AMPK as a Therapeutic Target for Treating Metabolic Diseases

Recent updates on targeting the molecular mediators of NAFLD

Nonalcoholic fatty liver disease (NAFLD) is rapidly becoming the most common disease worldwide in an era of rapid economic growth. NAFLD is a multifactorial disease, involving multiple genetic, metabolic, and environmental factors, and is closely associated with metabolic syndrome, obesity, and cardiovascular disease. NAFLD can be classified into nonalcoholic fatty liver disease (NAFL) and nonalcoholic steatohepatitis (NASH), which can both progress to cirrhosis and even hepatocellular carcinoma (HCC). Due to the enormous burden of NAFLD and its complications, no FDA-approved drugs for the treatment of NAFLD are on the market, and therapeutic targets and drug therapies are being actively investigated. In view of the various pathological mechanisms of NAFLD, numbers of preclinical studies and clinical trials have made rapid progress. This review mainly summarizes the most recently characterized mechanisms and therapeutic targets in each mechanism of NAFLD, focusing on the mechanism and application potential.

Preclinical and clinical evidence for the treatment of non-alcoholic fatty liver disease with soybean: A systematic review and meta-analysis

Non-alcoholic fatty liver disease (NAFLD), a prevalent public health issue, involves the accumulation of triglycerides in hepatocytes, which is generally considered to be an early lesion of liver fibrosis and cirrhosis. Thus, the development of treatments for NAFLD is urgently needed. This study explored the preclinical and clinical evidence of soybeans to alleviate NAFLD. Studies indexed in three relevant databases-Web of Science, PubMed, and Embase-between January 2002 and August 2022 were retrieved. A total of 13 preclinical studies and five RCTs that included 212 animals and 260 patients were included in the present analysis. The preclinical analysis showed that liver function indices (AST, SMD = -1.41, p < 0.0001 and ALT, SMD = -1.47, p < 0.0001) were significantly improved in the soybean group compared to the model group, and fatty liver indicators (TG, SMD = -0.78, p < 0.0001; TC, SMD = -1.38, p < 0.0001) and that oxidative stress indices (MDA, SMD = -1.09, p < 0.0001; SOD, SMD = 1.74, p = 0.022) were improved in the soybean group. However, the five RCTs were not entirely consistent with the preclinical results; however, the results confirmed the protective effect on the liver. The results of the clinical RCTs showed that soybean significantly affected liver function, fatty liver, and oxidative stress indicators (ALT, SMD = -0.42, p = 0.006; TG, SMD = -0.31, p = 0.039; MDA, SMD = -0.76, p = 0.007). The current meta-analysis combined preclinical and clinical studies and verified that soybean could protect the liver in NAFLD by regulating lipid metabolism and oxidative stress factors via the Akt/AMPK/PPARα signaling pathway. Soybean might be a promising therapeutic agent for treating non-alcoholic fatty liver disease. Systematic Review Registration: (https://www.crd.york.ac.uk/prospero/#myprospero), identifier (CRD42022335822).

Anti-Obesity Effects of Metformin: A Scoping Review Evaluating the Feasibility of Brown Adipose Tissue as a Therapeutic Target

Brown adipose tissue (BAT) is increasingly recognized as the major therapeutic target to promote energy expenditure and ameliorate diverse metabolic complications. There is a general interest in understanding the pleiotropic effects of metformin against metabolic complications. Major electronic databases and search engines such as PubMed/MEDLINE, Google Scholar, and the Cochrane library were used to retrieve and critically discuss evidence reporting on the impact of metformin on regulating BAT thermogenic activity to ameliorate complications linked with obesity. The summarized evidence suggests that metformin can reduce body weight, enhance insulin sensitivity, and improve glucose metabolism by promoting BAT thermogenic activity in preclinical models of obesity. Notably, this anti-diabetic agent can affect the expression of major thermogenic transcriptional factors such as uncoupling protein 1 (UCP1), nuclear respiratory factor 1 (NRF1), and peroxisome-proliferator-activated receptor gamma coactivator 1-alpha (PGC1-α) to improve BAT mitochondrial function and promote energy expenditure. Interestingly, vital molecular markers involved in glucose metabolism and energy regulation such as AMP-activated protein kinase (AMPK) and fibroblast growth factor 21 (FGF21) are similarly upregulated by metformin treatment in preclinical models of obesity. The current review also discusses the clinical relevance of BAT and thermogenesis as therapeutic targets. This review explored critical components including effective dosage and appropriate intervention period, consistent with the beneficial effects of metformin against obesity-associated complications.

Autophagy of naïve CD4+ T cells in aging - the role of body adiposity and physical fitness

Life expectancy has increased exponentially in the last century accompanied by disability, poor quality of life, and all-cause mortality in older age due to the high prevalence of obesity and physical inactivity in older people. Biologically, the aging process reduces the cell's metabolic and functional efficiency, and disrupts the cell's anabolic and catabolic homeostasis, predisposing older people to many dysfunctional conditions such as cardiovascular disease, neurodegenerative disorders, cancer, and diabetes. In the immune system, aging also alters cells' metabolic and functional efficiency, a process known as 'immunosenescence', where cells become more broadly inflammatory and their functionality is altered. Notably, autophagy, the conserved and important cellular process that maintains the cell's efficiency and functional homeostasis may protect the immune system from age-associated dysfunctional changes by regulating cell death in activated CD4+ T cells. This regulatory process increases the delivery of the dysfunctional cytoplasmic material to lysosomal degradation while increasing cytokine production, proliferation, and differentiation of CD4+ T cell-mediated immune responses. Poor proliferation and diminished responsiveness to cytokines appear to be ubiquitous features of aged T cells and may explain the delayed peak in T cell expansion and cytotoxic activity commonly observed in the 'immunosenescence' phenotype in the elderly. On the other hand, physical exercise stimulates the expression of crucial nutrient sensors and inhibits the mechanistic target of the rapamycin (mTOR) signaling cascade which increases autophagic activity in cells. Therefore, in this perspective review, we will first contextualize the overall view of the autophagy process and then, we will discuss how body adiposity and physical fitness may counteract autophagy in naïve CD4+ T cells in aging.

Anthocyanins as Promising Molecules Affecting Energy Homeostasis, Inflammation, and Gut Microbiota in Type 2 Diabetes with Special Reference to Impact of Acylation

Anthocyanins, the red-orange to blue-violet colorants present in fruits, vegetables, and tubers, have antidiabetic properties expressed via modulating energy metabolism, inflammation, and gut microbiota. Acylation of the glycosyl moieties of anthocyanins alters the physicochemical properties of anthocyanins and improves their stability. Thus, acylated anthocyanins with probiotic-like property and lower bioavailability are likely to have different biological effects from nonacylated anthocyanins on diabetes. This work highlights recent findings on the antidiabetic effects of acylated anthocyanins from the perspectives of energy metabolism, inflammation, and gut microbiota compared to the nonacylated anthocyanins and particularly emphasizes the cellular and molecular mechanisms associated with the beneficial effects of these bioactive molecules, providing a new perspective to explore the different biological effects induced by structurally different anthocyanins. Acylated anthocyanins may have greater modulating effects on energy metabolism, inflammation, and gut microbiota in type 2 diabetes compared to nonacylated anthocyanins.

Approved Small-Molecule ATP-Competitive Kinases Drugs Containing Indole/Azaindole/Oxindole Scaffolds: R&D and Binding Patterns Profiling

Kinases are among the most important families of biomolecules and play an essential role in the regulation of cell proliferation, apoptosis, metabolism, and other critical physiological processes. The dysregulation and gene mutation of kinases are linked to the occurrence and development of various human diseases, especially cancer. As a result, a growing number of small-molecule drugs based on kinase targets are being successfully developed and approved for the treatment of many diseases. The indole/azaindole/oxindole moieties are important key pharmacophores of many bioactive compounds and are generally used as excellent scaffolds for drug discovery in medicinal chemistry. To date, 30 ATP-competitive kinase inhibitors bearing the indole/azaindole/oxindole scaffold have been approved for the treatment of diseases. Herein, we summarize their research and development (R&D) process and describe their binding models to the ATP-binding sites of the target kinases. Moreover, we discuss the significant role of the indole/azaindole/oxindole skeletons in the interaction of their parent drug and target kinases, providing new medicinal chemistry inspiration and ideas for the subsequent development and optimization of kinase inhibitors.

