Nicotinamide riboside supplementation exerts an anti-obesity effect and prevents inflammation and fibrosis in white adipose tissue of female diet-induced obesity mice.

Nicotinamide riboside (NR) is a nicotinamide adenine dinucleotide (NAD+) precursor. We previously reported that NR supplementation prevented the development of liver fibrosis in male mice. However, whether NR exerts a similar effect in females is unknown. Therefore, we determined whether NR supplementation can prevent obesity-induced inflammation and fibrosis in the liver and white adipose tissue (WAT) by providing NAD+ in obese female mice. Female C57BL/6J mice at the age of 8 weeks (young) and 16 weeks (old) were fed a high-fat/high-sucrose/high-cholesterol diet (HF) or HF diet supplemented with NR at 400 mg/kg/d for 20 weeks. While NR had minor effects in young female mice, it significantly reduced body weight gain, fat mass, glucose intolerance, and serum cholesterol levels compared to the HF group in old females. Hepatic NAD+ level tended toward an increase in the NR group (P=.054), but NR did not attenuate serum alanine aminotransferase levels, steatosis, and liver fibrosis in old female mice. However, NR decreased weight and adipocyte size in gonadal WAT (gWAT) of old females. NR also reduced the number of crown-like structures and the expression of inflammatory genes, along with decreases in fibrogenic gene expression and collagen accumulation in gWAT compared with the HF group. Also, old mice fed NR showed increased metabolic rates, physical activity, and energy expenditure compared with the HF. Thus, our results indicated that NR supplementation exerted an anti-obesity effect and prevented the development of inflammation and fibrosis in the WAT of old, but not young, female mice with diet-induced obesity.

Consumption of Low Dose Fucoxanthin Does Not Prevent Hepatic and Adipose Inflammation and Fibrosis in Mouse Models of Diet-Induced Obesity.

Fucoxanthin (FCX) is a xanthophyll carotenoid present in brown seaweed. The goal of this study was to examine whether FCX supplementation could attenuate obesity-associated metabolic abnormalities, fibrosis, and inflammation in two diet-induced obesity (DIO) mouse models. C57BL/6J mice were fed either a high-fat/high-sucrose/high-cholesterol (HFC) diet or a high-fat/high-sucrose (HFS) diet. The former induces more severe liver injury than the latter model. In the first study, male C57BL/6J mice were fed an HFC diet, or an HFC diet containing 0.015% or 0.03% (w/w) FCX powder for 12 weeks to develop obesity-induced nonalcoholic steatohepatitis (NASH). In the second study, mice were fed an HFS diet or an HFS diet containing 0.01% FCX powder for 8 weeks. FCX did not change body weight gain and serum lipid profiles compared to the HFC or HFS controls. No significant differences were present in liver triglyceride and total cholesterol, hepatic fat accumulation, and serum alanine aminotransferase levels between control and FCX-fed mice regardless of whether they were on an HFC or HFS diet. FCX did not mitigate mRNA abundance of genes involved in lipid synthesis, cholesterol metabolism, inflammation, and fibrosis in the liver and white adipose tissue, while hepatic fatty acid ß-oxidation genes were significantly elevated by FCX in both HFC and HFS feeding studies. Additionally, in the soleus muscle, FCX supplementation significantly elevated genes that regulate mitochondrial biogenesis and fatty acid ß-oxidation, concomitantly increasing mitochondrial DNA copy number, compared with HFC. In summary, FCX supplementation had minor effects on hepatic and white adipose inflammation and fibrosis in two different DIO mouse models.

Anthocyanin-Rich Aronia Berry Extract Mitigates High-Fat and High-Sucrose Diet-Induced Adipose Tissue Inflammation by Inhibiting Nuclear Factor-κB Activation.

