Redox modulation of adipocyte differentiation: hypothesis of "Redox Chain" and novel insights into intervention of adipogenesis and obesity

MLPH is a novel adipogenic factor controlling redox homeostasis to inhibit lipid peroxidation in adipocytes

Abnormal adipose tissue formation is associated with metabolic disorders such as obesity, diabetes, and liver and cardiovascular diseases. Thus, identifying the novel factors that control adipogenesis is crucial for understanding these conditions and developing targeted treatments. In this study, we identified the melanosome-related factor MLPH as a novel adipogenic factor. MLPH was induced during the adipogenesis of 3T3-L1 cells and human mesenchymal stem cells. Although MLPH did not affect lipid metabolism, such as lipogenesis or lipolysis, adipogenesis was severely impaired by MLPH depletion. We observed that MLPH prevented excess reactive oxygen species (ROS) accumulation and lipid peroxidation during adipogenesis and in mature adipocytes. In addition, increased MLPH expression was observed under cirrhotic conditions in liver cancer cells and its overexpression also reduced ROS and lipid peroxidation. Our findings demonstrate that MLPH is a novel adipogenic factor that maintains redox homeostasis by preventing lipid peroxidation and ROS accumulation, which could lead to metabolic diseases.

The role of mesenchymal stem cells in early programming of adipose tissue in the offspring of women with obesity

Maternal obesity is a well-known risk factor for developing premature obesity, metabolic syndrome, cardiovascular disease and type 2 diabetes in the progeny. The development of white adipose tissue is a dynamic process that starts during prenatal life: fat depots laid down in utero are associated with the proportion of fat in children later on. How early this programming takes place is still unknown. However, recent evidence shows that mesenchymal stem cells (MSC), the embryonic adipocyte precursor cells, show signatures of the early setting of an adipogenic committed phenotype when exposed to maternal obesity. This review aims to present current findings on the cellular adaptations of MSCs from the offspring of women with obesity and how the metabolic environment of MSCs could affect the early commitment towards adipocytes. In conclusion, maternal obesity can induce early programming of fetal adipose tissue by conditioning MSCs. These cells have higher expression of adipogenic markers, altered insulin signalling and mitochondrial performance, compared to MSCs of neonates from lean pregnancies. Fetal MSCs imprinting by maternal obesity could help explain the increased risk of childhood obesity and development of further noncommunicable diseases.

Endoplasmic Reticulum Stress and Its Impact on Adipogenesis: Molecular Mechanisms Implicated

Endoplasmic reticulum (ER) stress plays a pivotal role in adipogenesis, which encompasses the differentiation of adipocytes and lipid accumulation. Sustained ER stress has the potential to disrupt the signaling of the unfolded protein response (UPR), thereby influencing adipogenesis. This comprehensive review illuminates the molecular mechanisms that underpin the interplay between ER stress and adipogenesis. We delve into the dysregulation of UPR pathways, namely, IRE1-XBP1, PERK and ATF6 in relation to adipocyte differentiation, lipid metabolism, and tissue inflammation. Moreover, we scrutinize how ER stress impacts key adipogenic transcription factors such as proliferator-activated receptor γ (PPARγ) and CCAAT-enhancer-binding proteins (C/EBPs) along with their interaction with other signaling pathways. The cellular ramifications include alterations in lipid metabolism, dysregulation of adipokines, and aged adipose tissue inflammation. We also discuss the potential roles the molecular chaperones cyclophilin A and cyclophilin B play in adipogenesis. By shedding light on the intricate relationship between ER stress and adipogenesis, this review paves the way for devising innovative therapeutic interventions.

Clozapine suppresses NADPH oxidase activation, counteracts cytosolic H2O2, and triggers early onset mitochondrial dysfunction during adipogenesis of human liposarcoma SW872 cells

Long-term treatment of schizophrenia with clozapine (CLZ), an atypical antipsychotic drug, is associated with an increased incidence of metabolic disorders mediated by poorly understood mechanisms. We herein report that CLZ, while slowing down the morphological changes and lipid accumulation occurring during SW872 cell adipogenesis, also causes an early (day 3) inhibition of the expression/nuclear translocation of CAAT/enhancer-binding protein β and peroxisome proliferator-activated receptor γ. Under the same conditions, CLZ blunts NADPH oxidase-derived reactive oxygen species (ROS) by a dual mechanism involving enzyme inhibition and ROS scavenging. These effects were accompanied by hampered activation of the nuclear factor (erythroid-derived2)-like 2 (Nrf2)-dependent antioxidant responses compared to controls, and by an aggravated formation of mitochondrial superoxide. CLZ failed to exert ROS scavenging activities in the mitochondrial compartment but appeared to actively scavenge cytosolic H2O2 derived from mitochondrial superoxide. The early formation of mitochondrial ROS promoted by CLZ was also associated with signs of mitochondrial dysfunction. Some of the above findings were recapitulated using mouse embryonic fibroblasts. We conclude that the NADPH oxidase inhibitory and cytosolic ROS scavenging activities of CLZ slow down SW872 cell adipogenesis and suppress their Nrf2 activation, an event apparently connected with increased mitochondrial ROS formation, which is associated with insulin resistance and metabolic syndrome. Thus, the cellular events characterised herein may help to shed light on the more detailed molecular mechanisms explaining some of the adverse metabolic effects of CLZ.

Mitochondrial respiratory complex I deficiency inhibits brown adipogenesis by limiting heme regulation of histone demethylation

Mitochondrial functions play a crucial role in determining the metabolic and thermogenic status of brown adipocytes. Increasing evidence reveals that the mitochondrial oxidative phosphorylation (OXPHOS) system plays an important role in brown adipogenesis, but the mechanistic insights are limited. Herein, we explored the potential metabolic mechanisms leading to OXPHOS regulation of brown adipogenesis in pharmacological and genetic models of mitochondrial respiratory complex I deficiency. OXPHOS deficiency inhibits brown adipogenesis through disruption of the brown adipogenic transcription circuit without affecting ATP levels. Neither blockage of calcium signaling nor antioxidant treatment can rescue the suppressed brown adipogenesis. Metabolomics analysis revealed a decrease in levels of tricarboxylic acid cycle intermediates and heme. Heme supplementation specifically enhances respiratory complex I activity without affecting complex II and partially reverses the inhibited brown adipogenesis by OXPHOS deficiency. Moreover, the regulation of brown adipogenesis by the OXPHOS-heme axis may be due to the suppressed histone methylation status by increasing histone demethylation. In summary, our findings identified a heme-sensing retrograde signaling pathway that connects mitochondrial OXPHOS to the regulation of brown adipocyte differentiation and metabolic functions.

Andrographolide and pterostilbene inhibit adipocyte differentiation by downregulating PPARγ through different regulators

Adipogenesis involves commitment of stem cells and their differentiation into mature adipocytes. It is tightly regulated by hormones, nutrients and adipokines. Many natural compounds are being tested for their anti-adipogenic activity which can be attributed to apoptosis induction in adipocytes, blocking adipocyte differentiation, or inhibiting intracellular triglyceride synthesis and accumulation. In this study, we have determined molecular mechanism of two phytocompounds: andrographolide (AN) and pterostilbene (PT) during differentiation of the human MSCs into adipocyte. Interestingly, AN upregulates miR27a, whereas, PT upregulated SIRT1 which inhibits the expression of PPARγ. Thus, our results clearly demonstrate that both AN and PT inhibited adipogenesis by blocking a surge of reactive oxygen species (ROS) during differentiation and inhibiting expression of crucial transcription factors like SREBP1c and PPARγ.