Ginsenoside Rd promotes omentin secretion in adipose through TBK1-AMPK to improve mitochondrial biogenesis via WNT5A/Ca2+ pathways in heart failure

Ginsenoside Rd is an active ingredient in Panax ginseng CA Mey and can be absorbed into the adipose tissue. Adipokines play an important role in the treatment of cardiovascular diseases. However, the potential benefit of Rd on heart failure (HF) and the underlying mechanism associated with the crosstalk between adipocytes and cardiomyocytes remains to be illustrated. Here, the results identified that Rd improved cardiac function and inhibited cardiac pathological changes in transverse aortic constriction (TAC), coronary ligation (CAL) and isoproterenol (ISO)-induced HF mice. And Rd promoted the release of omentin from the adipose tissue and up-regulated omentin expression in lipopolysaccharide (LPS)-induced 3T3-L1 adipocytes. Further, Rd could increase TBK1 and AMPK phosphorylation in adipocytes. And also, the TBK1-AMPK signaling pathway regulated the expression of omentin in LPS-induced adipocytes. Moreover, the omentin mRNA expression was significantly decreased by TBK1 knockdown in LPS-induced 3T3-L1 adipocytes. Additionally, molecular docking and SPR analysis confirmed that Rd had a certain binding ability with TBK1, and co-treatment with TBK1 inhibitors or TBK1 knockdown partially abolished the effect of Rd on increasing the omentin expression and the ratio of p-AMPK to AMPK in adipocytes. Moreover, we found that circulating omentin level diminished in the HF patients compared with healthy subjects. Meanwhile, the adipose tissue-specific overexpression of omentin improved cardiac function, reduced myocardial infarct size and ameliorated cardiac pathological features in CAL-induced HF mice. Consistently, exogenous omentin reduced mtROS levels and restored ΔψM to improve oxygen and glucose deprivation (OGD)-induced cardiomyocytes injury. Further, omentin inhibited the WNT5A/Ca²⁺ signaling pathway and promoted mitochondrial biogenesis function to ameliorate myocardial ischemia injury. However, WNT5A knockdown inhibited the impairment of mitochondrial biogenesis and partially counteracted the cardioprotective effect of omentin in vitro. Therefore, this study indicated that Rd promoted omentin secretion from adipocytes through the TBK1-AMPK pathway to improve mitochondrial biogenesis function via WNT5A/Ca²⁺ signaling pathway to ameliorate myocardial ischemia injury, which provided a new therapeutic mechanism and potential drugs for the treatment of HF.

Cryptotanshinone attenuates LPS-induced acute lung injury by regulating metabolic reprogramming of macrophage

Background

Acute lung injury (ALI) is a life-threatening inflammatory disease without effective therapeutic regimen. Macrophage polarization plays a key role in the initiation and resolution of pulmonary inflammation. Therefore, modulating macrophage phenotype is a potentially effective way for acute lung injury. Cryptotanshinone (CTS) is a lipophilic bioactive compound extracted from the root of Salvia miltiorrhiza with a variety of pharmacological effects, especially the anti-inflammatory role. In this study, we investigated the therapeutic and immunomodulatory effects of CTS on ALI.

Materials and methods

The rat model of ALI was established by intratracheal instillation of LPS (5 mg/kg) to evaluate the lung protective effect of CTS in vivo and to explore the regulation of CTS on the phenotype of lung macrophage polarization. LPS (1 μg/mL) was used to stimulate RAW264.7 macrophages in vitro to further explore the effect of CTS on the polarization and metabolic reprogramming of RAW264.7 macrophages and to clarify the potential mechanism of CTS anti-ALI.

Results

CTS significantly improved lung function, reduced pulmonary edema, effectively inhibited pulmonary inflammatory infiltration, and alleviated ALI. Both in vivo and in vitro results revealed that CTS inhibited the differentiation of macrophage into the M1 phenotype and promoted polarization into M2 phenotype during ALI. Further in vitro studies indicated that CTS significantly suppressed LPS-induced metabolic transition from aerobic oxidation to glycolysis in macrophages. Mechanistically, CTS blocked LPS-induced metabolic transformation of macrophages by activating AMPK.

Conclusion

These findings demonstrated that CTS regulates macrophage metabolism by activating AMPK, and then induced M1-type macrophages to transform into M2-type macrophages, thereby alleviating the inflammatory response of ALI, suggesting that CTS might be a potential anti-ALI agent.

Brazilian Propolis Intake Decreases Body Fat Mass and Oxidative Stress in Community-Dwelling Elderly Females: A Randomized Placebo-Controlled Trial

This study aimed to investigate the effects of Brazilian propolis on body fat mass and levels of adiponectin and reactive oxygen species among community-dwelling elderly females. This was a double-blind randomized placebo-controlled trial. Altogether, 78 females aged 66-84 years were randomly assigned to the propolis (PRO; n = 39) or placebo (PLA; n = 39) group. For 12 weeks, the PRO group were given three capsules containing 227 mg of propolis twice a day. Meanwhile, the PLA group were given daily placebo capsules. Of 78 participants, 53 (PLA group: n = 28, PRO group: n = 25) completed the study. Although no changes were observed in absolute or relative fat mass in the PLA group, they showed a significant decline in the PRO group. The level of serum adiponectin in the PLA group did not change, although that of the PRO group significantly increased. The level of d-ROMs in the PLA group significantly increased, whereas that of the PRO group significantly decreased. The serum SOD activity in the PLA group significantly decreased, whereas that of the PRO group tended to increase. These results suggest that propolis supplementation may decrease body fat mass and oxidative stress among community-dwelling elderly females.

The Pathogenetic Basis of the Action of Bempedoic Acid

The modern cardiology has a wide range of medications which affect various pathogenetic links of atherosclerosis, but even the best of them still obtain disadvantages causing intolerance and medicine discontinuation. The development of new hypolipidemic medications will allow not only to introduce alternative therapies into the cardiology practice, but also to completely execute the strategy of residual risk reduction by utilizing rational combinations of medications. One of such alternatives could be bempedoic acid, which can have a positive effect on a number of endpoints as the results of third phase trials have shown. These effects are also confirmed in Mendelian randomization studies. The mechanism of action of bempedoic acid is presumably associated with inhibition of the activity of ATP citrate lyase – the enzyme responsible for the breakdown of citrate into acetyl-CoA and oxaloacetate. Acetyl-CoA, in turn, is used by the cell to synthesize cholesterol and fatty acids. Thus, bempedoic acid affects in the same metabolic pathway as statins, but at an earlier stage. According to this, it is possible that medications of these classes will have similar side effects and pleiotropic effects associated with modulation of the mevalonic pathway, such as prenylation regulatory proteins (small GTPases) or reduction of coenzyme Q synthesis. However, there are also some specific features of the pharmacodynamics and pharmacokinetics of bempedoic acid to be considered. In particular, once entered the body, it must be activated via esterification by very long-chain acyl-CoA synthetase-1. The enzyme isoform required for this process is expressed in a tissue-specific manner and, for example, is absent in skeletal myocytes. In addition, citrate, oxaloacetate, and acetyl-CoA are important regulators of many intracellular processes: metabolism, growth and proliferation, mechanotransduction, posttranslational modifications of histones and other proteins. The levels of all three substances are altered by bempedoic acid, although no firm conclusions about the effects of these changes can be drawn at this time. The mentioned features probably have a significant impact on the clinical profile of bempedoic acid and underlie the differences from statins already observed in third phase trials, including, for example, a reduced risk of the onset or worsening of diabetes mellitus while taking bempedoic acid.

The Novel Inhibitory Effect of YM976 on Adipocyte Differentiation

The pyrimidine derivative YM976 (4-(3-chlorophenyl)-1,7-diethylpyrido(2,3-d)-pyrimidin-2(1H)-one) exerts anti-inflammatory and anti-asthmatic effects. Considering that accumulation of lipids in adipose tissue is accompanied by inflammation, we investigated whether YM976 affects adipocyte differentiation. We found that YM976 significantly decreased lipid accumulation without cytotoxicity and reduced the expression levels of peroxisome proliferator-activated receptor γ (PPARγ) and CCAAT/enhancer-binding protein α (C/EBPα) as well as their lipogenic regulators including fatty acid synthase (FASN) and fatty acid-binding protein 4 (FABP4) in 3T3-L1 cells induced for differentiation. YM976 mainly inhibited the early stage of adipocyte differentiation. Furthermore, intracellular cAMP level was elevated by YM976 resulting in increased phosphorylation of adenosine monophosphate-activated protein kinase (AMPK). Conversely, decreasing the levels of AMPK or treatment with Compound C, an AMPK inhibitor, lessened the suppressive effects of YM976 on PPARγ transcriptional activity and adipogenesis. Thus, our results suggest YM976 as a novel potential compound for controlling lipid accumulation and formation of adipocytes in obesity.

A positive feedback loop between AMPK and GDF15 promotes metformin antidiabetic effects

BACKGROUND AND AIMS

Metformin, the most prescribed drug for the treatment of type 2 diabetes mellitus, has been recently reported to promote weight loss by upregulating the anorectic cytokine growth differentiation factor 15 (GDF15). Since the antidiabetic effects of metformin are mostly mediated by the activation of AMPK, a key metabolic sensor in energy homeostasis, we examined whether the activation of this kinase by metformin was dependent on GDF15.

