Eicosapentaenoic acid stimulates AMP-activated protein kinase and increases visfatin secretion in cultured murine adipocytes

Visfatin is an adipokine highly expressed in visceral AT (adipose tissue) of humans and rodents, the production of which seems to be dysregulated in excessive fat accumulation and conditions of insulin resistance. EPA (eicosapentaenoic acid), an n−3 PUFA (polyunsaturated fatty acid), has been demonstrated to exert beneficial effects in obesity and insulin resistance conditions, which have been further linked to its reported ability to modulate adipokine production by adipocytes. TNF-α (tumour necrosis factor-α) is a pro-inflammatory cytokine whose production is increased in obesity and is involved in the development of insulin resistance. Control of adipokine production by some insulin-sensitizing compounds has been associated with the stimulation of AMPK (AMP-activated protein kinase). The aim of the present study was to examine in vitro the effects of EPA on visfatin production and the potential involvement of AMPK both in the absence or presence of TNF-α. Treatment with the pro-inflammatory cytokine TNF-α (1 ng/ml) did not modify visfatin gene expression and protein secretion in primary cultured rat adipocytes. However, treatment of these primary adipocytes with EPA (200 μmol/l) for 24 h significantly increased visfatin secretion (P<0.001) and mRNA gene expression (P<0.05). Moreover, the stimulatory effect of EPA on visfatin secretion was prevented by treatment with the AMPK inhibitor Compound C, but not with the PI3K (phosphoinositide 3-kinase) inhibitor LY294002. Similar results were observed in 3T3-L1 adipocytes. Moreover, EPA strongly stimulated AMPK phosphorylation alone or in combination with TNF-α in 3T3-L1 adipocytes and pre-adipocytes. The results of the present study suggest that the stimulatory action of EPA on visfatin production involves AMPK activation in adipocytes

Cerium oxide nanoparticles regulate insulin sensitivity and oxidative markers in 3T3-L1 adipocytes and C2C12 myotubes

Insulin resistance is associated with oxidative stress, mitochondrial dysfunction, and a chronic low-grade inflammatory status. In this sense, cerium oxide nanoparticles (CeO2 NPs) are promising nanomaterials with antioxidant and anti-inflammatory properties. Thus, we aimed to evaluate the effect of CeO2 NPs in mouse 3T3-L1 adipocytes, RAW 264.7 macrophages, and C2C12 myotubes under control or proinflammatory conditions. Macrophages were treated with LPS, and both adipocytes and myotubes with conditioned medium (25% LPS-activated macrophages medium) to promote inflammation. CeO2 NPs showed a mean size of ≤25.3 nm (96.7%) and a zeta potential of mV, suitable for cell internalization. CeO2 NPs reduced extracellular reactive oxygen species (ROS) in adipocytes with inflammation while increased in myotubes with control medium. The CeO2 NPs increased mitochondrial content was observed in adipocytes under proinflammatory conditions. Furthermore, the expression of Adipoq and Il10 increased in adipocytes treated with CeO2 NPs. In myotubes, both Il1b and Adipoq were downregulated while Irs1 was upregulated. Overall, our results suggest that CeO2 NPs could potentially have an insulin-sensitizing effect specifically on adipose tissue and skeletal muscle. However, further research is needed to confirm these findings

Identification of novel targets in adipose tissue involved in non-alcoholic fatty liver disease progression

Obesity is a major risk factor for the development of Nonalcoholic fatty liver disease (NAFLD). We hypothesize that a dysfunctional subcutaneous white adipose tissue (scWAT) may lead to an accumulation of ectopic fat in the liver. Our aim was to investigate the molecular mechanisms involved in the causative role of scWAT in NALFD progression. We performed a RNA-sequencing analysis in a discovery cohort (n = 45) to identify genes in scWAT correlated with fatty liver index, a qualitative marker of liver steatosis. We then validated those targets in a second cohort (n = 47) of obese patients who had liver biopsies available. Finally, we obtained scWAT mesenchymal stem cells (MSCs) from 13 obese patients at different stages of NAFLD and established in vitro models of human MSC (hMSC)-derived adipocytes. We observed impaired adipogenesis in hMSC-derived adipocytes as liver steatosis increased, suggesting that an impaired adipogenic capacity is a critical event in the development of NAFLD. Four genes showed a differential expression pattern in both scWAT and hMSC-derived adipocytes, where their expression paralleled steatosis degree: SOCS3, DUSP1, SIK1, and GADD45B. We propose these genes as key players in NAFLD progression. They could eventually constitute potential new targets for future therapies against liver steatosis