Obesity-induced inflammation in adipose tissue (AT) promotes the development of metabolic dysregulations by increasing macrophage recruitment in the stromal vascular fraction (SVF). The activation of nuclear factor-κB (NF-κB) signaling in macrophages serves as a pivotal mediator of AT inflammatory responses by increasing the expression of proinflammatory genes in obesity. Given the purported anti-inflammatory effects of berry consumption in humans, we evaluated if anthocyanin-rich aronia berry extract (ARN) can prevent obesity-induced AT inflammation in vivo. We also examined whether ARN suppresses lipopolysaccharide (LPS)-induced NF-κB activation in RAW 264.7 macrophages and mouse bone marrow-derived macrophages (BMDMs). Male C57BL/6J mice were fed a low-fat diet, a high-fat (HF), and high-sucrose (HS) diet or HF/HS diet supplemented with 0.2% ARN (HF/HS + ARN) for 14 weeks. Compared to HF-/HS-fed mice, ARN supplementation tended to decrease fasting serum glucose (P = .07). Furthermore, ARN supplementation significantly inhibited the phosphorylation of NF-κB p65 in epididymal AT with a concomitant decrease in the expression of Cd11b and Tnfα mRNAs in epididymal SVF isolated, compared with those from HF-/HS-fed mice. Consistent with these in vivo findings, ARN treatment significantly decreased the phosphorylation of p65 in LPS-stimulated RAW 264.7 macrophages and BMDMs. Moreover, ARN suppressed LPS-induced mRNA expression of inflammation mediators (iNos, Cox-2, Tnfα, Mcp-1, and Il-6) and glycolysis markers (Glut1, G6pdh, and Hk1) in both cell types. Taken together, our in vivo and in vitro results suggest that ARN supplementation may attenuate obesity-induced AT inflammation by inhibiting NF-κB signaling and glycolytic pathway in macrophages.

The effect of cranberry consumption on lipid metabolism and inflammation in human apo A-I transgenic mice fed a high-fat and high-cholesterol diet.

Lipid metabolism and inflammation contribute to CVD development. This study investigated whether the consumption of cranberries (CR; Vaccinium macrocarpon) can alter HDL metabolism and prevent inflammation in mice expressing human apo A-I transgene (hApoAITg), which have similar HDL profiles to those of humans. Male hApoAITg mice were fed a modified American Institute of Nutrition-93M high-fat/high-cholesterol diet (16 % fat, 0·25 % cholesterol, w/w; n 15) or the high-fat/high-cholesterol diet containing CR (5 % dried CR powder, w/w, n 16) for 8 weeks. There were no significant differences in body weight between the groups. Serum total cholesterol, non-HDL-cholesterol and TAG concentrations were significantly lower in the control than CR group with no significant differences in serum HDL-cholesterol and apoA-I. Mice fed CR showed significantly lower serum lecithin-cholesterol acyltransferase activity than the control. Liver weight and steatosis were not significantly different between the groups, but hepatic expression of genes involved in cholesterol metabolism was significantly lower in the CR group. In the epididymal white adipose tissue (eWAT), the CR group showed higher weights with decreased expression of genes for lipogenesis and fatty acid oxidation. The mRNA abundance of F4/80, a macrophage marker and the numbers of crown-like structures were less in the CR group. In the soleus muscle, the CR group also demonstrated higher expression of genes for fatty acid ß-oxidation and mitochondrial biogenesis than those of the control. In conclusion, although CR consumption elicited minor effects on HDL metabolism, it prevented obesity-induced inflammation in eWAT with concomitant alterations in soleus muscle energy metabolism.

n-3 PUFAs inhibit TGFß1-induced profibrogenic gene expression by ameliorating the repression of PPARγ in hepatic stellate cells.

Activated hepatic stellate cells (HSCs) are primarily responsible for the accumulation of extracellular matrix substances during the development of liver fibrosis. It has been shown that n-3 polyunsaturated fatty acids (PUFAs) can prevent liver fibrosis development. However, the underlying mechanisms of action need further investigation. The objective of this study was to determine the regulatory roles of fatty acids (FAs) on the expression of profibrogenic genes in HSCs with the elucidation of mechanisms. LX-2 cells and primary human and mouse HSCs were treated with palmitic acid, oleic acid, linoleic acid, α-linolenic acid, eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA) to determine their effect on profibrogenic gene expression upon the activation by transforming growth factor ß1 (TGFß1). PUFAs significantly suppressed TGFß1-induced expression of profibrogenic genes in LX-2 and primary human HSCs with n-3 being more potent than n-6 PUFAs. However, PUFAs did not inhibit the phosphorylation and nuclear translocation of SMA- and MAD-related protein in primary human HSCs. Furthermore, PUFAs did not alter the profibrogenic gene expression in primary mouse HSCs. The inhibitory effect of EPA and DHA on TGFß1-induced profibrogenic gene expression was diminished by peroxisome proliferator-activated receptor gamma (PPARG) knockdown, although chemical inhibition of PPARγ did not elicit a similar result. The results suggest that n-3 PUFAs possess the most potent protective effects against TGFß1-induced profibrogenic gene expression, which is, at least in part, PPARγ-dependent in HSCs.

