cardiometabolic diseases observed in individuals in high-stress occupations in the United States and in the US population in general. This review outlines the current rodent and human evidence in these areas and the efficacy of TRF for improving human health.

Isoorientin ameliorates lipid accumulation by regulating fat browning in palmitate-exposed 3T3-L1 adipocytes

Stimulation of fat browning using natural bioactive products is regarded as one of the promising approaches to treat obesity and insulin resistance. Here, we investigated the physiological effects of isoorientin on glucose uptake and lipid accumulation in insulin resistant 3T3-L1 adipocytes. To achieve this, 3T3-L1 adipocytes were exposed to 0.75 mM palmitate for 24 h, to induce insulin resistance, before treatment with 10 μM isoorientin or the comparative controls such as CL-316,243 (10 μM), pioglitazone (10 μM) and compound C (1 μM) for 4 h. Relevant bioassays and Western blot analysis were conducted on these insulin resistant cells. Our results showed that palmitate exposure could induce insulin resistance and mitochondrial dysfunction as measured by reduction in glucose uptake and impaired mitochondrial bioenergetics parameters. However, treatment with isoorientin reversed these effects by improving glucose uptake, blocking lipid accumulation, and modulating the process of mitochondrial respiration. Mechanistically, isoorientin could mediate lipid metabolism by activating 5' AMP-activated protein kinase (AMPK), while also effectively modulating the expression of genes involved in fat browning such as peroxisome proliferator-activated receptor gamma (PPAR)γ/α and uncoupling protein 1 (UCP1). In conclusion, isoorientin impacts insulin resistance in vitro by improving glucose uptake and mitochondrial function, consistent to modulating the expression of genes involved in energy metabolism and fat browning.

The Protective Effects of Imperatorin on Acetaminophen Overdose-Induced Acute Liver Injury

Acetaminophen (APAP) toxicity leads to severe acute liver injury (ALI) by inducing excessive oxidative stress, inflammatory response, and hepatocyte apoptosis. Imperatorin (IMP) is a furanocoumarin from Angelica dahurica, which has antioxidant and anti-inflammatory effects. However, its potential to ameliorate ALI is unknown. In this study, APAP-treated genetic knockout of Farnesoid X receptor (FXR) and Sirtuin 1 (SIRT1) mice were used for research. The results revealed that IMP could improve the severity of liver injury and inhibit the increase of proinflammatory cytokines, oxidative damage, and apoptosis induced by overdose APAP in an FXR-dependent manner. We also found that IMP enhanced the activation and translocation of FXR by increasing the expression of SIRT1 and the phosphorylation of AMPK. Besides, single administration of IMP at 4 h after APAP injection can also improve necrotic areas and serum transaminase, indicating that IMP have both preventive and therapeutic effects. Taken together, it is the first time to demonstrate that IMP exerts protective effects against APAP overdose-induced hepatotoxicity by stimulating the SIRT1-FXR pathway. These findings suggest that IMP is a potential therapeutic candidate for ALI, offering promise for the treatment of hepatotoxicity associated with APAP overdose.

The effects of dietary linoleic acid and hydrophilic antioxidants on basal, peak, and sustained metabolism in flight-trained European starlings