METHODS

Cultured hepatocytes and myotubes, and wild-type and Gdf15^-/- mice were utilized in a series of studies to investigate the involvement of GDF15 in the activation of AMPK by metformin.

RESULTS

A low dose of metformin increased GDF15 levels without significantly reducing body weight or food intake, but it ameliorated glucose intolerance and activated AMPK in the liver and skeletal muscle of wild-type mice but not Gdf15^-/- mice fed a high-fat diet. Cultured hepatocytes and myotubes treated with metformin showed AMPK-mediated increases in GDF15 levels independently of its central receptor GFRAL, while Gdf15 knockdown blunted the effect of metformin on AMPK activation, suggesting that AMPK is required for the metformin-mediated increase in GDF15, which in turn is needed to sustain the full activation of this kinase independently of the CNS.

CONCLUSION

Overall, these findings uncover a novel mechanism through which GDF15 upregulation by metformin is involved in achieving and sustaining full AMPK activation by this drug independently of the CNS.

Metabolism of NK cells during viral infections

Cellular metabolism is essential for the correct function of immune system cells, including Natural Killer cells (NK). These cells depend on energy to carry out their effector functions, especially in the early stages of viral infection. NK cells participate in the innate immune response against viruses and tumors. Their main functions are cytotoxicity and cytokine production. Metabolic changes can impact intracellular signals, molecule production, secretion, and cell activation which is essential as the first line of immune defense. Metabolic variations in different immune cells in response to a tumor or pathogen infection have been described; however, little is known about NK cell metabolism in the context of viral infection. This review summarizes the activation-specific metabolic changes in NK cells, the immunometabolism of NK cells during early, late, and chronic antiviral responses, and the metabolic alterations in NK cells in SARS-CoV2 infection. The modulation points of these metabolic routes are also discussed to explore potential new immunotherapies against viral infections.

Pancreastatin inhibitor PSTi8 balances energy homeostasis by attenuating adipose tissue inflammation in high fat diet fed mice

Pancreastatin (PST) is an endogenous bioactive peptide. PST is generated from chromogranin A (Chga) protein which is released by chromaffin and neuroendocrine cells. PST exhibits diabetogenic effect by antagonizing the action of insulin in adipocytes. The level of PST rises during obesity, resulting in persistent low-grade inflammation in adipocytes. Pancreastatin inhibitor 8 (PSTi8), which is developed by modification of PST sequence which antagonizes the action of PST. In this study, we investigated the immunometabolic effect of PSTi8 in the diet-induced obesity (DIO) model in C57BL/6 mice. Here we found PSTi8 decreased the body weight gain, fat mass and increased the lean mass in (DIO) mice. It also showed reduction of adipocyte hypertrophy in eWAT and lipid accumulation in liver of DIO mice. Immunoprofiling of stromal vascular fraction isolated from eWAT of PTSi8 treated mice showed increased anti-inflammatory M2 macrophages, Eosinophil, T-regulatory cells and reduced pro-inflammatory M1 macrophages, CD4 and CD8 T cell population. Apart from this, PSTi8 also improved the mitochondrial function by decreasing reactive oxygen species and increasing mitochondrial membrane potential, NADPH/NADP ratio and citrate synthase activity in eWAT of DIO mice. It also increased the protein expression of pAMPK, pAKT, Arginase -1 and decreased the expression of MHC-II and iNOS in eWAT of DIO mice. In conclusion, PSTi8 exerted its beneficial effect on restoring energy expenditure by reducing adipose tissue inflammation.

Tumor protein D52 (TPD52) affects cancer cell metabolism by negatively regulating AMPK

BACKGROUND

The AMP-activated protein kinase (AMPK) is a central regulator of energy homeostasis, with deregulation leading to cancer and other diseases. However, how this pathway is dysregulated in cancer has not been well clarified.

METHODS

Using a tandem affinity purification/mass-spec technique and biochemical analyses, we identified tumor protein D52 (TPD52) as an AMPKα-interacting molecule. To explore the biological effects of TPD52 in cancers, we conducted biochemical and metabolic assays in vitro and in vivo with cancer cells and TPD52 transgenic mice. Finally, we assessed the clinical significance of TPD52 expression in breast cancer patients using bioinformatics techniques.

RESULTS

TPD52, initially identified to be overexpressed in many human cancers, was found to form a stable complex with AMPK in cancer cells. TPD52 directly interacts with AMPKα and inhibits AMPKα kinase activity in vitro and in vivo. In TPD52 transgenic mice, overexpression of TPD52 leads to AMPK inhibition and multiple metabolic defects. Clinically, high TPD52 expression predicts poor survival of breast cancer patients.

CONCLUSION

The findings revealed that TPD52 is a novel regulator of energy stress-induced AMPK activation and cell metabolism. These results shed new light on AMPK regulation and understanding of the etiology of cancers with TPD52 overexpression.

Salicylate Sodium Suppresses Monocyte Chemoattractant Protein-1 Production by Directly Inhibiting Phosphodiesterase 3B in TNF-α-Stimulated Adipocytes

As a worldwide health issue, obesity is associated with the infiltration of monocytes/macrophages into the adipose tissue causing unresolved inflammation. Monocyte chemoattractant protein-1 (MCP-1) exerts a crucial effect on obesity-related monocytes/macrophages infiltration. Clinically, aspirin and salsalate are beneficial for the treatment of metabolic diseases in which adipose tissue inflammation plays an essential role. Herein, we investigated the effect and precise mechanism of their active metabolite salicylate on TNF-α-elevated MCP-1 in adipocytes. The results indicated that salicylate sodium (SAS) could lower the level of MCP-1 in TNF-α-stimulated adipocytes, which resulted from a previously unrecognized target phosphodiesterase (PDE), 3B (PDE3B), rather than its known targets IKKβ and AMPK. The SAS directly bound to the PDE3B to inactivate it, thus elevating the intracellular cAMP level and activating PKA. Subsequently, the expression of MKP-1 was increased, which led to the decrease in p-EKR and p-p38. Both PDE3B silencing and the pharmacological inhibition of cAMP/PKA compromised the suppressive effect of SAS on MCP-1. In addition to PDE3B, the PDE3A and PDE4B activity was also inhibited by SAS. Our findings identify a previously unrecognized pathway through which SAS is capable of attenuating the inflammation of adipocytes.

Mitochondrial function and nutrient sensing pathways in ageing: enhancing longevity through dietary interventions

Ageing is accompanied by alterations in several biochemical processes, highly influenced by its environment. It is controlled by the interactions at various levels of biological hierarchy. To maintain homeostasis, a number of nutrient sensors respond to the nutritional status of the cell and control its energy metabolism. Mitochondrial physiology is influenced by the energy status of the cell. The alterations in mitochondrial physiology and the network of nutrient sensors result in mitochondrial damage leading to age related metabolic degeneration and diseases. Calorie restriction (CR) has proved to be as the most successful intervention to achieve the goal of longevity and healthspan. CR elicits a hormetic response and regulates metabolism by modulating these networks. In this review, the authors summarize the interdependent relationship between mitochondrial physiology and nutrient sensors during the ageing process and their role in regulating metabolism.

Gallic acid ameliorates atherosclerosis and vascular senescence and remodels the microbiome in a sex-dependent manner in ApoE-/- mice

Polyphenols found in fruits and vegetables are associated with a reduced incidence of cardiovascular disease (CVD), the leading cause of death in the USA. Our lab demonstrated that blackberry supplementation reduces atherosclerosis in male, but not in female mice. The current study investigates whether gallic acid (GA), a polyphenol abundant in blackberry, decreases plaque and whether its effect is also sex-dependent. In vitro work using vascular smooth muscle cells (VSMCs) demonstrated that GA reduced cell signaling associated with proliferation, migration, and senescence. ApoE^-/- male and female mice were treated with and without 0.2% GA in drinking water and fed a chow diet (2 weeks), then switched to high-fat diet (HFD) (5 weeks) with the same GA regimen. Similar to the blackberry study, GA reduced atherosclerosis only in males. This GA-induced plaque reduction was independent of plasma cholesterol, triglycerides (TG), LDL, or HDL but corresponded with indices of lower inflammation. Males showed reduced spleen weight and serum IL3 and IL12 levels, and gut health improvement. In females, GA increased anti-atherogenic (HDL and IL10) molecules, while upregulating several pro-inflammatory cytokines and chemokines, including tumor necrosis factor α (TNFα). A major sex-dependent effect of GA was the almost complete disappearance of Eubacterium fissicatena and Turicibacter induced by HFD in males, a finding not seen in females. This study provides novel insights into how GA can improve gut microbiota alterations associated with CVD and suggests that males suffering from atherosclerosis may benefit from GA supplementation, as this polyphenol partially restored microbiome dysbiosis.