Role of plant microRNAs in altered physiological features of obesity: effects on inflammation and metabolism

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Effects of Maresin 1, an omega-3 fatty acid-derived lipid mediator, on adipose tissue and liver function in obesity

This research demonstrated the ability of the n-3 PUFA EPA to increase mitochondrial content, and to activate master regulators of mitochondrial biogenesis and to promote the expression of genes that typify beige adipocytes in cultured fully differentiated human subcutaneous adipocytes from overweight subjects. Moreover, EPA up-regulated genes involved in fatty acid oxidation while down-regulated lipogenic genes. These data suggest that EPA promotes a remodelling of adipocyte metabolism which could be in part responsible for EPA beneficial effects in obesity. Moreover, this research revealed for the first time that MaR1 inhibits TNF-a-induced lipolysis. This effect seems to be associated to MaR1 ability to prevent the reduction of perilipin and ATGL-inhibitor G0S2 protein expression induced by the cytokine. MaR1 also reversed the decrease on total hormone sensitive lipase (total HSL), and the ratio of phosphoHSL at Ser-565/total HSL, while preventing the increased ratio of phosphoHSL at Ser-660/total HSL as well as the phosphorylation of ERK1/2 induced by TNF-a. Moreover, MaR1 counteracted the cytokine-induced decrease of p62 protein content, and also prevented the induction of LC3II/LC3I ratio. These data point out that MaR1 ameliorate TNF-a-induced alterations on lipolysis and autophagy in adipocytes, which may contribute to the beneficial actions of MaR1 on adipose tissue inflammation and insulin sensitivity. The current study also demonstrated that MaR1 reverses obesity-related liver steatosis in two different models of obesity (ob/ob and diet-induced obese (DIO) mice) and characterized the mechanisms involved. Remarkably, oral gavage of MaR1 decreased serum transaminases, reduced liver weight and TG content. MaR1-treated mice exhibited reduced hepatic lipogenic enzymes content (FAS) or activation (by phosphorylation of ACC), accompanied by upregulation of genes involved in fatty acid oxidation (Cpt1a and Acox1) and autophagy (Atg 5 and Atg7), along with increased number of autophagic vacuoles and reduced p62 protein levels. MaR1 also induced AMPK phosphorylation in DIO mice and in primary hepatocytes, and preincubation of hepatocytes with the AMPK inhibitor Compound C reversed MaR1 effects on Cpt1a, Acox1, Atg5 and Atg7 expression, suggesting the implication of AMPK in MaR1 actions. The present study also reported that MaR1 treatment by oral gavage to DIO mice increased brown adipose tissue (BAT) UCP1 levels and upregulated other thermogenic-related genes along with an increase in the mRNA levels of glucose transporters and fatty acid oxidation-related genes. Indeed, in cultured brown adipocytes MaR1 also promoted glucose uptake and fatty acid utilization, in parallel with the upregulation of thermogenic genes and oxygen consumption rates. Interestingly, microPET studies with 18F-FDG revealed that acute treatment with MaR1 potentiates cold-induced BAT activation in mice. Furthermore, MaR1 induced beige adipocyte markers (Ucp1, Pgc-1a, Tmem26 and Tbx1) in subcutaneous white adipose tissue (WAT) of DIO mice as well as in human mesenchymal cells (hMSC)-derived adipocytes treated with MaR1 along the differentiation process. The fact that this effect was not observed when MaR1 treatment was tested on mature adipocytes, point toward that MaR1 exerts its browning effect via recruiting brite adipocytes and not by promoting transdifferentiation from mature white to beige adipocytes. Nevertheless, mature white adipocytes treated acutely with MaR1 exhibited higher fatty acid oxidation rates. These data reveal MaR1 as a novel agent able to promote BAT activation and WAT browning, which could also contribute to its insulin-sensitizing properties in obesity. In summary, the outcomes of the current project regarding the metabolic actions of MaR1 have uncover that MaR1 might constitutes a novel therapeutic candidate to tackle obesity comorbidities such as insulin resistance, type 2 diabetes and non-alcoholic fatty liver disease