PTPN2 targets TAK1 for dephosphorylation to improve cellular senescence and promote adipose tissue browning in T2DM

Introduction: The energy imbalance when energy intake exceeds expenditure acts as an essential factor in the development of insulin resistance (IR). The activity of brown adipose tissue, which is involved in the dissipation of energy via heat expenditure decreases under type 2 diabetic mellitus (T2DM) state when the number of pathological aging adipocytes increases. Protein tyrosine phosphatase non-receptor type 2 (PTPN2) regulates several biological processes by dephosphorylating several cellular substrates; however, whether PTPN2 regulates cellular senescence in adipocytes and the underlying mechanism has not been reported. Methods: We constructed a model of type 2 diabetic mice with PTPN2 overexpression to explore the role of PTPN2 in T2DM. Results: We revealed that PTPN2 facilitated adipose tissue browning by alleviating pathological senescence, thus improving glucose tolerance and IR in T2DM. Mechanistically, we are the first to report that PTPN2 could bind with transforming growth factor-activated kinase 1 (TAK1) directly for dephosphorylation to inhibit the downstream MAPK/NF-κB pathway in adipocytes and regulate cellular senescence and the browning process subsequently. Discussion: Our study revealed a critical mechanism of adipocytes browning progression and provided a potential target for the treatment of related diseases.

Kuanoniamine C Suppresses Adipogenesis and White Adipose Tissue Expansion by Modulating Mitochondrial Function

Obesity is characterized by the excessive accumulation of fat to adipose tissue, which is related to abnormal increasing white adipose tissue (WAT) in the body, and it upregulates the risk of multiple diseases. Here, kuanoniamine C, which is a pyridoacridine alkaloid, suppressed the differentiation of pre-adipose cells into white adipocytes via the modulation of mitochondrial function, and inhibited WAT expansion in the early phase of high-fat-diet-induced obesity model. Pharmacological analysis revealed that inhibition of mitochondrial respiratory complex II, which new target of kuanoniamine C, activated reactive oxygen species (ROS)-extracellular signal-regulated kinase (ERK)-β-catenin signaling, and this signaling was antagonized by insulin-, IBMX-, and dexamethasone-induced adipogenesis. Therefore, the kuanoniamine C might prevent abnormal WAT expansion even when eating a diet that is not calorie restricted.

P2X7 Activation Enhances Lipid Accumulation During Adipocytes Differentiation Through Suppressing the Expression of Sirtuin-3, Sirtuin-5, and Browning Genes

P2X7 signaling has been explored in adipose tissue because of its potential to promote ATP-activated inflammatory cascades during obesogenic environments. However, limited literature has investigated the role of the P2X7 receptor in lipid metabolism during adipocyte differentiation. This study sought to explore the regulatory roles of P2X7 in adipocytes. This study utilized the in vitro 3T3-L1 differentiation model. Lipid accumulation, intracellular triglyceride, and extracellular glycerol were determined. The selective P2X7 agonist BzATP and antagonist A438079 were administered to investigate the functions of P2X7. We found that the expression of P2X7 and the lipid accumulation increased during adipocyte differentiation from D0 to D4. When administered at D0/D2, A438079 attenuated, while BzATP enhanced the degree of lipid accumulation during adipocyte differentiation. Neither did BzATP and A438079 administration affect the expression of PPARγ and C/EBPα genes that increased at D4. In addition, both intracellular triglyceride and extracellular glycerol levels at D4 were reduced by A438079 treatment and enhanced by BzATP administration. When administered at stage 2 of adipocyte differentiation, BzATP consistently enhanced lipid accumulation and intracellular triglyceride and extracellular glycerol levels without affecting mRNA and protein levels of PPARγ and C/EBPα that increased at D4. However, treating A438079 or BzATP at D4 did not affect intracellular triglyceride formation and extracellular glycerol release in differentiated adipocytes at D7. Notably, BzATP administration at stage 2 exerted a concentration-dependent inhibition on the enhanced expression of PRDM16, PGC-1α, and UCP-1 at D4. Furthermore, BzATP administration at D0/D2 inhibited the protein and mRNA levels of sirtuin-3/5 at D4. BzATP treatment at stage 2 also suppressed the mRNA levels of sirtuin-3/5 genes upregulated by insulin. In conclusion, this study demonstrated P2X7 enhances lipid accumulation during adipogenesis by suppressing the expression of sirtuin-3/5 and the browning genes.

Growth Hormone Receptor Controls Adipogenic Differentiation of Chicken Bone Marrow Mesenchymal Stem Cells by Affecting Mitochondrial Biogenesis and Mitochondrial Function

Growth hormone receptor (GHR) can activate several signaling pathways after binding to growth hormone (GH) to regulate cell growth and development. Sex-linked dwarf (SLD) chickens, normal protein functions are prevented because of exon mutations in the GHR gene, have more severe fat deposition. However, the specific molecular mechanisms responsible for this phenotype remains unclear. We therefore investigated the effect of the GHR gene on adipogenic differentiation of chicken bone marrow mesenchymal stem cells (BMSCs). We found that bone marrow fat deposition was more severe in SLD chickens compared to normal chickens, and the expression of genes related to adipogenic differentiation was enhanced in SLD chicken BMSCs. We also detected enhanced mitochondrial function of BMSCs in SLD chickens. In vitro, overexpression of GHR in chicken BMSCs increased mitochondrial membrane potential but decreased reactive oxygen and ATP contents, oxidative phosphorylation complex enzyme activity, and mitochondrial number. Expression of genes associated with mitochondrial biogenesis and function was repressed during adipogenic differentiation in chicken BMSCs, the adipogenic differentiation capacity of chicken BMSCs was also repressed. With knockdown of GHR, opposite results were observed. We concluded that GHR inhibited adipogenic differentiation of chicken BMSCs by suppressing mitochondrial biogenesis and mitochondrial function.

Glutathione system activity in the blood of overweight postmenopausal women

One of the important components of the antioxidant defense system is the glutathione system, the activity of which, when overweight, changes direction depending on gender and ethnicity. The results of studies involving overweight menopausal women are mixed. The study involved 61 postmenopausal women, who, after clinical and anamnestic examination, were divided into 2 groups: control (BMI = 19-24.9 kg / m2) and overweight group (BMI = 25-29.9 kg/m2). The use of hormone replacement therapy; the use of antioxidant drugs; diseases of endocrine genesis; exacerbation of chronic diseases; premature early menopause; surgical menopause was the exclusion criteria for women from the study. The lipid profile parameters with the calculation of the atherogenic coefficient; reduced and oxidized glutathione levels with the calculation of their ratio, the glutathione S-transferase and glutathione reductase activities were determined in the blood. Overweight women showed an increase in the triacylglycerols (p = 0.041) and cholesterol in very low density lipoproteins levels (p = 0.044). When assessing the glutathione system activity in women of the main group, compared with the control, an increase in the glutathione-S-transferase (p = 0.023) and glutathione reductase (p = 0.022) activities was noted, however, the reduced and oxidized glutathione levels, as well as their ratio did not differ from the control values. The results obtained indicate the activation of the glutathione system enzymatic link in response to changes in lipid status in postmenopausal women with overweight.