Dietary micronutrients have the ability to strongly influence animal physiology and ecology. For songbirds, dietary polyunsaturated fatty acids (PUFAs) and antioxidants are hypothesized to be particularly important micronutrients because of their influence on an individual's capacity for aerobic metabolism and recovery from extended bouts of exercise. However, the influence of specific fatty acids and hydrophilic antioxidants on whole-animal performance remains largely untested. We used diet manipulations to directly test the effects of dietary PUFA, specifically linoleic acid (18:2n6), and anthocyanins, a hydrophilic antioxidant, on basal metabolic rate (BMR), peak metabolic rate (PMR), and rates of fat catabolism, lean catabolism, and energy expenditure during sustained flight in a wind tunnel in European starlings (Sturnus vulgaris). BMR, PMR, energy expenditure, and fat metabolism decreased and lean catabolism increased over the course of the experiment in birds fed a high (32%) 18:2n6 diet, while birds fed a low (13%) 18:2n6 diet exhibited the reverse pattern. Additionally, energy expenditure, fat catabolism, and flight duration were all subject to diet-specific effects of whole-body fat content. Dietary antioxidants and diet-related differences in tissue fatty acid composition were not directly related to any measure of whole-animal performance. Together, these results suggest that the effect of dietary 18:2n6 on performance was most likely the result of the signaling properties of 18:2n6. This implies that dietary PUFA influence the energetic capabilities of songbirds and could strongly influence songbird ecology, given their availability in terrestrial systems.

Fenofibrate Reverses Dysfunction of EPCs Caused by Chronic Heart Failure

The enhanced activity of endothelial progenitor cells (EPCs) by AMP-activated protein kinase (AMPK) agonists might explain the reversal of chronic heart failure (CHF)-mediated endothelial dysfunction. We studied baseline circulating EPC numbers in patients with heart failure and clarified the effect of fenofibrate on both circulating angiogenic cell (CAC) and late EPC activity. The numbers of circulating EPCs in CHF patients were quantified by flow cytometry. Blood-derived mononuclear cells were cultured, and CAC and late EPC functions, including fibronectin adhesion, tube formation, and migration, were evaluated. We focused on the effect of fenofibrate, an AMPK agonist, on EPC function and Akt/eNOS cascade activation in vitro. The number of circulating EPCs (CD34⁺/KDR⁺) was significantly lower in CHF patients (ischemic cardiomyopathy (ICMP): 0.07%, dilated cardiomyopathy (DCMP): 0.068%; p < 0.05) than in healthy subjects (0.102% of the gating region). In CACs, fibronectin adhesion function was reversed by fenofibrate treatment (p < 0.05). Similar results were also found for tube formation and migration in late EPCs, which were significantly improved by fenofibrate in an AMPK-dependent manner (p < 0.05), suggesting that fenofibrate reversed CACs and late EPC dysfunction in CHF patients. The present findings reveal the potential application of the AMPK agonist fenofibrate to reverse endothelial dysfunction in CHF patients.

Fructans as Immunomodulatory and Antiviral Agents: The Case of Echinacea

Throughout history, medicinal purposes of plants have been studied, documented, and acknowledged as an integral part of human healthcare systems. The development of modern medicine still relies largely on this historical knowledge of the use and preparation of plants and their extracts. Further research into the human microbiome highlights the interaction between immunomodulatory responses and plant-derived, prebiotic compounds. One such group of compounds includes the inulin-type fructans (ITFs), which may also act as signaling molecules and antioxidants. These multifunctional compounds occur in a small proportion of plants, many of which have recognized medicinal properties. Echinacea is a well-known medicinal plant and products derived from it are sold globally for its cold- and flu-preventative and general health-promoting properties. Despite the well-documented phytochemical profile of Echinacea plants and products, little research has looked into the possible role of ITFs in these products. This review aims to highlight the occurrence of ITFs in Echinacea derived formulations and the potential role they play in immunomodulation.

Phytanic acid activates PPARα to promote beige adipogenic differentiation of preadipocytes

