Prevent Lipid Accumulation Research Articles

Blocking Wnt5a signaling decreases CD36 expression and foam cell formation in atherosclerosis.

Wnt5a is a highly studied member of the Wnt family and recently has been implicated in the pathogenesis of atherosclerosis, but its precise role is unknown. Foam cell development is a critical process to atherosclerotic plaque formation. In the present study, we investigated the role of noncanonical Wnt5a signaling in the development of foam cells. Human carotid atherosclerotic tissue and THP-1-derived macrophages were used to investigate the contribution of Wnt5a signaling in the formation of foam cells. Immunohistochemistry was used to evaluate protein expression of scavenger receptors and noncanonical Wnt5a receptors [frizzled 5 (Fz5) and receptor tyrosine kinase-like orphan receptor 2 (Ror2)] in human atherosclerotic macrophages/foam cells. Changes in protein expression in response to Wnt5a stimulation/inhibition were determined by Western blot, and lipid accumulation was evaluated by fluorescent lipid droplet staining. Wnt5a (P<.05), Fz5 (P<.01), and Ror2 (P<.01) were significantly expressed in advanced atherosclerotic lesions compared to less advanced lesions (N=10). Wnt5a, Fz5, and Ror2 were expressed in macrophages/foam cells within the plaque. In vitro studies revealed that Wnt5a significantly increased the expression of the lipid uptake receptor CD36 (P<.05) but not the lipid efflux receptor ATP-binding cassette transporter (P>.05). rWnt5a also significantly increased lipid accumulation in THP-1 macrophages (P<.05). Furthermore, inhibition of Wnt5a signaling with Box5 prevented lipid accumulation (P<.01) and prevented CD36 up-regulation (P<.01). These results suggest a direct role for Wnt5a signaling in the pathogenesis of atherosclerosis, specifically the accumulation of lipid in macrophages and the formation of foam cells.

Activation of mammalian target of rapamycin induces lipid accumulation in the diaphragm of ventilated rats and hypoxia-treated C2C12 cells

BackgroundOur previous study demonstrated that ventilators increase diaphragmatic lipid accumulation in rabbits, but their cellular mechanism is poorly understood. Mammalian target of rapamycin (mTOR) plays an important role in atherosclerosis in rat vascular smooth muscle cells. The present study investigated the role of mTOR pathway activation in the diaphragmatic muscle of ventilated rats and hypoxia-induced C2C12 cells. Materials and methodsMale Sprague-Dawly rats were randomized into a control group (n = 8), controlled mechanical ventilation (CMV) group (n = 8), and CMV + Rapa group (n = 8). We evaluated the diaphragmatic contractility, lipid accumulation, and protein expression of the mTOR pathways. To explore the mechanism underlying ventilator-induced lipid accumulation, we observed protein expression of the mTOR and low-density lipoprotein receptor (LDLr) pathways in C2C12 cells under hypoxic and mTOR pathway inhibitor treatments. ResultsCompared with the control group, there was a significant decrease in the peak twitch and peak tetanic forces in the CMV group (384.24 ± 70.39 versus 496.33 ± 78.64 g/cm2, P < 0.05, and 869.24 ± 76.67 versus 1090.72 ± 118.91 g/cm2, P < 0.05, respectively). There was a significant increase in peak twitch and peak tetanic forces in the CMV + Rapa group compared with that in the CMV group (501.81 ± 23.15 versus 384.24 ± 70.39 g/cm2, P < 0.05, and 992.91 ± 88.99 versus 869.24 ± 76.67 g/cm2, P < 0.05, respectively). In the CMV group, there were significant increases in lipid accumulation (0.086 ± 0.009 versus 0.005 ± 0.002, P < 0.05) and expression of mTOR in diaphragmatic fibers compared with those in the control group (P < 0.05). Rapamycin prevented lipid accumulation in rats of the CMV + Rapa group compared with that in the CMV group rats (0.024 ± 0.004 versus 0.086 ± 0.009, P < 0.05). Compared with the CMV group, there was a significant decrease in the phosphorylated protein expression levels of mTOR in rats of the CMV + Rapa group (P < 0.05). Hypoxic conditions activated the mTOR and LDLr pathways in C2C12 cells, which were correlated with an increase in expression of the mTOR and LDLr pathways compared with the control group (P < 0.05). In C2C12 cells treated with hypoxia + rapamycin, activation of the mTOR and LDLr pathways was blocked compared with C2C12 cells treated with hypoxia (P < 0.05). ConclusionsThese data suggest that CMV and hypoxia-induced activation of the mTOR pathway, resulting in lipid accumulation, and impaired the diaphragmatic contractile function. Therefore, pharmacologic agents that inhibit the mTOR pathway could potentially be useful for mitigating the diaphragmatic contractile dysfunction induced by mechanical ventilation.

