Conjugated linoleic acid reduces adiposity and increases markers of browning and inflammation in white adipose tissue of mice

Ginsenoside Rb1 and berberine synergistically protect against type 2 diabetes mellitus via GDF15/HAMP pathway throughout the liver lobules: Insights from spatial transcriptomics analysis

Type 2 diabetes mellitus (T2DM) is a significant public health issue with high morbidity and mortality. Ginsenoside Rb1 (Rb1) and berberine (BBR), the main bioactive compounds of Panax ginseng and Coptis chinensis, respectively, are known for their hypoglycemic effects. Nevertheless, the synergistic effects and underlying mechanism of Rb1 and BBR on T2DM remain unclear. In this study, we utilized a leptin receptor-deficient (db/db) mouse model to investigate the protective effects of their combination treatment. Our findings demonstrated that the combined use of Rb1 and BBR at a 1:4 ratio had more pronounced effects than the first-line anti-diabetic drug metformin on reducing the weight ratio of white adipose tissue, ameliorating insulin resistance, and improving glucose and lipid metabolism. Using spatial transcriptomics, we revealed that metformin treatment improved gluconeogenesis and lipogenesis only in the periportal zone, while the combination treatment induced improvements throughout the liver lobule, with distinct key targets across different zones, thus underscoring a more comprehensive modulation of hepatic metabolism. This may be the key reason why this combination therapy demonstrated superior protective effects against T2DM. Additionally, the reversed expression of the key callback gene hepcidin (HAMP) and its regulator growth differentiation factor 15 (GDF15) following the combination therapy across all zones, along with validation experiments, further suggested that GDF15/HAMP pathway might be a key mechanism underlying the beneficial effects of Rb1 and BBR against T2DM. This study also indicates a path toward innovative drug cocktails for treating T2DM, offering a holistic approach to regulate the entire liver lobule metabolism.

Microwave-assisted synthesis of 4,4-dimethylsterol-conjugated linoleic acid ester and its lipid-lowering benefits evaluation

4,4-Dimethylsterol (RST), rich in rice bran oil, is often considered to have good lipid-lowering properties, and conjugated linoleic acid (CLA), a special fatty acid, is also considered to have similar properties, but the low solubility and poor oxidation stability limits their application in the food industry. Typically, sterol esters have better solubility after esterification. However, it is difficult to esterify 4,4-dimethylsterol for its additional methyl groups. Therefore, a microwave-assisted esterification of 4,4-dimethylsterol with CLA was developed in this study, and the lipid-lowering function of 4,4-dimethylsterol-CLA esters (RSE) was evaluated with a high-fat diet (HFD)-induced mice model. The results showed that when the reaction condition of the molar ratio of RST to CLA was 1:3 and catalyzed with 5% (mol%) p-toluene sulfonic acid and 25% (mol%) dodecyl benzene sulfonic acid, and maintained at a microwave reactor for 125 min at 100°C, the highest esterification rate of 93.63% was acquired. Furthermore, the results of HFD-induced mice experiments demonstrated that RSE could significantly reduce body weight, as well as serum and liver triglyceride (TG) levels, while also exert hepatoprotective properties compared to RST. Additionally, it was found that RSE could affect appetite and regulate the expression of lipid metabolism-related genes in mice. These findings suggest that RSE holds potential for application in the field of functional foods.

Thermogenic adipose tissues: Promising therapeutic targets for metabolic diseases

The ongoing increase in the prevalence of obesity and its comorbidities such as cardiovascular disease, type 2 diabetes (T2D) and dyslipidemia warrants discovery of novel therapeutic options for these metabolic diseases. Obesity is characterized by white adipose tissue expansion due to chronic positive energy balance as a result of excessive energy intake and/or reduced energy expenditure. Despite various efforts to prevent or reduce obesity including lifestyle and behavioral interventions, surgical weight reduction approaches and pharmacological methods, there has been limited success in significantly reducing obesity prevalence. Recent research has shown that thermogenic adipocyte (brown and beige) activation or formation, respectively, could potentially act as a therapeutic strategy to ameliorate obesity and its related disorders. This can be achieved through the ability of these thermogenic cells to enhance energy expenditure and regulate circulating levels of glucose and lipids. Thus, unraveling the molecular mechanisms behind the formation and activation of brown and beige adipocytes holds the potential for probable therapeutic paths to combat obesity. In this review, we provide a comprehensive update on the development and regulation of different adipose tissue types. We also emphasize recent interventions in harnessing therapeutic potential of thermogenic adipocytes by bioactive compounds and new pharmacological anti-obesity agents.

The Many Facets of PPAR-γ Agonism in Obesity and Associated Comorbidities: Benefits, Risks, Challenges, and Future Directions

PURPOSE OF REVIEW

Obesity is strongly associated with cardiometabolic disorders and certain malignancies, emphasizing the key role of adipose tissue in human health. While incretin mimetics have shown effectiveness in glycemic control and weight loss, a holistic strategy for combating obesity and associated comorbidities remains elusive. This review explores peroxisome proliferator-activated receptor gamma (PPAR-γ) agonism as a potential therapeutic approach, highlighting its benefits, addressing its limitations, and outlining future directions for developing more effective treatment strategies.

RECENT FINDINGS

Both natural and synthetic PPAR-γ agonists hold significant therapeutic potential as insulin sensitizers, while also demonstrating anti-inflammatory properties and playing a critical role in regulating lipid metabolism. However, the clinical use of natural agonists is limited by poor bioavailability, while synthetic agents like thiazolidinediones are associated with adverse effects, including fluid retention, weight gain, and bone loss. Current research is focused on developing modified, tissue-specific PPAR-γ agonists, as well as dual PPAR-α/PPAR-γ agonists, with improved safety profiles to mitigate these side effects. Nanotechnology-based drug delivery systems also hold promise for enhancing bioavailability and therapeutic efficacy. Furthermore, the transformative potential of machine learning and artificial intelligence offers opportunities to accelerate advancements in this field. PPAR-γ agonists exhibit significant potential in addressing metabolic syndrome, cardiovascular disease, and cancer. However, their clinical use is restricted by safety concerns and suboptimal pharmacokinetics. Innovations in modified PPAR-γ agonists, nanotechnology-based delivery systems, and computational tools hold promise for creating safer and more effective therapeutic options for obesity and its associated disorders.

Structural characterization of polysaccharide isolated from Inonotus hispidus and its anti-obesity effect based on regulation of the interleukin-17-mediated inflammatory response

A heteropolysaccharide (IHP3) with a molecular weight of 22.0 kDa was isolated from Inonotus hispidus (Bull.: Fr.) P. Karst using column chromatography purification from water extraction. Its backbone was predominantly composed of →6)-α-D-Galp-(1→, →2,6)-α-D-Galp-(1→,→6)-α-D-O-Me-Galp-(1→, →3)-α-D-Manp-(1→, and →3,4,6) -β-D-Galp-(1→ residues, branched at C2 of partial α-D-Galp, or C3 and C4 of β-D-Galp, and terminated by α-D-Manp, and α-L-Fucp. In high-fat diet (HFD)-fed obese mice, IHP3 effectively suppressed body weight and plasma glucose gain, decreased fat accumulation, ameliorated lipid metabolism, and protected liver function from HFD-induced damage. Combining the analysis of gut microbiota metabolomics, hepatic proteomics and biochemical detection revealed, IHP3 significantly altered cecum fecal metabolite abundances, inhibited the phosphorylation of peroxisome proliferator-activated receptor gamma, and promoted the browning of white adipose tissue and the activation of brown adipose tissue. These changes collectively contributed to alleviating obesity symptoms by suppressing the interleukin (IL)-17-mediated inflammatory response in obese mice. Therefore, these findings suggest that IHP3 could be a potential candidate for the development of anti-obesity drugs.