Cr (VI) induces abnormalities in glucose and lipid metabolism through ROS/Nrf2 signaling

The hexavalent form of chromium, Cr (VI), has been associated with various diseases in humans. In this study, we examined the mechanisms underlying the effect of Cr (VI) on glucose and lipid metabolism in vivo and in vitro. We found that Cr (VI) induced abnormal liver function, increased fasting blood glucose (FBG), as well as glucose and insulin intolerance in mice. Furthermore, Cr (VI) decreased glucose-6-phosphate (G6P) level and glucose transporter-2 (GLUT2) expression, increased the levels of triglyceride (TG), low-density lipoprotein-cholesterol (LDL-C), reduced high-density lipoprotein-cholesterol (HDL-C), and increased sterol regulatory element-binding proteins 1 (SREBP1) and fat synthase (FAS) in vitro and in vivo. Moreover, Cr (VI) promoted intracellular ROS production in vitro, and induced reduction of antioxidant enzyme level and Nrf2/HO-1 expression in vitro and in vivo. Also, N-acetyl cysteine (NAC, effective antioxidant and free radical scavenger) pretreatment inhibited the production of intracellular ROS, significantly suppressed Cr (VI)-induced oxidative stress, lipid accumulation, decreased G6P and GLUT2, and improved impaired glucose tolerance and glucose and insulin intolerance caused by Cr (VI) in mice. Dh404 activated expression of Nrf2 decreased ROS level, increased HO-1 expression, ameliorated activity of the antioxidant enzyme, inhibited Cr (VI) increase of SREBP1, FAS level, and reduction of G6P and GLUT2. To sum up, these data suggest that dysregulation of ROS/Nrf2/HO-1 has an important role in Cr (VI)-induced glucose/lipid metabolic disorder.

Carnosic Acid Attenuates an Early Increase in ROS Levels during Adipocyte Differentiation by Suppressing Translation of Nox4 and Inducing Translation of Antioxidant Enzymes

The objective of this study was to investigate molecular mechanisms underlying the ability of carnosic acid to attenuate an early increase in reactive oxygen species (ROS) levels during MDI-induced adipocyte differentiation. The levels of superoxide anion and ROS were determined using dihydroethidium (DHE) and 2′-7′-dichlorofluorescin diacetate (DCFH-DA), respectively. Both superoxide anion and ROS levels peaked on the second day of differentiation. They were suppressed by carnosic acid. Carnosic acid attenuates the translation of NADPH (nicotinamide adenine dinucleotide phosphate) oxidase 4 (Nox4), p47^phox, and p22^phox, and the phosphorylation of nuclear factor-kappa B (NF-κB) and NF-κB inhibitor (IkBa). The translocation of NF-κB into the nucleus was also decreased by carnosic acid. In addition, carnosic acid increased the translation of heme oxygenase-1 (HO-1), γ–glutamylcysteine synthetase (γ-GCSc), and glutathione S-transferase (GST) and both the translation and nuclear translocation of nuclear factor erythroid 2-related factor 2 (Nrf2). Taken together, these results indicate that carnosic acid could down-regulate ROS level in an early stage of MPI-induced adipocyte differentiation by attenuating ROS generation through suppression of NF-κB-mediated translation of Nox4 enzyme and increasing ROS neutralization through induction of Nrf2-mediated translation of phase II antioxidant enzymes such as HO-1, γ-GCS, and GST, leading to its anti-adipogenetic effect.

Novel microwell with a roof capable of buoyant spheroid culture

Microwells are used in studies to mimic the in vivo environment through an in vitro environment by generating three-dimensional cell spheroids. These microwells have been fabricated in various shapes using different methods according to the research purpose. However, because all microwells up to now have an open top, it has been difficult to culture spheroids of floating cells due to their low density, such as human adipose-derived stem cells (hASCs) that differentiate into adipocytes. Therefore, the labor-intensive hanging droplet method has been mainly used for the study of adipocytes. Here, we introduce a sigma-well, which is a microwell in the shape of the Greek letter sigma (σ) with a roof. Because of its unique shape, the sigma-well is advantageous for the culture of floating cells by reducing cell loss and external interference. The sigma-well was fabricated using the principle of surface tension of polydimethylsiloxane as well as air trapping and thermal expansion. Unlike conventional microwells, because the center of the bottom surface and the inlet of the sigma-well are not located on the same line and have a difference of approximately 218 μm, the spheroids are cultured more stably and may not escape the cavity. In this study, hASC and adipocyte spheroids differentiated using these sigma-wells were successfully cultured. In addition, through cytokine diffusion simulation, it was confirmed that the diffusion and mass transfer in the sigma-well was lower than that in the conventional microwell. It is expected that the morphological features of the sigma-well, which cannot be easily obtained by other methods, can be beneficial for the study of buoyant cell types such as adipocytes.

Adipose-specific BMP and activin membrane-bound inhibitor (BAMBI) deletion promotes adipogenesis by accelerating ROS production

With the improvement of people's living standards, the number of obese patients has also grown rapidly. It is reported that the level of oxidative stress in obese patients has significantly increased, mainly caused by the increase in reactive oxygen species (ROS) levels in adipose tissue. Studies have shown that the use of siRNA to interfere with bone morphogenetic protein and activin membrane-bound inhibitor (BAMBI) expression could promote adipocyte differentiation, and under hypoxic conditions, BAMBI could act as a regulator of HIF1α to regulate the polarity damage of epithelial cells. In view of these results, we speculated that BAMBI may regulate adipogenesis by regulating the level of ROS. In this study, we generated adipose-specific BAMBI knockout mice (BAMBI AKO) and found that compared with control mice, BAMBI AKO mice showed obesity when fed with high-fat diet, accompanied by insulin resistance, glucose intolerance, hypercholesterolemia, and increased inflammation in adipose tissue. Interestingly, adipose-specific deficiency of BAMBI could cause an increase in the expression level of Nox4, thereby promoting ROS production in cytoplasm and mitochondria and the DNA-binding activity of C/EBPβ and ultimately promoting adipogenesis. Consistently, our findings indicated that BAMBI may be a reactive oxygen regulator to affect adipogenesis, thereby controlling obesity and metabolic syndrome.

Plasma antioxidants and oxidative stress status in obese women: correlation with cardiopulmonary response

INTRODUCTION

A high body fat coupled with low cardiopulmonary fitness and an increase in oxidative stress has been connoted as contributing factors in developing cardiovascular comorbidities. This study aimed to investigate the correlation between antioxidants and oxidative stress status with cardiopulmonary responses in women of different body mass index (BMI).

SUBJECTS AND METHODS

Eighty female adults were recruited and divided into three groups; normal weight (n = 23), overweight (n = 28) and obese (n = 29), according to their BMI. Blood samples were obtained prior to cardiopulmonary exercise testing. Plasma samples were separated by centrifugation and analysed for enzymatic antioxidant activity including catalase, glutathione peroxidase and superoxide dismutase. Non-enzymatic antioxidant activities were assessed using 2, 2'-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical scavenging and ferric reducing ability of plasma (FRAP) assays. To evaluate the oxidative stress status of subjects, levels of reactive oxygen species and malondialdehyde, the by-product of lipid peroxidation, were measured. Cardiopulmonary responses were analysed using cardiopulmonary exercise testing (CPET) which involved 15 various parameters such as peak oxygen consumption, metabolic equivalents and respiratory exchange ratio.