Metabolomics studies on db/db diabetic mice in skeletal muscle reveal effective clearance of overloaded intermediates by exercise

Type 2 diabetes mellitus (T2DM) is characterized by hyperinsulinemia, hyperglycemia and insulin resistance, which correlated with high mortality worldwide. Exercise is one of the effective lifestyle interventions in maintaining blood glucose level in the normal range and lowering risk factors. Metabolomics approaches are powerful tools in systematic study of overall metabolic changes in response to disease or interventions. In this study, mass spectrometry-based metabolomics studies were performed to investigate the regulatory effect of moderate intensity of exercise on db/db diabetic mice in skeletal muscle. Both liquid chromatography-mass spectrometry (LC-MS) and gas chromatography-mass spectrometry (GC-MS) have been carried out to monitor a wide range of regulated metabolites. Ninety-five metabolites were identified which contributing to the discrimination of db/m + control and db/db diabetic mice. The regulatory effects of exercise on these metabolites were mainly focusing on attenuating the levels of long-chain fatty acids (C14 to C18) and medium-to long-chain acylcarnitines (C12 to C18), indicated that exercise might play a positive role in inhibiting the accumulation of excessive lipids, which is positively related to insulin resistance. In addition, uric acid, which is a risk factor for inflammation, cardiovascular complications, and fatty liver in diabetic patients, together with its intermediates (such as inosinic acid, hypoxanthine, etc.) in purine metabolism pathway, were also substantially down regulated after exercise, indicating exercise might also be protective against hyperuricemia related risks in T2DM. These findings reveal that moderate intensity of exercise might play a positive role in improving the efficiency of lipid metabolism in skeletal muscle and meanwhile enhancing uric acid clearance to prevent lipid accumulation, which might contribute to improved body fitness and body muscle composition.

Abstract 21015: Coronary Inflammation in Humans Drives Spatial Changes of Perivascular Adipose Tissue Composition Detectable by a Novel Computed Tomography-Based Technology

Background: Non-invasive detection of vascular inflammation remains an unmet goal. We hypothesized that phenotypic changes in perivascular adipose tissue (PVAT) induced by vascular inflammation can be quantified using a new computed tomography angiography (CTA) methodology. Methods: In Arm 1, human PVAT adipocytes were cultured +/- inflammatory cytokines (n=7) or co-cultured with vascular tissue (+/-Angiotensin-II, n=6) to assess the effects of vascular inflammation on PVAT differentiation. In Arm 2, AT explants (epicardial, subcutaneous and thoracic AT) from 453 cardiac surgery patients were used in histology and gene expression studies to relate the ex vivo images with in vivo CT scan information (n=105) on the biology of the explants. In Arm 3, in 267 patients undergoing diagnostic CTA, PVAT attenuation (Fat Attenuation Index (FAI) defined as the average CT attenuation of AT), was analysed around the proximal right coronary artery. In Arm 4, PVAT FAI around unstable (culprit) and stable coronary plaques was calculated in 22 CAD patients undergoing CTA. Results: In Arm 1, Angiotensin-II (A) and proinflammatory cytokines (B) prevented lipid accumulation and adipocyte differentiation in cultured PVAT. In Arm 2, adipocyte size by histology was inversely correlated with FAI in vivo (C). Both FAI of AT explants (not shown) and FAI in-vivo (n=105) were negatively associated with epicardial AT differentiation as assessed by FABP4 expression (D). In Arm 3, PVAT FAI change over distance from RCA wall was significantly different in CAD compared to no CAD patients (E). In Arm 4, PVAT FAI was significantly increased around unstable plaques (F). Conclusions: Human vessels exert paracrine effects on surrounding PVAT, affecting local intracellular lipid accumulation in preadipocytes, which can then be monitored using a CT imaging approach. This novel methodology can be implemented in clinical practice to detect unstable plaques in the human coronary vasculature.

The MXL-3/SBP-1 Axis Is Responsible for Glucose-Dependent Fat Accumulation in C. elegans.

