Improvement of Lipid and Glucose Metabolism by Capsiate in Palmitic Acid-Treated HepG2 Cells via Activation of the AMPK/SIRT1 Signaling Pathway

SIRT1 signaling pathways in sarcopenia: Novel mechanisms and potential therapeutic targets

Sarcopenia is an aging-related skeletal disease characterized by decreased muscle mass, strength, and physical function, severely affecting the quality of life (QoL) of the elderly population. Sirtuin 1 (SIRT1), as a nicotinamide adenine dinucleotide (NAD+)-dependent histone deacetylases, has been reported to participate in various aging-related signaling pathways and exert protective effect on many human diseases. SIRT1 functioned as an important role in the occurrence and progression of sarcopenia through regulating key pathways related to protein homeostasis, apoptosis, mitochondrial dysfunction, insulin resistance and autophagy in skeletal muscle, including SIRT1/Forkhead Box O (FoxO), AMP-activated protein kinase (AMPK)/SIRT1/nuclear factor κB (NF-κB), SIRT1/p53, AMPK/SIRT1/peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α), and SIRT1/live kinase B1 (LKB1)/AMPK pathways. However, the specific mechanisms of these processes have not been fully illuminated. Currently, several SIRT1-mediated interventions on sarcopenia have been preliminarily developed, such as SIRT1 activator polyphenolic compounds, exercising and calorie restriction. In this review, we summarized the predominant mechanisms of SIRT1 involved in sarcopenia and therapeutic modalities targeting the SIRT1 signaling pathways for the prevention and prognosis of sarcopenia.

NF-κB pathway as a molecular target for curcumin in diabetes mellitus treatment: Focusing on oxidative stress and inflammation

Diabetes mellitus (DM) is a collection of metabolic disorder that is characterized by chronic hyperglycemia. Recent studies have demonstrated the crucial involvement of oxidative stress (OS) and inflammatory reactions in the development of DM. Curcumin (CUR), a natural compound derived from turmeric, exerts beneficial effects on diabetes mellitus through its interaction with the nuclear factor kappa B (NF-κB) pathway. Research indicates that CUR targets inflammatory mediators in diabetes, including tumor necrosis factor α (TNF-α) and interleukin-6 (IL-6), by modulating the NF-κB signaling pathway. By reducing the expression of these inflammatory factors, CUR demonstrates protective effects in DM by improving pancreatic β-cells function, normalizing inflammatory cytokines, reducing OS and enhancing insulin sensitivity. The findings reveal that CUR administration effectively lowered blood glucose elevation, reinstated diminished serum insulin levels, and enhanced body weight in Streptozotocin -induced diabetic rats. CUR exerts its beneficial effects in management of diabetic complications through regulation of signaling pathways, such as calcium-calmodulin (CaM)-dependent protein kinase II (CaMKII), peroxisome proliferator-activated receptor gamma (PPAR-γ), NF-κB, and transforming growth factor β1 (TGFB1). Moreover, CUR reversed the heightened expression of inflammatory cytokines (TNF-α, Interleukin-1 beta (IL-1β), IL-6) and chemokines like MCP-1 in diabetic specimens, vindicating its anti-inflammatory potency in counteracting hyperglycemia-induced alterations. CUR diminishes OS, avert structural kidney damage linked to diabetic nephropathy, and suppress NF-κB activity. Furthermore, CUR exhibited a protective effect against diabetic cardiomyopathy, lung injury, and diabetic gastroparesis. Conclusively, the study posits that CUR could potentially offer therapeutic benefits in relieving diabetic complications through its influence on the NF-κB pathway.

The Antimicrobial Peptide Tilapia Piscidin 4 Induced the Apoptosis of Bladder Cancer Through ERK/SIRT1/PGC-1α Signaling Pathway

Marine antimicrobial peptides have been demonstrated in numerous studies to possess anti-cancer properties. This research investigation aimed to explore the fundamental molecular mechanisms underlying the antitumor activity of Tilapia piscidin 4 (TP4), an antimicrobial peptide, in human bladder cancer. TP4 exhibited a remarkable inhibitory effect on the proliferation of bladder cancer cells through cell cycle arrest at the G2/M phase. Additionally, TP4 upregulated the expression of cleaved caspase-3, caspase-9, and PARP, leading to the activation of apoptotic pathways in bladder cancer cells. TP4 exhibit a marked rise in mitochondria reactive oxygen species, leading to the subsequent loss of potential for the mitochondrial membrane. Furthermore, the inhibition of mitochondrial oxidative phosphorylation resulted in a decrease in downstream ATP production. Meanwhile, TP4-treated bladder cancer cells showed an increase in Bax and ERK but a decrease in SIRT1, PGC-1α, and Bcl2. ERK activation, SIRT1/PGC-1α-axis, and TP4-induced apoptosis were all significantly reversed by the ERK inhibitor SCH772984. Finally, the inhibitory effect of TP4 on tumor growth has been confirmed in a zebrafish bladder cancer xenotransplantation model. These findings suggest that TP4 may be a potential agents for human bladder cancer through apoptosis induction, ERK activation, and the promotion of SIRT1-mediated signaling pathways.

Purinergic ligands induce extracellular acidification and increased ATP turnover in HepG2 cells

Nucleosides and nucleotides at μM concentrations stimulated a 300% increase in acid secretion in HepG2 cells, which was quantitatively accounted for as increased export of lactate generated by glycogenolysis. Agonist selectivity encompassed nucleosides and nucleotides for all 5 natural nucleobases and, along with antagonist profiles, was inconsistent with a role for purinergic receptors in mediating this activity. Agonist catabolism did not contribute significantly to either low selectivity or lactate production. Lactate production was driven by an increase in ATP turnover of as much as 56%. For some agonists, especially adenosine, ATP turnover decreased precipitously at mM concentrations, correlating with known adenosine-stimulated apoptosis. We propose that nucleoside/nucleotide agonists induce a futile energy cycle via a novel mechanism, which results in increased ATP turnover and initiates a continuum of events that for some agonists culminates in apoptosis.

Correlations between the structure and anti-diabetic activity of novel polysaccharides from raw and "Nine Steaming Nine Sun-Drying" Polygonti rhizome

"Nine Steaming Nine Sun-Drying" Polygonti rhizome has been used as valuable tonic health-care products for thousands of years. This research aimed to determine the correlations between the structure and anti-diabetic activities of three novel polysaccharides isolated from the raw and "Nine Steaming Nine Sun-Drying" Polygonti rhizome, with PRP-R from the raw ones and PRP-9Z and PRP-9A from the steamed ones. Structures of the isolated polysaccharides were determined by IR and NMR spectra, as well as monosaccharide composition and methylation analysis. In vitro assays indicated that PRP-9Z could improve the glucose consumptions more effectively than PRP-R and PRP-9A via Akt/GSK3β insulin signal pathway by western blotting analysis. In vivo assays indicated PRP-9Z could improve the glucose tolerance in the BKS-db mice. Histopathological assay demonstrated that PRP-9Z effectively reduced the damage of the kidney and liver. The above results indicated that PRP-9Z from "Nine Steaming Nine Sun-Drying" Polygonti rhizome showed significant anti-diabetic properties, which indicated that PRP-9Z with higher content of →1)-β-Frup-(2→ was more active than PRP-R with higher →1,6)-β-Fruf-(2→ and PRP-9A with higher →4)-β-Galp(1→.

Secondary metabolites from Scindapsus officinalis (Roxb.) Schott. with in vitro antidiabetic activities

One new phenolic cyclobutantetraol ester united chromone glycoside (1), one new amide (2), and three new phenyl ethanol glycosides (3-5) were obtained from the water extract of Scindapsus officinalis (Roxb.) Schott, in which compound 1 was the first reported structure incorporating the phenolic cyclobutantetraol ester and chromone via the glucose phenolic metabolites in nature. Structures of the isolated compounds, including absolute configurations, were elucidated according to the analysis of HRESIMS, NMR, ECD and BLYP/6-31G* geometry optimization calculations of 13C NMR data. All isolates (1-5) were evaluated for the antidiabetic activity by the insulin resistance (IR) model and anti-inflammatory activity against NO production in vitro. Compounds 1-3 showed strong antidiabetic activities, greatly promoting the glucose consumption in the insulin resistance HepG2 cells compared with the model group, however, 1-5 showed weak anti-inflammatory activities.

SIRT1 activation attenuates palmitate induced apoptosis in C2C12 muscle cells

BACKGROUND

Type 2 diabetes is characterized by insulin resistance, which manifests mainly in skeletal muscles. SIRT1 has been found to play a role in the insulin signaling pathway. However, the molecular underpinnings of SIRT1's function in palmitate fatty acid-induced apoptosis still need to be better understood.

METHODS

In this research, skeletal muscle cells are treated with palmitate to be insulin resistant. It is approached that SIRT1 is downregulated in C2C12 muscle cells during palmitate-induced apoptosis and that activating SIRT1 mitigates this effect.

RESULTS

Based on these findings, palmitate-induced apoptosis suppressed mitochondrial biogenesis by lowering PGC-1 expression, while SIRT1 overexpression boosted. The SIRT1 inhibitor sirtinol, on the other hand, decreased mitochondrial biogenesis under the same conditions. This research also shows that ROS levels rise in the conditions necessary for apoptosis induction by palmitate, and ROS inhibitors can mitigate this effect. This work demonstrated that lowering ROS levels by boosting SIRT1 expression inhibited apoptotic induction in skeletal muscle cells.