RESULTS

The obese group had significantly lower ABTS radical scavenging and FRAP activities than the normal weight group. A higher catalase activity was observed in the obese group than the normal weight group. Spearman's correlation showed an inverse relationship between catalase and peak oxygen consumption, while partial correlation analysis showed inverse correlations between superoxide dismutase and respiratory frequency, ABTS activity and oxygen pulse, and between ABTS activity and cardiac output.

CONCLUSION

Our results demonstrate a lower cardiovascular fitness and antioxidant capacity in obese women; the higher catalase activity may be a compensatory mechanism. The negative correlations found between these two parameters may indicate the potential effect of antioxidants on the cardiopulmonary system and deserve further analysis in a larger population. Nevertheless, this study provides the basis for future studies to further explore the relationships between redox status and cardiopulmonary responses. This can potentially be used to predict future risk of developing diseases associated with oxidative stress, especially pulmonary and cardiovascular diseases.

Effect of body composition on redox homeostasis at rest and in response to exercise: The case of underfat women

Underfat individuals have been neglected as a malnourished population in terms of redox homeostasis. The aim of the present study was to evaluate the effect of body composition on redox homeostasis at rest and in response to exercise. Underfat, lean and overfat women, classified according to their BMI and body fat percentage, participated in the study and were subjected to an acute session of eccentric exercise. With regard to muscle function and damage, a significant group × time interaction was found for range of motion (P < .01), isometric peak torque at 90° (P < .01), delayed onset muscle soreness (P < .01) and creatine kinase (P < .05), with the lean group generally exhibiting faster recovery compared to the underfat and overfat groups. With regard to redox homeostasis, a significant group × time interaction was found for F₂-isoprostanes, protein carbonyls and glutathione (P < .01 for all biomarkers), with the underfat and overfat groups exhibiting increased resting oxidative stress levels and lower exercise-induced reactive species production . In conclusively, our data underline the importance of normal body composition for redox homeostasis, since underfat and overfat women demonstrate a similar pattern of redox disturbances both at rest and in response to exercise.

Effect of lipid fraction of digested milk from different sources in mature 3T3-L1 adipocyte

We evaluated the effect of in vitro digested milk on mature adipocytes 3T3-L1, paying particular attention to its fatty acid composition, and comparing human (HM), donkey (DM), bovine (BM), ovine (OM), caprine (CM) and formula (FM) milk. Cellular viability, apoptosis, oxidative response and gene expression levels of NF-κB p65, HMGB1, SREBP-1c and FAS were evaluated. Digested milk treatments significantly reduced 3T3-L1 mature adipocytes viability and caspase activity compared with control group, but no significant differences were observed among different sources of digested milk. In all digested milk samples, ROS level was higher than the control, however, the digested human and formula milk showed lower levels of ROS than DM, BM, OM and CM samples. Lower capacity of HM and FM to induce oxidative stress in mature adipocytes was ascribed to the peculiar free fatty acids profile of digested milk samples. All milk treatments elicited a significant over-expression of NF-κB p65 in 3T3-L1 adipocytes compared to the control; the lowest gene expression was found in HM, BM, OM and CM, the highest in FM and an intermediate behavior was shown in DM. All digested milk treatments influenced the gene expression of SRBP-1c with FM and HM showing the highest levels. For FAS expression, BM showed the highest level, OM and CM intermediate and FM, HM and DM the lowest levels, however HM and DM had comparable levels to the control.

Endocrine-Mediated Mechanisms of Metabolic Disruption and New Approaches to Examine the Public Health Threat

Obesity and metabolic disorders are of great societal concern and generate substantial human health care costs globally. Interventions have resulted in only minimal impacts on disrupting this worsening health trend, increasing attention on putative environmental contributors. Exposure to numerous environmental contaminants have, over decades, been demonstrated to result in increased metabolic dysfunction and/or weight gain in cell and animal models, and in some cases, even in humans. There are numerous mechanisms through which environmental contaminants may contribute to metabolic dysfunction, though certain mechanisms, such as activation of the peroxisome proliferator activated receptor gamma or the retinoid x receptor, have received considerably more attention than less-studied mechanisms such as antagonism of the thyroid receptor, androgen receptor, or mitochondrial toxicity. As such, research on putative metabolic disruptors is growing rapidly, as is our understanding of molecular mechanisms underlying these effects. Concurrent with these advances, new research has evaluated current models of adipogenesis, and new models have been proposed. Only in the last several years have studies really begun to address complex mixtures of contaminants and how these mixtures may disrupt metabolic health in environmentally relevant exposure scenarios. Several studies have begun to assess environmental mixtures from various environments and study the mechanisms underlying their putative metabolic dysfunction; these studies hold real promise in highlighting crucial mechanisms driving observed organismal effects. In addition, high-throughput toxicity databases (ToxCast, etc.) may provide future benefits in prioritizing chemicals for in vivo testing, particularly once the causative molecular mechanisms promoting dysfunction are better understood and expert critiques are used to hone the databases. In this review, we will review the available literature linking metabolic disruption to endocrine-mediated molecular mechanisms, discuss the novel application of environmental mixtures and implications for in vivo metabolic health, and discuss the putative utility of applying high-throughput toxicity databases to answering complex organismal health outcome questions.

High Glucose Level Impairs Human Mature Bone Marrow Adipocyte Function Through Increased ROS Production

Bone marrow adipocytes (BMAds) accumulate in aging, menopause, and metabolic diseases such as Type 2 diabetes. These osteoporotic conditions are associated with oxidative stress and hyperglycemia which are both considered as critical factors underlying bone fragility. Glucose excess and reactive oxygen species (ROS) are known to favor adipogenesis over osteoblastogenesis. In this study, we investigated whether high glucose exposure could determine dysfunction of mature BMAds, specifically through ROS production. The effects of low (LG, 5 mM) or high glucose (HG, 25 mM) concentrations were examined using human bone mesenchymal stromal cells (hBMSCs) in the time course of differentiation, and, up to 21 days once adipocytes were mature. HG did not alter the adipocyte differentiation process of hBMSCs. Yet, after 21 days under HG exposure, PPARG, CEBPA, and adiponectin mRNA expressions were decreased. These alterations were also observed following adipogenic inducer withdrawal as well as in adipocytes fully differentiated in LG then cultured in HG for the last 11 days. Without inducers, HG condition also led to decreased leptin mRNA level. Importantly, intracellular and extracellular ROS concentrations measured using Amplex Red were significantly raised by 50% under HG exposure. This rise was observed once adipocytes ended differentiation and was reproduced within the different cell culture settings without any cytotoxicity. Among genes involved in ROS metabolism, the mRNA level of the H₂O₂ generating enzyme NOX4 was found upregulated in the presence of HG. Following cell separation, mature BMAds were shown to overproduce ROS and to display the gene alterations in contrast to non-lipid-laden cells. Finally, a non-lethal treatment with a pro-oxidant agent under LG condition reduces the mRNA levels of PPARG, adiponectin, and leptin as the HG condition does in the absence of inducers, and amplifies the effect of glucose excess on gene expression. HG concentration drives mature BMAds toward altered expression of the main adipokines and transcriptional factors. These perturbations are associated with a rise in ROS generation likely mediated through enhanced expression of NOX4. Mature BMAds are thus responsive to changes in glucose and ROS concentrations, which is relevant regarding with their phenotype and function in age- or metabolic disease-related osteoporosis.

