Enhancement Of Fatty Acid Oxidation Research Articles

Interleukin-38 alleviates hepatic steatosis through AMPK/autophagy-mediated suppression of endoplasmic reticulum stress in obesity models.

Interleukin-38(IL-38), recently recognized as a cytokine with anti-inflammatory properties that mitigate type 2 diabetes, has been associated with indicators of insulin resistance and nonalcoholic fatty liver disease (NAFLD). This study investigated the impact of IL-38 on hepatic lipid metabolism and endoplasmic reticulum (ER) stress. We assessed protein expression levels using Western blot analysis, while monodansylcadaverinestaining was employed to detect autophagosomes in hepatocytes. Oil red O staining was utilized to examine lipid deposition. The study revealed elevated serum IL-38 levels in high-fat diet (HFD)-fed mice and IL-38 secretion from mouse keratinocytes. IL-38 treatment attenuated lipogenic lipid accumulation and ER stress markers in hepatocytes exposed to palmitate. Furthermore, IL-38 treatment increased AMP-activated protein kinase (AMPK) phosphorylation and autophagy. The effects of IL-38 on lipogenic lipid deposition and ER stress were nullified in cultured hepatocytes by suppressing AMPK through small interfering (si) RNA or 3-methyladenine (3MA). In animal studies, IL-38 administration mitigated hepatic steatosis by suppressing the expression of lipogenic proteins and ER stress markers while reversing AMPK phosphorylation and autophagy markers in the livers of HFD-fed mice. Additionally, AMPK siRNA, but not 3MA, mitigated IL-38-enhanced fatty acid oxidation in hepatocytes. In summary, IL-38 alleviates hepatic steatosis through AMPK/autophagy signaling-dependent attenuation of ER stress and enhancement of fatty acid oxidation via the AMPK pathway, suggesting a therapeutic strategy for treating NAFLD.

Regulation of pericyte metabolic reprogramming restricts the AKI to CKD transition

Background and aimsAcute kidney injury (AKI) is associated with high morbidity and mortality and is recognized as a long-term risk factor for progression to chronic kidney disease (CKD). The AKI to CKD transition is characterized by interstitial fibrosis and the proliferation of collagen-secreting myofibroblasts. Pericytes are the major source of myofibroblasts in kidney fibrosis. However, the underlying mechanism of pericyte-myofibroblast transition (PMT) is still unclear. Here we investigated the role of metabolic reprogramming in PMT. MethodsUnilateral ischemia/reperfusion-induced AKI to CKD mouse model and TGF-β-treated pericyte-like cells were used to detect the levels of fatty acid oxidation (FAO) and glycolysis, and the critical signaling pathways during PMT under the treatment of drugs regulating metabolic reprogramming. ResultsPMT is characterized by a decrease in FAO and an increase in glycolysis. Enhancement of FAO by the peroxisome proliferator-activated receptor gamma coactivator-1α (PGC1α) activator ZLN-005 or suppression of glycolysis by the hexokinase 2 (HK2) inhibitor 2-DG can inhibit PMT, preventing the transition of AKI to CKD. Mechanistically, AMPK modulates various pathways involved in the metabolic switch from glycolysis to FAO. Specifically, the PGC1α-CPT1A pathway activates FAO, while inhibition of the HIF1α-HK2 pathway drives glycolysis inhibition. The modulations of these pathways by AMPK contribute to inhibiting PMT. ConclusionsMetabolic reprogramming controls the fate of pericyte transdifferentiation and targets the abnormal metabolism of pericytes can effectively prevent AKI to CKD transition.

Oncolytic avian reovirus σA‐modulated fatty acid metabolism through the PSMB6/Akt/SREBP1/acetyl-CoA carboxylase pathway to increase energy production for virus replication

We have demonstrated previously that the σA protein of avian reovirus (ARV) functions as an activator of cellular energy, which upregulates glycolysis and the TCA cycle for virus replication. To date, there is no report with respect to σA-modulated regulation of cellular fatty acid metabolism. This study reveals that the σA protein of ARV inhibits fatty acids synthesis and enhance fatty acid oxidation by upregulating PSMB6, which suppresses Akt, sterol regulatory element-binding protein 1 (SREBP1), acetyl-coA carboxylase α (ACC1), and acetyl-coA carboxylase β (ACC2). SREBP1 is a transcription factor involved in fatty acid and cholesterol biosynthesis. Overexpression of SREBP1 reversed σA-modulated suppression of ACC1 and ACC2. In this work, a fluorescence resonance energy transfer‐based genetically encoded indicator, Ateams, was used to study σA-modulated inhibition of fatty acids synthesis which enhances cellular ATP levels in Vero cells and human cancer cell lines (A549 and HeLa). By using Ateams, we demonstrated that σA-modulated inhibition of Akt, SREBP1, ACC1, and ACC2 leads to increased levels of ATP in mammalian and human cancer cells. Furthermore, knockdown of PSMB6 or overexpression of SREBP1 reversed σA-modulated increased levels of ATP in cells, indicating that PSMB6 and SREBP1 play important roles in ARV σA-modulated cellular fatty acid metabolism. Furthermore, we found that σA R155/273A mutant protein loses its ability to enter the nucleolus, which impairs its ability to regulate fatty acid metabolism and does not increase ATP formation, suggesting that nucleolus entry of σA is critical for regulating cellular fatty acid metabolism to generate more energy for virus replication. Collectively, this study provides novel insights into σA-modulated inhibition of fatty acid synthesis and enhancement of fatty acid oxidation to produce more energy for virus replication through the PSMB6/Akt/SREBP1/ACC pathway.