Health benefits of fucoxanthin in the prevention of chronic diseases.

Fucoxanthin is a xanthophyll carotenoid abundant in macroalgae, such as brown seaweeds. When fucoxanthin is consumed, it can be esterified or hydrolyzed to fucoxanthinol in the gastrointestinal tract and further converted into amarouciaxanthin A in the liver. It has a unique chemical structure that confers its biological effects. Fucoxanthin has a strong antioxidant capacity by scavenging singlet molecular oxygen and free radicals. Also, it exerts an anti-inflammatory effect. Studies have demonstrated potential health benefits of fucoxanthin for the prevention of chronic diseases, such as cancer, obesity, diabetes mellitus, and liver disease. Animal studies have shown that fucoxanthin supplementation has no adverse effects. However, investigation of the safety of fucoxanthin consumption in humans is lacking. Clinical trials are required to assess the safety of fucoxanthin in conjunction with the study of mechanisms by which fucoxanthin exhibits its health benefits. This review focuses on current knowledge of metabolism and functions of fucoxanthin with its potential health benefits. This article is part of a Special Issue entitled Carotenoids recent advances in cell and molecular biology edited by Johannes von Lintig and Loredana Quadro.

Nicotinamide riboside, an NAD+ precursor, attenuates the development of liver fibrosis in a diet-induced mouse model of liver fibrosis.

OBJECTIVE: Liver fibrosis is part of the non-alcoholic fatty liver disease (NAFLD) spectrum, which currently has no approved pharmacological treatment. In this study, we investigated whether supplementation of nicotinamide riboside (NR), a nicotinamide adenine dinucleotide (NAD+) precursor, can reduce the development of liver fibrosis in a diet-induced mouse model of liver fibrosis. METHODS: Male C57BL/6 J mice were fed a low-fat control (LF), a high-fat/high-sucrose/high-cholesterol control (HF) or a HF diet supplemented with NR at 400 mg/kg/day (HF-NR) for 20 weeks. Features of liver fibrosis were assessed by histological and biochemical analyses. Whole-body energy metabolism was also assessed using indirect calorimetry. Primary mouse and human hepatic stellate cells were used to determine the anti-fibrogenic effects of NR in vitro. RESULTS: NR supplementation significantly reduced body weight of mice only 7 weeks after mice were on the supplementation, but did not attenuate serum alanine aminotransferase levels, liver steatosis, or liver inflammation. However, NR markedly reduced collagen accumulation in the liver. RNA-Seq analysis suggested that the expression of genes involved in NAD+ metabolism is altered in activated hepatic stellate cells (HSCs) compared to quiescent HSCs. NR inhibited the activation of HSCs in primary mouse and human HSCs. Indirect calorimetry showed that NR increased energy expenditure, likely by upregulation of ß-oxidation in skeletal muscle and brown adipose tissue. CONCLUSION: NR attenuated HSC activation, leading to reduced liver fibrosis in a diet-induced mouse model of liver fibrosis. The data suggest that NR may be developed as a potential preventative for human liver fibrosis.

Spirulina supplementation in a mouse model of diet-induced liver fibrosis reduced the pro-inflammatory response of splenocytes.

Treatment of liver fibrosis is very limited as there is currently no effective anti-fibrotic therapy. Spirulina platensis (SP) is a blue-green alga that is widely supplemented in healthy foods. The objective of this study was to determine whether SP supplementation can prevent obesity-induced liver fibrosis in vivo. Male C57BL/6J mice were randomly assigned to a low-fat or a high-fat (HF)/high-sucrose/high-cholesterol diet or an HF diet supplemented with 2·5 % SP (w/w) (HF/SP) for 16 or 20 weeks. There were no significant differences in body weight, activity, energy expenditure, serum lipids or glucose tolerance between mice on HF and HF/SP diets. However, plasma alanine aminotransferase level was significantly reduced by SP at 16 weeks. Expression of fibrotic markers and trichrome stains showed no differences between HF and HF/SP. Splenocytes isolated from HF/SP fed mice had lower inflammatory gene expression and cytokine secretion compared with splenocytes from HF-fed mice. SP supplementation did not attenuate HF-induced liver fibrosis. However, the expression and secretion of inflammatory genes in splenocytes were significantly reduced by SP supplementation, demonstrating the anti-inflammatory effects of SP in vivo. Although SP did not show appreciable effect on the prevention of liver fibrosis in this mouse model, it may be beneficial for other inflammatory conditions.