CONCLUSION

This study's findings suggested that SIRT1 can improve insulin resistance in type 2 diabetes by slowing the rate of lipo-apoptosis and boosting mitochondrial biogenesis, among other benefits.

Polystyrene nanoplastics induce lipid metabolism disorder and alter fatty acid composition in the hepatopancreas of Pacific whiteleg shrimp (Litopenaeus vannamei)

The impact of nanoplastics (NPs) on environmental pollution and aquatic organisms has gradually attracted attention, but there are relatively few reports of the effects of NPs on the lipid metabolism of crustaceans. In this study, we exposed Pacific whiteleg shrimp (Litopenaeus vannamei) to different concentrations of polystyrene NPs (0, 0.1, 1, 5, and 10 mg/L) for 28 days. We then evaluated the effects of NP exposure on metabolite content, histology, lipid metabolism-related enzyme activity, and gene expression. Our results showed that with increasing NPs concentrations and exposure time, (1) the crude protein and crude fat content decreased and fatty acid composition changed; (2) the tissue structure was destroyed and the number of lipid droplets increased in the hepatopancreas; (3) the activities of acetyl-CoA carboxylase, fatty acid synthase, carnitine palmitoyl transferase-1, pyruvate kinase and low-density lipoprotein content tended to decrease and that of lipase and high-density lipoprotein content first increased and then decreased; the content of triglycerides and total carbohydrate first decreased and then increased; (4) the expression of fatty acid synthesis-related genes (Fas, SREBP, and FAD), fatty acid transport-related genes (FATP, FABP, and ACBP), and fatty acid decomposition-related genes (Ampk and lip1) first increased and then decreased. These results indicate that exposure to NPs can cause physiological disorders of fat metabolism in L.vannamei and that high concentrations of NPs have a negative impact on lipid metabolism. These results of this study provide valuable ecotoxicological data for better interpretation of the mechanism of action of NPs in crustaceans.

Construction of the Gal-NH2/mulberry leaf polysaccharides-lysozyme/luteolin nanoparticles and the amelioration effects on lipid accumulation

Luteolin is a kind of natural flavonoid with great potential for lipid accumulation intervention. However, the poor water solubility and non-targeted release greatly diminish its efficiency. In this study, 4-aminophenyl β-D-galactopyranoside (Gal-NH2)/mulberry leaf polysaccharides- lysozyme/luteolin nanoparticles (Gal-MPL/Lut) were fabricated via amide reaction, self-assembly process and electrostatic interaction. The nanoparticles could hepatic-target of Lut and enhance action on liver tissue by specific recognition of asialoglycoprotein receptor (ASGPR). Physicochemical characterization of the nanoparticles showed a spherical shape with a uniform particle size distribution (77.8 ± 2.6 nm) with a polydispersity index (PDI) of 0.22 ± 0.06. Subsequently, in HepG2 cells model, administration with hepatic-targeted Gal-MPL/Lut nanoparticles promoted the cellular uptake of Lut, and regulated lipid metabolism manifested by remarkably inhibiting total cholesterol (TC) and triglyceride (TG) expression levels through the modulation of PI3K/SIRT-1/FAS/CEBP-α signaling pathway. This study provides a promising strategy for a highly hepatic-targeted therapy to ameliorate lipid accumulation using natural medicines facilitated by nano-technology.

Piperine Attenuates Bmal1-Mediated Glucose Metabolism Disorder in a Trpv1-Dependent Manner in HepG2 Cells

Piperine (PIP), a pungent alkaloid found in black pepper, has various pharmacological effects by activating the transient receptor potential vanilloid 1 (TRPV1) receptor. In this study, the regulating effect of PIP on glucose metabolism and the underlying mechanism were examined using an insulin-resistant cell model. Results showed that PIP alleviated glucosamine (GlcN)-induced glucose metabolism disorder (from 59.19 ± 1.90 to 88.36 ± 6.57%), restored cellular redox balance (from 148.43 ± 3.52 to 110.47 ± 3.52%), improved mitochondrial function (from 63.76 ± 4.87 to 85.98 ± 5.12%), and mitigated circadian disruption in HepG2 cells via the mediation of circadian clock gene Bmal1. After the knockdown of the Trpv1 gene, the modulating effect of PIP on Bmal1-mediated glucose metabolism was weakened, indicating that PIP alleviated Bmal1-involved insulin resistance and circadian misalignment in a Trpv1-dependent manner in HepG2 cells.

Sesamol Alleviates High-Fat Diet-Induced Hepatic Insulin Resistance in C57BL/6 J Mice Through AMPK Activation Mediated by Adipose Adiponectin

Sesamol is the major bioactive constituent isolated from sesame seeds and has a variety of bioactivities. However, its role and mechanism in liver insulin resistance remain unknown. The current study was designed to investigate the underlying adipose-liver crosstalk mechanism of sesamol ameliorating hepatic insulin sensitivity. The therapeutic effect of sesamol was evaluated in high-fat diet (HFD)-fed C57BL/6 J mice (100 mg/kg for 8 weeks, XYGW-2021-75) and the mechanism was further explored in HepG2 cells with/without adiponectin and adenosine 5 '-monophosphate-activated protein kinase (AMPK) inhibitor administration. Our in vivo data showed that sesamol reduced hepatic insulin resistance in HFD-induced mice with obesity by modulating protein expression levels of glycogen synthase (GS), phosphoenolpyruvate carboxykinase (PEPCK) and protein kinase B (AKT). Moreover, sesamol not only increased the serum and adipose tissue adiponectin concentrations but also activated the phosphorylation of AMPK in the liver. Furthermore, in vitro studies using recombinant human adiponectin and an AMPK inhibitor revealed that adiponectin and sesamol have a synergic impact on increasing glycogenesis and reducing gluconeogenesis, of which the effects could be attenuated by the AMPK inhibitor. Taken together, our results suggested that sesamol stimulated adiponectin secretion from adipocytes, whereby exhibited a co-effect on activating the downstream signal of hepatic AMPK, resulting in the alleviation of hepatic insulin resistance. The novel findings of sesamol on hepatic effects provides prospective therapeutic approaches to treat insulin resistance.

Exploring the pharmacological versatility of ficus carica: Modulating classical immunometabolism and beyond

The burden of metabolic disorders is alarmingly increasing globally. On the other hand, sustainability is the key project of the 21st century. Natural products offer a coherent option for the complementary management of both these challenges. Ficus carica (FC), commonly known as the fig fruit, has an experimentally proven potency for the modulation of cell cycle, immunity, inflammation, metabolism, and oxidative stress. Here, we review the potential of FC-derived products (FCDP) in slowing down the progression of cancers, acute/chronic inflammation-related conditions, infections, metabolic disorders, toxicities, neurological and neuromuscular diseases, gastrointestinal disorders, vascular diseases, and skin-stressing conditions, as well as, in boosting normal healthy functions of the endocrine, immune, metabolic, and nervous systems. It reveals a variety of cellular and molecular targets for FCDP: cytokines (TNF-α, IL-1β, IL-6, IL-10, IL-12, IL-18, IFN-γ), chemokines (CCL2), other inflammatory mediators (CRP, PGE2), immune receptors (TLR-2, TLR-4, FcεRI), oxidative stress-related markers (SOD, GSH, MDA, GPx, catalase, ROS, NO, protein carbonyls), kinases (MAPKs, hexokinase, G6Pase, FBPase, PEPCK, Akt, AMPK, GSK3, CDKs), other enzymes (COX-2, iNOS, MMPs, caspases), growth factors/receptors (VEGF, EGFR), hormones (DHEAS, prolactin, GnRH, FSH, LH, estradiol, DHT, insulin), cell death-related markers (Bcl-2, Bax, Bak, FasL, gasdermins, cytochrome C), glucose transporter protein (Glut4), and transcription factors (NF-κB, HNF-4α, Foxo, PGC-1α, PPAR-γ, C/EBP-α, CREB, NFATC1, STAT3). FCDP cause both activation and inhibition of AMPK, MAPK, and NF-κB signaling to confer condition-specific advantages. Such a broad-range activity might be attributed to different mechanisms of action of FCDP in modulating functions within the classical immunometabolic system, but also beyond.

Capsiate-Rich Fraction of Capsicum annuum Induces Muscular Glucose Uptake, Ameliorates Rosiglitazone-Induced Adipogenesis, and Exhibits Activation of NRs Regulating Multiple Signaling Pathways

Capsiate is a key ingredient in the fruits of a nonpungent cultivar of Capsicum annuum. We investigated the effects of a C. annuum extract (CE) and a capsiate-rich fraction of CE (CR) on nuclear receptors involved in multiple signaling pathways, glucose uptake, and adipogenesis in comparison to pure capsiate (Ca). Similar to the effect of Ca (100 μM), CE (500 μg/mL) and CR (100 μg/mL) caused the activation of PPARα and PPARγ (>3-fold), while CR also activated LXR and NRF2 (>2 fold). CR (200 μg/mL) and Ca (100 μM) decreased lipid accumulation (22.6 ± 14.1 and 49.7 ± 7.3%, respectively) in adipocytes and increased glucose uptake (44.7 ± 6.2 and 30.1 ± 12.2%, respectively) in muscle cells and inhibited the adipogenic effect induced by rosiglitazone by 41.2 ± 5.6 and 13.9 ± 4.3%, respectively. This is the first report to reveal the agonistic action of CR and Ca on multiple nuclear receptors along with their enhanced glucose uptake and antiadipogenic effects. The results indicate the potential utility of the capsiate-rich fraction of C. annuum in alleviating the symptoms of metabolic syndrome and in preventing the undesired adipogenic effects of full PPARγ agonists such as rosiglitazone.