Factors that influence the redox state in children: An exploratory study

OBJECTIVE

The aim of the present study was to investigate the association of the redox state via malondialdehyde (MDA) as a lipid peroxidation biomarker and hydrophilic antioxidant capacity (HAC) with dietary, anthropometric, demographic, socio-economic and clinical variables as well as the serum concentrations of vitamins in children aged 20-36 months. This cross-sectional study was conducted from May 2013 to May 2014 and included a total of 100 children.

METHODS

The variables studied included anthropometric measurements, dietary intake by the Food Frequency Questionnaire (FFQ), socio-demographic features, clinical attributes, serum redox status, and serum vitamin concentrations.

RESULTS

Children with a family income above the minimum wage and adequate body mass index (BMI) presented higher HAC. The MDA concentration was higher in children older than 24 months. Breastfeeding for up to 120 days provided greater antioxidant capacity. Children classified in the 2nd tertile for "fruit and vegetables" and "milk and dairy products" consumption showed lower levels of MDA. There was a positive correlation of MDA with serum vitamin A levels. These results show that among children in the 20-36 months age group, family income, breastfeeding, BMI and intake of fruits and vegetables can have an influence on the imbalance of the redox state.

CONCLUSION

One strategy to prevent the imbalance between oxidants and antioxidants could be for health professionals to raise awareness among families, as such knowledge could repress/prevent the progression/initiation of several diseases in adult life.

Nano-oleanolic acid alleviates metabolic dysfunctions in rats with high fat and fructose diet

Obesity, diabetes and related metabolic disorders are among the top prevalent metabolism-related diseases with increasing threat to human health throughout the world. Oleanolic acid (OA) is a natural triterpenoid and an aglycone of many saponins possessing anti-diabetic, antioxidant, hypolipidemic and anti-inflammatory activities. A nano-formulation of OA was recently developed to evaluate the efficiency of nano-OA in the treatment of insulin-resistance and metabolic disorders in high fat and fructose (HFF) diet-fed rats. This study further identified that nano-OA could reduce the increase of body weights, serum insulin, insulin sensitivity index, serum triglycerides, and cholesterol in HFF-fed rats. In consistence, nano-OA was able to attenuate HFF diet-induced lipid accumulation in the liver and improve the structural integrity of mitochondria and endoplasmic reticulum in liver and pancreas in animals fed with HFF diet. In addition, nan-OA can efficaciously mitigate the increase of levels of malondialdehyde (MDA) and nitric oxide (NO), and serum superoxide dismutase (SOD) and catalase (CAT) activities in blood samples. The beneficial effects of nano-OA was further evidenced to be superior to OA formulated in arabic gum and rosiglitazone treatment. Together, this study provides the evidence that nano-OA can effectively improve HFF diet-induced metabolic dysfunctions in rats by improving its bioavailability and pharmacodynamic properties and thus nano-OA may be a potentially efficient agent to treat obesity-related diabetes and metabolic disorders.

Oleanolic acid attenuates PCBs-induced adiposity and insulin resistance via HNF1b-mediated regulation of redox and PPARγ signaling

Polychlorinated biphenyls (PCBs) exposure is closely associated with obesity and diabetes. However, the mechanism of PCBs-induced adiposity and insulin resistance is not clear and the intervention is limited. We have found that oleanolic acid (OA) is a natural triterpenoid, possessing antioxidant and anti-diabetic activity, and hepatocyte nuclear factor 1b (HNF1b) is an important regulator of glucose and lipid metabolism. The present study aimed to investigate the effect of OA on Aroclor 1254-induced adiposity and insulin resistance and explore the possible involvement of HNF1b. We showed that OA significantly attenuated Aroclor 1254-induced insulin resistance and abnormal changes of glucose and lipid parameters. OA inhibited the increase of adipose weight and adipocyte size in Aroclor 1254-treated mice and repressed adipocyte differentiation in vitro. In addition, OA markedly inhibited Aroclor 1254-induced increase of ROS, oxidant products, NOX4 expression, decrease of SOD1, SOD2, GCLC, GCLM and Gpx1 expression, and increase of PPARγ signaling. Aroclor 1254 resulted in a decrease of HNF1b expression in adipose of mice and adipocytes, which was inhibited by OA. Upregulation of HNF1b blocked Aroclor 1254-induced oxidative stress, adipocyte differentiation and insulin resistance. Downregulation of HNF1b inhibited OA-induced protective effects against Aroclor 1254-associated oxidative stress, adipocyte differentiation and insulin resistance. The antioxidant Vitamin C reduced Aroclor 1254-induced ROS generation in vitro, but had no significant effect on HNF1b expression, oxidative stress and metabolic dysfunction in vivo. OA could inhibit PCBs mixture-induced oxidative injury and glucose/lipid metabolic dysfunction via HNF1b-mediated regulation of redox homeostasis. Our data suggest that HNF1b is a new on/off switch of redox homeostasis and OA-stimulated HNF1b-endogenous antioxidant activity is a potential option for the intervention of PCBs exposure-related adiposity and insulin resistance.

Curculigoside and polyphenol-rich ethyl acetate fraction of Molineria latifolia rhizome improved glucose uptake via potential mTOR/AKT activated GLUT4 translocation

Adipose tissue is one of the major organs responsible for rapid restoration of postprandial glucose fluxes. Being the major isoform of glucose transporter in adipose tissue, regulations of insulin-dependent GLUT4 trafficking have always been of research interest. The present study aimed to examine the molecular mechanisms underlying the efficacy of curculigoside and polyphenol-rich ethyl acetate fraction (EAF) of Molineria latifolia rhizome in triggering glucose uptake. We assessed the adipogenic potential and glucose uptake stimulatory activity of curculigoside and EAF by employing a murine 3T3-L1 adipocyte model. The transcriptional and translational expressions of selected intermediates in the insulin signalling pathway were evaluated. While curculigoside neither promoted adipogenesis nor activated peroxisome proliferator activated receptor gamma, treatment with polyphenol-rich EAF resulted otherwise. However, both treatments enhanced insulin-stimulated uptake of glucose. This was coupled with increased availability of GLUT4 at the plasma membrane of the differentiated adipocytes although the total GLUT4 protein level was unaffected. In addition, the treatment increased the phosphorylation of both AKT and mTOR, which have been reported to be associated with GLUT4 translocation. The present findings proposed that curculigoside and EAF increased glucose transport activity of 3T3-L1 adipocytes via GLUT4 translocation as a result of potential mTOR/AKT activation. The more potent efficacy observed with EAF suggested potential synergistic and multi-targeted action.