Chitosan oligosaccharide attenuates hepatic steatosis in HepG2 cells via the activation of AMP-activated protein kinase.

Chitosan oligosaccharides (COSs), oligomers of decomposed chitosan possess many biological functions including immunomodulatory, antitumor, and antiinflammation. The aim of this study was to investigate the protective effects of COS against free fatty acid (FFA)-induced cellular hepatic steatosis and underlying mechanisms in HepG2 cells. Results showed that COS significantly reduced the lipid contents and elevated the activities of antioxidant enzymes including total-superoxide dismutase, glutathione peroxidase, and catalase in FFA-stimulated HepG2 cells. COS phosphorylated the acetyl-CoA carboxylase and reduced both mRNA and protein levels of lipogenesis markers including fatty acid synthase and sterol regulatory element-binding protein 1c. COS also significantly increased the expression levels of fatty acid oxidation-related factors including carnitine palmitoyltransferase 1A, acyl-coenzyme A oxidase 1, and peroxisome proliferators-activated receptor α. Besides, COS markedly phosphorylated AMP-activated protein kinase (AMPK). The inhibition of lipogenesis and the enhancement of fatty acid oxidation induced by COS were all blocked by AMPK antagonist (compound C), showing that the attenuation of hepatic steatosis by COS was dependent on AMPK activation. In conclusion, COS attenuated hepatic steatosis via suppressing lipid synthesis and enhancing fatty acid oxidation. AMPK was also involved in the alleviation of hepatic steatosis by COS. These results indicated that COS might be used as a potential ingredient to ameliorate nonalcoholic fatty liver disease. PRACTICAL APPLICATIONS: Nonalcoholic fatty liver disease (NAFLD) has been regarded as pathological fat deposition in the liver, which includes a range of pathologies, from steatosis to steatohepatitis, fibrosis, and cellular carcinoma. Our findings demonstrated that Chitosan oligosaccharides (COS) attenuated steatosis via improving lipid metabolism. COS suppressed lipogenesis and also enhanced fatty acid oxidation. Besides, the underlying molecular mechanism whereby COS elicited these beneficial effects has also been proved to be through the modulation of upstream protein kinase, AMP-activated protein kinase. This study provides new knowledge to support that COS might be used as a food supplement for the prevention of NAFLD.

Macrophage HIF-2α suppresses NLRP3 inflammasome activation and alleviates insulin resistance.

The interrelation between hypoxia and immune response has pivotal roles in the pathogenesis of chronic metabolic diseases. However, the role of macrophage HIF-2α in NLRP3 inflammasome activation remains unclear. Here, we show that deficiency of HIF-2α in macrophages results in excessive activation of the NLRP3 inflammasome in a manner dependent on CPT1A-mediated enhancement of fatty acid oxidation (FAO). Mechanistically, HIF-2α binds directly to the Cpt1a promoter and is involved in the regulation of H3K27me3 methylation during NLRP3 inflammasome activation. Myeloid-specific Hif2α knockout mice exhibit exacerbated insulin resistance and increased activation of NLRP3 inflammasome in macrophages. Overexpression of the Hif2α gene or stabilization of the protein by FG-4592 ameliorates insulin resistance and reduces NLRP3 inflammasome activation in macrophages. Taken together, our results suggest that macrophage HIF-2α inhibits FAO-mediated activation of the NLRP3 inflammasome and alleviates insulin resistance.

CD38 Deficiency Protects Mice from High Fat Diet-Induced Nonalcoholic Fatty Liver Disease through Activating NAD+/Sirtuins Signaling Pathways-Mediated Inhibition of Lipid Accumulation and Oxidative Stress in Hepatocytes.