Long-Term Supplementation of Black Elderberries Promotes Hyperlipidemia, but Reduces Liver Inflammation and Improves HDL Function and Atherosclerotic Plaque Stability in Apolipoprotein E-Knockout Mice.

SCOPE: HDL particles are protective against atherosclerosis, but may become dysfunctional during inflammation and chronic disease progression. Anthocyanin-rich foods, such as the black elderberry, may improve HDL function and prevent disease development via antioxidant and/or anti-inflammatory effects. This study investigates the long-term consumption of black elderberry extract (BEE) on HDL function and atherosclerosis in apolipoprotein (apo) E-/- mice. METHODS AND RESULTS: ApoE-/- mice (n = 12/group) are fed a low-fat diet, supplemented with 0, 0.25%, or 1% (by weight) BEE (≈37.5-150 mg anthocyanins per kg body weight) for 24 weeks. Feeding 1% BEE increases total serum cholesterol (+31%) and non-HDL cholesterol (+32%) compared with the control diet. PON1 arylesterase (+32%) and lactonase (+45%) activities also increase with the 1% BEE diet. Both 0.25% BEE and 1% BEE diets strongly increase HDL cholesterol efflux capacity (CEC) by 64% and 85%, respectively. Further, BEE dose-dependently lowers serum liver enzymes and hepatic inflammatory gene expression. Although there is no change in neutral lipid accumulation in atherosclerotic lesions, BEE promotes connective tissue deposition in the aortic root. CONCLUSIONS: Chronic BEE supplementation in apoE-/- mice dose-dependently improves HDL function. Despite BEE promoting hyperlipidemia, which likely offsets HDL effects, BEE increases connective tissue content, suggesting improved atherosclerotic plaque stability.

Food components with antifibrotic activity and implications in prevention of liver disease.

Increasing prevalence of nonalcoholic fatty liver disease (NAFLD) in parallel with the obesity epidemic has been a major public health concern. NAFLD is the most common chronic liver disease in the United States, ranging from fatty liver to steatohepatitis, fibrosis and cirrhosis in the liver. In response to chronic liver injury, fibrogenesis in the liver occurs as a protective response; however, prolonged and dysregulated fibrogenesis can lead to liver fibrosis, which can further progress to cirrhosis and eventually hepatocellular carcinoma. Interplay of hepatocytes, macrophages and hepatic stellate cells (HSCs) in the hepatic inflammatory and oxidative milieu is critical for the development of NAFLD. In particular, HSCs play a major role in the production of extracellular matrix proteins. Studies have demonstrated that bioactive food components and natural products, including astaxanthin, curcumin, blueberry, silymarin, coffee, vitamin C, vitamin E, vitamin D, resveratrol, quercetin and epigallocatechin-3-gallate, have antifibrotic effects in the liver. This review summarizes current knowledge of the mechanistic insight into the antifibrotic actions of the aforementioned bioactive food components.

Blackcurrant anthocyanins stimulated cholesterol transport via post-transcriptional induction of LDL receptor in Caco-2 cells.