NEFA-induced ROS impaired insulin signalling through the JNK and p38MAPK pathways in non-alcoholic steatohepatitis

The aim of this study was to investigate the changes in hepatic oxidative phosphorylation (OXPHOS) complexes (COs) in patients and cows with non‐alcoholic steatohepatitis (NASH) and to investigate the mechanism that links mitochondrial dysfunction and hepatic insulin resistance induced by non‐esterified fatty acids (NEFAs). Patients and cows with NASH displayed high blood NEFAs, TNF‐α and IL‐6 concentrations, mitochondrial dysfunction and insulin resistance. The protein levels of peroxisome proliferator‐activated receptor‐γ coactivator‐1α (PGC‐1α), mitofusin‐2 (Mfn‐2) and OXPHOS complexes (human: COI and COIII; cow: COI‐IV) were significantly decreased in patients and cows with NASH. NEFA treatment significantly impaired mitochondrial function and, increased reactive oxygen species (ROS) production, and excessive ROS overactivated the JNK and p38MAPK pathways and induced insulin resistance in cow hepatocytes. PGC‐1α and Mfn‐2 overexpression significantly decreased the NEFA‐induced ROS production and TNF‐α and IL‐6 mRNA expressions, reversed the inhibitory effect of NEFAs on mitochondrial function and attenuated the overactivation of the ROS‐JNK/p38MAPK pathway, alleviated insulin resistance induced by NEFAs in cow hepatocytes and HepG2 cells. These findings indicate that NEFAs induce mitochondrial dysfunction and insulin resistance mediated by the ROS‐JNK/p38MAPK pathway. PGC‐1α or Mfn‐2 overexpression reversed the lipotoxicity of NEFAs on mitochondrial dysfunction and insulin resistance. Our study clarified the mechanism that links hepatic mitochondrial dysfunction and insulin resistance in NASH.

Expression enhancement in brown adipose tissue of genes related to thermogenesis and mitochondrial dynamics after administration of pepsin egg white hydrolysate

Pepsin egg white hydrolysate enhanced mitochondria proliferation on brown adipose tissue and thermogenesis. Reduced body weight and adiposity were observed.

Inhibition of hepatocyte nuclear factor 1b induces hepatic steatosis through DPP4/NOX1-mediated regulation of superoxide

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disorder that is closely associated with insulin resistance and type 2 diabetes. Previous studies have suggested that hepatocyte nuclear factor 1b (HNF1b) ameliorates insulin resistance. However, the role of HNF1b in the regulation of lipid metabolism and hepatic steatosis remains poorly understood. We found that HNF1b expression was decreased in steatotic livers. We injected mice with lentivirus (LV) expressing HNF1b shRNA to generate mice with hepatic knockdown of HNF1b. We also injected high fat (HF) diet-induced obese and db/db diabetic mice with LV expressing HNF1b to overexpress HNF1b. Knockdown of HNF1b increased hepatic lipid contents and induced insulin resistance in mice and in hepatocytes. Knockdown of HNF1b worsened HF diet-induced increases in hepatic lipid contents, liver injury and insulin resistance in mice and PA-induced lipid accumulation and impaired insulin signaling in hepatocytes. Moreover, overexpression of HNF1b alleviated HF diet-induced increases in hepatic lipid content and insulin resistance in mice. Knockdown of HNF1b increased expression of genes associated with lipogenensis and endoplasmic reticulum (ER) stress. DPP4 and NOX1 expression was increased by knockdown of HNF1b and HNF1b directly bound with the promoters of DPP4 and NOX1. Overexpression of DPP4 or NOX1 was associated with an increase in lipid droplets in hepatocytes and decreased expression of DPP4 or NOX1 suppressed the effects of knockdown of HNF1b knockdown on triglyceride (TG) formation and insulin signaling. Knockdown of HNF1b increased superoxide level and decreased glutathione content, which was inhibited by downregulation of DPP4 and NOX1. N-acetylcysteine (NAC) suppressed HNF1b knockdown-induced ER stress, TG formation and insulin resistance. Palmitic acid (PA) decreased HNF1b expression which was inhibited by NAC. Taken together, these studies demonstrate that HNF1b plays an essential role in controlling hepatic TG homeostasis and insulin sensitivity by regulating DPP4/NOX1mediated generation of superoxide.

Insulin-stimulated lipid accumulation is inhibited by ROS-scavenging chemicals, but not by the Drp1 inhibitor Mdivi-1

Adipocyte differentiation is regulated by intracellular reactive oxygen species (ROS) generation and mitochondrial fission and fusion processes. However, the correlation between intracellular ROS generation and mitochondrial remodeling during adipocyte differentiation is still unknown. Here, we investigated the effect on adipocyte differentiation of 3T3-L1 cells of intracellular ROS inhibition using N-acetyl cysteine (Nac) and Mito-TEMPO and of mitochondrial fission inhibition using Mdivi-1. Differentiated 3T3-L1 adipocytes displayed an increase in mitochondrial fission, ROS generation, and the expression of adipogenic and mitochondrial dynamics-related proteins. ROS scavenger (Nac or Mito-TEMPO) treatment inhibited ROS production, lipid accumulation, the expression of adipogenic and mitochondrial dynamics-related proteins, and mitochondrial fission during adipogenesis of 3T3-L1 cells. On the other hand, treatment with the mitochondrial fission inhibitor Mdivi-1 inhibited mitochondrial fission but did not inhibit ROS production, lipid accumulation, or the expression of adipogenic and mitochondrial dynamics-related proteins, with the exception of phosphorylated Drp1 (Ser616), in differentiated 3T3-L1 adipocytes. The inhibition of mitochondrial fission did not affect adipocyte differentiation, while intracellular ROS production decreased in parallel with inhibition of adipocyte differentiation. Therefore, our results indicated that ROS are an essential regulator of adipocyte differentiation in 3T3-L1 cells.

Lycium barbarum polysaccharide protects against neurotoxicity via the Nrf2-HO-1 pathway

The incidence of neurodegenerative diseases including Alzheimer's and Parkinson's disease has markedly increased over the past few decades. Oxidative stress is considered to be a common pathophysiological condition resulting in neurotoxicity. Lycium barbarum polysaccharide (LBP) is the major active component of Lycium barbarum L., which exhibit potent antioxidant activity. The current study investigated the neuroprotective effects of LBP in H₂O₂-treated PC12 cells in vitro and in CoCl₂-treated rats in vivo. It was determined that LBP concentration-dependently reversed the H₂O₂-induced increase in reactive oxygen species (ROS) levels, decrease in cell viability, increase in TUNEL-stained cells, increase in caspase-3 and −9 activity and decrease in mitochondrial membrane potential, indicating the amelioration of mitochondrial apoptosis. Furthermore, LBP inhibited the H₂O₂-induced decrease in nuclear factor erythroid 2-related factor 2 (Nrf)2 and heme oxygenase (HO)-1 expression and binding of Nrf2 to the promoters of HO-1. Silencing of Nrf2 and inhibition of HO-1 by zinc protoporphyrin IX (ZnPP) reversed the protective effects of LBP against H₂O₂-resulted neurotoxicity in PC12 cells. In CoCl₂-treated rats, it was demonstrated that LBP decreased brain tissue apoptosis, reduced the time spent by rats finding the platform site, decreased escape latencies and reduced the distance traveled to find the platform. In addition, LBP inhibited the CoCl₂-induced decrease of Nrf2 and HO-1 expression. Administration of ZnPP also suppressed the protective effects of LBP against CoCl₂-resulted neurotoxicity in rats. Thus, the current study indicated that LBP exhibits protective effects against neurotoxicity by upregulating Nrf2/HO-1 signaling. These data may increase understanding regarding the neuroprotective activities of LBP.