Trans 10, cis 12-conjugated linoleic acid in low concentration reduces while in high concentration enhances adipocyte metabolism but effectively improves hepatic steatosis of obese mice

Trans 10, cis 12-conjugated linoleic acid (t10c12-CLA)-producing mice were used to investigate the antiobesity of obese males. Compared to wild-type littermates, high concentration t10c12-CLA in biallelic Pai/Pai mice reduced fat by up-regulation lipid metabolism in white adipose tissue (WAT). In contrast, low concentration t10c12-CLA in monoallelic Pai/wt mice could not reduce fat for down-regulation lipid metabolism in WAT. Simultaneously, t10c12-CLA enhanced thermogenesis and beta-oxidation in brown adipose tissue, alleviated steatosis by declining lipid metabolism in the liver, and lowered circulating triglycerides. On the other hand, low concentration t10c12-CLA specifically resulted in decreased circulating fibroblast growth factor 21, elevated glucose and high-density lipoprotein, whereas high concentration t10c12-CLA specifically increased circulating and hepatic cholesterol levels via up-regulation of low-density lipoprotein receptor in the liver. In conclusion, high concentration t10c12-CLA enhances local lipid metabolism in WAT and leads to fat loss, whereas low concentration t10c12-CLA attenuates the enzymic activities in WAT and fails to reduce fat. T10c12-CLA can effectively and concentration independently improve steatosis by attenuating hepatic lipid metabolism. These results suggest that low concentration of t10c12-CLA is beneficial, but high concentration is unfavorable to obese male mammals.

Exploiting conjugated linoleic acid for health: a recent update

Conjugated linoleic acid (CLA) is widely used as a dietary supplement due to its reported benefits in enhancing immunity, regulating inflammation, treating obesity, and preventing cancer. However, there is a lack of comprehensive studies on its mechanisms and dose-effect relationships. Moreover, there are insufficient in-depth studies on CLA's new functions, safety, side effects, and clinical utility. This review systematically examines the structure and sources of CLA, summarizes its role in improving human health, and critically reviews the potential mechanisms behind these benefits. It also analyzes the side effects of CLA and addresses issues related to dosing and oxidative decomposition in CLA research. Additionally, the potential of using CLA-producing probiotics to manage diseases is explored. This review can guide and promote further research on CLA's functions and support the development of CLA dietary supplements. It will accelerate the development of CLA nutritional and medical foods, contribute to the improvement of human health, and have important social meaning and economic value.

The Combination of Resveratrol and Conjugated Linoleic Acid Dienes Enhances the Individual Effects of These Molecules on De Novo Fatty Acid Biosynthesis in 3T3-L1 Adipocytes

Consuming food containing ingredients with a documented impact on lipid metabolism can help fight overweight and obesity. The simplest way to reduce the level of fatty acids is to block their synthesis or increase the rate of their degradation. This study aimed to determine the effect of resveratrol, cis-9, trans-11 conjugated linoleic acid (CLA), trans-10, cis-12 CLA, and various variants of their combinations on de novo fatty acid biosynthesis in 3T3-L1 adipocytes. The influence of the above-mentioned bioactive substances on cells grown under standard conditions and after induction of oxidative stress was measured. The effect of the tested compounds on the expression of selected genes related to the de novo fatty acid biosynthesis process (Fasn, Acc1, Acly, Prkaa1, Prkaa2, Prkaca, Srebp1) was evaluated. As part of the conducted experiments, how the level of the corresponding mRNA translates into the content of selected proteins (acetyl-CoA carboxylase 1 (ACC) and fatty acid synthase (FASN) was studied. It was found that the inhibition of fatty acid biosynthesis processes was stronger in the case of the combination of the tested CLA isomers (cis-9, trans-11 CLA, trans-10, cis-12 CLA) with resveratrol than in cases of their individual action.

Microvesicle-Shuttled microRNA-130b Activates the Hepatic Inflammation by Inhibiting Glucocorticoid-Receptor-Mediated Immunosuppression in High-Fat Diet-Induced Obese Mice

Metabolism-disorder-induced liver diseases have become increasingly prevalent worldwide and are clinically linked to obesity and type 2 diabetes. In addition, a large number of previous literature studies have indicated that plasma miR-130b is a promising biomarker for the early diagnosis and treatment of obesity. However, whether miRNA-130b that was positively correlated with obesity resulted in hepatic inflammation needs to be further studied. Therefore, the study aims to determine the effect of microvesicle-shuttled miRNA-130b (miR-130b-MV) on the hepatic inflammation and its potential mechanism in high-fat diet-induced obese mice. Three-week-old C57BL/6 mice were fed a high-fat diet for eight weeks. Then, the obese mice received tail vein injections of MV-packaged scrambled control microRNA (miR-SC-MV) or miR-130b-MV every other day for 10 days. Compared with the control group, the miR-130b-MV injection significantly reduced the body weight while increasing the ratio of liver wet weight to total body weight. In addition, the miR-130b-MV injection significantly activated the hepatic inflammation by increasing the expression of proinflammatory genes, although the plasma concentrations of IL-6 and TNF-α were only slightly increased. Furthermore, the miR-130b-MV injection significantly increased the hepatic miR-130b expression while significantly suppressing the protein expression and phosphorylation of GR, a potential target of miR-130b. Moreover, the miR-130b overexpression results in a decrease in the expression of endogenous GR protein and a decrease in the activity of the luciferase reporter of GR 3'-UTR. In addition, the miR-130b-MV injection significantly upregulated NF-kB (p50) in both the cytoplasm and nucleus, showing enhanced proinflammation response. The above results demonstrated that miR-130b-MV activated the hepatic inflammation by inhibiting GR-mediated immunosuppression in high-fat diet-induced obese mice, suggesting a novel mechanism underlying the obesity-induced hepatic inflammation, and the inhibition of miR-130b may serve as a new molecular therapeutic target for the prevention and treatment of hepatic inflammation.

Impact of Conjugated Linoleic Acid on Obesity and Its Association with Macrophage Recruitment: Experimental and Immunohistochemical Study

Background

Conjugated linoleic acid (CLA) has been shown in humans and animals to have anti-adipose effects. The current study aims to assess the prophylactic and therapeutic impact of CLA and its effect on recruited macrophage type using immunohistochemistry against CD68 and CD 163.

Materials and Methods

Forty adult male albino rats of local strain were included in the study and divided into control, CLA-supplemented, obese, CLA-prophylactic obese, and CLA-treated obese groups. Biopsies from visceral fat of the investigated groups were obtained and assessed for histopathological changes and immunohistochemical staining for CD68 and CD163.

Results

Obese group showed hypertrophied adipocytes and infiltration by inflammatory cells compared to other groups. The obese group showed a marked increase in the CD68 positivity compared with that in the control and CLA-supplemented groups. CLA-prophylactic and CLA-treated groups showed mild immune reaction with a significant decrease in CD68 positivity compared to the obese group. The obese group showed a significant decrease in the CD163 positivity compared with that in the control and CLA-supplemented groups.

Conclusions

Adipose tissue in obese is characterized by inflammation with more M1 than M2 macrophages. CLA could direct the recruited macrophages toward the anti-inflammatory subtype (M2) which encourages its beneficial effects in prophylaxis from obesity.