Quinacrine attenuates diet-induced obesity by inhibiting adipogenesis via activation of AMPK signaling

Obesity, a global epidemic chronic metabolic disease, urgently demands novel therapies. As an antimalarial drug, quinacrine has not been reported for its anti-obesity effect to our knowledge. This study aimed to explore the ability of quinacrine to attenuate obesity. In an in vitro adipogenic model, quinacrine exhibited an outstanding suppression on adipogenesis of 3T3-L1 cells, mainly by activating the AMPK (Adenosine 5'-monophosphate (AMP)-activated protein kinase) signaling pathway to regulate preadipocytes differentiation and lipid accumulation. In addition, C57BL/6N female mice were fed with high-fat diet and high-fructose water for 14 weeks to establish an obesity model, followed by oral administration of quinacrine or orlistat. After 9 weeks of treatment, quinacrine significantly reduced the body weight and energy intake, ameliorated the impaired glucose tolerance and restored the homeostasis of serum lipids. Also, quinacrine improved lipid profile and optimized the expression of AMPK signaling pathway related proteins in livers and adipose tissues of obese mice. Quinacrine reverses obesity through activating AMPK phosphorylation to down-regulate adipogenesis, along with lowering the risk of type 2 diabetes and atherosclerosis. It should be a novel application for the treatment of obesity and its associated diseases.

Aqueous extract of Artemisia capillaris improves non-alcoholic fatty liver and obesity in mice induced by high-fat diet

Non-alcoholic fatty liver disease (NAFLD) is one of the most common chronic liver diseases and is a nutritional metabolic disease. Artemisia capillaris (AC) is the above-ground dried part of Artemisia capillaris Thunb. or Artemisia scoparia Waldst. et Kit., a natural medicinal plant with pharmacological effects of heat-clearing and biliary-promoting. In order to evaluate the therapeutic effect of Artemisia capillaris on NAFLD and obesity, experiments were conducted using aqueous extracts of Artemisia capillaris (WAC) to intervene in NAFLD models in vivo and in vitro. In vivo experiments were performed using HFD-fed (high fat diet) C57BL/6 mice to induce NAFLD model, and in vitro experiments were performed using oleic acid to induce HepG2 cells to construct NAFLD cell model. H.E. staining and oil red O staining of liver tissue were used to observe hepatocytes. Blood biochemistry analyzer was used to detect serum lipid levels in mice. The drug targets and mechanism of action of AC to improve NAFLD were investigated by western blotting, qRT-PCR and immunofluorescence. The results showed that C57BL/6 mice fed HFD continuously for 16 weeks met the criteria for NAFLD in terms of lipid index and hepatocyte fat accumulation. WAC was able to reverse the elevation of serum lipid levels induced by high-fat diet in mice. WAC promoted the phosphorylation levels of PI3K/AKT and AMPK in liver and HepG2 cells of NAFLD mice, inhibited SREBP-1c expression, reduced TG and lipogenesis, and decreased lipid accumulation. In summary, WAC extract activates PI3K/AKT pathway, reduces SREBP-1c protein expression by promoting AMPK phosphorylation, and decreases fatty acid synthesis and TG content in hepatocytes. AC can be used as a potential health herb to improve NAFLD and obesity.

The glucotoxicity protecting effect of honokiol in human hepatocytes via directly activating AMPK

Introduction

Sustained hyperglycemia causes glucotoxicity, which has been regarded as a contributor to hepatocyte damage in type 2 diabetes (T2D) and its metabolic comorbidities. Honokiol is a natural biphenolic component derived from the dietary supplement Magnolia officinalis extract. This study aimed to investigate the effects of honokiol on glucose metabolism disorders and oxidative stress in hepatocytes and the underlying mechanisms.

Methods

HepG2 cells were treated with glucosamines (18 mM) to induce glucotoxicity as a diabetic complication model in vitro.

Results and discussion

Honokiol significantly increased glucose consumption, elevated 2-NBDG uptake, and promoted GLUT2 translocation to the plasma membrane in glucosamine-treated HepG2 cells, indicating that honokiol ameliorates glucose metabolism disorders. Furthermore, glucosamine-induced ROS accumulation and loss of mitochondrial membrane potential were markedly reduced by honokiol, suggesting that honokiol alleviated glucotoxicity-induced oxidative stress. These effects were largely abolished by compound C, an AMPK inhibitor, suggesting an AMPK activation-dependent manner of honokiol function in promoting glucose metabolism and mitigating oxidative stress. Molecular docking results revealed that honokiol could interact with the amino acid residues (His151, Arg152, Lys243, Arg70, Lys170, and His298) in the active site of AMPK. These findings provide new insights into the antidiabetic effect of honokiol, which may be a promising agent for the prevention and treatment of T2D and associated metabolic comorbidities.

Therapeutic Effects of Heterotrigona itama (Stingless Bee) Bee Bread in Improving Hepatic Lipid Metabolism through theActivation of the Keap1/Nrf2 Signaling Pathway in an Obese Rat Model

Bee bread (BB) has traditionally been used as a dietary supplement to treat liver problems. This study evaluated the therapeutic effects of Heterotrigona itama BB from Malaysia on obesity-induced hepatic lipid metabolism disorder via the regulation of the Keap1/Nrf2 pathway. Male Sprague Dawley rats were fed with either a normal diet or high-fat diet (HFD) for 6 weeks to induce obesity. Following 6 weeks, obese rats were treated either with distilled water (OB group), BB (0.5 g/kg body weight/day) (OB + BB group) or orlistat (10 mg/kg body weight/day) (OB + OR group) concurrent with HFD for another 6 weeks. BB treatment suppressed Keap1 and promoted Nrf2 cytoplasmic and nuclear translocations, leading to a reduction in oxidative stress, and promoted antioxidant enzyme activities in the liver. Furthermore, BB down-regulated lipid synthesis and its regulator levels (SIRT1, AMPK), and up-regulated fatty acid β-oxidation in the liver of obese rats, being consistent with alleviated lipid levels, improved hepatic histopathological changes (steatosis, hepatocellular hypertrophy, inflammation and glycogen expression) and prevented progression to non-alcoholic steatohepatitis. These results showed the therapeutic potentials of H. itama BB against oxidative stress and improved lipid metabolism in the liver of obese rats possibly by targeting the Keap1/Nrf2 pathway, hence proposing its role as a natural supplement capable of treating obesity-induced fatty liver disease.

Exosomes derived from human umbilical cord mesenchymal stem cells ameliorate experimental non-alcoholic steatohepatitis via Nrf2/NQO-1 pathway

BACKGROUND

No approved effective therapy for non-alcoholic steatohepatitis (NASH) is currently available. Exosomes derived from mesenchymal stem cells (MSCs) perform the functions such as inhibiting inflammation, anti-oxidative stress, regulating immunity, but it is not clear whether human umbilical cord mesenchymal stem cells (hUC-MSCs) exosomes protect against NASH through Nrf2/NQO-1 pathway. Therefore, this study was conducted to investigate the effects of hUC-MSCs exosomes on NASH through Nrf2/NQO-1 pathway in vivo and in vitro.

METHODS

C57BL/6J male mice were fed with high fat and high cholesterol diet (HFHC) and methionine choline deficiency diet (MCD). Mice were treated with or without hUC-MSCs exosomes by tail intravenous injection. The liver histology, lipid metabolism and oxidative stress were evaluated. HepG2 and AML12 cells were incubated with palmitic acid (PA) and MCD conditioned medium, respectively. Then the therapeutic effect of hUC-MSCs exosomes in steatotic cells was evaluated. To elucidate the signaling pathways, the Nrf2-specific blocker ML385 was applied to intervene in vitro.

RESULTS

In NASH models, hUC-MSCs exosomes attenuated steatosis in hepatocytes, altered the abnormal expression of lipid-related genes including SREBP-1c, PPAR-α, Fabp5, CPT1α, ACOX and FAS, suppressed the hepatic inflammatory responses by decreasing the expression of F4/80⁺ macrophages, CD11c⁺ macrophages as well as the content of TNF-α and IL-6. hUC-MSCs exosomes also inhibited oxidative stress by reducing the level of MDA, CYP2E1 and ROS, increasing the activity of SOD and GSH in hepatocytes. Notably, hUC-MSCs exosomes enhanced the protein ratio of p-Nrf2/Nrf2 and the protein expression of NQO-1. Moreover, in vitro, the therapeutic effects of hUC-MSCs exosomes on lipid deposition and ROS were reversed by ML385. Also, ML385 reduced the protein expression of p-Nrf2 and NQO-1 in vitro.