Therapeutic efficacy of mitochondria-targeted esculetin in the improvement of NAFLD-NASH via modulating AMPK-SIRT1 axis

Mitochondrial dysfunction due to deregulated production of mitochondria-derived ROS is implicated in the development and progression of non-alcoholic fatty liver disease (NAFLD) to non-alcoholic steatohepatitis (NASH). Recently, we synthesized a novel mitochondria-targeted esculetin (Mito-Esc) and investigated its dose-response therapeutic efficacy in mitigating high-fat diet (HFD)-induced NAFLD and NASH in Apoe-/- mice. Mito-Esc administration, compared to simvastatin and pioglitazone, dose-dependently caused a significant reduction in body weight, improved lipid profile, glucose homeostasis, and pro-inflammatory cytokines level. Mito-Esc administration reduced adipose tissue hypertrophy and lipid accumulation presumably by regulating the levels of CD36, PPAR-γ, EBP-α, and their target genes. Mechanistically, Mito-Esc-induced activation of the AMPK1α-SIRT1 axis inhibited pre-adipocyte differentiation. Conversely, Mito-Esc failed to regulate pre-adipocyte differentiation under AMPK/SIRT1 depleted conditions. In parallel, Mito-Esc administration ameliorated HFD-induced steatosis, fibrosis of the liver, and NAFLD-associated atheromatous plaque formation in the aorta. Importantly, Mito-Esc administration inhibited HFD-induced infiltration of macrophages, a marker of steatohepatitis, in the adipose and liver tissues. The results of the in vitro studies showed that Mito-Esc treatment significantly inhibits TGF-β-induced hepatic stellate cell differentiation as well as the fibrotic markers. Consistent with the above observations, Mito-Esc treatment by activating the AMPK-SIRT1 pathway markedly reversed palmitate-induced mitochondrial superoxide production, depolarization of mitochondrial membrane potential, and lipid accumulation in HepG2 cells. Together, the therapeutic efficacy of Mito-Esc in the mitigation of HFD-induced lipotoxicity, and the associated NASH is in part, mediated by potentiating the AMPK-SIRT1 axis.

Theabrownin from Dark Tea Ameliorates Insulin Resistance via Attenuating Oxidative Stress and Modulating IRS-1/PI3K/Akt Pathway in HepG2 Cells

Dark tea has great potential in regulating glycolipid metabolism, and theabrownin (TB) is considered to be the characteristic and bioactive constituent of dark tea. This study evaluated the ability of TB1 (fermented for 7 days) and TB2 (fermented for 14 days) isolated from dark tea to reverse insulin resistance (IR) in HepG2 cells. The results indicated that TB significantly ameliorated oxidative stress by improving mitochondrial function. In addition, TB improved glycogen synthesis and glucose consumption, and inhibited gluconeogenesis and fatty acid synthesis, by regulating GSK3β (Glycogen synthase kinase 3β), G6Pase (Glucose-6-phosphatase), GCK (Glucokinase), PEPCK1 (Phosphoenolpyruvate carboxy kinase 1), SREBP-1C (sterol regulatory element-binding protein 1C), FASN (fatty acid synthase), and ACC (Acetyl-CoA carboxylase). Additionally, the results of Western blot and real-time PCR experiments demonstrated that TB modulated glucolipid metabolism through the IRS-1 (Insulin receptor substrate 1)/PI3K (phosphatidylinositol-3 kinase)/Akt (protein kinase B) signaling pathway. Treatment with the PI3K inhibitor demonstrated a favorable correlation between PI3K activation and TB action on glycolipid metabolism. Notably, we observed that TB2 had a greater effect on improving insulin resistance compared with TB1, which, due to its prolonged fermentation time, increased the degree of oxidative polymerization of TB.

P53-response circRNA_0006420 aggravates lung cancer radiotherapy resistance by promoting formation of HUR/PTBP1 complex

BACKGROUND

p53 wild-type lung cancer cells can develop radiation resistance. Circular RNA (circRNA) consists of a family of transcripts with exclusive structures. circRNA is critical in tumorigenesis and is a potential biomarker or therapeutic target. It is uncertain how circRNA expression and functions are regulated post-radiation in p53 wild-type cancer cells.

METHODS

A549 or H1299 cells were divided into p53-wt and p53-KO groups by CRISPR/Cas9; both groups were subjected to 4Gy ionizing radiation (IR: p53-wt-IR and p53-KO-IR). RNA-seq, CCK8, cell cycle, and other functional and mechanism experiments were performed in vivo. p53 gene knockout mice were generated to test the cell results in vitro.

RESULTS

circRNAs were found in differential groups. circRNA_0006420 (IRSense) was upregulated in p53-wt cells but had the same expression level as p53-KO cells after radiation, indicating that p53 silencing prevents its upregulation after IR. In the presence of p53, upregulated IRSense post-radiation induces G2/M arrest by regulating DNA damage repair (DDR) pathway-related proteins. Meanwhile, upregulated IRSense post-radiation aggravates the radiation-induced epithelial-mesenchymal transition (EMT). Interestingly, in the presence of p53, it promotes IRSense/HUR/PTBP1 complex formation resulting in the promotion of the radiation-induced EMT. Moreover, c-Jun regulates the upregulation of p53 transcription after radiation treatment. For these lung cancer cells with p53, upregulated IRSense aggravates lung cancer cell proliferation and increases radiation resistance by interacting with HUR (ElAV-like protein 1) and PTBP1 (polypyrimidine tract-binding protein 1) in the nucleus.

CONCLUSIONS

Lung cancer cells retaining p53 may upregulate circRNA_0006420 (IRSense) expression post radiation to form an IRSense/HUR/PTBP1 complex leading to radiotherapy resistance. This study furthers our understanding of the roles of circRNA in regulating the effect of radiotherapy and provides novel therapeutic avenues for effective clinical lung cancer therapies.

Combined transcriptomics and metabolomics analysis reveals lipid metabolic disruption in swamp eel (Monopterus albus) under chronic waterborne copper exposure

Excessive copper can induce many adverse effects although it's an essential trace element in organisms. The effects of copper on the lipid metabolism have aroused increasing attention. This study investigated the liver lipid metabolism in swamp eel (Monopterus albus, M. albus) chronically exposed to 0, 10, 50, and 100 μg/L Cu²⁺ for 56 days. The results showed that copper increased the contents of triglyceride (TG), total cholesterol (T-CHO), non-esterified fatty acids (NEFA), and lipid droplets. Transcriptomic analysis found 1901 differentially expressed genes (DEGs) and 140 differential alternative splicing (DAS) genes in the 50 μg/L Cu²⁺ group, and 1787 DEGs and 184 DAS genes in the 100 μg/L Cu²⁺ group, respectively, which were enriched in peroxisome proliferator-activated receptor (PPAR), adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK), and other signaling pathways. The expression levels of key genes related to PPAR and AMPK signaling pathways were significantly down-regulated after chronic exposure to Cu²⁺. Meanwhile, metabolomics analysis showed that 52 and 110 differentially expressed metabolites (DEMs) were identified, which were mainly enriched in glycerophospholipids metabolism and steroid synthesis. Moreover, combined analysis of transcriptome and metabolome showed that glycerophospholipid metabolism co-enriched 19 down-regulated DEGs and 4 down-regulated DEMs. Taken together, our results suggested that chronic waterborne copper exposure promoted lipid synthesis, disrupted the metabolic homeostasis of glycerophospholipid, and led to excessive hepatic lipid deposition in M. albus. The combined omics approach enhanced our understanding of copper pollution to lipid metabolism.

The role of lutein-rich purple sweet potato leaf extract on the amelioration of diabetic retinopathy in streptozotocin-induced Sprague-Dawley rats

The objective of this study is to access the effect of purple sweet potato leaf (PSPL) extract on diabetic retinopathy (DR) of streptozotocin (STZ)-induced male Sprague-Dawley (SD) rats. In this study, rats were injected intraperitoneally with a single dose of 60 mg/kg STZ, and diabetes was confirmed on day 7. Rats were further divided into a few groups, which were then orally administered with one of the following treatments: 25 mg/kg of gliclazide (D25G), 200 mg/kg of PSPL extract (DT 200), and 400 mg/kg of PSPL extract (DT 400). However, the normal control (NS) and control group for diabetic (DNS) were given normal saline (NS) for 12 weeks. The results show that the treated group demonstrated a reduction in serum oral glucose tolerance test (OGTT) levels of DT 200 and DT 400, and an increase in the serum and retinal insulin levels, and restored oxidative stress markers in serum and retina on week 12. The PSPL extract exhibited protective effects in maintaining the kidney, liver, retina, and pancreas architecture in 400 mg/kg compared to the 200 mg/kg treated group and D25G, thereby restoring fully transparent lenses in diabetes-induced rats. In conclusion, 400 mg/kg PSPL is the most effective dose for the amelioration of STZ-induced DR pathology in male SD rats.