Chronic exposure to elevated glucose levels leads to fatty acid accumulation, which promotes the development of metabolic diseases such as obesity and type 2 diabetes. MXL-3 is a conserved transcriptional factor that modulates the inhibition of lipolysis in Caenorhabditis elegans. However, the role of MXL-3 in lipid metabolism during nutrient excess remains unknown. We hypothesized that inhibition of MXL-3 prevents glucose-dependent fat accumulation. Nematodes from wild-type N2, MXL-3::GFP and sbp-1 or mxl-3 null strains were grown on standard, high glucose or high glucose plus metformin plates for 24 h. Using laser-scanning confocal microscopy, we monitored the glucose-induced activation of MXL-3 labeled with GFP (MXL-3::GFP). Lipid levels were determined by Oil Red O (ORO) staining and gas chromatography/mass spectrometry, and gene expression was assessed by qRT-PCR. We found that high glucose activated MXL-3 by increasing its rate of nuclear entry, which in turn increased lipid levels via sterol regulatory element-binding protein (SBP-1). This activated critical genes that synthesize long chain unsaturated fatty acids (MUFAs and PUFAs) and repress lipolytic genes. Interestingly, the anti-diabetic drug metformin inhibited MXL-3 activation and subsequently prevented glucose-dependent fat accumulation. These findings highlight the importance of the MXL-3/SBP-1 axis in the regulation of lipid metabolism during nutritional excess and provide new insight into the mechanism by which metformin prevents lipid accumulation. This study also suggests that inhibition of MXL-3 may serve as a potential target for the treatment of chronic metabolic diseases, including obesity, type 2 diabetes, and cardiovascular disease.

Vitamin D prevents lipid accumulation in murine muscle through regulation of PPARγ and perilipin-2 expression

Vitamin D plays an important role in regulation of skeletal muscle tone and contraction. Serum vitamin D status is linked to muscle power and force in adolescent girls, and vitamin D deficiency is associated with myopathies in children and poorer physical performance in the elderly. We previously reported that vitamin D deficiency is linked to a significant increase in muscle fatty infiltration in healthy young women, and studies in patients with neuromuscular disorders also associate muscle weakening and lipid content. In order to better understand the link between vitamin D status and skeletal muscle lipid metabolism, we compared the effect of a low (25 IU/kg) or normal (1000 IU/kg) vitamin D3 diet on muscle fat in female FVB mice maintained in a room without UVB lighting to minimize endogenous vitamin D production. Animals on low vitamin D diet displayed lower circulating 25(OH)D levels and a dramatic increase (287 ± 52% compared to normal diet, p < 0.0001) in lipid deposition in skeletal muscle accompanied by muscle fiber disorganization. Lipid droplet staining increased by 242 ± 23% (p < 0.0001) in low vitamin D diet, and lipid droplet coat protein perilipin-2 and nuclear receptor transcription factor PPARγ expression levels were increased compared to mice fed the normal vitamin D diet: average staining for PLIN2: 0.22 ± 0.08 (25 IU/kg diet) vs 0.10 ± 0.02 (1000 IU/kg). Average staining for PPARγ: 0.24 ± 0.06 (25 IU/kg diet) vs 0.07 ± 0.04 (1000 IU/kg) p < 0.0001. Tissue mass spectrometry imaging revealed major differences in muscle phospholipids profile depending on diet. In vitro, 1,25(OH)2D3 treatment of 3T3-L1 pre-adipocytes inhibited appearance of lipid droplets by 79 ± 9.3%, and caused a 80 ± 10% and 25 ± 8% (p = 0.001) reduction in PPARγ and perilipin-2 mRNA levels (by qPCR) compared to control cells. In summary, we report here the first in vivo model illustrating the important structural muscle fiber disorganization and fat accumulation inside and outside muscle fibers that accompany vitamin D deficiency. Furthermore, we show that the underlying mechanisms involve PPARγ and perilipin-2.

Chronic administration of mitochondrion-targeted peptide SS-31 prevents atherosclerotic development in ApoE knockout mice fed Western diet.

BackgroundOxidative stress and inflammatory factors are deeply involved in progression of atherosclerosis. Mitochondrion-targeted peptide SS-31, selectively targeting to mitochondrial inner membrane reacting with cardiolipin, has been reported to inhibit ROS generation and mitigate inflammation. The present study was designed to investigate whether SS-31 could suppress the development of atherosclerosis in vivo.MethodsMale ApoE-/- mice (8 weeks old) fed with Western diet were treated with normal saline or SS-31 (1 mg/kg/d or 3 mg/kg/d) through subcutaneous injection for 12 weeks. Oil Red O staining was performed to evaluate area and sizes of the plaques. DHE staining and immunohistochemical staining of 8-OHDG was performed to assess the oxidative stress. The aorta ATP contents were assessed by the ATP bioluminescence assay kit. Immunohistochemical staining of CD68 and α-SMA and Masson’s trichrome staining were performed to evaluate the composition of atherosclerotic plaque. Biochemical assays were performed to determine the protein level and activity of superoxide dismutase (SOD). The levels of CD36, LOX-1 and ABCA1 were immunohistochemically and biochemically determined to evaluate the cholesterol transport in aorta and peritoneal macrophages. Inflammatory factors, including ICAM-1, MCP-1, IL-6 and CRP in serum, were detected through ELISA.ResultsSS-31 administration reduced the area and sizes of western diet-induced atherosclerotic plaques and changed the composition of the plaques in ApoE-/- mice. Oxidative stress was suppressed, as evidenced by the reduced DHE stain, down-regulated 8-OHDG expression, and increased SOD activity after chronic SS-31 administration. Moreover, systemic inflammation was ameliorated as seen by decreasing serum ICAM-1, MCP-1, and IL-6 levels. Most importantly, SS-31 administration inhibited cholesterol influx by down-regulating expression of CD36 and LOX-1 to prevent lipid accumulation to further suppress the foam cell formation and atherosclerotic progression.ConclusionAdministration of SS-31 prevents against atherosclerotic formation in ApoE-/- mice suggesting that SS-31 might be considered to be a potential drug to prevent atherosclerotic progression.