PURPOSES: We previously showed that polyphenol-rich blackcurrant extract (BCE) showed a hypocholesterolemic effect in mice fed a high fat diet. As direct cholesterol removal from the body via the intestine has been recently appreciated, we investigated the effect of BCE on the modulation of genes involved in intestinal cholesterol transport using Caco-2 cells as an in vitro model. METHODS: Caco-2 cells were treated with BCE to determine its effects on mRNA and protein expression of genes important for intestinal cholesterol transport, low-density lipoprotein (LDL) uptake, cellular cholesterol content, and cholesterol transport from basolateral to apical membrane of Caco-2 cell monolayers. Cells were also treated with anthocyanin-rich or -poor fraction of BCE to determine the role of anthocyanin on BCE effects. RESULTS: BCE significantly increased protein levels of LDL receptor (LDLR) without altering its mRNA, which consequently increased LDL uptake into Caco-2 cells. This post-transcriptional induction of LDLR by BCE was markedly attenuated in the presence of rapamycin, an inhibitor of mechanistic target of rapamycin complex 1 (mTORC1). In addition, BCE altered genes involved in cholesterol transport in the enterocytes, including apical and basolateral cholesterol transporters, in such a way that could enhance cholesterol flux from the basolateral to apical side of the enterocytes. Indeed, BCE significantly increased the flux of LDL-derived cholesterol from the basolateral to the apical chamber of Caco-2 monolayer. LDLR protein levels were markedly increased by anthocyanin-rich fraction, but not by anthocyanin-free fraction. CONCLUSION: mTORC1-dependent post-transcriptional induction of LDLR by BCE anthocyanins drove the transport of LDL-derived cholesterol to the apical side of the enterocytes. This may represent a potential mechanism for the hypocholesterolemic effect of BCE.

Astaxanthin inhibits inflammation and fibrosis in the liver and adipose tissue of mouse models of diet-induced obesity and nonalcoholic steatohepatitis.

The objective of this study was to determine if astaxanthin (ASTX), a xanthophyll carotenoid, can prevent obesity-associated metabolic abnormalities, inflammation and fibrosis in diet-induced obesity (DIO) and nonalcoholic steatohepatitis (NASH) mouse models. Male C57BL/6J mice were fed a low-fat (6% fat, w/w), a high-fat/high-sucrose control (HF/HS; 35% fat, 35% sucrose, w/w), or a HF/HS containing ASTX (AHF/HS; 0.03% ASTX, w/w) for 30 weeks. To induce NASH, another set of mice was fed a HF/HS diet containing 2% cholesterol (HF/HS/HC) a HF/HS/HC with 0.015% ASTX (AHF/HS/HC) for 18 weeks. Compared to LF, HF/HS significantly increased plasma total cholesterol, triglyceride and glucose, which were lowered by ASTX. ASTX decreased hepatic mRNA levels of markers of macrophages and fibrosis in both models. The effect of ASTX was more prominent in NASH than DIO mice. In epididymal fat, ASTX also decreased macrophage infiltration and M1 macrophage marker expression, and inhibited hypoxia-inducible factor 1-α and its downstream fibrogenic genes in both mouse models. ASTX significantly decreased tumor necrosis factor α mRNA in the splenocytes from DIO mice upon lipopolysaccharides stimulation compared with those from control mice fed an HF/HS diet. Additionally, ASTX significantly elevated the levels of genes that regulate fatty acid ß-oxidation and mitochondrial biogenesis in the skeletal muscle compared with control obese mice, whereas no differences were noted in adipose lipogenic genes. Our results indicate that ASTX inhibits inflammation and fibrosis in the liver and adipose tissue and enhances the skeletal muscle's capacity for mitochondrial fatty acid oxidation in obese mice.

The Potential Role of an Endotoxin Tolerance-Like Mechanism for the Anti-Inflammatory Effect of Spirulina platensis Organic Extract in Macrophages.

Endotoxin tolerance is a phenomenon where exposure of innate immune cells to lipopolysaccharide (LPS) induces a refractory state to subsequent endotoxin exposures. The goal of this study was to investigate if Spirulina platensis organic extract (SPE) induces an endotoxin tolerance-like state. We used splenocytes and peritoneal macrophages from C57BL/6J mice fed a high-fat/high-sucrose (HF/HS) control or a HF/HS diet containing 0.25% (w/w) SPE for 16 weeks for ex vivo LPS stimulation and endotoxin-tolerant (ET) macrophages to evaluate the effects of SPE on endotoxin tolerance. Cells from SPE-fed mice displayed significantly less expression of proinflammatory genes than those from control mice. ET macrophages were produced in vitro by incubating RAW 264.7 macrophages with low-dose LPS to determine the energy phenotype of naive, SPE-treated, and ET macrophages. Compared to naive macrophages exposed to a high-dose LPS (100 ng/mL) for the first time, ET macrophages showed significantly less proinflammatory gene expression after LPS stimulation, which was also observed with SPE treatment. Consistently, nuclear translocation of p65 was markedly reduced in both ET- and SPE-treated macrophages on LPS stimulation with increase in nuclear protein levels of p50 and B cell lymphoma 3-encoded protein. In conclusion, the anti-inflammatory effect of SPE is at least partly attributable to the induction of an endotoxin tolerance-like state in macrophages, which shares common characteristics of macrophage endotoxin tolerance.