Lipidome remodeling activities of DPA-EA in palmitic acid-stimulated HepG2 cells and the in vivo anti-obesity effect of the DPA-EA and DHA-EA mixture prepared from algae oil

Background: The nuclear receptor Nur77 has been demonstrated to play a vital role in the inflammatory response and cellular metabolisms, and its ligands exhibit efficacy in the treatment of inflammation-related diseases (e.g., improving mouse acute lung injury (ALI) and obesity. Recently, ω-3 polyunsaturated fatty acid-ethanolamine derivatives (ω-3 PUFA-EAs), including DPA-EA and DHA-EA, have been reported as new Nur77-targeting anti-inflammatory agents. However, the lipid-lowering effect of ω-3 PUFA-EAs is still unknown, and lipid profile changes induced by Nur77-targeting anti-inflammatory agents also remain unclear.

Objective: This study aimed to evaluate the lipid-lowering effect and the underlying mechanism of DPA-EA acting as Nur77-targeting anti-inflammatory agents. It also aimed to investigate the in vitro and in vivo lipid-lowering effects of the DPA-EA and DHA-EA mixture prepared from algae oil.

Methods: The in vitro lipid-lowing effect of DPA-EA and its mixture with DHA-EA was first evaluated in palmitic acid-stimulated HepG2 Cells. To confirm the lipid-lowering effect and explore the underlying mechanism, we performed untargeted lipidomic analysis using ultra-performance liquid chromatography/triple quadrupole-time-of-flight (TOF) mass spectrometry coupled with multivariate statistical analysis, with another Nur77-targeting anti-inflammatory compound Celastrol (Cel) as a reference. Finally, we examined the anti-obesity effect of the DPA-EA and DHA-EA mixture synthesized from algae oil in a high-fat diet (HFD)-fed mice model.

Results: DPA-EA significantly alleviated lipid accumulation with lower toxicity than Celastrol. Nur77-targeting compounds DPA-EA and Celastrol could simultaneously reduce 14 lipids (9 TGs, 2 PCs, 1 PA, 1 SM, and 1 LacCer) and increase 13 lipids (4 DGs, 6 LPEs, 2 PEs, and 1PC) in Pal-stimulated HepG2 cells. However, Cer lipids were more sensitive to DPA-EA, while the over-downregulation of SM lipids might be associated with the off-target toxicity of Celastrol. The mixture of DPA-EA and DHA-EA synthesized from algae oil could significantly decrease TG, TC, and LDL levels and increase HDL levels in HFD-fed mice, exerting an excellent anti-obesity effect.

Conclusion: Nur77-targeting anti-inflammatory compound DAP-EA could promote the hydrolysis of PEs and TGs to ameliorate lipid accumulation. The DPA-EA and DHA-EA mixture prepared from algae oil might be a potential therapeutic agent for obesity and other inflammation-related diseases.

The gut microbiota metabolite capsiate regulate SLC2A1 expression by targeting HIF-1α to inhibit knee osteoarthritis-induced ferroptosis

Ferroptosis is an iron-dependent cell death that has been found to aggravate the progression of osteoarthritis (OA) and gut microbiota- OA axis refers to the bidirectional information network between the gut microbiota and OA, which may provide a new way to protect the OA. However, the role of gut microbiota-derived metabolites in ferroptosis-relative osteoarthritis remains unclear. The objective of this study was to analyze the protective effect of gut microbiota and its metabolite capsiate (CAT) on ferroptosis-relative osteoarthritis in vivo and in vitro experiments. From June 2021 to February 2022, 78 patients were evaluated retrospectively and divided into two groups: The health group (n = 39) and the OA group (n = 40). Iron and oxidative stress indicators were determined in peripheral blood samples. And then in vivo and in vitro experiments, a surgically destabilized medial meniscus (DMM) mice model was established and treated with CAT or Ferric Inhibitor-1 (Fer-1). Solute Carrier Family 2 Member 1 (SLC2A1) short hairpin RNA (shRNA) was utilized to inhibit SLC2A1 expression. Serum iron was increased significantly but total iron binding capacity was decreased significantly in OA patients than healthy people (p < 0.0001). The least absolute shrinkage and selection operator clinical prediction model suggested that serum iron, total iron binding capacity, transferrin, and superoxide dismutase were all independent predictors of OA (p < 0.001). Bioinformatics results suggested that SLC2A1, Metastasis-Associated Lung Adenocarcinoma Transcript 1 (MALAT1), and HIF-1α (Hypoxia Inducible Factor 1 Alpha)-related oxidative stress signaling pathways play an important role in iron homeostasis and OA. In addition, gut microbiota 16s RNA sequencing and untargeted metabolomics were used to find that gut microbiota metabolites CAT in mice with osteoarthritis were negatively correlated with Osteoarthritis Research Society International (OARSI) scores for chondrogenic degeneration (p = 0.0017). Moreover, CAT reduced ferroptosis-dependent osteoarthritis in vivo and in vitro. However, the protective effect of CAT against ferroptosis-dependent osteoarthritis could be eliminated by silencing SLC2A1. SLC2A1 was upregulated but reduced the SLC2A1 and HIF-1α levels in the DMM group. HIF-1α, MALAT1, and apoptosis levels were increased after SLC2A1 knockout in chondrocyte cells (p = 0.0017). Finally, downregulation of SLC2A1 expression by Adeno-associated Virus (AAV) -SLC2A1 shRNA improves osteoarthritis in vivo. Our findings indicated that CAT inhibited HIF-1a expression and reduced ferroptosis-relative osteoarthritis progression by activating SLC2A1.

Global Trends of Lipid Metabolism Research in Epigenetics Field: A Bibliometric Analysis from 2012-2021

Most common diseases are characterized by metabolic changes, among which lipid metabolism is a hotspot. Numerous studies have demonstrated a strong correlation between epigenetics and lipid metabolism. This study of publications on the epigenetics of lipid metabolism searched in the Web of Science Core Collection from 2012 to 2022, and a total of 3685 publications were retrieved. Much of our work focused on collecting the data of annual outputs, high-yielding countries and authors, vital journals, keywords and citations for qualitative and quantitative analysis. In the past decade, the overall number of publications has shown an upward trend. China (1382, 26.69%), the United States (1049, 20.26%) and Italy (206, 3.98%) were the main contributors of outputs. The Chinese Academy of Sciences and Yale University were significant potential cooperation institutions. Articles were mainly published in the "International Journal of Molecular Sciences". In addition to typical liver-related diseases, "ferroptosis", "diabetes" and "atherosclerosis" were identified as potential research topics. "NF-κB" and "oxidative stress" were referred to frequently in publications. METTL3 and ALKBH5 were the most discussed m⁶A-related enzymes in 2022. Our study revealed research hotspots and new trends in the epigenetics of lipid metabolism, hoping to provide significant information and inspiration for researchers to further explore new directions.

Berberine Ameliorates Abnormal Lipid Metabolism via the Adenosine Monophosphate-Activated Protein Kinase/Sirtuin 1 Pathway in Alcohol-Related Liver Disease

Alcoholic fatty liver disease (AFLD) is an early stage of alcohol-related liver disease characterized by abnormal lipid metabolism in hepatocytes. To date, to our knowledge, there have been no effective strategies for preventing or treating alcohol-related liver disease besides alcohol abstinence. Berberine (BBR) is the main bioactive ingredient extracted from traditional Chinese medicines, such as Coptis and Scutellaria, which protect liver function and relieve liver steatosis. However, the potential role of BBR in AFLD remains unclear. Therefore, this study investigated the protective effects of BBR against Gao-binge model-induced AFLD in 6- to 8-week-old C57BL/6J male mice in vivo and ethyl alcohol (EtOH)-induced alpha mouse liver 12 (AML-12) cells in vitro. The results showed that BBR (200 mg/kg) attenuated alcoholic liver injury and suppressed lipid accumulation and metabolism disorders in vivo. Consistently, BBR effectively inhibited the expression of sterol regulatory element-binding transcription factor 1C, sterol regulatory element-binding transcription factor 2, fatty acid synthase, and 3-hydroxy-3-methylglutaryl-CoenzymeA reductase in EtOH-stimulated AML-12 cells in vitro and promoted the expression of sirtuin 1 (SIRT1) in EtOH-fed mice and EtOH-treated AML-12 cells. Furthermore, SIRT1 silencing attenuated the hepatic steatosis alleviation potential of BBR treatment. Mechanistically, molecular docking revealed the binding effect of BBR and adenosine monophosphate-activated protein kinase (AMPK). The results of further studies showed that a decrease in AMPK activity was accompanied by a significant inhibition of SIRT1 expression. SIRT1 silencing attenuated the protective effect of BBR, whereas the inhibition of its expression had no apparent effect on AMPK phosphorylation, suggesting that SIRT1 acts downstream of AMPK in AFLD. Collectively, BBR ameliorated abnormal lipid metabolism and alleviated EtOH-induced liver injury via the AMPK/SIRT1 pathway in AFLD mice.

Targeting AMPK signaling by polyphenols: a novel strategy for tackling aging

Aging is an inevitable biological process and is accompanied by a gradual decline of physiological functions, such as the incidence of age-related diseases. Aging becomes a major burden and challenge for society to prevent or delay the occurrence and development of these age-related diseases. AMPK is a key regulator of intracellular energy and participates in the adaptation of calorie restriction. It is also an important mediator of nutritionally sensitive pathways that regulate the biological effects of nutrient active ingredients. AMPK can limit proliferation and activate autophagy. Recent studies have shown that nutritional intervention can delay aging and lessen age-related diseases in many animal and even human models. Polyphenols function as a natural antidote and are important anti-inflammatory and antioxidant agents in human diets. Polyphenols can prevent age-related diseases because they regulate complex networks of cellular processes such as oxidative damage, inflammation, cellular aging, and autophagy, and have also attracted wide attention as a potential beneficial substance for longevity. In this review, we systemically summarized the progress of targeting AMPK signaling by dietary polyphenols in aging prevention. Polyphenols can reduce oxidative stress and inflammatory response, and maintain the steady state of energy. Polyphenols can also modulate sirtuins/NAD+, nutrient-sensing, proteostasis, mitochondrial function, autophagy and senescence via targeting AMPK signaling. Therefore, targeting the AMPK signaling pathway by dietary polyphenols may be a novel anti-aging strategy.