Dietary creatine supplementation lowers hepatic triacylglycerol by increasing lipoprotein secretion in rats fed high-fat diet

Recent studies have shown that dietary creatine supplementation can prevent lipid accumulation in the liver. Creatine is a small molecule that plays a large role in energy metabolism, but since the enzyme creatine kinase is not present in the liver, the classical role in energy metabolism does not hold in this tissue. Fat accumulation in the liver can lead to the development of nonalcoholic fatty liver disease (NAFLD), a progressive disease that is prevalent in humans. We have previously reported that creatine can directly influence lipid metabolism in cell culture to promote lipid secretion and oxidation. Our goal in the current study was to determine whether similar mechanisms that occur in cell culture were present in vivo. We also sought to determine whether dietary creatine supplementation could be effective in reversing steatosis. Sprague–Dawley rats were fed a high-fat diet or a high-fat diet supplemented with creatine for 5 weeks. We found that rats supplemented with creatine had significantly improved rates of lipoprotein secretion and alterations in mitochondrial function that were consistent with greater oxidative capacity. We also find that introducing creatine into a high-fat diet halted hepatic lipid accumulation in rats with fatty liver. Our results support our previous report that liver cells in culture with creatine secrete and oxidize more oleic acid, demonstrating that dietary creatine can effectively change hepatic lipid metabolism by increasing lipoprotein secretion and oxidation in vivo. Our data suggest that creatine might be an effective therapy for NAFLD.

Inhibition of sarcolemmal FAT/CD36 by sulfo-N-succinimidyl oleate rapidly corrects metabolism and restores function in the diabetic heart following hypoxia/reoxygenation.

AimsThe type 2 diabetic heart oxidizes more fat and less glucose, which can impair metabolic flexibility and function. Increased sarcolemmal fatty acid translocase (FAT/CD36) imports more fatty acid into the diabetic myocardium, feeding increased fatty acid oxidation and elevated lipid deposition. Unlike other metabolic modulators that target mitochondrial fatty acid oxidation, we proposed that pharmacologically inhibiting fatty acid uptake, as the primary step in the pathway, would provide an alternative mechanism to rebalance metabolism and prevent lipid accumulation following hypoxic stress.Methods and resultsHearts from type 2 diabetic and control male Wistar rats were perfused in normoxia, hypoxia and reoxygenation, with the FAT/CD36 inhibitor sulfo-N-succinimidyl oleate (SSO) infused 4 min before hypoxia. SSO infusion into diabetic hearts decreased the fatty acid oxidation rate by 29% and myocardial triglyceride concentration by 48% compared with untreated diabetic hearts, restoring fatty acid metabolism to control levels following hypoxia-reoxygenation. SSO infusion increased the glycolytic rate by 46% in diabetic hearts during hypoxia, increased pyruvate dehydrogenase activity by 53% and decreased lactate efflux rate by 56% compared with untreated diabetic hearts during reoxygenation. In addition, SSO treatment of diabetic hearts increased intermediates within the second span of the Krebs cycle, namely fumarate, oxaloacetate, and the FAD total pool. The cardiac dysfunction in diabetic hearts following decreased oxygen availability was prevented by SSO-infusion prior to the hypoxic stress. Infusing SSO into diabetic hearts increased rate pressure product by 60% during hypoxia and by 32% following reoxygenation, restoring function to control levels.ConclusionsDiabetic hearts have limited metabolic flexibility and cardiac dysfunction when stressed, which can be rapidly rectified by reducing fatty acid uptake with the FAT/CD36 inhibitor, SSO. This novel therapeutic approach not only reduces fat oxidation but also lipotoxicity, by targeting the primary step in the fatty acid metabolism pathway.