Nonalcoholic fatty liver disease (NAFLD) is characterized by excessive lipid accumulation in hepatocytes. CD38 was initially identified as a lymphocyte surface antigen and then has been found to exist in a variety of cell types. Our previous studies showed that CD38-/- mice were resistant to high-fat diet (HFD)-induced obesity. However, the role and mechanism of CD38 in HFD-induced NAFLD is still unclear. Here, we reported that CD38-/- mice significantly alleviated HFD-induced hepatic steatosis. HFD or oleic acid (OA) remarkably increased the mRNA and protein expressions of CD38 in mouse hepatic tissues and primary hepatocytes or hepatic cell lines in vitro and in vivo, suggesting that CD38 might play a role in HFD-induced hepatic steatosis. We observed that CD38 deficiency markedly decreased HFD- or OA-induced the lipid accumulation and oxidative stress in CD38-/- livers or primary hepatocytes, respectively. In contrast, overexpression of CD38 in Hep1-6 cells aggravated OA-induced lipid accumulation and oxidative stress. Furthermore, CD38 deficiency markedly inhibited HFD- or OA-induced the expressions of NOX4, and increased the expression of PPARα, CPT1, ACOX1 and SOD2 in liver tissue and hepatocytes from CD38-/- mice, indicating that CD38 deficiency-mediated the enhancement of fatty acid oxidation and the inhibition of oxidative stress contributed to protecting NAFLD. More importantly, Ex527 (Sirt1 inhibitor) and 3-TYP (Sirt3 inhibitor) significantly enhanced OA-induced lipid accumulation and oxidative stress in CD38-/- primary hepatocytes, suggesting that the anti-lipid accumulation of CD38 deficiency might be dependent on NAD/Sirtuins-mediated enhancement of FAA β-oxidation and suppression of oxidative stress in hepatocytes. In conclusion, we demonstrated that CD38 deficiency protected mice from HFD-induced NAFLD by reducing lipid accumulation and suppressing oxidative stress via activating NAD/Sirtuins signaling pathways.

Brain-Derived Neurotrophic Factor Improves Impaired Fatty Acid Oxidation Via the Activation of Adenosine Monophosphate-Activated Protein Kinase-ɑ - Proliferator-Activated Receptor-r Coactivator-1ɑ Signaling in Skeletal Muscle of Mice With Heart Failure.

We recently reported that treatment with rhBDNF (recombinant human brain-derived neurotrophic factor) improved the reduced exercise capacity of mice with heart failure (HF) after myocardial infarction (MI). Since BDNF is reported to enhance fatty acid oxidation, we herein conducted an in vivo investigation to determine whether the improvement in exercise capacity is due to the enhancement of the fatty acid oxidation of skeletal muscle via the AMPKα-PGC1α (adenosine monophosphate-activated protein kinase-ɑ-proliferator-activated receptor-r coactivator-1ɑ) axis. MI and sham operations were conducted in C57BL/6J mice. Two weeks postsurgery, we randomly divided the MI mice into groups treated with rhBDNF or vehicle for 2 weeks. AMPKα-PGC1α signaling and mitochondrial content in the skeletal muscle of the mice were evaluated by Western blotting and transmission electron microscopy. Fatty acid β-oxidation was examined by high-resolution respirometry using permeabilized muscle fiber. BDNF-knockout mice were treated with 5-aminoimidazole-4-carboxamide-1-beta-d-riboruranoside, an activator of AMPK. The rhBDNF treatment significantly increased the expressions of phosphorylated AMPKα and PGC1α protein and the intermyofibrillar mitochondrial density in the MI mice. The lowered skeletal muscle mitochondrial fatty acid oxidation was significantly improved in the rhBDNF-treated MI mice. The reduced exercise capacity and mitochondrial dysfunction of the BDNF-knockout mice were improved by 5-aminoimidazole-4-carboxamide-1-beta-d-riboruranoside. Beneficial effects of BDNF on the exercise capacity of mice with HF are mediated through an enhancement of fatty acid oxidation via the activation of AMPKα-PGC1α in skeletal muscle. BDNF may become a therapeutic option to improve exercise capacity as an alternative or adjunct to exercise training.

Abstract 6180: The role of radiation dose-dependent enhancement of fatty acid oxidation on radiation surviving/resistant lung cancer cells