Catalase overexpression modulates metabolic parameters in a new 'stress-less' leptin-deficient mouse model

Oxidative stress plays a key role in obesity by modifying the function of important biological molecules, thus altering obesogenic pathways such as glucose and lipid signaling. Catalase, is an important endogenous antioxidant enzyme that catabolizes hydrogen peroxide produced by the dismutation of superoxide. Recent studies have shown knockdown of catalase exacerbates insulin resistance and leads to obesity. We hypothesized that overexpressing catalase in an obese mouse will modulate obesogenic pathways and protect against obesity. Therefore, we bred catalase transgenic ([Tg(CAT)^+/-] mice with Ob/Ob mice to generate the hybrid "Bob-Cat" mice. This newly generated "stress-less" mouse model had decreased oxidative stress (oxidized carbonylated proteins). ECHO-MRI showed lower fat mass but higher lean mass in "Bob-Cat" mice. Comprehensive Lab Animal Monitoring System (CLAMS) showed light and dark cycle increase in energy expenditure in Bob-Cat mice compared to wild type controls. Circulating levels of leptin and resistin showed no change. Catalase mRNA expression was increased in key metabolic tissues (adipose, liver, intestinal mucosa, and brain) of the Bob-Cat mice. Catalase activity, mRNA and protein expression was increased in adipose tissue. Expression of the major adipokines leptin and adiponectin was increased while pro-inflammatory genes, MCP-1/JE and IL-1β were lowered. Interestingly, sexual dimorphism was seen in body composition, energy expenditure, and metabolic parameters in the Bob-Cat mice. Overall, the characteristics of the newly generated "Bob-Cat" mice make it an ideal model for studying the effect of redox modulators (diet/exercise) in obesity.

Hepatocyte nuclear factor 1b is a novel negative regulator of white adipocyte differentiation

Hepatocyte nuclear factor 1b (HNF1b) is a transcription factor belonging to the HNF family. We aimed to investigate the role of HNF1b in white adipocyte differentiation. The expression of HNF1b was reduced in white adipose tissue (WAT) of both diet-induced and genetic obese mice and decreased during the process of 3T3-L1 adipocyte differentiation. Downregulation of HNF1b enhanced 3T3-L1 adipocyte differentiation and upregulation of HNF1b inhibited this process. Upregulation of HNF1b inhibited peroxisome proliferator-activated receptor γ (PPARγ) and its target gene expression, while downregulation of HNF1b increased those genes expression. Overexpression of PPARγ suppressed HNF1b upregulation-induced inhibition of adipocyte differentiation. HNF1b can directly bind with the promoter of PPARγ in 3T3-L1 cells, which was decreased after adipogenic differentiation. HNF1b promoted apoptotic and autophagic cell death in early differentiated adipocytes through regulation of cell cycle progress and cell death-related factors, and thus inhibited the process of mitotic clonal expansion (MCE). HNF1b acted as an antioxidant regulator through regulating various antioxidant enzymes via binding with antioxidant response element. Oxidant treatment suppressed HNF1b upregulation-induced inhibition of adipocyte differentiation. Overall, our results suggest that HNF1b is a novel negative regulator of adipocyte differentiation through regulation of PPARγ signaling, MCE and redox state.

Polychlorinated biphenyls-153 induces metabolic dysfunction through activation of ROS/NF-κB signaling via downregulation of HNF1b

Polychlorinated biphenyls (PCB) is a major type of persistent organic pollutants (POPs) that act as endocrine-disrupting chemicals. In the current study, we examined the mechanism underlying the effect of PCB-153 on glucose and lipid metabolism in vivo and in vitro. We found that PCB-153 induced per se and worsened high fat diet (HFD)-resulted increase of blood glucose level and glucose and insulin intolerance. In addition, PCB-153 induced per se and worsened HFD-resulted increase of triglyceride content and adipose mass. Moreover, PCB-153 concentration-dependently inhibited insulin-dependent glucose uptake and lipid accumulation in cultured hepatocytes and adipocytes. PCB-153 induced the expression and nuclear translocation of p65 NF-κB and the expression of its downstream inflammatory markers, and worsened HFD-resulted increase of those inflammatory markers. Inhibition of NF-κB significantly suppressed PCB-153-induced inflammation, lipid accumulation and decrease of glucose uptake. PCB-153 induced oxidative stress and decreased hepatocyte nuclear factor 1b (HNF1b) and glutathione peroxidase 1 (GPx1) expression in vivo and in vitro. Overexpression of HNF1b increased GPx1 expression, decreased ROS level, decreased Srebp1, ACC and FAS expression, and inhibited PCB-153-resulted oxidative stress, NF-κB-mediated inflammation, and final glucose/lipid metabolic disorder. Our results suggest that dysregulation of HNF1b/ROS/NF-κB plays an important role in PCB-153-induced glucose/lipid metabolic disorder.

Differential proteomic and oxidative profiles unveil dysfunctional protein import to adipocyte mitochondria in obesity-associated aging and diabetes

Human age-related diseases, including obesity and type 2 diabetes (T2DM), have long been associated to mitochondrial dysfunction; however, the role for adipose tissue mitochondria in these conditions remains unknown. We have tackled the impact of aging and T2DM on adipocyte mitochondria from obese patients by quantitating not only the corresponding abundance changes of proteins, but also the redox alterations undergone by Cys residues thereof. For that, we have resorted to a high-throughput proteomic approach based on isobaric labeling, liquid chromatography and mass spectrometry. The alterations undergone by the mitochondrial proteome revealed aging- and T2DM-specific hallmarks. Thus, while a global decrease of oxidative phosphorylation (OXPHOS) subunits was found in aging, the diabetic patients exhibited a reduction of specific OXPHOS complexes as well as an up-regulation of the anti-oxidant response. Under both conditions, evidence is shown for the first time of a link between increased thiol protein oxidation and decreased protein abundance in adipose tissue mitochondria. This association was stronger in T2DM, where OXPHOS mitochondrial- vs. nuclear-encoded protein modules were found altered, suggesting impaired mitochondrial protein translocation and complex assembly. The marked down-regulation of OXPHOS oxidized proteins and the alteration of oxidized Cys residues related to protein import through the redox-active MIA (Mitochondrial Intermembrane space Assembly) pathway support that defects in protein translocation to the mitochondria may be an important underlying mechanism for mitochondrial dysfunction in T2DM and physiological aging. The present draft of redox targets together with the quantification of protein and oxidative changes may help to better understand the role of oxidative stress in both a physiological process like aging and a pathological condition like T2DM.

Amentoflavone protects against high fat-induced metabolic dysfunction: Possible role of the regulation of adipogenic differentiation

In the present study, we evaluated the protective effects of amentoflavone (AMF) against high-fat (HF) diet-induced metabolic dysfunction and focused on the influence of AMF on adipogenic differentiation during 3T3-L1 adipocyte differentiation. For this purpose, male Wistar rats were fed a HF diet or a HF diet with AMF (10 or 50 mg/kg). We found that AMF protected against HF diet-induced metabolic dysfunction in a dose-dependent manner, as evidenced by a decrease in the fasting blood glucose levels, fasting insulin levels and the homeostatic model assessment-insulin resistance index (HOMA-IR), as well as by a decrease in the glucose level, as shown by the intraperitoneal glucose tolerance test and intraperitoneal insulin tolerance test. Moreover, the results revealed that AMF significantly inhibited the increase in body weight, the weight of perirenal adipose tissues and the serum triglyceride (TG) content of the rats fed the HF diet in a dose-dependent manner. AMF also inhibited the accumulation of oil droplets in differentiated 3T3-L1 adipocytes in a concentration-dependent manner. The incubation of the cells with AMF for 0–8, 0–2, 2–4, or 4–8 days markedly inhibited adipogenesis. During the early phase of the adipocyte differentiation of 3T3-L1 cells, AMF decreased CCAAT/enhancer-binding protein (C/EBP) β expression in a concentration-dependent manner, leading to the inhibition of mitotic clonal expansion (MCE). Moreover, our results demonstrated that AMF significantly increased reactive oxygen species (ROS) generation in the cells and the antioxidant, N-acetylcysteine (NAC), markedly attenuated the inhibitory effects of AMF on adipogenesis. AMF also inhibited the expression of peroxisome proliferator-activated receptor γ (PPARγ) and C/EBPα and the expression of downstream targets in a concentration-dependent manner. The overexpression of PPARγ and C/EBPα (by transfection with respective overexpression plasmids) attentuated the inhibitory effects of AMF on the formation of oil droplets. The inhibitory effects of AMF on adipocyte differentiation may contribute to its protective effects against HF diet-induced metabolic dysfunction. Overall, the data in our study provide novel insight into the mechanisms responsible for the protective effects of AMF against HF diet-induced metabolic dysfunction and those for its inhibitory effect on adipocyte differentiation.