Vitamin A or E and a catechin synergize as vaccine adjuvant to enhance immune responses in mice by induction of early interleukin-15 but not interleukin-1ß responses.

Vitamins A and E and select flavonoids in the family of catechins are well-defined small molecules that, if proven to possess immunomodulatory properties, hold promise as vaccine adjuvants and various therapies. In an effort to determine the in vivo immunomodulatory properties of these molecules, we found that although mucosal and systemic vaccinations with a recombinant HIV-1BaL gp120 with either a catechin, epigallo catechin gallate (EGCG) or pro-vitamin A (retinyl palmitate) alone in a vegetable-oil-in-water emulsion (OWE) suppressed antigen-specific responses, the combination of EGCG and vitamin A or E in OWE (Nutritive Immune-enhancing Delivery System, NIDS) synergistically enhanced adaptive B-cell, and CD4(+) and CD8(+) T-cell responses, following induction of relatively low local and systemic innate tumour necrosis factor-α (TNF-α), interleukin-6 (IL-6) and IL-17, but relatively high levels of early systemic IL-15 responses. For induction of adaptive interferon-γ and TNF-α responses by CD4(+) and CD8(+) T cells, the adjuvant effect of NIDS was dependent on both IL-15 and its receptor. In addition, the anti-oxidant activity of NIDS correlated positively with higher expression of the superoxide dismutase 1, an enzyme involved in reactive oxygen species elimination but negatively with secretion of IL-1ß. This suggests that the mechanism of action of NIDS is dependent on anti-oxidant activity and IL-15, but independent of IL-1ß and inflammasome formation. These data show that this approach in nutritive vaccine adjuvant design holds promise for the development of potentially safer effective vaccines.

Blue-Green Algae Inhibit the Development of Atherosclerotic Lesions in Apolipoprotein E Knockout Mice.

Hyperlipidemia and inflammation contribute to the development of atherosclerotic lesions. Our objective was to determine antiatherogenic effect of edible blue-green algae (BGA) species, that is, Nostoc commune var. sphaeroides Kützing (NO) and Spirulina platensis (SP), in apolipoprotein E knockout (ApoE(-/-)) mice, a well-established mouse model of atherosclerosis. Male ApoE(-/-) mice were fed a high-fat/high-cholesterol (HF/HC, 15% fat and 0.2% cholesterol by wt) control diet or a HF/HC diet supplemented with 5% (w/w) of NO or SP powder for 12 weeks. Plasma total cholesterol (TC) and triglycerides (TG) were measured, and livers were analyzed for histology and gene expression. Morphometric analysis for lesions and immunohistochemical analysis for CD68 were conducted in the aorta and the aortic root. NO supplementation significantly decreased plasma TC and TG, and liver TC, compared to control and SP groups. In the livers of NO-fed mice, less lipid droplets were present with a concomitant decrease in fatty acid synthase protein levels than the other groups. There was a significant increase in hepatic low-density lipoprotein receptor protein levels in SP-supplemented mice than in control and NO groups. Quantification of aortic lesions by en face analysis demonstrated that both NO and SP decreased aortic lesion development to a similar degree compared with control. While lesions in the aortic root were not significantly different between groups, the CD68-stained area in the aortic root was significantly lowered in BGA-fed mice than controls. In conclusion, both NO and SP supplementation decreased the development of atherosclerotic lesions, suggesting that they may be used as a natural product for atheroprotection.

Hypolipidemic Effect of a Blue-Green Alga (Nostoc commune) Is Attributed to Its Nonlipid Fraction by Decreasing Intestinal Cholesterol Absorption in C57BL/6J Mice.