Abstract Objective: Radiotherapy plays a critical role in the integrated management of lung cancer. However, radioresistance limits the long-term control. Exploring the dynamic changes of metabolic reprogramming in radiation surviving/resistance lung cancer cells is helpful to clarify the metabolic mechanism of radiation resistance and to develop new targets for intervention and early detection. Methods: Multiple lung cancer cell lines were irradiated with different doses (2Gy × 20F, 2Gy × 30F, 2Gy × 40F) in conventional dose fractionation. The cellular radiosensitivity was verified by colony formation assay and neutral comet assay. Cell proliferation ability was determined by EdU assay. Metabonomic analysis was used to identify the differentially expressed metabolites between high-dose radiation-resistant cells and their parent cells. Lipid droplet content was detected by Oil Red O staining. Cell oxygen consumption rate (OCR) was measured by Seahorse XF24e analyzer. Western blot was used to detect the expression of metabolic enzymes. The growth of xenograft tumors from these cell lines in BALB/c nude mice were measured after the treatment of radiation (2Gy × 5F), Etomoxir, or radiation combined with Etomoxir. Results: Compared with parent cells, the radioresitance of surviving/resistant lung cancer cells after different doses of radiation was significantly increased with the increase of radiation exposure. Oil Red O staining showed that fatty deposition of radiation surviving/resistant cells was obviously higher than their parent cells, and more fatty deposition in cells received higher dose of radiation. The ketone body metabolism-related substances, including acetoacetic acid, a metabolite of FAO, were significantly enriched in high-dose radiation-resistant lung cancer cells. The expression of carnitine palmitoyltransferase1 (CPT1) and the OCR in radiation surviving/resistant lung cancer cells were also radiation-dose dependently increased. Etomoxir, an inhibitor of fatty acid oxidation, significantly enhanced the radiosensitivity and decreased the OCR and DNA repair ability of various surviving/resistant lung cancer cells exposed to radiation. We further confirmed that Etomoxir could significantly inhibit proliferation of radiation surviving/resistant cells in vivo, which also presented with radiation-dose dependent model. Conclusions: The establishment of equidifferent dose radiation surviving/resistance lung cancer cell lines in this study provides a preclinical research model for exploring the mechanism of dose-dependent radiation resistance. The enhancement of radiation dose-dependent FAO promotes radiation surviving/resistance of lung cancer cells. CPT1A, a key metabolic enzyme mediating FAO, may be a potential target for treatment of radiation resistant lung cancer. Funding: 81972853, 81572279, 2016J004, LC2019ZD009, 2018CR033. Citation Format: Xiaoxia Zhu, Shangbiao Li, Lijuan Wang, Zhihao Zheng. The role of radiation dose-dependent enhancement of fatty acid oxidation on radiation surviving/resistant lung cancer cells [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 6180.

The role of radiation dose-dependent enhancement of fatty acid oxidation in radiation surviving/resistant lung cancer cells.

e21724 Background: Radiotherapy plays a critical role in the integrated management of lung cancer. However, radioresistance limits the long-term control. Exploring the dynamic changes of metabolic reprogramming in radiation surviving/resistant (S/R) lung cancer cells is helpful to clarify the metabolic mechanism of radiation resistance and to develop new targets for intervention and early detection. Methods: Cell lines were irradiated with different doses (2Gy × 20F, 2Gy × 30F, 2Gy × 40F) in conventional dose fractionation. The cellular radiosensitivity was verified by colony formation assay and neutral comet assay. Cell proliferation ability was determined by EdU assay. Metabonomic analysis was used to identify the differentially expressed metabolites between high-dose radiation-resistant cells and their parent cells. Lipid droplet content was detected by Oil Red O (ORO) staining. Cell oxygen consumption rate (OCR) was measured by Seahorse XF24e analyzer. Western blot was used to detect the expression of metabolic enzymes. The growth of xenograft tumors from these cell lines in BALB/c nude mice were measured after the treatment of radiation (2Gy×5F), Etomoxir, or radiation combined with Etomoxir. Results: Compared with parent cells, the radioresitance of S/R lung cancer cells after different doses of radiationwas significantly increased with the increase of radiation exposure. ORO staining showed that fatty deposition of radiation S/R cells was obviously higher than their parent cells, and more fatty deposition in cells received higher dose of radiation. The ketone body metabolism-related substances, including acetoacetic acid, a metabolite of FAO, were significantly enriched in high-dose radiation-resistant cells. The expression of carnitine palmitoyltransferase1 (CPT1) and the OCR in radiation S/R cells were also radiation-dose dependently increased. Etomoxir, an inhibitor of fatty acid oxidation, significantly enhanced the radiosensitivity and decreased the OCR and DNA repair ability of various S/R cells exposed to radiation. We further confirmed that Etomoxir could significantly inhibit proliferation of radiation S/R cells in vivo, which also presented with radiation-dose dependent model. Conclusions: The enhancement of radiation dose-dependent FAO promotes radiation surviving/resistance of lung cancer cells. CPT1A, a key metabolic enzyme mediating FAO, may be a potential target for treatment of radiation resistant lung cancer. Funding: 81972853, 81572279, 2016J004, LC2019ZD009, 2018CR033.

SUN-300 CHRONIC EXERCISE EXERTS RENOPROTECTIVE EFFECTS THROUGH ACTIVATION OF FATTY ACID OXIDATION IN THE KIDNEY OF FRUCTOSE-FED RATS

high-fructose (HFr) causes metabolic syndrome and renal lipid accumulation, leading to renal dysfunction. Long-term exercise (Ex) has beneficial effects against metabolic disorders, but the mechanisms have not been fully elucidated in the kidney. Present study investigated the effects of Ex on renal function and fatty acid (FA) metabolism in rats fed with HFr. Thirty-two, male Sprague-Dawley rats were fed with high-fructose or control diet (CON-Sed/HFr-Sed), and half of rats in each diet group underwent chronic treadmill exercise for 12 weeks (CON-Ex/HFr-Ex). Renal histology including glomerulosclerosis, interstitial fibrosis, podocytes injury were measured. expression of regulators in FA metabolism in the kidney were then assessed. HFr intake induced glomerulosclerosis, podocyte injury, interstitial fibrosis, and lipids accumulation in the kidney, and Ex significantly attenuated the renal histological changes in HFr-Ex group while the CON-Ex showed no changes. HFr intake increased the expression of proteins involved in FA synthesis, including FA synthase (FAS), acetyl-CoA carboxylase (ACC), and sterol regulatory element-binding protein 1c (SREBP-1c), while reducing the expression of genes involved in beta-oxidation, including very long, medium, and short-chain acyl-CoA dehydrogenase (VLCD, MCAD, and SCAD), acyl-CoA oxidase (ACOX), peroxisome proliferator-activated receptor (PPAR) alpha and PPARgamma coactivator-1α (PGC-1alpha) in the kidney. Ex decreased the expression of FAS and ACC in the HFr-Ex but increased the expression in CON-Ex. Ex increased the expression of VL/L/M/SCAD, carnitine palmitoyltransferase type I, ACOX, PPARalpha, and PGC-1alpha in both Ex groups. Ex exerts renoprotective effects with attenuation of renal histological pathogenesis and enhancement of FA oxidation.