Effects of Maresin 1, an omega-3 fatty acid-derived lipid mediator, on adipose tissue and liver function in obesity

This research demonstrated the ability of the n-3 PUFA EPA to increase mitochondrial content, and to activate master regulators of mitochondrial biogenesis and to promote the expression of genes that typify beige adipocytes in cultured fully differentiated human subcutaneous adipocytes from overweight subjects. Moreover, EPA up-regulated genes involved in fatty acid oxidation while down-regulated lipogenic genes. These data suggest that EPA promotes a remodelling of adipocyte metabolism which could be in part responsible for EPA beneficial effects in obesity. Moreover, this research revealed for the first time that MaR1 inhibits TNF-a-induced lipolysis. This effect seems to be associated to MaR1 ability to prevent the reduction of perilipin and ATGL-inhibitor G0S2 protein expression induced by the cytokine. MaR1 also reversed the decrease on total hormone sensitive lipase (total HSL), and the ratio of phosphoHSL at Ser-565/total HSL, while preventing the increased ratio of phosphoHSL at Ser-660/total HSL as well as the phosphorylation of ERK1/2 induced by TNF-a. Moreover, MaR1 counteracted the cytokine-induced decrease of p62 protein content, and also prevented the induction of LC3II/LC3I ratio. These data point out that MaR1 ameliorate TNF-a-induced alterations on lipolysis and autophagy in adipocytes, which may contribute to the beneficial actions of MaR1 on adipose tissue inflammation and insulin sensitivity. The current study also demonstrated that MaR1 reverses obesity-related liver steatosis in two different models of obesity (ob/ob and diet-induced obese (DIO) mice) and characterized the mechanisms involved. Remarkably, oral gavage of MaR1 decreased serum transaminases, reduced liver weight and TG content. MaR1-treated mice exhibited reduced hepatic lipogenic enzymes content (FAS) or activation (by phosphorylation of ACC), accompanied by upregulation of genes involved in fatty acid oxidation (Cpt1a and Acox1) and autophagy (Atg 5 and Atg7), along with increased number of autophagic vacuoles and reduced p62 protein levels. MaR1 also induced AMPK phosphorylation in DIO mice and in primary hepatocytes, and preincubation of hepatocytes with the AMPK inhibitor Compound C reversed MaR1 effects on Cpt1a, Acox1, Atg5 and Atg7 expression, suggesting the implication of AMPK in MaR1 actions. The present study also reported that MaR1 treatment by oral gavage to DIO mice increased brown adipose tissue (BAT) UCP1 levels and upregulated other thermogenic-related genes along with an increase in the mRNA levels of glucose transporters and fatty acid oxidation-related genes. Indeed, in cultured brown adipocytes MaR1 also promoted glucose uptake and fatty acid utilization, in parallel with the upregulation of thermogenic genes and oxygen consumption rates. Interestingly, microPET studies with 18F-FDG revealed that acute treatment with MaR1 potentiates cold-induced BAT activation in mice. Furthermore, MaR1 induced beige adipocyte markers (Ucp1, Pgc-1a, Tmem26 and Tbx1) in subcutaneous white adipose tissue (WAT) of DIO mice as well as in human mesenchymal cells (hMSC)-derived adipocytes treated with MaR1 along the differentiation process. The fact that this effect was not observed when MaR1 treatment was tested on mature adipocytes, point toward that MaR1 exerts its browning effect via recruiting brite adipocytes and not by promoting transdifferentiation from mature white to beige adipocytes. Nevertheless, mature white adipocytes treated acutely with MaR1 exhibited higher fatty acid oxidation rates. These data reveal MaR1 as a novel agent able to promote BAT activation and WAT browning, which could also contribute to its insulin-sensitizing properties in obesity. In summary, the outcomes of the current project regarding the metabolic actions of MaR1 have uncover that MaR1 might constitutes a novel therapeutic candidate to tackle obesity comorbidities such as insulin resistance, type 2 diabetes and non-alcoholic fatty liver disease