We previously demonstrated that Nostoc commune var. sphaeroids Kützing (NO), a blue-green alga (BGA), exerts a hypolipidemic effect in vivo and its lipid extract regulates the expression of genes involved in cholesterol and lipid metabolism in vitro. The objective of this study was to investigate whether the hypolipidemic effect of NO is attributed to an algal lipid or a delipidated fraction in vivo compared with Spirulina platensis (SP). Male C57BL/6J mice were fed an AIN-93M diet containing 2.5% or 5% of BGA (w/w) or a lipid extract equivalent to 5% of BGA for 4 weeks to measure plasma and liver lipids, hepatic gene expression, intestinal cholesterol absorption, and fecal sterol excretion. Plasma total cholesterol (TC) was significantly lower in 2.5% and 5% NO-fed groups, while plasma triglyceride (TG) levels were decreased in the 5% NO group compared with controls. However, neither NO organic extract (NOE) nor SP-fed groups altered plasma lipids. Hepatic mRNA levels of sterol regulatory element-binding protein 2, 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMGR), carnitine palmitoyltransferase-1α, and acyl-CoA oxidase 1 were induced in 5% NO-fed mice, while there were no significant changes in hepatic lipogenic gene expression between groups. NO, but not NOE and SP groups, significantly decreased intestinal cholesterol absorption. When HepG2 cells and primary mouse hepatocytes were incubated with NOE and SP organic extract (SPE), there were marked decreases in protein levels of HMGR, low-density lipoprotein receptor, and fatty acid synthase. In conclusion, the nonlipid fraction of NO exerts TC and TG-lowering effects primarily by inhibiting intestinal cholesterol absorption and by increasing hepatic fatty acid oxidation, respectively.

Polyphenol-rich blackcurrant extract exerts hypocholesterolaemic and hypoglycaemic effects in mice fed a diet containing high fat and cholesterol.

Obesity is associated with an increased risk of metabolic abnormalities, such as hyperlipidaemia and hyperglycaemia. We investigated whether polyphenol-rich blackcurrant extract (BCE) can prevent high fat/high cholesterol (HF/HC) diet-induced metabolic disturbances in mice. Male C57BL/6J mice were fed a modified AIN-93M diet containing HF/HC (16% fat, 0·25% cholesterol, w/w) or the same diet supplemented with 0·1% BCE (w/w) for 12 weeks. There were no differences in total body weight and liver weight between groups. Plasma total cholesterol (TC) and glucose levels were significantly lower in BCE group than in controls, while plasma TAG levels were not significantly different. There was a decreasing trend in hepatic TAG levels, and histological evaluation of steatosis grade was markedly lower in the livers of mice fed BCE. Although the mRNA levels of major regulators of hepatic cholesterol metabolism, i.e. 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMGR) and LDL receptor (LDLR), were not significantly altered by BCE supplementation, protein expression of mature sterol-regulatory element-binding protein and LDLR was significantly increased with no change in HMGR protein. The expression of proprotein convertase subtilisin/kexin type 9 that facilitates LDLR protein degradation, as well as one of its transcriptional regulators, i.e. hepatocyte nuclear factor 4α, was significantly decreased in the livers of mice fed BCE. Taken together, BCE supplementation decreased plasma TC and glucose, and inhibited liver steatosis, suggesting that this berry may be consumed to prevent metabolic dysfunctions induced by diets high in fat and cholesterol.

Green Tea Lowers Hepatic COX-2 and Prostaglandin E2 in Rats with Dietary Fat-Induced Nonalcoholic Steatohepatitis.

Green tea extract (GTE) protects against nonalcoholic steatohepatitis (NASH) by decreasing hepatic steatosis and nuclear factor kappa B (NFκB) activation. We hypothesized that hypolipidemic and anti-inflammatory activities of GTE would protect against NASH by reducing cyclooxygenase-2 (COX-2), an NFκB-dependent enzyme, and prostaglandin E2 (PGE2) in a dietary fat-induced obese model. Male Wistar rats were fed a low-fat diet containing no GTE or a high-fat (HF) diet containing GTE at 0%, 1%, or 2% for 8 weeks. Insulin resistance and total hepatic fatty acids increased following HF feeding (P<.05) and these were normalized by GTE at 1-2%. GTE (1-2%) normalized hepatic malondialdehyde without affecting cytochrome P450 2E1 mRNA expression, which was otherwise increased by HF feeding. HF-mediated increases in hepatic COX-2 protein and activity as well as PGE2 concentrations were normalized by GTE (1-2%). COX-2 activity and PGE2 were correlated to each other, and to serum alanine aminotransferase (ALT) and hepatic NFκB-binding activity (P<.05; r=0.28-0.49). GTE attenuated HF-mediated increases in total hepatic n-6 and n-3, without affecting the n-6/n-3 ratio. GTE did not affect HF-mediated increases in n-6 in nonesterified fatty acid (NEFA) and phospholipid pools, whereas n-3 and n-6/n-3 in both pools were unaffected by GTE and HF feeding. GTE decreased total hepatic arachidonic acid without affecting HF-mediated increases in arachidonic acid in NEFA or phospholipid pools. Thus, GTE attenuates lipid peroxidation and PGE2 accumulation by decreasing COX-2 activity independent of arachidonic acid availability and supports an additional mechanism by which GTE protects against liver injury during NASH in an HF-feeding model.