Abstract 5212: Metabolic reprogramming of radiation fibrosis using adipose derived stromal cells

Abstract Background: Soft tissue radiation fibrosis (RF) affects up to 70% of cancer survivors post-radiotherapy. RF is an irreversible and progressive side effect of radiotherapy characterized by poor tissue elasticity and increased ECM deposition, clinically translating to increased morbidity due to hardening, distortion, and pain. Recent evidence has highlighted the potential role of metabolic alterations in the onset and progression of fibrosis. Adipose derived stromal cells (ADSCs) have been used effectively for enhancing complex wound repair in a number of clinical trials. The therapeutic effect of ADSCs has been attributed to its secretion of paracrine factors, which can regulate the metabolism of target cells. Even so, the metabolic effects of ADSCs on target cells is not well described. Methods and Results: Transcriptomic profiling and targeted metabolomics of human radiated tissue and a murine model of RF revealed that suppression of fatty acid oxidation (FAO) is hallmark of RF. TGF-B, a master regulator of fibrosis, has a large effect in suppressing FAO in primary human fibroblasts in vitro through downregulating genes in the PPAR pathway, a major regulatory pathway for FAO, and through inhibiting oxidation of the long chain fatty acid, palmitic acid (p<0.05, t-test). Treatment of TGF-B stimulated fibroblasts with ADSC conditioned media resulted in an improvement in FAO and a reduction in fibronectin, collagen-1, and PAI-1 protein levels, three of major contributors to fibrosis. Transplantation of ADSCs into murine RF resulted in a metabolic shift back to FAO and a significant reduction in RF both functionally (percentage leg contracture 36% vs 26%, 2-way ANOVA < 0.05) and histologically through image analysis of trichrome staining (p<0.01, t-test). Pathway analysis of significant genes altered by ADSCs revealed an upregulation of the PPAR pathway was the most significant effect of ADSC transplantation. Untargeted metabolomics confirmed that FAO metabolites were significantly upregulated with ADSC transplantation. To confirm the importance of metabolic regulation by ADSCs, we utilized a pharmacogenomics strategy to uncover a compound that mimicked the effect of ADSCs. Drug A ranked highest and replicated the anti-fibrotic and pro-FAO effects of ADSCs both on TGF-B stimulated primary fibroblasts and in murine RF. Etomoxir, a FAO inhibitor, inhibited the effect of ADSCs and Drug A in regulating protein levels of fibronectin and collagen, revealing that ADSCs and Drug A require an intact FAO pathway to exert their anti-fibrotic effects. Conclusions: Inhibition of FAO is a novel hallmark of RF. ADSC-mediated metabolic reprogramming resulted in an enhancement of FAO and a reduction in RF through upregulating the PPAR pathway. ADSC-directed pharmacogenomics uncovered Drug A, which mimicked the pro-FAO and anti-fibrotic effects of ADSCs. Our research has highlighted the importance of reversing metabolic aberrations to reduce RF. Citation Format: Xiao Zhao, Laleh Soltan Ghoraie, Pamela Psarianos, Kenneth Yip, Laurie Ailles, Benjamin Haibe-Kains, Fei-Fei Liu. Metabolic reprogramming of radiation fibrosis using adipose derived stromal cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5212. doi:10.1158/1538-7445.AM2017-5212

The AMP analog AICAR modulates the Treg/Th17 axis through enhancement of fatty acid oxidation.