Ginger (Zingiber officinale) extract inhibits the lipid droplet accumulation and expression of adipogenic transcription factors in 3T3‐L1 preadipocytes

In this study, we investigated the effects of ginger extract on the inhibition of adipogenesis and it's possible mechanism of action in 3T3‐L1 cells. Cell viability was analyzed using the MTT assay. After treatment with various concentrations of the ginger extract in differentiation medium for 8 days, the morphological changes were visualized by staining of lipid with Oil‐Red O stain. The differentiated 3T3‐L1 cells were lysed and measured for triglyceride contents. Detection of mRNA levels of adipocyte‐specific transcription factors were analyzed using RT‐PCR. Ginger extract suppressed oil droplet accumulation in the cells and gene expression of PPARγ and C/EBPα. The increased levels of mRNA in ACC, GLUT4, aP2, FAS in control cells were decreased upon treatment with ginger extract, suggesting that ginger prevented lipid accumulation by reducing lipogenesis. These results suggest that ginger extract would have antiobesity effects which needs to be further studied in rodents.Support or Funding Information[This research was supported by the Ministry of Agriculture, Food and Rural Affairs (MAFRA), through the 2015 Healthy Local Food Branding Project of the Rural Resources Complex Industrialization Support Program]

The signalling mechanisms of a novel mitochondrial complex I inhibitor prevent lipid accumulation and attenuate TNF-α-induced insulin resistance in vitro

RTC-1 has recently been identified as a member of a new class of anti-diabetic compounds acting through the inhibition of complex I of the mitochondrial respiratory chain (NADH:ubiquinone oxidoreductase) to improve glucose handling and inhibit weight gain in mice fed a high-fat diet (HFD). The exact mechanism by which the reduced activity of NADH:ubiquinone oxidoreductase, in response to RTC-1, promotes these improved metabolic parameters remains to be established. Through extensive in vitro analysis, new molecular insights into these downstream signalling pathways have been obtained. RTC-1-induced inhibition of NADH:ubiquinone oxidoreductase was found to promote glucose uptake in C2C12 myotubes in vitro, through the activation of the Akt substrate of 160kDa (AS160), in response to the increased activity of Akt and AMP-activated protein kinase (AMPK). RTC-1-induced phosphorylation of the AMPK substrate, acetyl-CoA carboxylase (ACC) in vitro, was associated with a decrease in lipid accumulation in 3T3-L1 adipocytes and murine mesenchymal stromal cells (MSC). The novel compound also prevented tumour necrosis factor-alpha (TNF-α)-induced insulin resistance and demonstrated insulin sensitising effects in C2C12 myotubes. Taken together, these results present a systematic analysis of the signalling mechanisms responsible for the potent anti-diabetic and anti-obesogenic effects of this modulator of mitochondrial function, strengthening the potential use of such compounds for the treatment of type 2 diabetes mellitus (T2DM).

Maternal resveratrol intake during lactation attenuates hepatic triglyceride and fatty acid synthesis in adult male rat offspring

Resveratrol (3,5,4-trihydroxystilbene) is a natural polyphenolic compound found in grapes and red wine and has been shown to exert protective effects on the liver preventing lipid accumulation induced by a high-fat diet. However, no studies have shown that the nutritional resveratrol intake by the parental generation has modified lipogenesis in an adult offspring. The aim of this study was to investigate whether maternal resveratrol intake during lactation affects lipogenesis in adult male rat offspring, and if it does, what is the molecular mechanistic basis. Six male pups born from mothers given a control diets during lactation (CC group) and six male pups born from mothers given a control diet as well as resveratrol during lactation (CR group) were fed a standard diet until sacrifice at 36 weeks. Adult male offspring from mothers given resveratrol during lactation (CR group) had lower body weight from the fourth week of lactation until adulthood, but no significant change was observed in the relative food intake. Low levels of plasma triacylglycerol were found in the CR group compared to the CC group. Histopathological analysis of the livers of adult male rat offspring revealed lipid accumulation in hepatocytes in the CC group, whereas lipid droplets were rare in the CR group. Hepatic protein levels of AMPK-phosphorylated at ser403, Sirt1, and Nampt in the CR group were upregulated significantly compared to the CC group. These results indicated the maternal resveratrol intake during lactation-induced activation of AMPK through Sirt1 upregulation. In this study, significant upregulation of the levels of precursor of sterol regulatory element binding protein-1c (SREBP-1c) and downregulation of the ratio of active-SREBP-1c/precusor-SREBP-1c were observed in the CR group compared to the CC group. These results suggested that proteolytic processing of SREBP-1c was suppressed by AMPK in the livers of the CR group. It is well known that SREBP-1c regulates the lipogenic pathway by activating genes involved in triglyceride and fatty acid synthesis. The present study showed significant downregulation of hepatic fatty acid synthase (FAS) and acetyl-CoA carboxylase (ACC) levels in the CR group. These results indicated that maternal resveratrol intake during lactation suppressed SREBP-1c cleavage and nuclear translocation and repressed SREBP-1c target gene expression such as FAS and ACC in the livers of adult male offspring. These changes attenuate hepatic triacylglycerol and fatty acid synthesis in adult male offspring.