Metformin mitigates cholesterol accumulation via the AMPK/SIRT1 pathway to protect osteoarthritis chondrocytes

In this study, we aim to investigate the effect of metformin on cholesterol synthesis and efflux-related genes in chondrocytes during osteoarthritis (OA) and explore the underlying mechanisms. Primary chondrocytes were harvested from Wistar rat cartilage and divided into control and treatment groups. Chondrocytes in the treatment group were treated with interleukin-1β (IL-1β) mimicking the inflammatory environment of osteoarthritis. Subsequently, RT-qPCR, Western blotting, immunofluorescence staining, and Cell Counting Kit-8 (CCK-8) were conducted. Significant reductions in phosphorylated AMP-activated protein kinase (p-AMPK) and silent information regulator 1 (SIRT1) protein expression were observed in both human OA chondrocytes and cultured primary murine chondrocytes treated with IL-1β, while AMP-activated protein kinase (AMPK) was not inhibited. Moreover, in the presence of IL-1β, metformin significantly increased the expression of p-AMPK and SIRT1 at the protein and mRNA level. Meanwhile, metformin could reverse IL-1β-induced cartilage extracellular matrix degradation in chondrocytes from the rat model of OA (treated by IL-β) by activating the AMPK/SIRT1 pathway. Moreover, metformin activated AMPK and SIRT1, mediated by the activation of SREBP-2 and HMGCR in OA chondrocytes. Inhibiting AMPK/SIRT1 activity by its specific inhibitor could suppress IL-1β-induced expression of LXRα, ABCA1 and ApoA1 and cholesterol efflux. Thus, metformin inhibits cholesterol synthesis and promotes cholesterol efflux by activating the AMPK/SIRT1 pathway in OA chondrocytes. This study improves our understanding of the effect of metformin on cholesterol accumulation in OA chondrocytes.

Aloe Vera-Fermented Beverage Ameliorates Obesity and Gut Dysbiosis in High-Fat-Diet Mice

Aloe vera has been proven to have various medicinal properties, including anti-inflammatory and anti-obesity functions. However, the effects of Aloe vera-fermented beverages (AFB) on obesity and its complications are still not clear. In this study, HepG2 cells in high-fat environment and high-fat diet (HFD) mice were used to investigate the potential obesity-preventing function of AFB. We found that AFB intervention decreased the amount of lipid droplets of HepG2 cells, suppressed the body weight gain and adipose accumulation, and reduced the serum contents of total cholesterol (TC), alanine aminotransferase (ALT), and interleukin 10 (IL-10) of HFD-mice. In addition, it also changed the composition of the gut microbiota. The ratio of Firmicutes/Bacteroidetes was decreased, while the relative abundance of Muribaculaceae, Alistipes and Rikenellaceae_RC9_gut_group was increased after the administration of AFB compared with HFD-mice. These results demonstrated that AFB can prevent diet-induced obesity (DIO) and provides a new option to modulate obesity-related gut dysbiosis.

Allicin and Capsaicin Ameliorated Hypercholesterolemia by Upregulating LDLR and Downregulating PCSK9 Expression in HepG2 Cells

Hypercholesterolemia is a common cause of cardiovascular diseases (CVDs). Although allicin and capsaicin possess hypolipidemic effects through several molecular mechanisms, their effects on LDLR and PCSK9 expression are still unknown. This study aimed to investigate the effects of allicin and capsaicin on LDLR and PCSK9 expression in HepG2 cells. The effects of allicin and capsaicin on cell viability were evaluated by MTT assay and trypan blue exclusion assay. Low-density lipoprotein receptor (LDLR) levels and LDL uptake were determined by flow cytometry and confocal laser scanning microscopy (CLSM), respectively. RT-qPCR and Western blot analyses were performed to evaluate the expression of PCSK9, LDLR, SREBP-2, and HNF1α. ELISA was used to measure PCSK9 levels in culture media. Allicin and capsaicin increased the protein expression levels of LDLR via activation of the transcription factor SREBP2. However, allicin and capsaicin decreased the expression of PCSK9 protein and the secretion of PCSK9 in culture media via the suppression of HNF1α. Moreover, allicin and capsaicin increased LDL uptake into HepG2 cells. The efficacies of the hypolipidemic effects of allicin (200 µM) and capsaicin (200 µM) were comparable to that of atorvastatin (10 µM) in this study. In conclusion, allicin and capsaicin possessed hypolipidemic effects via the upregulation of LDLR and downregulation of PCSK9 expression, thereby enhancing LDL uptake into HepG2 cells. This indicates that allicin and capsaicin should be used as potent supplements to ameliorate hypercholesterolemia.

Triticonazole enantiomers induced enantioselective metabolic phenotypes in Fusarium graminearum and HepG2 cells

The management of Fusarium head blight relies heavily on triazole fungicides. Most of triazole fungicides are chiral, and their enantioselective effects on metabolic phenotypes are poorly understood. Herein, we analyzed the bioactivity of triticonazole against Fusarium graminearum, and ¹H-nuclear magnetic resonance-based metabolomics was used to assess the metabolic disturbances of triticonazole enantiomers in Fusarium graminearum and human hepatocarcinoma cells. Results indicated that the bioactivity of R-triticonazole was 4.28-fold higher than its antipode since it bound stronger with fungal CYP51B and induced more abnormal metabolic processes of Fusarium graminearum, including lipid metabolism, glycolysis, and amino acid metabolism. In human hepatocarcinoma cells, pathways of "alanine, aspartic acid and glutamate metabolism" and "pyruvate metabolism" were disturbed significantly by R-triticonazole; "phenylalanine metabolism" and "taurine-hypotaurine metabolism" were abnormal in the exposure of S-triticonazole. These results suggested that R- and S-triticonazole could affect different metabolic pathways of human hepatocarcinoma cells, and the massively use of inefficient S-triticonazole should be avoided. Our data will help to better understand the enantioselectivity of chiral pesticides and provide a reference for the development of green pesticides.

Reducing VEGFB accelerates NAFLD and insulin resistance in mice via inhibiting AMPK signaling pathway

Objective

Vascular endothelial growth factor B (VEGFB) was regarded to improve lipid metabolism and reduce obesity-related hyperlipidemia. Whether VEGFB participates in lipid metabolism in nonalcoholic fatty liver disease (NAFLD) has not been clear yet. This study investigated the involvement of VEGFB in lipid metabolism and insulin resistance via the AMPK signaling pathway in NAFLD.

Methods

We constructed the animal and cell model of NAFLD after VEGFB gene knockout to detect liver damage and metabolism in NAFLD. Bioinformatics analysis of VEGFB and the AMPK signaling pathway relative genes to verify the differential proteins. And mRNA levels of NAFLD fatty acid metabolism-related genes were detected.

Results

After the systemic VEGFB knockout mice were fed with high fat, the body fat, serum lipoprotein, NAFLD score, and insulin resistance were increased. Animal and cell experiments showed that the expression levels of phosphorylated proteins of CaMKK2 and AMPK decreased, the expression of proteins related to AMPK/ACC/CPT1 signaling pathway decreased, and the target genes CPT1α and Lcad decreased accordingly, reducing fatty acid oxidation in hepatocyte mitochondria; The expression of AMPK/SREBP1/Scd1 signaling pathway relative proteins increased, ACC1 and FAS increased correspondingly, which increased lipid synthesis in the endoplasmic reticulum.

Conclusion

VEGFB can participate in lipid metabolism and insulin resistance of NAFLD through the AMPK signaling pathway.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-022-03540-2.

Lipid Metabolism and Cancer

Lipid metabolism is involved in the regulation of numerous cellular processes, such as cell growth, proliferation, differentiation, survival, apoptosis, inflammation, movement, membrane homeostasis, chemotherapy response, and drug resistance. Reprogramming of lipid metabolism is a typical feature of malignant tumors. In a variety of cancers, fat uptake, storage and fat production are up-regulated, which in turn promotes the rapid growth, invasion, and migration of tumors. This paper systematically summarizes the key signal transduction pathways and molecules of lipid metabolism regulating tumors, and the role of lipid metabolism in programmed cell death. In conclusion, understanding the potential molecular mechanism of lipid metabolism and the functions of different lipid molecules may facilitate elucidating the mechanisms underlying the occurrence of cancer in order to discover new potential targets for the development of effective antitumor drugs.

HPLC-DVD combined with chemometrics to analyze the correlation between the Q-marker content and color of Corni Fructus

Although Corni Fructus (CF) is a fruit with great economic value and development potential in medicine and food, too much reliance on personal experience for quality evaluation seriously limits the trading and circulation of CF. In the present study, through the research on the correlation between the chemical composition and the appearance color, a standard colorimetric card related to CF quality was established, which simplified the quality evaluation process and improved the accuracy of the visual evaluation of CF. Firstly, a total of 29 batches of CF from different places were collected. Then, "imread" in the MATLAB software was used to convert the color of all samples into RGB values, and HPLC-DVD was used to measure the content of the main chemical components in CF. Thereafter, the correlation between the content and color was studied by using MLR, BP-ANNs and SVM chemometric tools to screen the Q-marker of CF, which was further confirmed by in vivo and in vitro experiments. Finally, the Q-marker standard colorimetric card with the best fitting degree is established according to the prediction model. Thus, this study provides an auxiliary reference for the color evaluation of CF and a reference for the standardization and quantification of the macro characteristics of traditional Chinese medicine and food.