CONCLUSION

Nrf2/NQO-1 antioxidant signaling pathway may play a key role in the treatment of NASH by hUC-MSCs exosomes.

Irisin improves adiposity and exercise tolerance in a rat model of postmenopausal obesity through enhancing adipo-myocyte thermogenesis

The prevalence of obesity and its associated metabolic disorders, along with their healthcare costs, is rising exponentially. Irisin, an adipomyokine, may serve as a critical cross-organ messenger, linking skeletal muscle with adipose tissue and the liver to integrate the energy homeostasis under diet-induced obesity. We aimed to explore the putative role of irisin in the protection against obesity in a postmenopausal rat model by modulating energy expenditure (EE). Bilateral ovariectomy (OVX) was performed. After 3 weeks of recovery, the OVX rats were classified according to their dietary protocol into rats maintained on normal diets (ND) (OVX) or high-fat diet (HFD) groups. The HFD-fed animals were equally divided into OVX/HFD, or irisin-treated OVX/HFD groups. Sham rats, maintained on ND, were selected as the control group. We evaluated anthropometric, EE, and molecular biomarkers of browning and thermogenesis in inguinal white adipose tissue and skeletal muscle, and the activity of the proteins related to mitochondrial long chain fatty acid transport, oxidation, and glycolysis. HFD of OVX further deteriorated the disturbed glucose homeostasis, lipid profile, and the reduced irisin, thermogenic parameters in adipose tissue and skeletal muscle, and EE. Irisin treatment improved the lipid profile and insulin resistance. That was associated with reduced hepatic gluconeogenic enzyme activities and restored hepatic glycogen content. Irisin reduced ectopic lipid infiltration. Irisin augmented EE by activating non-shivering thermogenesis in muscle and adipose tissues and decreasing metabolic efficiency. Our experimental evidence suggests irisin's use as a potential thermogenic agent, therapeutically targeting obesity in postmenopausal patients. Irisin modulates the non-shivering thermogenesis in skeletal muscle and adipose tissue in postmenopausal model.

Metformin: Activation of 5′ AMP-activated protein kinase and its emerging potential beyond anti-hyperglycemic action

Metformin is a plant-based drug belonging to the class of biguanides and is known to treat type-2 diabetes mellitus (T2DM). The drug, combined with controlling blood glucose levels, improves the body’s response to insulin. In addition, trials have identified the cardioprotective potential of metformin in the diabetic population receiving the drug. Activation of 5′ AMP-activated protein kinase (AMPK) is the major pathway for these potential beneficial effects of metformin. Historically, much emphasis has been placed on the potential indications of metformin beyond its anti-diabetic use. This review aims to appraise other potential uses of metformin primarily mediated by the activation of AMPK. We also discuss various mechanisms, other than AMPK activation, by which metformin could produce beneficial effects for different conditions. Databases including PubMed/MEDLINE and Embase were searched for literature relevant to the review’s objective. Reports from both research and review articles were considered. We found that metformin has diverse effects on the human body systems. It has been shown to exert anti-inflammatory, antioxidant, cardioprotective, metabolic, neuroprotective, anti-cancer, and antimicrobial effects and has now even been identified as effective against SARS-CoV-2. Above all, the AMPK pathway has been recognized as responsible for metformin’s efficiency and effectiveness. Owing to its extensive potential, it has the capability to become a part of treatment regimens for diseases apart from T2DM.

Studies on the mechanism of energy metabolism via AMPK/PGC-1α signaling pathway induced by compatibility of Ligusticum chuanxiong Hort and Gastrodia

AMP-activated protein kinase (AMPK) regulates overall energy consumption and energy intake through cytokines. Ligusticum striatum DC (CX) combined with Gastrodia elata Blume (TM) has been used for migraine treatment for millennia. When used alone in clinical practice, CX causes symptoms of thirst, irritability, and yellow urine and has influenced the levels of cytokines such as AMP that activate the AMPK pathway of energy metabolism. However, relationships between this compatibility prescription, integral biological energy metabolism, and the AMPK pathway remain unclear. Studies were performed by treating normal rats with physiological saline, CX extract, CX coupled TM extract, and TM extracts separately for 4 weeks. Food intake, water intake, urine output, stool output, and body weight were monitored once a week by the metabolic cage method. Values of FBG, BUN, TP, TC and TG in blood samples were detected approaching the whole blood automatic detector from 1 to 4 weeks. Na+ -K+ -ATPase, Ca2+ -Mg2+ -ATPase, cAMP, and cGMP activity were determined by the enzyme-linked immunosorbent assay (ELISA); the biological samples that were obtained at 1, 2, 3, and 4 weeks after drug administration were tested by GC-TOF-MS. Then real-time PCR and Western Blot were applied to detect changes in expression of some substances involved in energy metabolism. The results demonstrated that administering CX alone increased energy input, mobility, and respiratory exchange ratio, accelerated energy consumption, and caused inflammatory infiltration in the liver. CX coupled with TM led to lower energy metabolism and liver damage in comparison with CX used alone. Moreover, CX-treated rats harbored higher levels of differential metabolites (including pyrophosphate, oxaloacetic acid, and galactinol). Glycerophospholipid metabolism and the citrate cycle are closely related to the differential metabolites above. In addition, CX-induced unbalanced energy metabolism depends on cAMP activation mediated by the AMPK/PGC-1α pathway in rats. Our findings suggest that CX-induced energy metabolism imbalance was corrected after coupling with TM by mediating the AMPK/PGC-1α pathway.

AMPK Amplifies IL2-STAT5 Signaling to Maintain Stability of Regulatory T Cells in Aged Mice

AMP-activated protein kinase (AMPK), an important regulator of the aging process, is expressed in various immune cells. However, its role in regulatory T cell (Treg) stability during aging is poorly understood. Here, we addressed the role of AMPK in Treg function and stability during aging by generating Treg-specific AMPKα1 knockout mice. In this study, we found that AMPKα1-deficient Tregs failed to control inflammation as effectively as normal Tregs did during aging. AMPK knockout from Tregs reduces STAT5 phosphorylation in response to interleukin (IL)-2 stimulation, thereby destabilizing Tregs by decreasing CD25 expression. Thus, our study addressed the role of AMPK in Tregs in sensing IL-2 signaling to amplify STAT5 phosphorylation, which, in turn, supports Treg stability by maintaining CD25 expression and controlling inflamm-aging.

Role of Oxidative Stress in Liver Disorders

Oxygen is vital for life as it is required for many different enzymatic reactions involved in intermediate metabolism and xenobiotic biotransformation. Moreover, oxygen consumption in the electron transport chain of mitochondria is used to drive the synthesis of ATP to meet the energetic demands of cells. However, toxic free radicals are generated as byproducts of molecular oxygen consumption. Oxidative stress ensues not only when the production of reactive oxygen species (ROS) exceeds the endogenous antioxidant defense mechanism of cells, but it can also occur as a consequence of an unbalance between antioxidant strategies. Given the important role of hepatocytes in the biotransformation and metabolism of xenobiotics, ROS production represents a critical event in liver physiology, and increasing evidence suggests that oxidative stress contributes to the development of many liver diseases. The present review, which is part of the special issue “Oxidant stress in Liver Diseases”, aims to provide an overview of the sources and targets of ROS in different liver diseases and highlights the pivotal role of oxidative stress in cell death. In addition, current antioxidant therapies as treatment options for such disorders and their limitations for future trial design are discussed.

Caenorhabditis elegans as an emerging model in food and nutrition research: importance of standardizing base diet

As a model organism that has helped revolutionize life sciences, Caenorhabditis elegans has been increasingly used in nutrition research. Here we explore the tradeoffs between pros and cons of its use as a dietary model based primarily on literature review from the past decade. We first provide an overview of its experimental strengths as an animal model, focusing on lifespan and healthspan, behavioral and physiological phenotypes, and conservation of key nutritional pathways. We then summarize recent advances of its use in nutritional studies, e.g. food preference and feeding behavior, sugar status and metabolic reprogramming, lifetime and transgenerational nutrition tracking, and diet-microbiota-host interactions, highlighting cutting-edge technologies originated from or developed in C. elegans. We further review current challenges of using C. elegans as a nutritional model, followed by in-depth discussions on potential solutions. In particular, growth scales and throughputs, food uptake mode, and axenic culture of C. elegans are appraised in the context of food research. We also provide perspectives for future development of chemically defined nematode food ("NemaFood") for C. elegans, which is now widely accepted as a versatile and affordable in vivo model and has begun to show transformative potential to pioneer nutrition science.