Hypoxia mimetic induces lipid accumulation through mitochondrial dysfunction and stimulates autophagy in murine preadipocyte cell line

BackgroundHypoxia occurs within adipose tissue of obese human and mice. However, its role in adipose tissue regulation is still controversial. MethodsWe used murine preadipocyte 3T3-L1 cells and hypoxia was induced by using hypoxia mimetic agents, as CoCl2. To study adipocyte differentiation, we evaluated the adipocyte markers (PPARγ, C/EBPα and aP2), and a preadipocyte marker (pref-1) by qPCR, western blotting and immunofluorescence. Lipid accumulation was evaluated by Oil red-O assay and perilipin levels by western blotting and immunofluorescence. The effect of CoCl2 in microRNA, miR-27a and miR-27b, levels was evaluated by qPCR. We also assessed the mitochondrial membrane potential and reactive oxygen species (ROS), superoxide and ATP production. The effect of hypoxia mimetic in autophagy was determined by LC3B and p62 level evaluation by western blotting. ResultsOur results show that the hypoxia mimetic cobalt chloride increases lipid accumulation with no expression of PPARγ2. Furthermore, using qPCR we observed that the hypoxia mimetic increases microRNAs miR-27a and miR-27b, which are known to block PPARγ2 expression. In contrast, cobalt chloride induces mitochondrial dysfunction, and increases ROS production and autophagy. Moreover, an antioxidant agent, glutathione, prevents lipid accumulation induced by hypoxia mimetic indicating that ROS are responsible for hypoxia-induced lipid accumulation. ConclusionsAll these results taken together suggest that hypoxia mimetic blocks differentiation and induces autophagy. Hypoxia mimetic also induces lipid accumulation through mitochondrial dysfunction and ROS accumulation. General significanceThis study highlights the importance of adipocyte response to hypoxia, which might impair adipocyte metabolism and compromise adipose tissue function.

Rice endosperm protein slows progression of fatty liver and diabetic nephropathy in Zucker diabetic fatty rats.

We previously reported that rice endosperm protein (REP) has renoprotective effects in Goto-Kakizaki rats, a non-obese diabetic model. However, whether these effects occur in obese diabetes remains unclear. This study aimed to clarify the effects of REP on obese diabetes, especially on fatty liver and diabetic nephropathy, using the obese diabetic model Zucker diabetic fatty (ZDF) rats. In total, 7-week-old male ZDF rats were fed diets containing 20 % REP or casein (C) for 8 weeks. Changes in fasting blood glucose levels and urinary markers were monitored during the experimental period. Hepatic lipids and metabolites were measured and renal glomeruli were observed morphologically. HbA1c levels were significantly lower in rats fed REP, compared with C (P<0·05). Compared with C in the liver, REP prevented lipid accumulation (total lipid, TAG and total cholesterol, P<0·01). Liver metabolome analysis indicated that levels of metabolites associated with glycolysis, the pentose phosphate pathway and carnitine metabolism were significantly greater in the REP group than in the C group (P<0·05), suggesting activation of both glucose catabolism and fatty acid oxidation. The metabolite increases promoted by REP may contribute to suppression of liver lipid accumulation. Urinary excretion of albumin and N-acetyl-β-d-glucosaminidase was significantly reduced in rats fed REP for 8 weeks (P<0·01). In addition, there was a distinct suppression of mesangial matrix expansion and glomerular hypertrophy in response to REP (P<0·01). Thus, REP had preventive effects on obese diabetes, fatty liver and diabetic nephropathy.

Oxidized tea polyphenols prevent lipid accumulation in liver and visceral white adipose tissue in rats.

Tea polyphenols are the prominent component in tea. After the fermentation process, tea polyphenols are oxidized by polyphenol oxidase to form oxidized tea polyphenols (OTPs). OTPs contain a significant amount of hydrophobic phenyl groups that can bind with non-aqueous materials. Here, we determined whether OTPs can bind with lipids and reduce fat uptake and assessed the effect of OTPs on decreasing obesity and alleviating hyperlipidaemia and other metabolic syndromes. Rats were divided into three groups: control, high-fat diet (HFD) and OTP groups. The control and HFD groups were fed a chow diet and a high-fat diet, respectively, for 12weeks; the OTP group was fed a high-fat diet for 6weeks and then a high-fat diet containing 2% OTP for 6weeks. The serum and excrement triglyceride (TAG) and total cholesterol (CHOL) concentrations were determined, and liver tissue and white adipose tissue were collected to detect the expression levels of genes involved in lipid metabolism. Our results revealed that OTPs failed to decrease the serum concentrations of TAG and CHOL. OTPs alleviated the accumulation of lipids in the liver tissue and changed the expression levels of the regulators of lipid metabolism, i.e., peroxisome proliferation-activated receptors (ppars), compared with the rats fed a high-fat diet alone. We also observed a significantly decreased reduction of weight in the visceral white adipose, enhanced regulation of fatty acid β-oxidation by PPARα and enhanced biosynthesis of mitochondria in the visceral white adipose of the OTP rats compared with the HFD rats. Additionally, OTPs promoted the excretion of lipids. Our results suggest that OTPs alleviate the accumulation of lipids in liver and visceral white adipose tissue and promote lipid excretion in rats in vivo.