T cells must tightly regulate their metabolic processes to cope with varying bioenergetic demands depending on their state of differentiation. The metabolic sensor AMPK is activated in states of low energy supply and modulates cellular metabolism toward a catabolic state. Although this enzyme is known to be particularly active in regulatory T (Treg) cells, its impact on T helper (Th)-cell differentiation is poorly understood. We investigated the impact of several AMPK activators on Treg-cell differentiation and found that the direct activator AICAR (5-aminoimidazole-4-carboxamide ribonucleotide), but not the indirect activators metformin and 2-deoxyglucose, strongly enhanced Treg-cell induction by specifically enhancing Treg-cell expansion. Conversely, Th17 generation was impaired by the agent. Further investigation of the metabolic background of our observations revealed that AICAR enhanced both cellular mitochondrogenesis and fatty acid uptake. Consistently, increased Treg induction was entirely reversible on inhibition of fatty acid oxidation, thus confirming the dependence of AICAR's effects on metabolic pathways alterations. Translating our findings to an in vivo model, we found that the substance enhanced Treg cell generation on IL-2 complex-induced immune stimulation. We provide a previously unrecognized insight into the delicate interplay between immune cell function and metabolism and delineate a potential novel strategy for metabolism-targeting immunotherapy.-Gualdoni, G. A., Mayer, K. A., Göschl, L., Boucheron, N., Ellmeier, W., Zlabinger, G. J. The AMP analog AICAR modulates the Treg/Th17 axis through enhancement of fatty acid oxidation.

Grape seed procyanidins administered at physiological doses to rats during pregnancy and lactation promote lipid oxidation and up-regulate AMPK in the muscle of male offspring in adulthood

The aim of the present study was to test whether the administration of a grape seed procyanidin extract (GSPE) during pregnancy and lactation, at doses extrapolated to human consumption, programs male offspring toward improved metabolism in adulthood. For this purpose, female rats were fed a normal-fat diet (NFD) and treated with either GSPE (25 mg kg−1 of body weight/day) or vehicle during gestation and lactation. The metabolic programming effects of GSPE were evaluated in the male offspring fed NFD from 30 to 170 days of life. No changes were observed in body weight, adiposity, circulating lipid profile and insulin sensitivity between the offspring of dams treated with GSPE (STD-GSPE group) and their counterparts (STD-veh). However, the STD-GSPE offspring had lower circulating levels of C-reactive protein and lower respiratory quotient values, shifting whole-body energy catabolism from carbohydrate to fat oxidation. Furthermore, the STD-GSPE animals also exhibited increased levels of total and phosphorylated AMP-activated protein kinase (AMPK) and an over-expression of the mRNA levels of key genes related to fatty acid uptake (Fatp1 and CD36) and β-oxidation (pparα and had) in skeletal muscle. Our results indicate that GSPE programs healthy male offspring towards a better circulating inflammatory profile and greater lipid utilisation in adulthood. The metabolic programming effects of GSPE that are related to the enhancement of fatty acid oxidation in skeletal muscle seem to be mediated, at least in part, by AMPK. These findings could be of relevance in the prevention of pathologies associated to lifestyle and aging, such as obesity and insulin resistance.

Rosehip Extract Inhibits Lipid Accumulation in White Adipose Tissue by Suppressing the Expression of Peroxisome Proliferator-activated Receptor Gamma

Recent studies have shown that Rosa canina L. and tiliroside, the principal constituent of its seeds, exhibit anti-obesity and anti-diabetic activities via enhancement of fatty acid oxidation in the liver and skeletal muscle. However, the effects of rosehip, the fruit of this plant, extract (RHE), or tiliroside on lipid accumulation in adipocytes have not been analyzed. We investigated the effects of RHE and tiliroside on lipid accumulation and protein expression of key transcription factors in both in vitro and in vivo models. RHE and tiliroside inhibited lipid accumulation in a dose-dependent manner in 3T3-L1 cells. We also analyzed the inhibitory effect of RHE on white adipose tissue (WAT) in high-fat diet (HFD)-induced obesity mice model. Male C57BL/6J mice were fed HFD or HFD supplemented with 1% RHE (HFDRH) for 8 weeks. The HFDRH-fed group gained less body weight and had less visceral fat than the HFD-fed group. Liver weight was significantly lower in the HFDRH-fed group and total hepatic lipid and triglyceride (TG) content was also reduced. A significant reduction in the expression of peroxisome proliferator-activated receptor gamma (PPARγ) was observed in epididymal fat in the HFDRH-fed group, in comparison with controls, through Western blotting. These results suggest that downregulation of PPARγ expression is involved, at least in part, in the suppressive effect of RHE on lipid accumulation in WAT.

Activation of peroxisome proliferator-activated receptor-α (PPARα) in proximal intestine improves postprandial lipidemia in obese diabetic KK-Ay mice

Postprandial lipidemia is a risk factor for cardiovascular diseases. Thus, the suppression of postprandial lipidemia is valuable for disease management. Peroxisome proliferator-activated receptor- (PPAR ) is a key regulator in the lipid metabolism of peripheral tissues such as the liver and skeletal muscle, whose activation enhances fatty acid oxidation and decreases circulating lipid level. Recently, we have shown that bezafibrate, an agonistic compound for PPAR , suppresses post-prandial lipidemia by enhancing fatty acid oxidation in intestinal epithelial cells under physiological conditions. However, it was not elucidated whether the effect of PPAR on postprandial lipidemia is also observed under obese conditions, which change lipid metabolisms in various tissues and cells. Here, we observed that bezafibrate enhanced fatty acid oxidation in intestinal epithelial cells of obese diabetic KK-Ay mice. Bezafibrate treatment increased the mRNA expression levels of fatty acid oxidation-related genes, which are targets of PPAR , and enhanced CO2 production from [14C]-palmitic acid. The bezafibrate-treated mice showed the suppression of increasing serum triacylglyceride level after the oral administration of olive oil. Moreover, the effects of bezafibrate on mRNA expression and fatty acid oxidation were shown in only the proximal intestinal epithelial cells. These findings indicate that PPAR activation suppresses postprandial lipidemia under obese conditions through the enhancement of fatty acid oxidation, and that only the proximal intestine con-tributes to the effects in mice, suggesting that intestinal PPAR can be a target for prevention of obese-induced postprandial lipidemia.