∆nFGF1 Protects β-Cells against High Glucose-Induced Apoptosis via the AMPK/SIRT1/PGC-1α Axis

Long-term exposure to high glucose leads to β-cell dysfunction and death. Fibroblast growth factor 1 (FGF1) has emerged as a promising diabetes treatment, but its pharmaceutical role and mechanism against glucolipotoxicity-induced β-cell dysfunction remain uncharacterized. Wild-type FGF1 (FGF1^WT) may exhibit in vivo mitogenicity, but deletion of N-terminal residues 1-27 gives a nonmitogenic variant, ∆nFGF1, that does not promote cell proliferation and still retains the metabolic activity of FGF1^WT. To investigate the roles of ∆nFGF1 on glucose regulation and potential islet β-cell dysfunction, db/db mice were used as a model of type 2 diabetes. The results showed that insulin secretion and apoptosis of islet β-cells were dramatically improved in ∆nFGF1-treated db/db mice. To further test the effects of ∆nFGF1 treatment, pancreatic β-cell (MIN6) cells were exposed to a mixture of palmitic acid (PA) and high glucose (HG) to mimic glucolipotoxic conditions in vitro. Treatment with ∆nFGF1 significantly inhibited glucolipotoxicity-induced apoptosis. Mechanistically, ∆nFGF1 exerts a protective effect on β-cells via activation of the AMPK/SIRT1/PGC-1α signaling pathway. These findings demonstrate that ∆nFGF1 protects pancreatic β-cells against glucolipotoxicity-induced dysfunction and apoptosis.

The aldolase inhibitor aldometanib mimics glucose starvation to activate lysosomal AMPK

The activity of 5'-adenosine monophosphate-activated protein kinase (AMPK) is inversely correlated with the cellular availability of glucose. When glucose levels are low, the glycolytic enzyme aldolase is not bound to fructose-1,6-bisphosphate (FBP) and, instead, signals to activate lysosomal AMPK. Here, we show that blocking FBP binding to aldolase with the small molecule aldometanib selectively activates the lysosomal pool of AMPK and has beneficial metabolic effects in rodents. We identify aldometanib in a screen for aldolase inhibitors and show that it prevents FBP from binding to v-ATPase-associated aldolase and activates lysosomal AMPK, thereby mimicking a cellular state of glucose starvation. In male mice, aldometanib elicits an insulin-independent glucose-lowering effect, without causing hypoglycaemia. Aldometanib also alleviates fatty liver and nonalcoholic steatohepatitis in obese male rodents. Moreover, aldometanib extends lifespan and healthspan in both Caenorhabditis elegans and mice. Taken together, aldometanib mimics and adopts the lysosomal AMPK activation pathway associated with glucose starvation to exert physiological roles, and might have potential as a therapeutic for metabolic disorders in humans.

Hernandezine, a natural herbal alkaloid, ameliorates type 2 diabetes by activating AMPK in two mouse models

BACKGROUND

AMP-activated protein kinase (AMPK) is an effective target for treating diabetes. However, successful drug development is delayed due to issues including toxicity. Plant-derived natural product AMPK activators have emerged as a new way to treat diabetes due to its potential low safety risks. Here, we studied the effect of hernandezine (HER), a natural product derived from Thalictrum, in activating AMPK and treating T2D in mouse models.

METHOD

We tested HER in various cells and tissues, including primary hepatocytes, skeletal myotubes cell lines, as well as major metabolic tissues from diabetic (db/db) and diet-induced obesity (DIO) model mice. The effect of HER on glucose uptake via AMPK in vitro and in vivo was confirmed utilizing cell transfection and adenovirus interference analysis. Tissue staining assessed the effect of HER on adipogenesis. Real-time quantitative polymerase chain reaction (real-time PCR) was applied to verify the effect of HER on transcription factors. Western blot analysis was used to determine the activation of phosphorylated AMPK and ACC pathways.

RESULTS

Biochemically, we found that HER prevented pAMPK from dephosphorylation to prolong its activity, disproving previous direct activation model and providing a new model to explain HER-mediated AMPK activation. HER could be orally delivered to animals and has a 3-fold long half-life in vivo as compared to metformin. Importantly, long-term oral HER treatment potently reduced body weight and blood glucose in both type 2 diabetes mullitus (T2DM) mouse models by increasing glucose disposal and reducing lipogenesis, and appeared not to induce cardiac hypertrophy.

CONCLUSION

Natural product HER indirectly activates AMPK by suppressing its dephosphorylation. Oral HER effectively alleviated hyperglycemia and reduced body weight in T2D mouse models, appeared to have a low risk of causing cardiac hypertrophy, and might be a potential therapeutic option for T2DM.

Melatonin protects against body weight gain induced by sleep deprivation in mice

Sleep deprivation is an epidemic phenomenon in modern society. Lack of sleep has been shown to result in metabolic and endocrine disorders that predispose to obesity and other chronic metabolic diseases. Melatonin is a sleep-related neurohormone and affected by the circadian rhythm and light/dark cycles. Melatonin has recently been used to ameliorate diet-induced or night light-induced energy metabolic imbalance. However, the effect of melatonin on sleep deprivation-induced obesity has been poorly characterized. This study focuses on the protective effects of melatonin on lipid metabolism and body weight homeostasis in sleep-deprived mice. Mice subjected to sleep deprivation had significantly decreased plasma melatonin content and increased food intake and body weight gain compared to that of control. Meanwhile, the transcription factor PPARγ protein in liver increased, but there were no significant changes in hepatic circadian proteins BMAL1 and REV-ERBα after 10 consecutive days of sleep deprivation. Moreover, melatonin supplementation increased liver AMPKα/PPARα signaling pathway activity, which leads to lipid catabolism and reduced fat accumulation. These findings suggested that melatonin may be a potential agent for protecting against sleep deprivation-induced obesity.

Dietary astaxanthin-rich extract ameliorates atherosclerosis/retinopathy and restructures gut microbiome in apolipoprotein E-deficient mice fed on a high-fat diet

Scope: Atherosclerosis (AS) is the leading cause of ischemic disease. However, the anti-AS effects of astaxanthin and its potential mechanisms remain unclear. This study is aimed to investigate the function of astaxanthin-rich extract (ASTE) on AS and gut microbiota as well as the difference from atorvastatin (ATO) in apolipoprotein E-deficient (ApoE^-/-) mice. Methods and results: Wild type (WT) and ApoE^-/- mice were divided into seven groups: the low-fat diet (LFD) and high-fat diet (HFD) groups (in both types) as well as three ApoE^-/- groups based on HFD added with two doses of ASTE and one dose of ATO, respectively. After 30 weeks of intervention, results showed that ASTE significantly inhibited body weight increase, lipids accumulation in serum/liver, and AS-lesions in the aorta. Furthermore, fundus fluorescein angiography and retinal CD31 immunohistochemical staining showed that ASTE could alleviate the occurrence of AS-retinopathy. H&E staining showed that ASTE could protect the colon's mucosal epithelium from damage. The gas chromatographic and gene expression analyses showed that ASTE promoted the excretion of fecal acidic and neutral sterols from cholesterol by increasing LXRα, CYP7A1, and ABCG5/8 and decreasing FXR, NPC1L1, ACAT2, and MTTP expressions. Remarkably, the ASTE administration maintained the gut barrier by enhancing gene expression of JAM-A, Occludin, and mucin2 in the colon and reshaped gut microbiota with the feature of blooming Akkermansia. Conclusion: Our results suggested that ASTE could prevent AS in both macrovascular and/or microvascular as well as used as novel prebiotics by supporting the bile acid excretion and growth of Akkermansia.

Liquorice root extract and isoliquiritigenin attenuate high-fat diet-induced hepatic steatosis and damage in rats by regulating AMPK

Objective: This study compared the ability of Liquorice roots aqueous extract (LRE) and its ingredient, isoliquiritigenin (ISL), in alleviating high-fat diet (HFD)-induced hepatic steatosis and examined if this effect involves activation of AMPK.Materials and methods: Control or HFD-fed rats were treated with the vehicle, LRE (200 mg/kg), or ISL (30 mg/kg) for 8 weeks orally.Results: ISL and LRE reduced HFD-induced hyperglycaemia, improved liver structure, lowered serum and hepatic lipids, and attenuated hepatic oxidative stress and inflammation. In the control and HFD-fed rats, ISL and LRE significantly stimulated the muscular and hepatic mRNA and protein levels of AMPK, improved oral glucose tolerance, reduced hepatic mRNA levels of SREBP1/2, and upregulated hepatic levels of PPARα and Bcl2. These effects were comparable for ISL and LRE and were prevented by co-administration of compound C, an AMPK inhibitor.Discussion and conclusion: ISL and LRE provide an effective theory to alleviate hepatic steatosis through activating AMPK.