0264 : Imidazoline-like drug improves lipid metabolism in hepatic cell through a direct action on the cellular energy sensor AMPK

Metabolic syndrome (MetS) is defined as a cluster of cardiovascular and metabolic disorders. Previous studies have demonstrated that ligands selective for I 1 imidazoline receptor (LNPs) ameliorate lipid metabolism (plasma total cholesterol and triglycerides levels) in rat models of metabolic syndrome. The objective of this study was to explore possible direct actions on hepatocytes which are involved in the regulation of lipid metabolism. Experiments were carried out in HepG2 cells, a cell line of hepatocytes. In order to evaluate the effect of LNP509 on lipid metabolism, the activation (i.e. phosphorylation) of a key actor of this signaling pathway, AMPK, was evaluated by measuring the ratio pAMPK/AMPK by Western Blot. AMPK is the main regulator of Acetyl-CoA-carboxylase (ACC) which is known to provide the malonyl-CoA substrate for the biosynthesis of fatty acids and to play a major role in hepatic steatosis. The effect of LNP509 on ACC phosphorylation (inactivation of ACC) was evaluated by measuring pACC/ACC by Western Blot. Hepatic steatosis, induced by treating HepG2 cells with oleic acid, was quantified by Oil Red O coloration and colorimetric measurements after oil Red O extraction. LNP509 (1 μM, 60 min) induced the M, phosphorylation of AMPK (pAMPK/ AMPK=1.15±0.27) compared to control (pAMPK/AMPK=0.37±0.06). Interestingly, treatment by LNP509 during 60 min also increased the phosphorylation (inhibition) of ACC (untreated cells: pACC/ACC=0.24±0.06; LNP 509 pACC/ACC=0.70±0.22). Concerning hepatic steatosis, LNP509 seemed to prevent lipid accumulation in HepG2 cell (cells alone=100%, cells+oleic acid=138.54%±10.34, cells+oleic acid+LNP509=112.81%±9.29). These data suggest that LNPs act directly on hepatic cells to activate AMPK pathway and prevent lipid accumulation. This mechanism probably accounts, at least partly, for the beneficial effects of LNPs on dyslipidemia observed in vivo. The author hereby declares no conflict of interest

Inhibition of acetyl-CoA carboxylases by soraphen A prevents lipid accumulation and adipocyte differentiation in 3T3-L1 cells

Acetyl-CoA carboxylases (ACC) 1 and 2 catalyze the carboxylation of acetyl-CoA to malonyl-CoA and depend on biotin as a coenzyme. ACC1 localizes in the cytoplasm and produces malonyl-CoA for fatty acid (FA) synthesis. ACC2 localizes in the outer mitochondrial membrane and produces malonyl-CoA that inhibits FA import into mitochondria for subsequent oxidation. We hypothesized that ACCs are checkpoints in adipocyte differentiation and tested this hypothesis using the ACC1 and ACC2 inhibitor soraphen A (SA) in murine 3T3-L1 preadipocytes. When 3T3-L1 cells were treated with 100nM SA for 8 days after induction of differentiation, the expression of PPARγ mRNA and FABP4 mRNA decreased by 40% and 50%, respectively, compared with solvent controls; the decrease in gene expression was accompanied by a decrease in FABP4 protein expression and associated with a decrease in lipid droplet accumulation. The rate of FA oxidation was 300% greater in SA-treated cells compared with vehicle controls. Treatment with exogenous palmitate restored PPARγ and FABP4 mRNA expression and FABP4 protein expression in SA-treated cells. In contrast, SA did not alter lipid accumulation if treatment was initiated on day eight after induction of differentiation. We conclude that loss of ACC1-dependent FA synthesis and loss of ACC2-dependent inhibition of FA oxidation prevent lipid accumulation in adipocytes and inhibit early stages of adipocyte differentiation.