A better understanding of the mechanisms of beige and brown adipogenesis is needed for developing strategies to prevent and treat obesity and associated metabolic disorders. Phytanic acid (PA) exists in a wide range of foods, especially in milk fat and marine foods, but its effects on obesity and beige adipogenesis remain poorly defined. The objective is to investigate the effects and regulatory mechanisms of PA in the beige adipogenesis. In 3T3-L1 preadipocytes, PA elevated the expression of brown adipogenic markers, suggesting that PA promotes beige adipogenic differentiation in committed adipogenic cells. In uncommitted C3H10T1/2 cells, while PA increased PGC1α expression, it did not increase brown adipogenic regulators PRDM16 or UCP1 expression, suggesting that PA had no significant effects on brown adipocyte commitment. PA also enhanced mitochondrial biogenesis and oxygen consumption. Promotion of both mitochondriogenesis and beige adipogenic differentiation were blocked by using PPARα antagonist or with Pparα knockdown, showing that PA-mediated beige/brown adipogenic differentiation is dependent on PPARα. Additionally, the PA-regulated effect is independent on β3-adrenergic receptor. Taken together, PA promotes beige adipogenic differentiation, but not the commitment of progenitor cells to the brown adipocyte lineage. PPARα is a key mediator during PA-induced beige/brown adipogenic differentiation.

Peroxisome Proliferator-Activated Receptor α Agonist and Its Target Nanog Cooperate to Induce Pluripotency

The pharmaceutical compounds that modulate pluripotent stem cell (PSC) identity and function are increasingly adopted to generate qualified PSCs and their derivatives, which have promising potential in regenerative medicine, in pursuit of more accuracy and safety and less cost. Here, we demonstrate the peroxisome proliferator-activated receptor α (PPARα) agonist as a novel enhancer of pluripotency acquisition and induced pluripotent stem cell (iPSC) generation. We found that PPARα agonist, examined and selected Food and Drug Administration (FDA) -approved compound libraries, increase the expression of pluripotency-associated genes, such as Nanog, Nr5A2, Oct4, and Rex1, during the reprogramming process and facilitate iPSC generation by enhancing their reprogramming efficiency. A reprogramming-promoting effect of PPARα occurred via the upregulation of Nanog, which is essential for the induction and maintenance of pluripotency. Through bioinformatic analysis, we identified putative peroxisome proliferator responsive elements (PPREs) located within the promoter region of the Nanog gene. We also determined that PPARα can activate Nanog transcription by specific binding to putative PPREs. Taken together, our findings suggest that PPARα is an important regulator of PSC pluripotency and reprogramming, and PPARα agonists can be used to improve PSC technology and regenerative medicine.

IL-15 improves skeletal muscle oxidative metabolism and glucose uptake in association with increased respiratory chain supercomplex formation and AMPK pathway activation

BACKGROUND

IL-15 is believed to play a role in the beneficial impact of exercise on muscle energy metabolism. However, previous studies have generally used supraphysiological levels of IL-15 that do not represent contraction-induced IL-15 secretion.

METHODS

L6 myotubes were treated acutely (3 h) and chronically (48 h) with concentrations of IL-15 mimicking circulating (1-10 pg/ml) and muscle interstitial (100 pg/ml -20 ng/ml) IL-15 levels with the aim to better understand its autocrine/paracrine role on muscle glucose uptake and mitochondrial function.

RESULTS

Acute exposure to IL-15 levels representing muscle interstitial IL-15 increased basal glucose uptake without affecting insulin sensitivity. This was accompanied by increased mitochondrial oxidative functions in association with increased AMPK pathway and formation of complex III-containing supercomplexes. Conversely, chronic IL-15 exposure resulted in a biphasic effect on mitochondrial oxidative functions and ETC supercomplex formation was increased with low IL-15 levels but decreased with higher IL-15 concentrations. The AMPK pathway was activated only by high levels of chronic IL-15 treatment. Similar results were obtained in skeletal muscle from muscle-specific IL-15 overexpressing mice that show very high circulating IL-15 levels.

CONCLUSIONS

Acute IL-15 treatment that mimics local IL-15 concentrations enhances muscle glucose uptake and mitochondrial oxidative functions. That mitochondria respond differently to different levels of IL-15 during chronic treatments indicates that IL-15 might activate two different pathways in muscle depending on IL-15 concentrations.

GENERAL SIGNIFICANCE

Our results suggest that IL-15 may act in an autocrine/paracrine fashion and be, at least in part, involved in the positive effect of exercise on muscle energy metabolism.