Astaxanthin lowers plasma TAG concentrations and increases hepatic antioxidant gene expression in diet-induced obesity mice.

Non-alcoholic fatty liver disease (NAFLD) is significantly associated with hyperlipidaemia and oxidative stress. We have previously reported that astaxanthin (ASTX), a xanthophyll carotenoid, lowers plasma total cholesterol and TAG concentrations in apoE knockout mice. To investigate whether ASTX supplementation can prevent the development of NAFLD in obesity, male C57BL/6J mice (n 8 per group) were fed a high-fat diet (35%, w/w) supplemented with 0, 0.003, 0.01 or 0.03% of ASTX (w/w) for 12 weeks. The 0.03% ASTX-supplemented group, but not the other groups, exhibited a significant decrease in plasma TAG concentrations, suggesting that ASTX at a 0.03% supplementation dosage exerts a hypotriacylglycerolaemic effect. Although there was an increase in the mRNA expression of fatty acid synthase and diglyceride acyltransferase 2, the mRNA levels of acyl-CoA oxidase 1, a critical enzyme in peroxisomal fatty acid ß-oxidation, exhibited an increase in the 0.03% ASTX-supplemented group. There was a decrease in plasma alanine transaminase (ALT) and aspartate transaminase (AST) concentrations in the 0.03% ASTX-supplemented group. There was a significant increase in the hepatic mRNA expression of nuclear factor erythroid 2-related factor 2 and its downstream genes, which are critical for endogenous antioxidant mechanism, in the 0.03% ASTX-supplemented group. Furthermore, there was a significant decrease in the mRNA abundance of IL-6 in the primary splenocytes isolated from the 0.03% ASTX-supplemented group upon lipopolysaccharide (LPS) stimulation when compared with that in the splenocytes isolated from the control group. In conclusion, ASTX supplementation lowered the plasma concentrations of TAG, ALT and AST, increased the hepatic expression of endogenous antioxidant genes, and rendered splenocytes less sensitive to LPS stimulation. Therefore, ASTX may prevent obesity-associated metabolic disturbances and inflammation.

Polyphenol-rich blackcurrant extract prevents inflammation in diet-induced obese mice.

Obesity is closely associated with chronic, low-grade inflammation. We investigated if polyphenol-rich blackcurrant extract (BCE) can prevent inflammation in vivo. Male C57BL/6J mice were fed a modified AIN-93M control diet containing high fat/high cholesterol (16% fat, 0.25% cholesterol by weight) or the control diet supplemented with 0.1% BCE (wt/wt) for 12 weeks. In BCE-fed mice, the percentage of body weight and adipocyte size of the epididymal fat were significantly lower than those of control mice. There were fewer crown-like structures (CLS) with concomitant decreases in F4/80, cluster of differentiation 68 and inhibitor of nuclear factor κB kinase ε (IKKε) mRNA in the epididymal adipose of BCE-fed mice. F4/80 and IKKε mRNA levels were positively correlated with CLS number. In the skeletal muscle of mice fed with BCE, mRNA expression of genes involved in energy expenditure and mitochondrial biogenesis, including PPARα, PPARδ, UCP-2, UCP-3 and mitochondrial transcription factor A, were significantly increased. When splenocytes from BCE-fed mice were stimulated by lipopolysaccharides, tumor necrosis factor α and interleukin-1ß mRNA were significantly lower than control splenocytes. Together, the results suggest that BCE supplementation decreases obesity-induced inflammation in adipose tissue and splenocytes, at least in part, by modulating energy metabolism in skeletal muscle.