Apolipoprotein A-1 binding protein promotes macrophage cholesterol efflux by facilitating apolipoprotein A-1 binding to ABCA1 and preventing ABCA1 degradation

RationalePrevious studies have shown that apolipoprotein-1 (apoA-1) binding protein (AIBP) is highly associated with the regulation of apoA-1 metabolism, suggesting its role in the treatment of atherosclerosis. However, how AIBP regulates foam cell formation remains largely unexplored. ObjectiveTo investigate the mechanisms underlying AIBP inhibition of foam cell formation from macrophages. Methods and resultsTHP-1-derived macrophages were incubated without or with apoA-1 and AIBP, followed by assessing the formation of foam cells and the potential mechanisms. Our results showed that AIBP and apoA-1 enhanced cholesterol efflux, altered the levels of cellular free cholesterol and cholesterol ester and prevented lipid accumulation so as to reduce the formation of foam cells. Meanwhile, lack of AIBP 115–123 amino acids resulted in the loss of AIBP binding to apoA-1. Moreover, our chemiluminescent analysis showed that AIBP promoted biotin-labeled apoA-1 binding to macrophages. Besides with AIBP, more apoA-1 bound to ABCA1, a key transporter responsible for cholesterol efflux to apoA-1, as indicated by our co-immunoprecipitation assay. Our results also showed that AIBP did not regulate ABCA1 mRNA expression, but stabilized its protein from CSN2-mediated degradation. ConclusionsAIBP promotes apoA-1 binding to ABCA1 on the cell membrane of macrophages and prevents ABCA1 protein from CSN2-mediated degradation so as to prevent foam cell formation. AIBP 115–123 amino acids is at least partially responsible for its binding to apoA-1.

Cinnamaldehyde supplementation prevents fasting-induced hyperphagia, lipid accumulation, and inflammation in high-fat diet-fed mice.

Cinnamaldehyde, a bioactive component of cinnamon, is increasingly gaining interest for its preventive and therapeutic effects against metabolic complications like type-2 diabetes. This study is an attempt to understand the effect of cinnamaldehyde in high-fat diet (HFD)-associated increase in fasting-induced hyperphagia and related hormone levels, adipose tissue lipolysis and inflammation, and selected cecal microbial count in mice. Cinnamaldehyde, at 40 µM dose, prevented lipid accumulation and altered gene expression toward lipolytic phenotype in 3T3-L1 preadipocyte cell lines. In vivo, cinnamaldehyde coadministration prevented HFD-induced body weight gain, decreased fasting-induced hyperphagia, as well as circulating leptin and leptin/ghrelin ratio. In addition to that, cinnamaldehyde altered serum biochemical parameters related to lipolysis, that is, glycerol and free fatty acid levels. At transcriptional level, cinnamaldehyde increased anorectic gene expression in hypothalamus and lipolytic gene expression in visceral white adipose tissue. Furthermore, cinnamaldehyde also decreased serum IL-1β and inflammatory gene expression in visceral white adipose tissue. However, cinnamaldehyde did not modulate the population of selected gut microbial (Lactobacillus, Bifidibaceria, and Roseburia) count in cecal content. In conclusion, cinnamaldehyde increased adipose tissue lipolysis, decreased fasting-induced hyperphagia, normalized circulating levels of leptin/ghrelin ratio, and reduced inflammation in HFD-fed mice, which augurs well for its antiobesity role.

Wild ginseng cambial meristematic cells ameliorate hepatic steatosis and mitochondrial dysfunction in high-fat diet-fed mice.

The aim of this study was to determine the protective mechanisms of wild ginseng cambial meristematic cells (CMCs) on non-alcoholic fatty liver disease in high-fat diet (HFD)-fed mice. Male C57BL/6 mice received either normal-fat diet or HFD for 10 weeks along with wild ginseng CMCs (75, 150 and 300 mg/kg) or vehicle (0.5% carboxyl methyl cellulose) by oral administration once a day. Triglyceride and total cholesterol contents were measured in liver and serum samples. Parameters for hepatic lipid metabolism and mitochondria biogenesis were assessed. Treatment with wild ginseng CMCs markedly attenuated body weight, serum and hepatic lipid contents, and serum aminotransferase activity. While wild ginseng CMCs attenuated the increases in sterol regulatory element-binding transcription factor 1 (SREBP-1) and carbohydrate-responsive element-binding protein (ChREBP) expression, it enhanced the increases in carnitine palmitoyltransferase 1A (CPT1A) and peroxisome proliferator-activated receptor alpha (PPAR-α) expression. HFD decreased glutamate dehydrogenase activity and glutathione content, and increased lipid peroxidation, which were all attenuated by wild ginseng CMCs. Furthermore, wild ginseng CMCs enhanced mitochondrial biogenesis-related factors, including peroxisome proliferator-activated receptor-γ co activator 1α (PGC1α), nuclear respiratory factor 1 (NRF1) and mitochondrial transcription factor A (TFAM). Wild ginseng CMCs protect against HFD-induced liver injury, which prevents lipid accumulation and mitochondrial oxidative stress, and enhances mitochondrial biogenesis.