Ramulus Mori (Sangzhi) Alkaloids Alleviate High-Fat Diet-Induced Obesity and Nonalcoholic Fatty Liver Disease in Mice

Nonalcoholic fatty liver disease (NAFLD), obesity, and type 2 diabetes mellitus (T2DM) have highly related mechanisms. Ramulus Mori (Sangzhi) alkaloids (SZ-A) from Morus alba L. were approved in 2020 for the treatment of T2DM. In this study, we examined the therapeutic effects and mechanism of SZ-A on obesity and NAFLD in mice. Mice (C57BL/6J) fed a high-fat diet (HFD) for 14 weeks were treated with SZ-A for another 6 weeks. HFD-induced weight gain was reduced by SZ-A in a dose-dependent manner. SZ-A treatment significantly stimulated adiponectin expression and secretion in adipose tissue and 3T3-L1 adipocytes. Additionally, SZ-A markedly reduced hepatic steatosis (triglyceride, total cholesterol) and expression of pro-inflammatory and pro-fibrotic genes. SZ-A regulated lipid metabolism and oxidative stress (malondialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase (GPx), and glutathione (GSH)) in the liver. Palmitic acid-induced insulin resistance and lipid accumulation in HepG2 cells were also repressed by SZ-A. Collectively, SZ-A protected mice from HFD-induced NAFLD through an indirect effect of improved systemic metabolism reducing bodyweight, and a direct effect by enhancing the lipid metabolism of HepG2 cells. The weight-loss effect of SZ-A in mice was partly due to improved fatty oxidation instead of influencing food consumption.

Maternal Sodium p-Perfluorous Nonenoxybenzene Sulfonate Exposure Disturbed Lipid Metabolism and Induced an Imbalance in Tyrosine Metabolism in the F1 Generation of Mice

The toxicity of perfluorinated compounds (PFCs) to mammals has recently received increasing attention. However, the effects of maternal sodium p-perfluorous nonenoxybenzene sulfonate (OBS) exposure during pregnancy and lactation on the liver function of dams (F0) and offspring (F1) mice are still unknown. The results demonstrated that maternal OBS treatment could not only induce lipid metabolism dysfunction but also disrupt amino acid metabolism in the liver of F0 and F1 generations. OBS had marked accumulation in the liver, and the serum and liver triglyceride (TG) levels increased in the F0 and F1 generations after maternal OBS exposure. Moreover, maternal OBS exposure changed the transcriptional levels of genes related to lipid metabolism (fatty acid (FA) synthesis, TG synthesis, and transport) and induced changes in the amino acid level in dams and 20-day-old mice offspring (F1-20 d). Additionally, the regulation of lipid metabolism by OBS was mainly dependent on the activation of peroxisome proliferator-activated receptor γ (PPARγ) and cluster of differentiation 36 (CD36). Interestingly, OBS could also disturb tyrosine (TYR) metabolism by increasing the TYR level and downregulating fumarate acetoacetate hydrolase (FAH). Together, these results indicated that the liver can be perceived as the major target tissue of OBS, which strongly affected metabolic function and ultimately led to an imbalance in the metabolism of lipids and TYR. In summary, maternal OBS exposure during pregnancy and lactation has toxic effects on the hepatic metabolism of dams and offspring, indicating that the toxic effects could obviously cross generations of mice, and we should pay more attention to understanding the health risk to both dams and offspring.

Bulk Process for Enrichment of Capsinoids from Capsicum Fruit

Various methods to synthesize capsinoids (the nonpungent analogs of capsaicinoids) from precursor molecules have been reported. Capsinoids are also naturally present, at typically low concentrations, in the fruit of many Capsicum species and genotypes. However, they are also present in the fruit of select genotypes at high concentrations. The fruit of high-capsiate genotypes represents a commercial source of these compounds. To date, no method has been published that efficiently extracts and purifies capsinoids from Capsicum fruit in a rapid and simple bulk process. This study evaluated the efficacy of various organic solvents for the extraction of capsinoids from dried Capsicum annuum fruit. Among the organic solvents evaluated, pentane appeared to provide a good combination of both recovery and purity. A subsequent liquid/liquid extraction step, utilizing pentane and acetonitrile, resulted in 26.3 % (wt/wt) capsiate and 19.4 % (wt/wt) dihydrocapsiate for a combined capsinoids yield of 45.7 % (wt/wt). A third step, involving a rapid hp20ss chromatography column using a water/acetonitrile gradient, resulted in a combined capsinoids yield of 96.6 % (wt/wt).

Phytochemicals from the Cocoa Shell Modulate Mitochondrial Function, Lipid and Glucose Metabolism in Hepatocytes via Activation of FGF21/ERK, AKT, and mTOR Pathways

The cocoa shell is a by-product that may be revalorized as a source of bioactive compounds to prevent chronic cardiometabolic diseases. This study aimed to investigate the phytochemicals from the cocoa shell as targeted compounds for activating fibroblast growth factor 21 (FGF21) signaling and regulating non-alcoholic fatty liver disease (NAFLD)-related biomarkers linked to oxidative stress, mitochondrial function, and metabolism in hepatocytes. HepG2 cells treated with palmitic acid (PA, 500 µmol L⁻¹) were used in an NAFLD cell model. Phytochemicals from the cocoa shell (50 µmol L⁻¹) and an aqueous extract (CAE, 100 µg mL⁻¹) enhanced ERK1/2 phosphorylation (1.7- to 3.3-fold) and FGF21 release (1.4- to 3.4-fold) via PPARα activation. Oxidative stress markers were reduced though Nrf-2 regulation. Mitochondrial function (mitochondrial respiration and ATP production) was protected by the PGC-1α pathway modulation. Cocoa shell phytochemicals reduced lipid accumulation (53–115%) and fatty acid synthase activity (59–93%) and prompted CPT-1 activity. Glucose uptake and glucokinase activity were enhanced, whereas glucose production and phosphoenolpyruvate carboxykinase activity were diminished. The increase in the phosphorylation of the insulin receptor, AKT, AMPKα, mTOR, and ERK1/2 conduced to the regulation of hepatic mitochondrial function and energy metabolism. For the first time, the cocoa shell phytochemicals are proved to modulate FGF21 signaling. Results demonstrate the in vitro preventive effect of the phytochemicals from the cocoa shell on NAFLD.

Association of Sirtuin 1 Gene Polymorphisms with the Risk of Coronary Heart Disease in Chinese Han Patients with Type 2 Diabetes Mellitus

AIMS

To explore the associations between polymorphisms in SIRT1 and coronary heart disease (CHD) risk in Chinese Han patients with type 2 diabetes (T2D).

METHODS

This case-controlled study enrolled 492 patients with T2D: 297 with CHD and 195 without CHD. Five SIRT1 haplotype-tagging single-nucleotide polymorphisms (rs3818291, rs12242965, rs3818292, rs4746720, and rs16924934) were selected from Chinese Han data in the GRCh37.p13 phase 3 database and genotyped by polymerase chain reaction-restriction fraction length polymorphism or sequencing.

RESULTS

The rs16924934 G allele was associated with a higher risk of CHD than the A allele (odds ratio (OR) = 1.429; 95% confidence interval (CI) = 1.003-2.037; P = 0.048). Using an additive inheritance model, the rs3818291 G/A genotype was associated with a higher CHD risk than the G/G genotype (OR' = 1.683; 95%CI = 1.033-2.743; P' = 0.037 after adjustment for CHD risk factors). Smokers carrying G/A or A/A rs3818291 genotypes had a 3-fold higher CHD risk than those carrying GG (adjusted OR' = 3.035; P' = 0.011) and a 2.6-fold higher CHD risk than nonsmokers carrying GG (adjusted OR' = 2.604; P' = 0.033).

CONCLUSIONS

Genetic polymorphisms of SIRT1 are associated with the risk of CHD in a Chinese Han population with T2D.

Effect of Metformin on Glycemic Control Regarding Carriers of the SLC22A1/OCT1 (rs628031) Polymorphism and Its Interactions with Dietary Micronutrients in Type 2 Diabetes

PURPOSE

Differences in metformin effect on glycemic control in type 2 Diabetes (T2D) have been associated with diet, obesity, years since T2D diagnosis and genetic factors, such as the Met408Val (rs628031) SLC22A1/OCT1 gene polymorphism. This study aimed to analyze the effect of metformin and diet on glycemic control and its association with the Met408Val polymorphism in patients with T2D from western Mexico.

PATIENTS AND METHODS

A total of 240 T2D adult patients were enrolled in this cross-sectional study. Anti-hyperglycemic therapy, dietary intake, body composition and glycemic profile were recorded and the determination of genotypes of SLC22A1/OCT1 gene (rs628031) was performed using an allelic discrimination assay.