Fenofibrate improves vascular endothelial function and contractility in diabetic mice

Fenofibrate, a peroxisome proliferator-activated receptors α (PPARα) agonist, reduces vascular complications of diabetic patients but its protective mechanisms are not fully understood. Here we tested the hypothesis that fenofibrate improves vascular endothelial dysfunction by balancing endothelium-dependent relaxation and contractility of the aorta in diabetes mellitus (DM). In streptozotocin-induced diabetic mice, eight weeks of fenofibrate treatment (100 mg/Kg/d) improved endothelium dependent relaxation in the macro- and microvessels, increased nitric oxide (NO) levels, reduced renal damage markers and effects of the vasoconstrictor prostaglandin. Levels of superoxide dismutase and catalase were both reduced and hydrogen peroxide was increased in vehicle-treated DM, but these changes were reversed by fenofibrate treatment. Vasodilation of the aorta after fenofibrate treatment was reversed by PPARα or AMPKα inhibitors. Western blots showed that fenofibrate treatment elevated PPARα expression, induced liver kinase B1 (LKB1) translocation from the nucleus to the cytoplasm and activated AMP-activated protein kinase-α (AMPKα), thus activating endothelial NO synthase (eNOS). Also, fenofibrate treatment decreased NF-κB p65 and cyclooxygenase 2 proteins in aortas. Finally, incubation with indomethacin in vitro improved aortic contractility in diabetic mice. Overall, our results show that fenofibrate treatment in diabetic mice normalizes endothelial function by balancing vascular reactivity via increasing NO production and suppressing the vasoconstrictor prostaglandin, suggesting mechanism of action of fenofibrate in mediating diabetic vascular complications.

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Fenofibrate improves diabetic endothelial function is via PPAR/LKB1/AMPK/eNOS signal.

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Fenofibrate reduces diabetic endothelial contractility is via NF-κB/COX-2 pathway.

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Diabetes-associated oxidative stress is attenuated by fenofibrate treatment.

Arhalofenate acid inhibits monosodium urate crystal-induced inflammatory responses through activation of AMP-activated protein kinase (AMPK) signaling

Background

Arhalofenate acid, the active acid form of arhalofenate, is a non-agonist peroxisome proliferator-activated receptor γ (PPARγ) ligand, with uricosuric activity via URAT1 inhibition. Phase II studies revealed decreased acute arthritis flares in arhalofenate-treated gout compared with allopurinol alone. Hence, we investigated the anti-inflammatory effects and mechanisms of arhalofenate and its active acid form for responses to monosodium urate (MSU) crystals.

Methods

We assessed in-vivo responses to MSU crystals in murine subcutaneous air pouches and in-vitro responses in murine bone marrow-derived macrophages (BMDMs) by enzyme-linked immunosorbent assay (ELISA), SDS-PAGE/Western blot, immunostaining, and transmission electron microscopy analyses.

Results

Oral administration of arhalofenate (250 mg/kg) blunted total leukocyte ingress, neutrophil influx, and air pouch fluid interleukin (IL)-1β, IL-6, and CXCL1 in response to MSU crystal injection (p < 0.05 for each). Arhalofenate acid (100 μM) attenuated MSU crystal-induced IL-1β production in BMDMs via inhibition of NLRP3 inflammasome activation. In addition, arhalofenate acid dose-dependently increased activation (as assessed by phosphorylation) of AMP-activated protein kinase (AMPK). Studying AMPKα1 knockout mice, we elucidated that AMPK mediated the anti-inflammatory effects of arhalofenate acid. Moreover, arhalofenate acid attenuated the capacity of MSU crystals to suppress AMPK activity, regulated expression of multiple downstream AMPK targets that modulate mitochondrial function and oxidative stress, preserved intact mitochondrial cristae and volume density, and promoted anti-inflammatory autophagy flux in BMDMs.