Digestive interaction between dietary nitrite and dairy products generates novel nitrated linolenic acid products

Nitrated fatty acids are important anti-inflammatory and protective lipids formed in the gastric compartment, with conjugated linoleic acid (rumenic acid, RA, 9Z,11E-18:2) being the primary substrate for lipid nitration. The recently reported identification of nitrated rumelenic acid (NO2-RLA) in human urine has led to hypothesize that rumelenic acid (RLA, 9Z,11E,15Z-18:3) from dairy fat is responsible for the formation of NO2-RLA. To evaluate the source and mechanism of NO2-RLA formation, 15N labeled standards of NO2-RLA were synthesized and characterized. Afterward, milk fat with different RA and RLA levels was administered to mice in the presence of nitrite, and the appearance of nitrated fatty acids in plasma and urine followed. We confirmed the formation of NO2-RLA and defined the main metabolites in plasma, urine, and tissues. In conclusion, RLA obtained from dairy products is the main substrate for forming this novel electrophilic lipid reported to be present in human urine.

Conjugated linoleic acid (CLA) reduces HFD-induced obesity by enhancing BAT thermogenesis and iWAT browning via the CD36-AMPK pathway

The antiobesity effect of conjugated linoleic acid (CLA) has been reported. However, the underlying mechanisms have not been fully clarified. Thus, this study aimed to investigate the effects of CLA on thermogenesis of interscapular brown adipose tissue (iBAT) and browning of inguinal subcutaneous white adipose tissue (iWAT) and explore the possible signaling pathway. The in vivo results showed that CLA enhanced the O2 consumption and heat production in HFD (high-fat diet)-fed female mice by roughly 38%. Meanwhile, CLA increased the average iBAT temperature by 2°C at the room temperature and cold exposure, respectively. Correspondingly, CLA caused 1.6- and 2.4-fold increases in the expression of UCP1 (uncoupling protein 1) of BAT and iWAT, respectively, suggesting the activated iBAT thermogenesis and iWAT browning in HFD-fed female mice. Meanwhile, CLA could promote the formation of brown and beige adipocytes in differentiated stromal vascular cells (SVCs) isolated from iBAT and iWAT (the expressions of UCP1 were promoted by about twofold changes). In possible mechanisms, CLA stimulated the expression of CD36 and the activation of the AMPK pathway in mice iBAT and iWAT as well as the differentiated SVCs. However, inhibition of CD36 and AMPK (adenosine 5'-monophosphate-activated protein kinase) abolished the promotive effects of CLA on brown and beige adipocytes formation. Hence, we showed that CLA reduced HFD-induced obesity through enhancing iBAT thermogenesis and iWAT browning via the  CD36-AMPK pathway.

Conjugated Linoleic Acid Reduces Lipid Accumulation via Down-regulation Expression of Lipogenic Genes and Up-regulation of Apoptotic Genes in Grass Carp (Ctenopharyngodon idella) Adipocyte In Vitro

The relationship between conjugated linoleic acid (CLA) and lipogenesis has been extensively studied in mammals and some cell lines, but it is relatively rare in fish, and the potential mechanism of action of CLA reducing fat mass remains unclear. The established primary culture model for studying lipogenesis in grass carp (Ctenopharyngodon idella) preadipocytes was used in the present study, and the objective was to explore the effects of CLA on intracellular lipid and TG content, fatty acid composition, and mRNA levels of adipogenesis transcription factors, lipase, and apoptosis genes in grass carp adipocytes in vitro. The results showed that CLA reduced the size of adipocyte and lipid droplet and decreased the content of intracellular lipid and TG, which was accompanied by a significant down-regulation of mRNA abundance in transcriptional regulators including peroxisome proliferator-activated receptor (PPAR) γ, CCAAT/enhancer-binding protein (C/EBP) α, sterol regulatory element-binding protein (SREBP) 1c, lipase genes including fatty acid synthase (FAS), acetyl-CoA carboxylase (ACC), lipoprotein lipase (LPL). Meanwhile, it decreased the content of saturated fatty acids (SFAs) and n - 6 polyunsaturated fatty acid (n-6 PUFA) and increased the content of monounsaturated fatty acid (MUFA) and n - 3 polyunsaturated fatty acid (n-3 PUFA) in primary grass carp adipocyte. In addition, CLA induced adipocyte apoptosis through downregulated anti-apoptotic gene B-cell CLL/lymphoma 2 (Bcl-2) mRNA level and up-regulated pro-apoptotic genes tumor necrosis factor-α (TNF-α), Bcl-2-associated X protein (Bax), Caspase-3, and Caspase-9 mRNA level in a dose-dependent manner. These findings suggest that CLA can act on grass carp adipocytes through various pathways, including decreasing adipocyte size, altering fatty acid composition, inhibiting adipocyte differentiation, promoting adipocyte apoptosis, and ultimately decreasing lipid accumulation.

Transgenic mice producing the trans 10, cis 12-conjugated linoleic acid present reduced adiposity and increased thermogenesis and fibroblast growth factor 21 (FGF21)

Trans 10, cis 12-conjugated linoleic acid (t10c12-CLA) from ruminant-derived foodstuffs can induce body fat loss after oral administration. In the current study, a transgenic mouse that produced t10c12-CLA had been generated by inserting the Propionibacterium acnes isomerase (Pai) expression cassette into the Rosa26 locus, and its male offspring were used to elucidate the enduring influence of t10c12-CLA on overall health. Compared to their wild-type (wt) C57BL/6J littermates, both biallelic Pai/Pai and monoallelic Pai/wt mice exhibited reduced plasma triglycerides levels, and Pai/wt mice exclusively showed increased serum fibroblast growth factor 21. Further analysis of Pai/Pai mice found a decrease in white fat and an increase in brown fat, with more heat release and less physical activity. Analysis of Pai/Pai brown adipose tissues revealed that hyperthermia was associated with the over-expression of carnitine palmitoyltransferase 1B, uncoupling proteins 1 and 2. These findings suggest that the systemic and long-term impact of t10c12-CLA on obesity might be mediated through the pathway of fibroblast growth factor 21 when low doses are administered or through enhanced thermogenesis of brown adipose tissues when high doses are employed.

Conjugated linoleic acid (CLA) as a functional food: Is it beneficial or not?

Conjugated linoleic acid (CLA) has attracted great attention in recent years as a popular class of functional food that is broadly used. It refers to a group of geometric and positional isomers of linoleic acid (LA) with a conjugated double bond. The main natural sources of CLA are dairy products, beef and lamb, whereas only trace amounts occur naturally in plant lipids. CLA has been shown to improve various health issues, having effects on obesity, inflammatory, anti-carcinogenicity, atherogenicity, immunomodulation, and osteosynthesis. Also, compared to studies on humans, many animal researches reveal more positive benefits on health. CLA represents a nutritional avenue to improve lifestyle diseases and metabolic syndrome. Most of these effects are attributed to the two major CLA isomers [conjugated linoleic acid cis-9,trans-11 isomer (c9,t11), and conjugated linoleic acid trans-10,cis-12 isomer (t10,c12)], and their mixture (CLA mix). In contrast, adverse effects of CLA have been also reported, such as glucose homeostasis, insulin resistance, hepatic steatosis and induction of colon carcinogenesis in humans, as well as milk fat inhibition in ruminants, lowering chicken productivity, influencing egg quality and altering growth performance in fish. This review article aims to discuss the health benefits of CLA as a nutraceutical supplement and highlight the possible mechanisms of action that may contribute to its outcome. It also outlines the feasible adverse effects of CLA besides summarizing the recent peer-reviewed publications on CLA to ensure its efficacy and safety for proper application in humans.