RESULTS

The type of metformin therapy was 47% monotherapy, 45% dual therapy (metformin+glibenclamide or metformin+insulin) and 8% triple therapy (metformin+glibenclamide+insulin). Individuals with metformin monotherapy had a higher glycemic control frequency (%HbA1c <7.0) compared with the dual and triple treatment schemes (77% vs 35% and 15%, respectively; p<0.001). Interestingly, a high potassium intake was documented in the three anti-hyperglycemic therapies and a lower intake of micronutrients, including calcium, magnesium, and zinc. An interaction was found between calcium intake and carriers of the risk allele A (408Val) with %HbA1c (P interaction=0.028), and potassium intake with the TyG index (P interaction=0.027). In addition, there was a positive correlation between calcium intake and %HbA1c (r=0.682; p=0.010), and potassium intake vs TyG index (r=0.593; p=0.033) in risk allele A (408Val) carriers with metformin monotherapy. Genotype frequencies were GG homozygotes (76.6%), GA heterozygotes (21.5%) and AA homozygotes (1.9%). The allele frequency was 87.4% for the ancestral allele G and 12.6% for the risk allele A.

CONCLUSION

These findings suggest a differing effect of metformin on glycemic control regarding calcium and potassium intake and the Met408Val SLC22A1/OCT1 gene polymorphism in T2D patients.

Polysaccharides from mulberry (Morus alba L.) leaf prevents obesity by inhibiting pancreatic lipase in high-fat diet induced mice

Pancreatic lipase (PL) is a key enzyme related to the prevention and treatment of obesity. The aim of the study was to evaluate the inhibitory effects of mulberry leaf polysaccharides (MLP) on PL and possible interaction mechanism, inhibition on lipid accumulation in vitro and in vivo. The results revealed that MLP had obvious inhibitory effects on PL (P < 0.05). The interaction of MLP-PL complexes was in a spontaneous way driven by enthalpy, and hydrogen bonds were the main factors in the binding. MLP could significantly inhibit the development of lipid accumulation in HepG2 cells (P < 0.05). Furthermore, consumption of high-fat diet containing MLP showed protective effects on liver and adipose tissue damages in mice, and inhibited the lipid absorption in digestive tract. MLP also significantly reduced the increased expression level of pancreatic digestive enzymes (P < 0.05). The study indicated that the anti-obesity effect of MLP might be caused by inhibition of lipid absorption via reducing PL activity.

Plant Extracts in Obesity: A Role of Gut Microbiota

Obesity has become one of the most serious chronic diseases threatening human health. Its occurrence and development are closely associated with gut microbiota since the disorders of gut microbiota can promote endotoxin production and induce inflammatory response. Recently, numerous plant extracts have been proven to mitigate lipid dysmetabolism and obesity syndrome by regulating the abundance and composition of gut microbiota. In this review, we summarize the potential roles of different plant extracts including mulberry leaf extract, policosanol, cortex moutan, green tea, honokiol, and capsaicin in regulating obesity via gut microbiota. Based on the current findings, plant extracts may be promising agents for the prevention and treatment of obesity and its related metabolic diseases, and the mechanisms might be associated with gut microbiota.

Atractylodes chinensis Water Extract Ameliorates Obesity via Promotion of the SIRT1/AMPK Expression in High-Fat Diet-Induced Obese Mice

Obesity remains a continuing global health concern, as it is associated with an increased risk of many chronic diseases. Atractylodes chinensis Koidz. (Ac) is traditionally used in the treatment of inflammatory diseases, such as arthritis, hepatitis, and gastric ulcers. Despite the diverse pharmacological activities of Ac, scientific evidence for the use of Ac in obesity is still limited. Therefore, the present study aimed to determine the anti-obesity effects of Ac. C57BL/6N mice were divided into five groups as follows: chow diet group (CON), 45% HFD group, HFD + oral administration of orlistat group, and HFD + oral administration of Ac groups. RT-PCR and western blotting were used to examine the expression of molecules relating to obesity progression. Ac-administered mice showed dramatically decreased body weight and weight gain compared to the high-fat diet (HFD)-fed mice. In addition, Ac administration attenuated the protein expression levels of adipogenic transcription factors in the white adipose tissue (WAT) and livers of HFD-fed mice. Furthermore, Ac administration declined the expression levels of lipogenic genes, while enhancing those of the fatty acid oxidation genes in the WAT of HFD-fed mice. Importantly, Ac administration highly upregulated the AMP-activated kinase (AMPK) and sirtuin 1 (SIRT1) expression levels in WAT of the HFD-induced obese mouse model. Our results provide evidence that Ac can effectively ameliorate weight gain and adipose tissue expansion.

γ-Linolenic Acid Prevents Lipid Metabolism Disorder in Palmitic Acid-Treated Alpha Mouse Liver-12 Cells by Balancing Autophagy and Apoptosis via the LKB1-AMPK-mTOR Pathway

Excessive fat deposition is the main character in nonalcoholic fatty liver disease (NAFLD), while γ-linolenic acid (GLA) is a polyunsaturated fatty acid that can reduce lipid deposition. This study investigated the effect and regulatory mechanism of GLA (100 μM) on lipid metabolism in alpha mouse liver 12 (AML-12) cells treated by 400 μM palmitic acid (PA). GLA reduced lipid content and increased fatty acid β oxidation, as indicated by decreasing triglyceride and cholesterol contents and increasing mRNA and protein expressions of CPT1α and PPARα. GLA relieved oxidative stress caused by PA, upregulated mRNA levels of superoxide dismutase and glutathione peroxidase, and decreased reactive oxygen species content. GLA reduced apoptosis, as indicated by decreases in the BAX/BCL2 expression level and apoptosis percentage. GLA activated autophagy, autophagosome-lysosome fusion, and LKB1-AMPK-mTOR signaling and upregulated mRNA and protein expressions of Beclin-1, autophagy-related 5, and liver kinase B1 (LKB1). These effects of GLA on lipid metabolism disorders of PA-treated hepatocytes were reversed by autophagy inhibitor 3MA and AMPK inhibitor compound C, confirming our conclusions. Overall, GLA can protect AML-12 cells from lipid metabolism disorder caused by PA via balancing autophagy and apoptosis mediated by the LKB1-AMPK-mTOR pathway. Consequently, GLA, as a dietary supplement, can help to prevent and treat NAFLD by regulating lipid metabolism and autophagy.

Sweet pepper and its principle constituent capsiate: functional properties and health benefits

Capsiate is a non-pungent analogue of capsaicin. It belongs to the family of capsinoids which are esters of vanillyl alcohol with fatty acids while capsaicin belongs to the family of capsaicinoids that are amides of vanillylamine with a variety of branched-chain fatty acids. While capsaicin is extensively reported for plethora of pharmacological actions, capsiate remains much less explored. Extracted from various species of Capsicum plant, the molecule has also been chemically synthesized via a number of synthetic and enzymatic routes. Based on its action on transient receptor potential vanilloid subfamily member 1 receptors, recent research has focused on its potential roles in treatment of obesity, metabolic disorders, cancer, cardiovascular disorders and gastro-intestinal disorders. Its toxicity profile has been reported to be much safe. The molecule, however, faces the challenge of low aqueous solubility and stability. It has been commercialized for its use as a weight loss supplement. However, the therapeutic potential of the compound which is much beyond boosting metabolism remains unexplored hitherto. This comprehensive review summarizes the studies demonstrating the therapeutic potential of capsiate in various pathological conditions. Discussed also are potential future directions for formulation strategies to develop efficient, safe and cost-effective dosage forms of capsiate to explore its role in various disease conditions. The databases investigated include Cochrane library, Medline, Embase, Pubmed and in-house databases. The search terms were "capsiate," "capsinoids," "thermogenesis," and their combinations. The articles were screened for relevance by going through their abstract. All the articles pertaining to physicochemical, physiological, pharmacological and therapeutic effects of capsiate have been included in the manuscript.

25-Hydroxycholesterol 3-sulfate is an endogenous ligand of DNA methyltransferases in hepatocytes

The oxysterol sulfate, 25-hydroxycholesterol 3-sulfate (25HC3S), has been shown to play an important role in lipid metabolism, inflammatory response, and cell survival. However, the mechanism(s) of its function in global regulation is unknown. The current study investigates the molecular mechanism by which 25HC3S functions as an endogenous epigenetic regulator. To study the effects of oxysterols/sterol sulfates on epigenetic modulators, 12 recombinant epigenetic enzymes were used to determine whether 25HC3S acts as their endogenous ligand. The enzyme kinetic study demonstrated that 25HC3S specifically inhibited DNA methyltransferases (DNMTs), DNMT1, DNMT3a, and DNMT3b with IC50 of 4.04, 3.03, and 9.05 × 10-6 M, respectively. In human hepatocytes, high glucose induces lipid accumulation by increasing promoter CpG methylation of key genes involved in development of nonalcoholic fatty liver diseases. Using this model, whole genome bisulfate sequencing analysis demonstrated that 25HC3S converts the 5mCpG to CpG in the promoter regions of 1,074 genes. In addition, we observed increased expression of the demethylated genes, which are involved in the master signaling pathways, including MAPK-ERK, calcium-AMP-activated protein kinase, and type II diabetes mellitus pathways. mRNA array analysis showed that the upregulated genes encoded for key elements of cell survival; conversely, downregulated genes encoded for key enzymes that decrease lipid biosynthesis. Taken together, our results indicate that the expression of these key elements and enzymes are regulated by the demethylated signaling pathways. We summarized that 25HC3S DNA demethylation of 5mCpG in promoter regions is a potent regulatory mechanism.

Exercise improves lipid droplet metabolism disorder through activation of AMPK-mediated lipophagy in NAFLD

AIM

To emphasize the mechanism of the effect of exercise on lipid droplet (LD) metabolism disorder in nonalcoholic fatty liver disease (NAFLD).