Conclusions

Arhalofenate acid is anti-inflammatory and acts via AMPK activation and its downstream signaling in macrophages. These effects likely contribute to a reduction of gout flares.

Electronic supplementary material

The online version of this article (10.1186/s13075-018-1699-4) contains supplementary material, which is available to authorized users.

Protective effect of Letinous edodes foot peptides against ethanol‑induced liver injury in L02 cells

The aim of the present study was to evaluate the protective effect and mechanism of Letinous edodes foot peptides on ethanol‑induced L02 cells. A cell model of ethanol‑induced damage was established in vitro to study the effects of the Letinous edodes foot peptides on human L02 hepatocytes. The expression and activity of superoxide dismutase (SOD), malondialdehyde (MDA), aspartate aminotransferase (AST), alanine aminotransferase (ALT), alcohol dehydrogenase (ADH) and acetaldehyde dehydrogenase (ALDH), following treatment were examined to determine the anti‑alcoholism and hepatoprotective functions of Letinous edodes foot peptides. Taking Letinous edodes foot peptides prior to ethanol exposure was more beneficial, which significantly increased SOD activity and the mRNA expression of ADH and ALDH suppressed by ethanol. In addition, the intracellular MDA content, and AST and ALT activity decreased in ethanol‑induced L02 cells pretreated with the peptides, when compared with the control. Furthermore, Letinous edodes foot peptides inhibited the ethanol‑induced activation of the proinflammatory cytokines, interleukin‑6 and tumor necrosis factor‑α, and promoted the metabolic regulation factors, AMP‑activated protein kinase‑α2 and peroxisome proliferator‑activated receptor‑α.

Heme oxygenase-1 induction by rosiglitazone via PKCα/AMPKα/p38 MAPKα/SIRT1/PPARγ pathway suppresses lipopolysaccharide-mediated pulmonary inflammation

HO-1 (heme oxygenase-1), an antioxidant enzyme, induced by rosiglitazone (PPAR ligands) can be a potential treatment of inflammation. However, the mechanisms of rosiglitazone-induced HO-1 expression in human pulmonary alveolar epithelial cells (HPAEpiCs) remain largely unknown. In this study, we found that upregulation of HO-1 in vitro or in vivo by rosiglitazone attenuated VCAM-1 gene expression and monocyte adhesion to HPAEpiCs challenged with lipopolysaccharide (LPS). The inhibitory effects of rosiglitazone on LPS-mediated responses were reversed by transfection with HO-1 siRNA. LPS-induced VCAM-1 expression was mediated through NF-κB activation which was attenuated by rosiglitazone via suppressing p65 activation and translocation into the nucleus. Moreover, pretreatment with the inhibitor of PKCs (H7), PKCα (Gö6976), AMPKα (Compound C), p38 MAPKα (p38i VIII), SIRT1 (Sirtinol), or PPARγ (T0070907) and transfection with siRNA of PKCα, AMPKα, p38 MAPKα, SIRT1, or PPARγ abolished the rosiglitazone-induced HO-1 expression in HPAEpiCs. Further studies indicated that rosiglitazone stimulated SIRT1 deacetylase leading to PGC1α translocation from the cytosol into the nucleus, promoting fragmentation of NCoR and phosphorylation of PPARγ. Subsequently, PPARγ was activated by phosphorylation of PKCα, AMPKα, p38 MAPKα, and SIRT1, which turned on transcription of HO-1 gene by binding to PPAR response element (PPRE) and enhancing PPARγ promoter activity. These results suggested that rosiglitazone-induced HO-1 expression is mediated through PKCα/AMPKα/p38 MAPKα/SIRT1-dependent deacetylation of Ac-PGC1α and fragmentation of NCoR/PPARγ activation in HPAEpiCs. Up-regulation of HO-1 protected against the inflammatory responses triggered by LPS, at least in part, through attenuation of NF-κB.