miRNAs and novel food compounds related to the browning process

Obesity prevalence is rapidly increasing worldwide. With the discovery of brown adipose tissue (BAT) in adult humans, BAT activation has emerged as a potential strategy for increasing energy expenditure. Recently, the presence of a third type of fat, referred to as beige or brite (brown in white), has been recognized to be present in certain kinds of white adipose tissue (WAT) depots. It has been suggested that WAT can undergo the process of browning in response to stimuli that induce and enhance the expression of thermogenesis: a metabolic feature typically associated with BAT. MicroRNAs (miRNAs) are small transcriptional regulators that control gene expression in a variety of tissues, including WAT and BAT. Likewise, it was shown that several food compounds could influence miRNAs associated with browning, thus, potentially contributing to the management of excessive adipose tissue accumulation (obesity) through specific nutritional and dietetic approaches. Therefore, this has created significant excitement towards the development of a promising dietary strategy to promote browning/beiging in WAT to potentially contribute to combat the growing epidemic of obesity. For this reason, we summarize the current knowledge about miRNAs and food compounds that could be applied in promoting adipose browning, as well as the cellular mechanisms involved

Effects of gut microbiota–derived extracellular vesicles on obesity and diabetes and their potential modulation through diet

Obesity and diabetes incidence rates are increasing dramatically, reaching pandemic proportions. Therefore, there is an urgent need to unravel the mechanisms underlying their pathophysiology. Of particular interest is the close interconnection between gut microbiota dysbiosis and obesity and diabetes progression. Hence, microbiota manipulation through diet has been postulated as a promising therapeutic target. In this regard, secretion of gut microbiota–derived extracellular vesicles is gaining special attention, standing out as key factors that could mediate gut microbiota-host communication. Extracellular vesicles (EVs) derived from gut microbiota and probiotic bacteria allow to encapsulate a wide range of bioactive molecules (such as/or including proteins and nucleic acids) that could travel short and long distances to modulate important biological functions with the overall impact on the host health. EV-derived from specific bacteria induce differential physiological responses. For example, a high-fat diet–induced increase of the proteobacterium Pseudomonas panacis–derived EV is closely associated with the progression of metabolic dysfunction in mice. In contrast, Akkermansia muciniphila EV are linked with the alleviation of high-fat diet–induced obesity and diabetes in mice. Here, we review the newest pieces of evidence concerning the potential role of gut microbiota and probiotic-derived EV on obesity and diabetes onset, progression, and management, through the modulation of inflammation, metabolism, and gut permeability. In addition, we discuss the role of certain dietary patterns on gut microbiota–derived EV profile and the clinical implication that dietary habits could have on metabolic diseases progression through the shaping of gut microbiota–derived EV

Effects of gut microbiota–derived extracellular vesicles on obesity and diabetes and their potential modulation through diet

Obesity and diabetes incidence rates are increasing dramatically, reaching pandemic proportions. Therefore, there is an urgent need to unravel the mechanisms underlying their pathophysiology. Of particular interest is the close interconnection between gut microbiota dysbiosis and obesity and diabetes progression. Hence, microbiota manipulation through diet has been postulated as a promising therapeutic target. In this regard, secretion of gut microbiota–derived extracellular vesicles is gaining special attention, standing out as key factors that could mediate gut microbiota-host communication. Extracellular vesicles (EVs) derived from gut microbiota and probiotic bacteria allow to encapsulate a wide range of bioactive molecules (such as/or including proteins and nucleic acids) that could travel short and long distances to modulate important biological functions with the overall impact on the host health. EV-derived from specific bacteria induce differential physiological responses. For example, a high-fat diet–induced increase of the proteobacterium Pseudomonas panacis–derived EV is closely associated with the progression of metabolic dysfunction in mice. In contrast, Akkermansia muciniphila EV are linked with the alleviation of high-fat diet–induced obesity and diabetes in mice. Here, we review the newest pieces of evidence concerning the potential role of gut microbiota and probiotic-derived EV on obesity and diabetes onset, progression, and management, through the modulation of inflammation, metabolism, and gut permeability. In addition, we discuss the role of certain dietary patterns on gut microbiota–derived EV profile and the clinical implication that dietary habits could have on metabolic diseases progression through the shaping of gut microbiota–derived EV