Anti-Obesogenic Effects of Sulforaphane-Rich Broccoli (Brassica oleracea var. italica) Sprouts and Myrosinase-Rich Mustard (Sinapis alba L.) Seeds in Vitro and in Vivo

Glucoraphanin (GRA), a glucosinolate particularly abundant in broccoli (Brassica oleracea var. italica) sprouts, can be converted to sulforaphane (SFN) by the enzyme myrosinase. Herein, we investigated the anti-obesogenic effects of broccoli sprout powder (BSP), mustard (Sinapis alba L.) seed powder (MSP), and sulforaphane-rich MSP-BSP mixture powder (MBP) in bisphenol A (BPA)-induced 3T3-L1 cells and obese C57BL/6J mice. In vitro experiments showed that MBP, BSP, and MSP have no cytotoxic effects. Moreover, MBP and BSP inhibited the lipid accumulation in BPA-induced 3T3-L1 cells. In BPA-induced obese mice, BSP and MBP treatment inhibited body weight gain and ameliorated dyslipidemia. Furthermore, our results showed that BSP and MBP could activate AMPK, which increases ACC phosphorylation, accompanied by the upregulation of lipolysis-associated proteins (UCP-1 and CPT-1) and downregulation of adipogenesis-related proteins (C/EBP-α, FAS, aP2, PPAR-γ, and SREBP-1c), both in vitro and in vivo. Interestingly, MBP exerted a greater anti-obesogenic effect than BSP. Taken together, these findings indicate that BSP and MBP could inhibit BPA-induced adipocyte differentiation and adipogenesis by increasing the expression of the proteins related to lipid metabolism and lipolysis, effectively treating BPA-induced obesity. Thus, BSP and MBP can be developed as effective anti-obesogenic drugs.

Metformin alleviates long-term high-fructose diet-induced skeletal muscle insulin resistance in rats by regulating purine nucleotide cycle

Nutrient excess caused by excessive fructose intake can lead to insulin resistance and dyslipidemia, which further causes the development of metabolic syndrome. Metformin is a well-known AMPK activator widely used for the treatment of metabolic syndrome, while the mechanism of AMPK activation remains unclear. The present study aimed to investigate the pharmacological effects of metformin on fructose-induced insulin resistance rat, and the potential mechanism underlying AMPK activation in skeletal muscle tissue. Results indicated that metformin significantly ameliorated features of insulin resistance, including body weight, Lee's index, hyperinsulinemia, dyslipidemia, insulin intolerance and pancreatic damage. Moreover, treatment with metformin attenuated the inflammatory response in serum and enhanced the antioxidant capacity in skeletal muscle tissue. The therapeutic effects of metformin on fructose-induced insulin resistance may be related to the activation of AMPK to regulate Nrf2 pathway and mitochondrial abnormality. Additionally, metformin suppressed the expression of adenosine monophosphate deaminase 1 (AMPD1) and up-regulated the expression of adenylosuccinate synthetase (ADSS) in the purine nucleotide cycle (PNC), which facilitated the increase of AMP level and the ratio of AMP/ATP. Therefore, we proposed a novel mechanism that metformin activated AMPK via increasing AMP by regulating the expression of AMPD1 and ADSS in PNC pathway.

Inhibition of Hepatic AMPK Pathway Contributes to Free Fatty Acids-Induced Fatty Liver Disease in Laying Hen

Metabolism-associated fatty liver disease (MAFLD) is one of the most common causes of liver disease; however, the underlying processes remain unknown. This study aimed to investigate the changes of free fatty acids (FFA) on the expression of genes related to the AMP-activated protein kinase (AMPK) signaling pathway in the primary hepatocytes of laying hens. The primary hepatocytes of laying hens were treated with FFA (containing a 2:1 ratio of oleic and palmitic acids) for 24 h. FFA significantly increased lipid droplet accumulation, decreased glycogen synthesis, increased the levels of triglycerides (TG), total cholesterol (TC), reactive oxygen species (ROS), malondialdehyde (MDA), and glucose content in the supernatant (GLU) in the primary hepatocytes of laying hens, and decreased the levels of total antioxidant capacity (T-AOC) and superoxide dismutase (SOD), as well as mitochondrial membrane potential (MMP). The results of the PCR array combined with Western blotting experiments showed that the activity of AMPK was inhibited. Inhibition of AMPK signaling pathway decreases the expression of genes involved in fatty acid oxidation, increases the expression of genes involved in lipid synthesis, decreases the expression of genes involved in glycogen synthesis, increases the expression of genes involved in glycolysis, increases the expression of genes involved in oxidative stress, and increases the expression of genes involved in cell proliferation and apoptosis. Taken together, our results suggest that FFA can affect the homeostasis of the AMPK signaling pathway by altering energy metabolic homeostasis, inducing oxidative stress, and adjusting the onset of cell proliferation and apoptosis.

Dietary carbohydrates: Pathogenesis and potential therapeutic targets to obesity-associated metabolic syndrome

Metabolic syndrome (MetS) is a common feature in obesity, comprising a cluster of abnormalities including abdominal fat accumulation, hyperglycemia, hyperinsulinemia, dyslipidemia, and hypertension, leading to diabetes and cardiovascular diseases (CVD). Intake of carbohydrates (CHO), particularly a sugary diet that rapidly increases blood glucose, triglycerides, and blood pressure levels is the predominant determining factor of MetS. Complex CHO, on the other hand, are a stable source of energy taking a longer time to digest. In particular, resistant starch (RS) or soluble fiber is an excellent source of prebiotics, which alter the gut microbial composition, which in turn improves metabolic control. Altering maternal CHO intake during pregnancy may result in the child developing MetS. Furthermore, lifestyle factors such as physical inactivity in combination with dietary habits may synergistically influence gene expression by modulating genetic and epigenetic regulators transforming childhood obesity into adolescent metabolic disorders. This review summarizes the common pathophysiology of MetS in connection with the nature of CHO, intrauterine nutrition, genetic predisposition, lifestyle factors, and advanced treatment approaches; it also emphasizes how dietary CHO may act as a key element in the pathogenesis and future therapeutic targets of obesity and MetS.

AMPK and NRF2: Interactive players in the same team for cellular homeostasis?

NRF2 (Nuclear factor E2 p45-related factor 2) is a stress responsive transcription factor lending cells resilience against oxidative, xenobiotic, and also nutrient or proteotoxic insults. AMPK (AMP-activated kinase), considered as prime regulator of cellular energy homeostasis, not only tunes metabolism to provide the cell at any time with sufficient ATP or building blocks, but also controls redox balance and inflammation. Due to observed overlapping cellular responses upon AMPK or NRF2 activation and common stressors impinging on both AMPK and NRF2 signaling, it is plausible to assume that AMPK and NRF2 signaling may interdepend and cooperate to readjust cellular homeostasis. After a short introduction of the two players this narrative review paints the current picture on how AMPK and NRF2 signaling might interact on the molecular level, and highlights their possible crosstalk in selected examples of pathophysiology or bioactivity of drugs and phytochemicals.

A Review of Signaling Transduction Mechanisms in Osteoclastogenesis Regulation by Autophagy, Inflammation, and Immunity

Osteoclastogenesis is an ongoing rigorous course that includes osteoclast precursors fusion and bone resorption executed by degradative enzymes. Osteoclastogenesis is controlled by endogenous signaling and/or regulators or affected by exogenous conditions and can also be controlled both internally and externally. More evidence indicates that autophagy, inflammation, and immunity are closely related to osteoclastogenesis and involve multiple intracellular organelles (e.g., lysosomes and autophagosomes) and certain inflammatory or immunological factors. Based on the literature on osteoclastogenesis induced by different regulatory aspects, emerging basic cross-studies have reported the emerging disquisitive orientation for osteoclast differentiation and function. In this review, we summarize the partial potential therapeutic targets for osteoclast differentiation and function, including the signaling pathways and various cellular processes.

Potato protease inhibitor II prevents obesity by inducing browning of white adipose tissue in mice via β3 adrenergic receptor signaling pathway

There are currently few effective and safe pharmacologic means for inducing beige adipogenesis in humans. This study highlights the role of potato protease inhibitor II (PPI II) in regulating the browning of adipose tissue. The in vitro results showed that PPI II increased the expression of the uncoupling protein 1 (UCP1) protein and gene and beige-specific genes, including Cd137, Cited1, Tbx1, and Tmem26 in vitro. PPI II treatment for three months in diet-induced obesity mice increased the levels of the UCP1 protein in white adipose tissue, causing elevated energy expenditure, thus preventing obesity and improving glucose tolerance. Mechanistic studies further revealed that PPI II regulated the abundance and activity of β₃ adrenergic receptor (β₃ -AR) in white adipocytes. Chemical-inhibition experiments revealed the crucial role of β₃ -AR-dependent protein kinase A (PKA)-p38 kinase (p38)/extracellular signal-related kinase1/2 (ERK1/2) signaling in PPI II-mediated browning program of white adipose tissues. In summary, our findings highlight the role of PPI II in beige adipocyte differentiation and thermogenesis and provide new insights into its use in preventing obesity.