Transcriptional analysis reveals a high impact of conjugated linoleic acid on stearoyl-Coenzyme A desaturase 1 mRNA expression in mice gastrocnemius muscle

We examined the potential implication of skeletal muscle in the fat-lowering effect observed in mice treated with moderate doses of CLA. In experiment 1, mice fed with a standard-fat diet were orally treated with sunflower oil (control) and 3 or 10mg CLA mixture/day for 37days. In experiment 2, mice were fed with a high-fat diet for 65days. For the first 30days, they received the same doses as in experiment 1 and, from that time onwards, animals received double doses. Gene expression of key proteins involved in fatty acid transport, oxidation, regulation of lipid and carbohydrate utilization, composition of muscle fiber, and thermogenesis were determined and, in most of them, no major impact of CLA was seen. Therefore, enhancement of fatty acid oxidation in muscle did not seem to contribute to the antiobesity effect of CLA as seen in other studies with higher CLA doses. However, a strong induction of classically associated lipogenic genes such as Fasn (up to twofold) and, particularly, Scd1 (up to ninefold) was found. This activation could contribute to a protective role in muscle cells, since expression of ER stress markers was decreased and inversely correlated with the induction of Scd1.

Blood Lactate Functions as a Signal for Enhancing Fatty Acid Metabolism during Exercise via TGF-^|^beta; in the Brain

Moderate-intensity running (treadmill velocity of 21 m/min) increased blood lactate and actived transforming growth factor-β (TGF-β) concentration in rat cerebrospinal fluid (CSF). On the other hand, low-intensity running (15 m/min) did not increase blood lactate and caused no change in CSF TGF-β. Intraperitoneal (i.p.) administration of lactate to anesthetized rats caused an increase in blood lactate similar to that observed after a 21 m/min running exercise and increased the level of active TGF-β in CSF. Intraperitoneal administration of lactate at the same dose to awake and unrestricted rats caused a decrease in the respiratory exchange ratio, that is, enhancement of fatty acid oxidation and depression of spontaneous motor activity (SMA). Given that intracisternal administration of TGF-β to rats has been reported to enhance fatty acid metabolism and to depress SMA, we surmise that the observed changes caused by i.p. lactate administration in this study were mediated, at least in part, by TGF-β in the brain.

Balanced pan-PPAR activator bezafibrate in combination with statin: comprehensive lipids control and diabetes prevention?

All fibrates are peroxisome proliferators-activated receptors (PPARs)-alpha agonists with ability to decrease triglyceride and increase high density lipoprotein- cholesterol (HDL-C). However, bezafibrate has a unique characteristic profile of action since it activates all three PPAR subtypes (alpha, gamma and delta) at comparable doses. Therefore, bezafibrate operates as a pan-agonist for all three PPAR isoforms. Selective PPAR gamma agonists (thiazolidinediones) are used to treat type 2 diabetes mellitus (T2DM). They improve insulin sensitivity by up-regulating adipogenesis, decreasing free fatty acid levels, and reversing insulin resistance. However, selective PPAR gamma agonists also cause water retention, weight gain, peripheral edema, and congestive heart failure. The expression of PPAR beta/ delta in essentially all cell types and tissues (ubiquitous presence) suggests its potential fundamental role in cellular biology. PPAR beta/ delta effects correlated with enhancement of fatty acid oxidation, energy consumption and adaptive thermogenesis. Together, these data implicate PPAR beta/delta in fuel combustion and suggest that pan-PPAR agonists that include a component of PPAR beta/delta activation might offset some of the weight gain issues seen with selective PPAR gamma agonists, as was demonstrated by bezafibrate studies. Suggestively, on the whole body level all PPARs acting as one orchestra and balanced pan-PPAR activation seems as an especially attractive pharmacological goal. Conceptually, combined PPAR gamma and alpha action can target simultaneously insulin resistance and atherogenic dyslipidemia, whereas PPAR beta/delta properties may prevent the development of overweight. Bezafibrate, as all fibrates, significantly reduced plasma triglycerides and increased HDL-C level (but considerably stronger than other major fibrates). Bezafibrate significantly decreased prevalence of small, dense low density lipoproteins particles, remnants, induced atherosclerotic plaque regression in thoracic and abdominal aorta and improved endothelial function. In addition, bezafibrate has important fibrinogen-related properties and anti-inflammatory effects. In clinical trials bezafibrate was highly effective for cardiovascular risk reduction in patients with metabolic syndrome and atherogenic dyslipidemia. The principal differences between bezafibrate and other fibrates are related to effects on glucose level and insulin resistance. Bezafibrate decreases blood glucose level, HbA1C, insulin resistance and reduces the incidence of T2DM compared to placebo or other fibrates. Currently statins are the cornerstone of the treatment and prevention of cardiovascular diseases related to atherosclerosis. However, despite the increasing use of statins as monotherapy for low density lipoprotein- cholesterol (LDL-C) reduction, a significant residual cardiovascular risk is still presented in patients with atherogenic dyslipidemia and insulin resistance, which is typical for T2DM and metabolic syndrome. Recently, concerns were raised regarding the development of diabetes in statin-treated patients. Combined bezafibrate/statin therapy is more effective in achieving a comprehensive lipid control and residual cardiovascular risk reduction. Based on the beneficial effects of pan-PPAR agonist bezafibrate on glucose metabolism and prevention of new-onset diabetes, one could expect a neutralization of the adverse pro-diabetic effect of statins using the strategy of a combined statin/fibrate therapy.