Dietary fatty acids activate or deactivate brown and beige fat

Brown adipose tissue (BAT) and beige fat have been documented to rapidly consume fatty acids (FAs) rather than deposit of lipid, and they have high capacity to dissipate energy via nonshivering thermogenesis, making BAT and beige fat potential organs to fight obesity and related chronic diseases. As the main substrate for thermogenesis and the basic constituent unit of triacylglycerol, FAs could modify BAT and remodel white adipose tissue (WAT) to beige fat. However, there are few comprehensive review covering the link between dietary FAs and thermogenic adipocyte..In this review, we described the metabolism of thermogenic adipose upon activation and comprehensively summarized publications on the dietary FAs that activate or deactivate BAT and beige fat. Specifically, eicosapentaenoic acid/docosahexaenoic acid (EPA/DHA), α-linolenic acid (α-ALA), conjugated linoleic acid (CLA), oleic acid (OA), long-chain saturated fatty acid (LC-SFA) and medium-chain fatty acid (MCFA). in addition, the influences on BAT function, WAT remodeling, and lipid metabolism, as well as delineated the possible mechanisms are also reviewed. Characterizing thermogenic or obesogenic dietary FAs may offer novel insight into dietary oil and nutritional treatment.

Conjugated Linoleic Acid-Mediated Connexin-43 Remodeling and Sudden Arrhythmic Death in Myocardial Infarction

Connexin 43 (Cx43) is expressed in the left and right ventricles and is primarily responsible for conducting physiological responses in microvasculature. Studies have demonstrated that NADPH oxidase (NOX) enzymes are essential in cardiac redox biology and are responsible for the generation of reactive oxygen species (ROS). NOX2 is linked to left ventricular remodeling following myocardial infarction (MI). It was hypothesized that conjugated linoleic acid (cLA) treatment increases NOX-2 levels in heart tissue and disrupts connexins between the myocytes in the ventricle. Data herein demonstrate that cLA treatment significantly decreases survival in a murine model of MI. The observance of cLA-induced ventricular tachyarrhythmia's (VT) led to the subsequent investigation of the underlying mechanism in this MI model. Mice were treated with cLA for 12 h, 24 h, 48 h, or 72 h to determine possible time-dependent changes in NOX and Cx43 signaling pathways in isolated left ventricles (LV) extracted from cardiac tissue. The results suggest that ROS generation, through the stimulation of NOX2 in the LV, triggers a decrease in Cx43 levels, causing dysfunction of the gap junctions following treatment with cLA. This cascade of events may initiate VT and subsequent death during MI. Taken together, individuals at risk of MI should use caution regarding cLA consumption.

Browning of the white adipose tissue regulation: new insights into nutritional and metabolic relevance in health and diseases

Adipose tissues are dynamic tissues that play crucial physiological roles in maintaining health and homeostasis. Although white adipose tissue and brown adipose tissue are currently considered key endocrine organs, they differ functionally and morphologically. The existence of the beige or brite adipocytes, cells displaying intermediary characteristics between white and brown adipocytes, illustrates the plastic nature of the adipose tissue. These cells are generated through white adipose tissue browning, a process associated with augmented non-shivering thermogenesis and metabolic capacity. This process involves the upregulation of the uncoupling protein 1, a molecule that uncouples the respiratory chain from Adenosine triphosphate synthesis, producing heat. β-3 adrenergic receptor system is one important mediator of white adipose tissue browning, during cold exposure. Surprisingly, hyperthermia may also induce beige activation and white adipose tissue beiging. Physical exercising copes with increased levels of specific molecules, including Beta-Aminoisobutyric acid, irisin, and Fibroblast growth factor 21 (FGF21), which induce adipose tissue browning. FGF21 is a stress-responsive hormone that interacts with beta-klotho. The central roles played by hormones in the browning process highlight the relevance of the individual lifestyle, including circadian rhythm and diet. Circadian rhythm involves the sleep-wake cycle and is regulated by melatonin, a hormone associated with UCP1 level upregulation. In contrast to the pro-inflammatory and adipose tissue disrupting effects of the western diet, specific food items, including capsaicin and n-3 polyunsaturated fatty acids, and dietary interventions such as calorie restriction and intermittent fasting, favor white adipose tissue browning and metabolic efficiency. The intestinal microbiome has also been pictured as a key factor in regulating white tissue browning, as it modulates bile acid levels, important molecules for the thermogenic program activation. During embryogenesis, in which adipose tissue formation is affected by Bone morphogenetic proteins that regulate gene expression, the stimuli herein discussed influence an orchestra of gene expression regulators, including a plethora of transcription factors, and chromatin remodeling enzymes, and non-coding RNAs. Considering the detrimental effects of adipose tissue browning and the disparities between adipose tissue characteristics in mice and humans, further efforts will benefit a better understanding of adipose tissue plasticity biology and its applicability to managing the overwhelming burden of several chronic diseases.

Differential Inflammatory Responses in Cultured Endothelial Cells Exposed to Two Conjugated Linoleic Acids (CLAs) under a Pro-Inflammatory Condition

Conjugated linoleic acid (CLA) isomers have been shown to possess anti-atherosclerotic properties, which may be related to the downregulation of inflammatory pathways in different cell types, including endothelial cells (ECs). However, whether different CLA isomers have different actions is not entirely clear, with inconsistent reports to date. Furthermore, in cell culture studies, CLAs have often been used at fairly high concentrations. Whether lower concentrations of CLAs are able to affect EC responses is not clear. The aim of this study was to evaluate the effects of two CLAs (cis-9, trans-11 (CLA9,11) and trans-10, cis-12 (CLA10,12)) on the inflammatory responses of ECs. ECs (EA.hy926 cells) were cultured under standard conditions and exposed to CLAs (1 to 50 μM) for 48 h. Then, the cells were cultured for a further 6 or 24 h with tumour necrosis factor alpha (TNF-α, 1 ng/mL) as an inflammatory stimulant. ECs remained viable after treatments with 1 and 10 μM of each CLA, but not after treatment with 50 μM of CLA10,12. CLAs were incorporated into ECs in a concentration-dependent manner. CLA10,12 increased the levels of ICAM-1, IL-6, and RANTES in the culture medium, while CLA9,11 had null effects. Both CLAs (1 μM) decreased the appearance of NFκB1 mRNA, but only CLA9,11 maintained this downregulation at 10 μM. CLA10,12 had no effect on THP-1 cell adhesion to ECs while significantly decreasing the percentage of ECs expressing ICAM-1 and also levels of ICAM-1 expression per cell when used at 10 µM. Although CLA9,11 did not have any effect on ICAM-1 cell surface expression, it reduced THP-1 cell adhesion to the EA.hy926 cell monolayer at both concentrations. In summary, CLA10,12 showed some pro-inflammatory effects, while CLA9,11 exhibited null or anti-inflammatory effects. The results suggest that each CLA has different effects in ECs under a pro-inflammatory condition, highlighting the need to evaluate the effects of CLA isomers independently.