MAIN METHODS

C57BL/6J mice were randomly divided into three groups: The first group was fed with a normal diet (CON), the second group was fed a high-fat diet (HF), and finally group with a high-fat diet intervention and swim training (HF-EX). The total intervention period was 16 weeks. RT-PCR and Western blot were performed to evaluate the effect of exercise on LDs metabolism and the AMPK pathway. Histopathological examinations and immunofluorescence were performed to evaluate the lipid deposition and lipophagy in the liver.

KEY FINDINGS

Exercise reduced liver steatosis and insulin resistance along with the stimulation of AMPK/SIRT1 signaling and downstream regulation of lipid metabolism. In addition, exercise increased the expression of autophagy marker and colocalization of LC3 and LAMP1 with LDs.

SIGNIFICANCE

Exercise stimulated AMPK/SIRT1 and activated lipophagy in NAFLD. Enhancing lipophagy may be one of the key mechanisms of regulation and resolution of NAFLD by exercise.

Ursolic acid alleviates lipid accumulation by activating the AMPK signaling pathway in vivo and in vitro

The mechanism underlying the effect of ursolic acid (UA) on lipid metabolism remains unclear. This study aimed to explore the mechanisms of UA in reducing lipid accumulation in free fatty acids-cultured HepG2 cells and in high-fat-diet-fed C57BL/6J mice. In vivo, UA effectively alleviated liver steatosis and decreased the size of adipocytes in the epididymis. It also significantly decreased the total cholesterol (TC) and triglyceride (TG) contents in the liver and plasma in C57BL/6 mice. In vitro, UA (20 µM) significantly reduced lipid accumulation; the intracellular TC contents decreased from 0.078 ± 0.0047 to 0.049 ± 0.0064 µmol/mg protein, and TG contents from 0.133 ± 0.005 to 0.066 ± 0.0047 µmol/mg protein, in HepG2 cells. Furthermore, UA reduced the mRNA expression related to fat synthesis, enhanced the mRNA expression related to adipose decomposition, and dramatically upregulated the protein expression of P-AMPK in vivo and in vitro. Of note, these protective effects of UA on a high-fat environment were blocked by the AMPK inhibitor (compound C) in vitro. In addition, the molecular docking results suggested that UA could be docked to the AMPK protein as an AMPK activator. These results indicated that UA lowered the lipid content probably via activating the AMPK signaling pathway, thereby inhibiting lipid synthesis and promoting fat decomposition. PRACTICAL APPLICATION: Ursolic acid (UA) widely exists in vegetables and fruits. This study highlighted a lipid-lowing mechanism of UA in HepG2 cells and C57BL/6J mice. The data indicated that UA might be used in lipid-lowering functional foods.

Coniferaldehyde ameliorates the lipid and glucose metabolism in palmitic acid-induced HepG2 cells via the LKB1/AMPK signaling pathway

Impaired lipid and glucose metabolism in the liver is a crucial characteristic of nonalcoholic fatty liver disease (NAFLD). Coniferaldehyde (CA), a kind of phenolic compound found in many edible plants, has multiple biological and pharmacological functions. However, since the effect and molecular mechanism of CA on hepatic lipid and glucose metabolism disorders in NAFLD remain unknown, this study investigated its impact on the lipid and glucose metabolism of palmitic acid (PA)-induced HepG2 cells. Compared with the HepG2 cells treated only with PA, supplementation with 25, 50, and 100 µM CA reduced the levels of intracellular triglyceride (by 7.11%, 19.62%, and 31.57%) and total cholesterol (by 8.46%, 23.32%, and 27.17%), and enhanced glucose uptake (by 40.91%, 57.49%, and 61.32%) and intracellular glycogen content (by 12.75%, 41.27%, and 53.77%). Moreover, CA supplementation downregulated the expression of sterol regulatory element-binding protein-1, fatty acid synthase, and stearoyl-CoA desaturase 1 related to lipogenesis while upregulating the expression of carnitine palmitoyltransferase 1α related to fatty acid oxidation. CA supplementation also upregulated the glucose transporter 2 protein expression and phosphorylation of glycogen synthase kinase 3β while downregulating the phosphorylation of glycogen synthase. Most importantly, most of these effects of CA were reversed by pretreatment with AMP-activated protein kinase (AMPK) inhibitor and small interfering RNA-liver kinase B1 (LKB1). In conclusion, CA ameliorated the lipid and glucose metabolism in PA-induced HepG2 cells via the LKB1/AMPK signaling pathway. PRACTICAL APPLICATION: In this study, coniferaldehyde appeared to be effective in ameliorating hepatic lipid and glucose metabolism disorders in nonalcoholic fatty liver disease by reducing the levels of intracellular triglyceride and total cholesterol and enhancing glucose uptake and intracellular glycogen content via the LKB1/AMPK signaling pathway in vitro. Therefore, our findings provide new evidence in support of that supplementation with coniferaldehyde or food rich in coniferaldehyde might be considered as a viable dietary intervention strategy for preventing and treating nonalcoholic fatty liver disease.

Mechanism of Action of Ketogenic Diet Treatment: Impact of Decanoic Acid and Beta-Hydroxybutyrate on Sirtuins and Energy Metabolism in Hippocampal Murine Neurons

The ketogenic diet (KD), a high-lipid and low-carbohydrate diet, has been used in the treatment of epilepsy, neurodegenerative disorders, inborn errors of metabolism and cancer; however, the exact mechanism/s of its therapeutic effect is not completely known. We hypothesized that sirtuins (SIRT)—a group of seven NAD-dependent enzymes and important regulators of energy metabolism may be altered under KD treatment. HT22 hippocampal murine neurons were incubated with two important KD metabolites–beta-hydroxybutyrate (BHB) (the predominant ketone body) and decanoic acid (C10), both accumulating under KD. Enzyme activity, protein, and gene expressions of SIRT 1-4, enzyme capacities of the mitochondrial respiratory chain complexes (MRC), citrate synthase (CS) and gene expression of monocarboxylate transporters were measured in control (untreated) and KD-treated cells. Incubation with both–BHB and C10 resulted in significant elevation of SIRT1 enzyme activity and an overall upregulation of the MRC. C10 incubation showed prominent increases in maximal activities of complexes I + III and complex IV of the MRC and ratios of their activities to that of CS, pointing towards a more efficient functioning of the mitochondria in C10-treated cells.

Different Phenolic Extracts of Oil Palm Fruits and Caffeic Acid Prevent Palmitic Acid-Induced Lipotoxicity in HepG2 Cells via Improving Mitochondrial Function

Oil palm (Elaeis guineensis Jacq.) fruits are rich in antioxidative phenolic compounds, which exert various health improving effects. This study aimed to comparatively study the protective effects of different phenolic fractions from the fruits treated with or without ultrahigh pressure (UHP) and their most abundant phenolic substance, caffeic acid, against the palmitic acid-induced lipotoxicity in HepG2 cells and to clarify the potential mechanisms. Results showed that the TG accumulation, intracellular reactive oxygen species content, cell apoptosis, and mitochondrial membrane potential depolarization were relieved by the administration of those phenolic fractions and caffeic acid. The protection of insoluble-bound (IB) phenolic fraction was the best, and UHP treatment significantly enhanced its protective effect on lipotoxicity. The lipotoxicity preventive effect may be achieved by alleviating intracellular oxidative stress, downregulating the expression of P-P38, COX-2, and iNOS to relieve inflammation, and downregulating Bax and cytochrome C and upregulating Bcl-2 to suppress the mitochondrial-mediated apoptosis. Therefore, the oil palm fruits phenolic fractions, especially the IB phenolic fraction, might be utilized as dietary antioxidants to relieve the adverse effects of a high-fat diet on the body, and UHP treatment is a potential method to increase this bioactivity.

Effect of Carotenoids from Phaeodactylum tricornutum on Palmitate-Treated HepG2 Cells

Non-alcoholic fatty liver disease represents the most common liver disease and is characterized by an excess of lipid accumulation in hepatocytes, mainly stored as triglycerides. Phaeodactylum tricornutum is a marine microalga, which is rich in bioactive molecules known to be hepatoprotective, such as n-3 long-chain polyunsaturated fatty acids and fucoxanthin. The aim of this study was to investigate the effects of a carotenoid extract from P. tricornutum in a cellular model of non-alcoholic fatty liver disease induced by palmitate treatment. The combined effects of carotenoids and lipids, especially n-3 long-chain polyunsaturated fatty acids, were also investigated by using a total lipophilic extract. HepG2 cells were exposed for 24 h to 250 µM palmitate with or without the addition of carotenoid extract (6 μg/mL) or total lipophilic extract (100 μg/mL). The addition of carotenoid extract or total lipophilic extract prevented the accumulation of triglycerides, total cholesterol and cholesterol esters. The carotenoid extract and total lipophilic extract also decreased the mRNA expression levels of genes involved in lipogenesis (ACACA, FASN, SCD and DGAT1) and cholesterol esterification (ACAT1/SOAT1). In addition, the total lipophilic extract also downregulated the LXR/NR1H3 and SREBF1 genes, which are involved in lipogenesis regulation. By contrast, the carotenoid extract increased the mRNA level of CPT1A, a β-oxidation related gene, and reduced the lipid droplet accumulation. In conclusion, this study highlights the preventive effects against non-alcoholic fatty liver disease of the two microalga extracts.