Inhibition of stearoyl-CoA desaturase1 activates AMPK and exhibits beneficial lipid metabolic effects in vitro

Stearoyl-CoA desaturase1 (SCD1) whole body deficiency protects mice from diet-induced obesity. However the specific mechanism of how SCD1 deficiency protects mice from obesity is not clear yet. To understand the tissue-specific role of SCD1 in energy homeostasis, we investigated the responses of adipocytes, hepatocytes and myotubes to SCD1 inhibition. 3T3-L1 adipocytes treated with a SCD1 inhibitor had decreased expression of lipogenic genes including fatty acid synthase (FAS), acetyl-CoA carboxylase (ACC), and sterol-regulatory element binding protein 1c (SREBP1c) while the expression of fatty acid oxidative genes including carnitine palmitoyltransferase 1 (CPT1), uncoupling protein 2 (UCP2), and peroxisome proliferator-activated receptor gamma coactivator 1-α (PGC1-α) remained unaltered. In mouse primary hepatocytes, treatment with the inhibitor reduced the expression of FAS, ACC, and SREBP1c but increased the expression of fatty acid oxidative genes including acyl-CoA oxidase (AOX), CPT1, and PGC1-α. In addition, inhibitor-treated C2C12 myotubes showed decrease in ACC and FAS expression and increase in expression of CPT1, AOX and PGC1-α. AMP-activated protein kinase (AMPK) is known to regulate cellular metabolism in response to available energy and AMPK activation is associated with enhancement of fatty acid oxidation and suppression of lipogenesis. In all tested cell models, AMPK phosphorylation was increased significantly when SCD1 was inhibited. Taken together, our results indicate that inhibition of SCD1 activity has beneficial lipid metabolic effects of decreased lipogenesis and/or increased fatty acid oxidation, which is at least in part due to an increase of AMPK activation.

Tiliroside, a glycosidic flavonoid, ameliorates obesity-induced metabolic disorders via activation of adiponectin signaling followed by enhancement of fatty acid oxidation in liver and skeletal muscle in obese–diabetic mice

Tiliroside contained in several dietary plants, such as rose hips, strawberry and raspberry, is a glycosidic flavonoid and possesses anti-inflammatory, antioxidant, anticarcinogenic and hepatoprotective activities. Recently, it has been reported that the administration of tiliroside significantly inhibited body weight gain and visceral fat accumulation in normal mice. In this study, we evaluated the effects of tiliroside on obesity-induced metabolic disorders in obese–diabetic KK-Ay mice. In KK-Ay mice, the administration of tiliroside (100 mg/kg body weight/day) for 21 days failed to suppress body weight gain and visceral fat accumulation. Although tiliroside did not affect oxygen consumption, respiratory exchange ratio was significantly decreased in mice treated with tiliroside. In the analysis of metabolic characteristics, it was shown that plasma insulin, free fatty acid and triglyceride levels were decreased, and plasma adiponectin levels were increased in mice administered tiliroside. The messenger RNA expression levels of hepatic adiponectin receptor (AdipoR)-1 and AdipoR2 and skeletal muscular AdipoR1 were up-regulated by tiliroside treatment. Furthermore, it was indicated that tiliroside treatment activated AMP-activated protein kinase in both the liver and skeletal muscle and peroxisome proliferator-activated receptor α in the liver. Finally, tiliroside inhibited obesity-induced hepatic and muscular triglyceride accumulation. These findings suggest that tiliroside enhances fatty acid oxidation via the enhancement adiponectin signaling associated with the activation of both AMP-activated protein kinase and peroxisome proliferator-activated receptor α and ameliorates obesity-induced metabolic disorders, such as hyperinsulinemia and hyperlipidemia, although it does not suppress body weight gain and visceral fat accumulation in obese–diabetic model mice.