Metabolic switches during the first steps of adipogenic stem cells differentiation

The understanding of metabolism during cell proliferation and commitment provides a greater insight into the basic biology of cells, allowing future applications. Here we evaluated the energy and oxidative changes during the early adipogenic differentiation of human adipose tissue-derived stromal cells (hASCs). hASCs were maintained under differentiation conditions during 3 and 7days. Oxygen consumption, mitochondrial mass and membrane potential, reactive oxygen species (ROS) generation, superoxide dismutase (SOD) and catalase activities, non-protein thiols (NPT) concentration and lipid peroxidation were analyzed. We observed that 7days of adipogenic induction are required to stimulate cells to consume more oxygen and increase mitochondrial activity, indicating organelle maturation and a transition from glycolytic to oxidative energy metabolism. ROS production was only increased after 3days and may be involved in the differentiation commitment. ROS source was not only the mitochondria and we suggest that NOX proteins are related to ROS generation and therefore adipogenic commitment. ROS production did not change after 7days, but an increased activity of catalase and NPT concentration as well as a decreased lipid peroxidation were observed. Thus, a short period of differentiation induction is able to change the energetic and oxidative metabolic profile of hASCs and stimulate cytoprotection processes.

Herbal medicines and nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD), which is characterized by excessive fat accumulation in the liver of patients who consume little or no alcohol, becomes increasingly common with rapid economic development. Long-term excess fat accumulation leads to NAFLD and represents a global health problem with no effective therapeutic approach. NAFLD is considered to be a series of complex, multifaceted pathological processes involving oxidative stress, inflammation, apoptosis, and metabolism. Over the past decades, herbal medicines have garnered growing attention as potential therapeutic agents to prevent and treat NAFLD, due to their high efficacy and low risk of side effects. In this review, we evaluate the use of herbal medicines (including traditional Chinese herbal formulas, crude extracts from medicinal plants, and pure natural products) to treat NAFLD. These herbal medicines are natural resources that can inform innovative drug research and the development of treatments for NAFLD in the future.

Glyphosate Inhibits PPAR Gamma Induction and Differentiation of Preadipocytes and is able to Induce Oxidative Stress

Glyphosate-based herbicides (GF) are extensively used for weed control. Thus, it is important to investigate their putative toxic effects. We have reported that GF at subagriculture concentrations inhibits proliferation and differentiation to adipocytes of 3T3-L1 fibroblasts. In this investigation, we evaluated the effect of GF on genes upregulated during adipogenesis. GF was able to inhibit the induction of PPAR gamma, the master gene in adipogenesis but not C/EBP beta, which precedes PPAR gamma activation. GF also inhibited differentiation and proliferation of another model of preadipocyte: mouse embryonic fibroblasts. In exponentially growing 3T3-L1 cells, GF increased lipid peroxidation and the activity of the antioxidant enzyme, superoxide dismutase. We also found that proliferation was inhibited with lower concentrations of GF when time of exposure was extended. Thus, GF was able to inhibit proliferation and differentiation of preadipocytes and to induce oxidative stress, which is indicative of its ability to alter cellular physiology.

Bioprospecting the Curculigoside-Cinnamic Acid-Rich Fraction from Molineria latifolia Rhizome as a Potential Antioxidant Therapeutic Agent

Increasing evidence from both experimental and clinical studies depicts the involvement of oxidative stress in the pathogenesis of various diseases. Specifically, disruption of homeostatic redox balance in accumulated body fat mass leads to obesity-associated metabolic syndrome. Strategies for the restoration of redox balance, potentially by exploring potent plant bioactives, have thus become the focus of therapeutic intervention. The present study aimed to bioprospect the potential use of the curculigoside-cinnamic acid-rich fraction from Molineria latifolia rhizome as an antioxidant therapeutic agent. The ethyl acetate fraction (EAF) isolated from M. latifolia rhizome methanolic extract (RME) contained the highest amount of phenolic compounds, particularly curculigoside and cinnamic acid. EAF demonstrated glycation inhibitory activities in both glucose- and fructose-mediated glycation models. In addition, in vitro chemical-based and cellular-based antioxidant assays showed that EAF exhibited high antioxidant activities and a protective effect against oxidative damage in 3T3-L1 preadipocytes. Although the efficacies of individual phenolics differed depending on the structure and concentration, a correlational study revealed strong correlations between total phenolic contents and antioxidant capacities. The results concluded that enriched phenolic contents in EAF (curculigoside-cinnamic acid-rich fraction) contributed to the overall better reactivity. Our data suggest that this bioactive-rich fraction warrants therapeutic potential against oxidative stress-related disorders.

Protective effects of naringenin in cardiorenal syndrome

BACKGROUND

Cardiorenal syndrome is a complicated and bidirectional interrelationship between the heart and kidneys. Naringenin (NG) is a naturally occurring flavonoid possessing various biological and pharmacological properties.

MATERIALS AND METHODS

We tested whether NG could improve cardiac and renal function in a rat model of cardiorenal syndrome.

RESULTS

The results showed that NG-attenuated cardiac remodeling and cardiac dysfunction in rats with cardiorenal syndrome, as evidenced by decrease of left ventricle weight (LVW), increase of body weight (BW), decrease of LVW/BW, decrease of concentrations of serum creatinine, blood urea nitrogen, type-B natriuretic peptide, aldosterone, angiotensin (Ang) II, C-reactive protein, and urine protein, increase of left ventricular systolic pressure and falling rates of left ventricular pressure (dp/dtmax), and decrease of left ventricular diastolic pressure, left ventricular end-diastolic pressure, and -dp/dtmax. NG significantly inhibited the increase of lipid profiles including low-density lipoprotein, TC, and TG in rats. In addition, NG significantly inhibited the increase of cardiac expression of IL-1β, IL-6, and interferon γ. Moreover, NG decreased malonaldehyde level, increased superoxide dismutase activity and glutathione content in rats, and increased the expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and catalytic subunit of γ-glutamylcysteine ligase (GCLc) in rats and Ang II-treated cardiac fibroblasts. Inhibition of Nrf2 and glutathione synthesis significantly suppressed NG-induced decrease of ROS level. Inhibition of Nrf2 markedly suppressed NG-induced increase of GCLc expression in Ang II-treated cardiac fibroblasts.

CONCLUSIONS

The data provide novel options for therapy of patients and new insights into the cardioprotective effects of NG in cardiorenal syndrome.