Paeoniflorin alleviates liver injury in hypercholesterolemic rats through the ROCK/AMPK pathway

Paeoniflorin (PF) is the main active component in Paeonia lactiflora Pall, and it has multiple effects. However, the precise mechanism of PF in hypercholesterolemia is unclear. In this study, rats were either fed a high-cholesterol diet (HCD) for 4 weeks to establish the hypercholesterolemic model or administered normal saline or PF (20 mg/kg/day). PF significantly reduced liver weight and the liver index. PF reduced hepatic lipid deposition and inflammation, improved serum lipid metabolism, and significantly inhibited serum and hepatic oxidative stress and the inflammatory response. PF treatment caused a marked decrease in the phosphorylated myosin phosphatase target subunit (p-MYPT)-1, nuclear sterol regulatory element-binding protein-1c (SREBP-1c), fatty acid synthase (FAS) levels, and an increase in the low-density lipoprotein receptor (LDLR) and phosphorylated-AMP-activated protein kinase (p-AMPK). Thus, PF could alleviate liver injury in hypercholesterolemic rats, and the specific mechanism may be related to the antioxidant, anti-inflammatory properties, and ROCK/AMPK/SREBP-1c signaling pathway.

DHHC17 Is a New Regulator of AMPK Signaling

The association of AMP-activated protein kinase (AMPK) with membranes plays a critical role in the regulation of AMPK activation and function. Protein lipid modification, including palmitoylation, myristoylation, and farnesyation, constitutes a crucial mechanism in the regulation of protein dynamic interactions with membranes. Among the three subunits of the AMPK heterotrimeric complex, the structural subunit AMPKβ is myristoylated and the catalytic subunit AMPKα is palmitoylated. Here, we report the characterization of AMPKα palmitoylation. We found that AMKPα was palmitoylated at Cys209 and Cys543, and this was required for AMPK activation and subcellular membrane compartmentalization. To understand the regulation of AMPKα palmitoylation, we have identified DHHC17 as a candidate palmitoyltransferase for AMPKα and found that DHHC17, by palmitoylating AMPKα, modulated AMPK membrane association and activation in response to energy stress. To determine the role of DHHC17 in cell function, we generated DHHC17 liver-specific knockout mice and found that inactivation of DHHC17 in the mouse liver impaired AMPK activation and hepatic autophagy and caused a type 2 diabetes-like syndrome. Overall, our studies demonstrate that AMPKα palmitoylation plays a critical role in AMPK activation and that DHHC17, through its modulation of AMPK signaling, constitutes a new regulator of hepatic metabolism.

Supplementation of Lycium barbarum Polysaccharide Combined with Aerobic Exercise Ameliorates High-Fat-Induced Nonalcoholic Steatohepatitis via AMPK/PPARα/PGC-1α Pathway

Nonalcoholic steatohepatitis (NASH) is a subtype of nonalcoholic fatty liver disease (NAFLD). Either Lycium barbarum polysaccharide (LBP) or aerobic exercise (AE) has been reported to be beneficial to hepatic lipid metabolism. However, whether the combination of LBP with AE improves lipid accumulation of NASH remains unknown. Our study investigated the influence of 10 weeks of treatment of LBP, AE, and the combination (LBP plus AE) on high-fat-induced NASH in Sprague-Dawley rats. The results showed that LBP or AE reduced the severity of the NASH. LBP plus AE treatment more effectively ameliorated liver damage and lowered levels of serum lipid and inflammation. In addition, the combination can also regulate genes involved in hepatic fatty acid synthesis and oxidation. LBP plus AE activated AMPK, thereby increasing the expression of PPARα which controls hepatic fatty acid oxidation and its coactivator PGC-1α. Our study demonstrated the improvement of LBP plus AE on NASH via enhancing fatty acid oxidation (FAO) which was dependent on AMPK/PPARα/PGC-1α pathway.

Pathogenesis and Therapeutic Strategies Related to Non-Alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD), one of the most common types of chronic liver disease, is strongly correlated with obesity, insulin resistance, metabolic syndrome, and genetic components. The pathological progression of NAFLD, consisting of non-alcoholic fatty liver (NAFL), non-alcoholic steatohepatitis (NASH), and liver cirrhosis, is characterized by a broad spectrum of clinical phenotypes. Although patients with mild NAFL are considered to show no obvious clinical symptoms, patients with long-term NAFL may culminate in NASH and further liver fibrosis. Even though various drugs are able to improve NAFLD, there are no FDA-approved medications that directly treat NAFLD. In this paper, the pathogenesis of NAFLD, the potential therapeutic targets, and their underlying mechanisms of action were reviewed.

Notch-activated mesenchymal stromal/stem cells enhance the protective effect against acetaminophen-induced acute liver injury by activating AMPK/SIRT1 pathway

Background

Notch signaling plays important roles in regulating innate immunity. However, little is known about the role of Notch in mesenchymal stromal/stem cell (MSC)-mediated immunomodulation during liver inflammatory response.

Methods

Notch activation in human umbilical cord-derived MSCs was performed by a tissue culture plate coated with Notch ligand, recombinant human Jagged1 (JAG1). Mice were given intravenous injection of Notch-activated MSCs after acetaminophen (APAP)-induced acute liver injury. Liver tissues were collected and analyzed by histology and immunohistochemistry.

Results

MSC administration reduced APAP-induced hepatocellular damage, as manifested by decreased serum ALT levels, intrahepatic macrophage/neutrophil infiltration, hepatocellular apoptosis and proinflammatory mediators. The anti-inflammatory activity and therapeutic effects of MSCs were greatly enhanced by Notch activation via its ligand JAG1. However, Notch2 disruption in MSCs markedly diminished the protective effect of MSCs against APAP-induced acute liver injury, even in the presence of JAG1 pretreatment. Strikingly, Notch-activated MSCs promoted AMP-activated protein kinase (AMPKα) phosphorylation, increased the sirtuins 1 (SIRT1) deacetylase expression, but downregulated spliced X-box-binding protein 1 (XBP1s) expression and consequently reduced NLR family pyrin domain-containing 3 (NLRP3) inflammasome activation. Furthermore, SIRT1 disruption or XBP1s overexpression in macrophages exacerbated APAP-triggered liver inflammation and augmented NLRP3/caspase-1 activity in MSC-administrated mice. Mechanistic studies further demonstrated that JAG1-pretreated MSCs activated Notch2/COX2/PGE2 signaling, which in turn induced macrophage AMPK/SIRT1 activation, leading to XBP1s deacetylation and inhibition of NLRP3 activity.

Conclusions

Activation of Notch2 is required for the ability of MSCs to reduce the severity of APAP-induced liver damage in mice. Our findings underscore a novel molecular insights into MSCs-mediated immunomodulation by activating Notch2/COX2/AMPK/SIRT1 pathway and thus provide a new strategy for the treatment of liver inflammatory diseases.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-02999-6.

Alginate Oligosaccharides Ameliorate DSS-Induced Colitis through Modulation of AMPK/NF-κB Pathway and Intestinal Microbiota

Alginate oligosaccharides (AOS) are shown to have various biological activities of great value to medicine, food, and agriculture. However, little information is available about their beneficial effects and mechanisms on ulcerative colitis. In this study, AOS with a polymerization degree between 2 and 4 were found to possess anti-inflammatory effects in vitro and in vivo. AOS could decrease the levels of nitric oxide (NO), IL-1β, IL-6, and TNFα, and upregulate the levels of IL-10 in both RAW 264.7 and bone-marrow-derived macrophage (BMDM) cells under lipopolysaccharide (LPS) stimulation. Additionally, oral AOS administration could significantly prevent bodyweight loss, colonic shortening, and rectal bleeding in dextran sodium sulfate (DSS)-induced colitis mice. AOS pretreatment could also reduce disease activity index scores and histopathologic scores and downregulate proinflammatory cytokine levels. Importantly, AOS administration could reverse DSS-induced AMPK deactivation and NF-κB activation in colonic tissues, as evidenced by enhanced AMPK phosphorylation and p65 phosphorylation inhibition. AOS could also upregulate AMPK phosphorylation and inhibit NF-κB activation in vitro. Moreover, 16S rRNA gene sequencing of gut microbiota indicated that supplemental doses of AOS could affect overall gut microbiota structure to a varying extent and specifically change the abundance of some bacteria. Medium-dose AOS could be superior to low- or high-dose AOS in maintaining remission in DSS-induced colitis mice. In conclusion, AOS can play a protective role in colitis through modulation of gut microbiota and the AMPK/NF-kB pathway.