Dietary Conjugated Linoleic Acid Reduces Body Weight and Fat in Snord116m+/p- and Snord116m-/p- Mouse Models of Prader-Willi Syndrome

Prader–Willi Syndrome (PWS) is a human genetic condition that affects up to 1 in 10,000 live births. Affected infants present with hypotonia and developmental delay. Hyperphagia and increasing body weight follow unless drastic calorie restriction is initiated. Recently, our laboratory showed that one of the genes in the deleted locus causative for PWS, Snord116, maintains increased expression of hypothalamic Nhlh2, a basic helix–loop–helix transcription factor. We have previously also shown that obese mice with a deletion of Nhlh2 respond to a conjugated linoleic acid (CLA) diet with weight and fat loss. In this study, we investigated whether mice with a paternal deletion of Snord116 (Snord116^m+/p−) would respond similarly. We found that while Snord116^m+/p− mice and mice with a deletion of both Snord116 alleles were not significantly obese on a high-fat diet, they did lose body weight and fat on a high-fat/CLA diet, suggesting that the genotype did not interfere with CLA actions. There were no changes in food intake or metabolic rate, and only moderate differences in exercise performance. RNA-seq and microbiome analyses identified hypothalamic mRNAs, and differentially populated gut bacteria, that support future mechanistic analyses. CLA may be useful as a food additive to reduce obesity in humans with PWS.

Withaferin A Promotes White Adipose Browning and Prevents Obesity Through Sympathetic Nerve-Activated Prdm16-FATP1 Axis

The increasing prevalence of obesity has resulted in demands for the development of new effective strategies for obesity treatment. Withaferin A (WA) shows a great potential for prevention of obesity by sensitizing leptin signaling in the hypothalamus. However, the mechanism underlying the weight- and adiposity-reducing effects of WA remains to be elucidated. In this study, we report that WA treatment induced white adipose tissue (WAT) browning, elevated energy expenditure, decreased respiratory exchange ratio, and prevented high-fat diet-induced obesity. The sympathetic chemical denervation dampened the WAT browning and also impeded the reduction of adiposity in WA-treated mice. WA markedly upregulated the levels of Prdm16 and FATP1 (Slc27a1) in the inguinal WAT (iWAT), and this was blocked by sympathetic denervation. Prdm16 or FATP1 knockdown in iWAT abrogated the WAT browning-inducing effects of WA and restored the weight gain and adiposity in WA-treated mice. Together, these findings suggest that WA induces WAT browning through the sympathetic nerve-adipose axis, and the adipocytic Prdm16-FATP1 pathway mediates the promotive effects of WA on white adipose browning.

Food phenolics stimulate adipocyte browning via regulating gut microecology

Fat browning has piqued the interest of researchers as a potential target for treating obesity and related metabolic disorders. Recruitment of brown adipocytes leads to enhanced energy dissipation and reduced adiposity, thus facilitating the maintenance of metabolic homeostasis. Evidence is increasing to support the crucial roles of polyphenols and gut microecology in turning fat "brown". However, it is not clear whether the intestinal microecology is involved in polyphenol-mediated regulation of adipose browning, so this concept is worthy of exploration. In this review, we summarize the current knowledge, mostly from studies with murine models, supporting the concept that the effects of food phenolics on brown fat activation and white fat browning can be attributed to their regulatory actions on gut microecology, including microbial community profile, gut metabolites, and gut-derived hormones. Furthermore, the potential underlying pathways involved are also discussed. Basically, understanding gut microecology paves the way to determine the underlying roles and mechanisms of food phenolics in adipose browning.

Nutritional Regulation of Human Brown Adipose Tissue

The recent identification of brown adipose tissue in adult humans offers a new strategy to increase energy expenditure to treat obesity and associated metabolic disease. While white adipose tissue (WAT) is primarily for energy storage, brown adipose tissue (BAT) is a thermogenic organ that increases energy expenditure to generate heat. BAT is activated upon cold exposure and improves insulin sensitivity and lipid clearance, highlighting its beneficial role in metabolic health in humans. This review provides an overview of BAT physiology in conditions of overnutrition (obesity and associated metabolic disease), undernutrition and in conditions of altered fat distribution such as lipodystrophy. We review the impact of exercise, dietary macronutrients and bioactive compounds on BAT activity. Finally, we discuss the therapeutic potential of dietary manipulations or supplementation to increase energy expenditure and BAT thermogenesis. We conclude that chronic nutritional interventions may represent a useful nonpharmacological means to enhance BAT mass and activity to aid weight loss and/or improve metabolic health.

Supplementing conjugated linoleic acid (CLA) in breeder hens diet increased CLA incorporation in liver and alters hepatic lipid metabolism in chick offspring

This experiment was designed to investigate the effect of supplementing conjugated linoleic acid (CLA) in breeder hens diet on development and hepatic lipid metabolism of chick offspring. Hy-Line Brown breeder hens were allocated into two groups, supplemented with 0 (CT) or 0.5% CLA for 8 weeks. Offspring chicks were grouped according to the mother generation and fed for 7 days. CLA treatment had no significant influence on development, egg quality, and fertility of breeder hens, but darkened the egg yolks in shade and increased yolk sac mass compared to CT group. Addition of CLA resulted in increased body mass and liver mass, and decreased deposition of subcutaneous adipose tissue in chick offspring. The serum triglyceride (TG) and cholesterol (TC) levels of chick offspring were decreased in CLA group. CLA treatment increased the incorporation of both CLA isomers (c9t11 and t10c12) in liver of chick offspring, accompanied by the decreased hepatic TG levels, related to the significant reduction of fatty acid synthase (FAS) and acetyl-CoA carboxylase (ACC) enzyme activities and the increased of carnitine palmitoyltransferase-1 (CPT1) enzyme activity. Meanwhile, CLA treatment reduced the mRNA expression of genes related to fatty acid biosynthesis (FAS, ACC, and sterol regulatory element-binding protein-1c), and induced the expression of genes related to β-oxidative (CPT1, AMP-activated protein kinase, and peroxisome proliferator-activated receptor α) in chick offspring liver. In summary, the addition of CLA in breeder hens diet significantly increased incorporation of CLA in liver of chick offspring, which further regulate hepatic lipid metabolism.

Dietary conjugated linoleic acid supplementation alters skeletal muscle mitochondria and antioxidant status in young horses

Conjugated linoleic acid (CLA) improves oxidative stress and mitochondrial biogenesis in various species but has not been thoroughly investigated in horses. We collected blood and muscle samples from lightly exercising horses before and 6 and 12 wk after receiving either soybean oil (CON; n = 5) or CLA (CLA; n = 5) supplementation. Samples were analyzed for markers of mitochondrial characteristics, antioxidant status, oxidative stress, and muscle damage. Data were analyzed using a linear model with repeated measures. In the triceps brachii (TB), citrate synthase (CS) activity was higher in CON than CLA horses (P = 0.003) but was unaffected by diet in the gluteus medius (GM). Integrative (relative to mg protein) cytochrome c oxidase (CCO) activity was higher in TB than the GM (P < 0.0001), while intrinsic (relative to CS) CCO was lower in the TB than the GM (P = 0.02) and tended to be lower in CON than CLA horses (P = 0.06). Neither CS nor integrative CCO activities were affected by time. In the GM, superoxide dismutase activity tended to increase in CON through week 12 (P = 0.10). Over both muscle groups, glutathione peroxidase activity tended to be higher in CON compared with CLA at week 12 (P = 0.06). Malondialdehyde was higher in the TB than the GM (P = 0.0004) but was unaffected by diet, while serum creatine kinase activity tended to be lower in CLA than CON horses (P = 0.07). These results suggest that CLA supplementation may lead to mitochondrial adaptations and prevent myofiber perturbation in skeletal muscle of young, lightly exercised horses.

Grape pomace extract supplementation activates FNDC5/irisin in muscle and promotes white adipose browning in rats fed a high-fat diet

Irisin is a myokine regulated by peroxisome proliferator-activated receptor gamma co-activator-1α (PGC-1α) in the exercising skeletal muscle and released into the bloodstream after cleavage of FNDC5. Circulating irisin can up-regulate UCP-1 expression in white adipose tissue (WAT) promoting the formation of brown-like adipocytes. The aim of this study was to evaluate if supplementation with a grape pomace extract (GPE) could activate the FNDC5/irisin pathway via PGC-1α in rats fed a high fat diet (HFD). For this purpose we characterized the activation of: i. the FNDC5/irisin pathway and AMPK in skeletal muscle and ii. proteins involved in the formation of brown-like cells in epididymal WAT (eWAT). Consumption of the GPE activated the FNDC5/irisin pathway, increased AMPK phosphorylation in skeletal muscle and enhanced irisin plasma levels. In eWAT, the GPE increased the level of proteins involved in WAT browning, i.e. PGC-1α, PPARγ, PRDM16 and UCP-1. The GPE also prevented HFD-induced adipocyte hypertrophy and systemic insulin resistance. Consistently, in L6 myotubes, (-)-epicatechin (EC), a flavonoid abundant in the GPE, prevented palmitate-mediated downregulation of FNDC5/irisin protein expression and secretion, in part via PGC-1α activation. Consumption of the GPE, a winemaking residue rich in bioactive compounds, could be a beneficial strategy to counteract the adverse effects of Western style diets through the promotion of WAT browning.

Current Evidence to Propose Different Food Supplements for Weight Loss: A Comprehensive Review

The use of food supplements for weight loss purposes has rapidly gained popularity as the prevalence of obesity increases. Navigating through the vast, often low quality, literature available is challenging, as is providing informed advice to those asking for it. Herein, we provide a comprehensive literature revision focusing on most currently marketed dietary supplements claimed to favor weight loss, classifying them by their purported mechanism of action. We conclude by proposing a combination of supplements most supported by current evidence, that leverages all mechanisms of action possibly leading to a synergistic effect and greater weight loss in the foreseen absence of adverse events. Further studies will be needed to confirm the weight loss and metabolic improvement that may be obtained through the use of the proposed combination.

Meat of South American camelids - Sensory quality and nutritional composition

Meat contains a range of nutrients in a highly bioavailable form and when meat is excluded from the diet, without being replaced with suitable alternatives, nutrient deficiencies may occur. For this reason, it is very important to extend our knowledge of nutrients in alternative red meats, such as that provided from the South American camelids- llama and alpaca. This review summarises the current information on the nutritional and sensory parameters of llama and alpaca meat and factors affecting quality. South American camelids produce lean carcases, with an uneven fat distribution across the carcase. Llama and alpaca meat quality traits are mostly influenced by animal nutrition, animal age and processing methods. A feeding strategy based on pasture and hay supplement of barley and alfalfa, and processing younger animals (18 months) has improved the fatty acid composition respectively in llama and alpaca meat, whereas meat colour and tenderness are influenced by processing treatments including electrical stimulation, tenderstretching and enzymatic infusion.

Alpha-Linolenic Acid-Enriched Butter Promotes Fatty Acid Remodeling and Thermogenic Activation in the Brown Adipose Tissue

Supplementation with n-3 long-chain (LC) polyunsaturated fatty acids (PUFA) is known to promote thermogenesis via the activation of brown adipose tissue (BAT). Agricultural products that are biofortified with α-linolenic acid (ALA), the precursor of n-3 LC PUFA, have been launched to the market, but their impact on BAT function is unknown. This study aimed to evaluate the effects of ALA-biofortified butter on lipid metabolism and thermogenic functions in the BAT. C57BL/6 mice were fed a high-fat diet containing ALA-biofortified butter (n3Bu, 45% calorie from fat) for ten weeks in comparison with the isocaloric high-fat diets prepared from conventional butter or margarine. The intake of n3Bu significantly reduced the whitening of BAT and increased the thermogenesis in response to acute-cold treatment. Also, n3Bu supplementation is linked with the remodeling of BAT by promoting bioconversion into n-3 LC PUFA, FA elongation and desaturation, and mitochondrial biogenesis. Taken together, our results support that ALA-biofortified butter is a novel source of n-3 PUFA, which potentiates the BAT thermogenic function.

Maternal conjugated linoleic acid alters hepatic lipid metabolism via the AMPK signaling pathway in chick embryos

The effects of maternal conjugated linoleic acid (CLA) on embryonic development and hepatic lipid metabolism were investigated in chick embryos. A total of 180 Arbor Acres female broiler breeders (36 wk old) were randomly divided into the following 3 dietary treatment groups: a basic diet (control), a basic diet containing 0.5% CLA (CLA1), and a basic diet containing 1.0% CLA (CLA2). The females were fed for 8 wk, and the eggs from each group were collected and hatched during the last 2 wk. The results showed that the addition of dietary CLA increased the broken egg rate and reduced the fertilization rate and the egg hatchability (P < 0.05). CLA enrichment decreased the polyunsaturated and monounsaturated fatty acids and increased the saturated fatty acids in the yolk sac (P < 0.05). The yolk sac weight, body weight, and body length had a linear decrease with CLA supplementation (P < 0.05). In the developing chick embryo (at E14) and newly hatched chick (D0), the serum triglyceride concentration decreased with maternal CLA supplementation and was accompanied by a reduction in subcutaneous adipose tissue deposition. In addition, maternal CLA supplementation mediated the hepatic lipid metabolism by decreasing the mRNA expression of sterol regulatory element-binding proteins-1c (SREBP-1c), fatty acid synthase and acetyl-CoA carboxylase, and increasing the mRNA expression of adenosine 5'-monophosphate-activated protein kinase α (AMPKα), peroxisome proliferator-activated receptors α (PPARα), liver fatty acid-binding protein, adipose triglyceride lipase and carnitine palmitoyltransferase in embryonic chick livers (P < 0.05). A drop in SREBP-1c protein expression and an increase in the protein expression of p-AMPKα and PPARα were also observed in the liver of chick embryo (P < 0.05). In conclusion, maternal CLA supplementation regulated the fatty acid composition in the yolk sac, and mediated embryonic chick development and hepatic lipometabolism, and these effects may be related to the AMPK pathway. These findings suggest the potential ability of maternal CLA supplementation to reduce fat deposition in chick embryos.

Uncovering the Role of p38 Family Members in Adipose Tissue Physiology

The complex functions of adipose tissue have been a focus of research interest over the past twenty years. Adipose tissue is not only the main energy storage depot, but also one of the largest endocrine organs in the body and carries out crucial metabolic functions. Moreover, brown and beige adipose depots are major sites of energy expenditure through the activation of adaptive, non-shivering thermogenesis. In recent years, numerous signaling molecules and pathways have emerged as critical regulators of adipose tissue, in both homeostasis and obesity-related disease. Among the best characterized are members of the p38 kinase family. The activity of these kinases has emerged as a key contributor to the biology of the white and brown adipose tissues, and their modulation could provide new therapeutic approaches against obesity. Here, we give an overview of the roles of the distinct p38 family members in adipose tissue, focusing on their actions in adipogenesis, thermogenic activity, and secretory function.

Milagro F, Sánchez J, de la Garza AL, Castro H. 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.

Eighteen‑carbon trans fatty acids and inflammation in the context of atherosclerosis

Endothelial dysfunction is a pro-inflammatory state characterized by chronic activation of the endothelium, which leads to atherosclerosis and cardiovascular disease (CVD). Intake of trans fatty acids (TFAs) is associated with an increased risk of CVD. This risk is usually associated with industrial TFAs (iTFAs) rather than ruminant TFAs (rTFAs); however it is not clear how specific TFA isomers differ in their biological activity and mechanisms of action with regard to inflammation. Here we review the literature on 18‑carbon TFAs, including the research associating their intake or levels with CVD and studies relating 18‑carbon TFA exposure to modulation of inflammatory processes. The evidence associating iTFAs with CVD risk factors is fairly consistent and studies in humans usually show a relation between iTFAs and higher levels of inflammatory markers. In contrast, studies in humans, animals and in vitro suggest that rTFAs have null or mildly beneficial effects in cardiovascular health, metabolic parameters and inflammatory markers, although the evidence is not always consistent. More studies are needed to better identify the beneficial and detrimental effects of the different TFAs, including those with 18 carbons.

Systematic review of factors associated with energy expenditure in the critically ill

BACKGROUND AND AIMS

Indirect calorimetry is the reference standard for energy expenditure measurement. Predictive formulae that replace it are inaccurate. Our aim was to review the patient and clinical factors associated with energy expenditure in critically ill patients.

METHODS

We conducted a systematic review of the literature. Eligible studies were those reporting an evaluation of factors and energy expenditure. Energy expenditure and factor associations with p-values were extracted from each study, and each factor was classified as either significantly, indeterminantly, or not associated with energy expenditure. Regression coefficients were summarized as measures of central tendency and spread. Metanalysis was performed on correlations.

RESULTS

The search strategy yielded 8521 unique articles, 307 underwent full text review, and 103 articles were included. Most studies were in adults. There were 95 factors with 352 evaluations. Minute volume, weight, age, % body surface area burn, sedation, post burn day, and caloric intake were significantly associated with energy expenditure. Heart rate, fraction of inspired oxygen, respiratory rate, respiratory disease diagnosis, positive end expiratory pressure, intensive care unit days, C- reactive protein, and size were not associated with energy expenditure. Multiple factors (n = 37) were identified with an unclear relationship with energy expenditure and require further evaluation.

CONCLUSIONS

An important interval step in the development of accurate formulae for energy expenditure estimation is a better understanding of relationships between patient and clinical factors and energy expenditure. The review highlights the limitations of currently available data, and identifies important factors that are not included in current prediction formulae of the critically ill.

Small molecules for fat combustion: targeting obesity

Obesity is increasing in an alarming rate worldwide, which causes higher risks of some diseases, such as type 2 diabetes, cardiovascular diseases, and cancer. Current therapeutic approaches, either pancreatic lipase inhibitors or appetite suppressors, are generally of limited effectiveness. Brown adipose tissue (BAT) and beige cells dissipate fatty acids as heat to maintain body temperature, termed non-shivering thermogenesis; the activity and mass of BAT and beige cells are negatively correlated with overweight and obesity. The existence of BAT and beige cells in human adults provides an effective weight reduction therapy, a process likely to be amenable to pharmacological intervention. Herein, we combed through the physiology of thermogenesis and the role of BAT and beige cells in combating with obesity. We summarized the thermogenic regulators identified in the past decades, targeting G protein-coupled receptors, transient receptor potential channels, nuclear receptors and miscellaneous pathways. Advances in clinical trials were also presented. The main purpose of this review is to provide a comprehensive and up-to-date knowledge from the biological importance of thermogenesis in energy homeostasis to the representative thermogenic regulators for treating obesity. Thermogenic regulators might have a large potential for further investigations to be developed as lead compounds in fighting obesity.

Conjugated Linoleic Acid Effects on Cancer, Obesity, and Atherosclerosis: A Review of Pre-Clinical and Human Trials with Current Perspectives

Obesity and its comorbidities, including type 2 diabetes and cardiovascular disease, are straining our healthcare system, necessitating the development of novel strategies for weight loss. Lifestyle modifications, such as exercise and caloric restriction, have proven effective against obesity in the short term, yet obesity persists because of the high predilection for weight regain. Therefore, alternative approaches to achieve long term sustainable weight loss are urgently needed. Conjugated linoleic acid (CLA), a fatty acid found naturally in ruminant animal food products, has been identified as a potential anti-obesogenic agent, with substantial efficacy in mice, and modest efficacy in obese human populations. Originally described as an anti-carcinogenic fatty acid, in addition to its anti-obesogenic effects, CLA has now been shown to possess anti-atherosclerotic properties. This review summarizes the pre-clinical and human studies conducted using CLA to date, which collectively suggest that CLA has efficacy against cancer, obesity, and atherosclerosis. In addition, the potential mechanisms for the many integrative physiological effects of CLA supplementation will be discussed in detail, including an introduction to the gut microbiota as a potential mediator of CLA effects on obesity and atherosclerosis.

Grape pomace extract induced beige cells in white adipose tissue from rats and in 3T3-L1 adipocytes

This study investigated the effects of a grape pomace extract (GPE) rich in phenolic compounds on brown-like adipocyte induction and adiposity in spontaneously hypertensive (SHR) and control normotensive Wistar-Kyoto (WKY) rats fed a high-fat diet (HFD). HFD consumption for 10 weeks significantly increased epididymal white adipose tissue (eWAT) in WKY but not in SHR rats. Supplementation with GPE (300 mg/kg body weight/day) reduced adipocyte diameter and increased levels of proteins that participate in adipogenesis and angiogenesis, i.e., peroxisome-proliferator activated receptor gamma (PPARγ), vascular endothelial grow factor-A (VEGF-A) and its receptor 2 (VEGF-R2), and partially increased the uncoupling protein 1 (UCP-1) in WKY. In both strains, GPE attenuated adipose inflammation. In eWAT from SHR, GPE increased the expression of proteins involved in adipose tissue "browning," i.e., PPARγ-coactivator-1α (PGC-1α), PPARγ, PR domain containing 16 (PRDM16) and UCP-1. In primary cultures of SHR adipocytes, GPE-induced UCP-1 up-regulation was dependent on p38 and ERK activation. Accordingly, in 3T3-L1 adipocytes treated with palmitate, the addition of GPE (30 μM) activated the β-adrenergic signaling cascade (PKA, AMPK, p38, ERK). This led to the associated up-regulation of proteins involved in mitochondrial biogenesis (PGC-1α, PPARγ, PRDM16 and UCP-1) and fatty acid oxidation (ATGL). These effects were similar to those exerted by (-)-epicatechin and quercetin, major phenolic compounds in GPE. Overall, in HFD-fed rats, supplementation with GPE promoted brown-like cell formation in eWAT and diminished adipose dysfunction. Thus, winemaking residues, rich in bioactive compounds, could be useful to mitigate the adverse effects of HFD-induced adipose dysfunction.

Implication of trans-11,trans-13 conjugated linoleic acid in the development of hepatic steatosis

SCOPE

Conjugated linoleic acids are linoleic acid isomers found in the diet that can also be produced through bacterial metabolism of polyunsaturated fatty acids. Our objective was to evaluate the contribution of fatty acid metabolites produced from polyunsaturated fatty acids by the gut microbiota in vivo to regulation of hepatic lipid metabolism and steatosis.

METHODS AND RESULTS

In mice with depleted n-3 polyunsaturated fatty acids, we observed an accumulation of trans-11,trans-13 CLA and cis-9,cis-11 conjugated linoleic acids in the liver tissue that were associated with an increased triglyceride content and expression of lipogenic genes. We used an in vitro model to evaluate the impact of these two conjugated linoleic acids on hepatic lipid metabolism. In HepG2 cells, we observed that only trans-11,trans-13 conjugated linoleic acids recapitulated triglyceride accumulation and increased lipogenic gene expression, which is a phenomenon that may implicate the nuclear factors sterol regulatory element binding protein 1c (SREBP-1c) and carbohydrate-responsive element-binding protein (ChREBP).

CONCLUSION

The trans-11,trans-13 conjugated linoleic acids can stimulate hepatic lipogenesis, which supports the conclusion that gut microbiota and related metabolites should be considered in the treatment of non-alcoholic liver disease.

Effects of Conjugated Linoleic Acid Supplementation on the Expression Profile of miRNAs in Porcine Adipose Tissue

Conjugated linoleic acids (CLAs) play a major role in adipocyte differentiation and lipid metabolism in animals. MicroRNAs (miRNAs) appear to be involved in many biological processes in adipose tissue. However, the specific influence on miRNAs by CLA supplementation in porcine adipose tissue remains unclear. Thus, we continuously added 1.5% CLA to the pig diet from the embryo stage to the finishing period and conducted a high-throughput sequencing approach to analyse the changes in adipose tissue miRNAs. We identified 283 known porcine miRNAs, and 14 miRNAs were differentially expressed in response to CLA treatment. A Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that the targets of the 14 differentially expressed miRNAs were involved in the Wnt signalling pathway. The CLA treatment downregulated the gene expression of PPARγ, C/EBPα, FAS, and FATP1 in both subcutaneous and abdominal fat tissues; the analysis showed that ssc-miR-21 expression was significantly correlated with PPARγ expression (p < 0.05), and speculated that ssc-miR-21 might influence adipogenesis through PPARγ. In conclusion, our study analysed the miRNA profiles in porcine adipose tissues by CLA treatment, and demonstrated that miRNAs are important regulators of fat lipogenesis. This study provides valuable information for the molecular regulatory mechanism of CLA on adipose tissue.

The Transcriptome of Estrogen-Independent Mammary Growth in Female Mice Reveals That Not All Mammary Glands Are Created Equally

Allometric growth of ducts in the mammary glands (MGs) is widely held to be estrogen dependent. We previously discovered that the dietary fatty acid trans-10, cis-12 conjugated linoleic acid (CLA) stimulates estrogen-independent allometric growth and terminal end bud formation in ovariectomized mice. Given the similar phenotype induced by estrogen and CLA, we investigated the shared and/or divergent mechanisms underlying these changes. We confirmed MG growth induced by CLA is temporally distinct from that elicited by estrogen. We then used RNA sequencing to compare the transcriptome of the MG during similar proliferative and morphological states. Both estrogen and CLA affected the genes involved in proliferation. The transcriptome for estrogen-treated mice included canonical estrogen-induced genes, including Pgr, Areg, and Foxa1. In contrast, their expression was unchanged by CLA. However, CLA, but not estrogen, altered expression of a unique set of inflammation-associated genes, consistent with stromal changes. This CLA-altered signature included increased expression of epidermal growth factor receptor (EGFR) pathway components, consistent with the demonstration that CLA-induced MG growth is EGFR dependent. Our findings highlight a unique role for diet-induced inflammation that underlies estrogen-independent MG development.

Foxc2 coordinates inflammation and browning of white adipose by leptin-STAT3-PRDM16 signal in mice

AIMS

The objective of this study is to characterize the relationship between forkhead box C2 protein (Foxc2) and leptin under adipose inflammatory response.

METHODS

Lipopolysaccharide (LPS)-induced inflammatory model was conducted. Data from wild-type and ob/ob mice were used to compare the alternative role of leptin on Foxc2-mediated inflammation and browning. Transcriptional regulation and protein-protein interaction were analyzed by bioinformatics and proved by chromatin immunoprecipitation and co-immunoprecipitation experiment.

RESULTS

Foxc2 and leptin correlated with inflammation and browning of white adipose tissue (WAT) in LPS-treated mice. Moreover, Foxc2-mediated inhibition of inflammation involved downstream activation of leptin signal and promoted WAT browning. We then determined CREB, the potential transcriptional factor of leptin, was required for Foxc2-mediated inflammation in the regulation of WAT browning. Foxc2 alleviated adipocyte inflammation by reducing leptin-mediated Janus-activated kinase 2/signal transducer and activator of transcription 3 (STAT3) pathway. Importantly, STAT3 physically interacted with PRDM16 and formed a complex to promote WAT browning. Exogenous Foxc2 overexpression also ameliorated inflammation and promoted adipose browning in high fat diet (HFD)-induced obese mice.

CONCLUSIONS

Our results indicated that Foxc2 inhibited inflammation and promoted browning of WAT through positive regulation of leptin signal and the STAT3-PRDM16 complex. These findings identify a new potential means to prevent and treat obese caused metabolic syndrome of mammals.

Nutrient Regulation: Conjugated Linoleic Acid's Inflammatory and Browning Properties in Adipose Tissue

Obesity is the most widespread nutritional disease in the United States. Developing effective and safe strategies to manage excess body weight is therefore of paramount importance. One potential strategy to reduce obesity is to consume conjugated linoleic acid (CLA) supplements containing isomers cis-9, trans-11 and trans-10, cis-12, or trans-10, cis-12 alone. Proposed antiobesity mechanisms of CLA include regulation of (a) adipogenesis, (b) lipid metabolism, (c) inflammation, (d) adipocyte apoptosis, (e) browning or beiging of adipose tissue, and (f) energy metabolism. However, causality of CLA-mediated responses to body fat loss, particularly the linkage between inflammation, thermogenesis, and energy metabolism, is unclear. This review examines whether CLA's antiobesity properties are due to inflammatory signaling and considers CLA's linkage with lipogenesis, lipolysis, thermogenesis, and browning of white and brown adipose tissue. We propose a series of questions and studies to interrogate the role of the sympathetic nervous system in mediating CLA's antiobesity properties.

The Combination of Green Tea Extract and Eriodictyol Inhibited High-Fat/High-Sucrose Diet-Induced Cholesterol Upregulation Is Accompanied by Suppression of Cholesterol Synthesis Enzymes

Western diets induce obesity associated with an increased risk of hypercholesterolaemia. Indeed, obesity-induced hypercholesterolaemia is correlated with increased coronary cardiovascular disease (CVD) risk. Male C57BL/6J mice were fed a normal diet, high-fat and high-sucrose diet (HF/HS), HF/HS with green tea extract powder diet (HF/HS+GT), HF/HS with eriodictyol diet (HF/HS+Eri), or HF/HS with green tea extract powder and eriodictyol diet (HF/HS+GT+Eri) for 8 wk. Body weight was lower in the HF/HS+GT+Eri group than in the HF/HS group (-8.3%, p<0.01). The HF/HS diet elicited an upregulation of total cholesterol levels (-63%, p<0.001), and low-density lipoprotein (LDL) levels (-89%, p<0.001) were significantly suppressed by the GT+Eri diet. Conversely, no change (p>0.05) was observed in the HF/HS+GT and HF/HS+Eri groups. The HF/HS diet-induced hepatic mRNA increase in 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR) was ameliorated (-73%) by the oral administration of green tea extract and eriodictyol. Moreover, the GT+Eri diet suppressed HF/HS diet-induced upregulation of 3-hydroxy-3-methylglutaryl-coenzyme A synthase (HMGCS) (-75%, p<0.05). Furthermore, the LDL receptor (LDLR) levels were higher in the HF/HS+GT+Eri group (+50%, p<0.05) than in the HF/HS group. These results suggest that a combination of green tea and eriodictyol decreases cholesterol levels, particularly LDL levels, accompanied by the suppression of HMGCR and HMGCS levels and upregulation of LDLR levels in the liver.