Intestinal Cholesterol Research Articles

Siamese neem flower extract suppresses cholesterol absorption by interfering NPC1L1 and micellar property in vitro and in intestinal Caco-2 cells.

Siamese neem (Azadirachta indica A. Juss var. siamensis Valeton) (A. indica) leaf extract, a traditional ayurvedic medicine, has been reported to exhibit antipyretic, antibacterial, antidyslipidemic, and antihyperglycemia effects. This study investigated the mechanism of hypocholesterolemic effect of methanolic extract of Siamese neem flowers in in vitro studies and in Caco-2 cells. Pancreatic cholesterol esterase and 3-hydroxy 3-methylglutaryl-CoA (HMG-CoA) reductase activities were assessed. Cholesterol micelle formation was prepared for in vitro cholesterol physicochemical property analyses, micelle size and solubility, and transport of cholesterol into the Caco-2 cells. The expression of niemann-pick C1 like 1 (NPC1L1), and its major regulator, peroxisome proliferator-activated receptor δ (PPARδ), were determined by western blot and real time polymerase chain reaction, respectively. A. indica flower extract inhibited pancreatic cholesterol esterase activity and increased cholesterol micelles size. Uptake of cholesterol into Caco-2 cells was inhibited by A. indica flower extract in a dose-dependent manner. In addition, A. indica extract inhibited HMG-CoA reductase activity, resulting in low level of intracellular cholesterol accumulation, together with increased cytosolic NPC1L1 protein expression and decreased PPARδ gene expression. In conclusion, A. indica flower extract has cholesterol-lowering effects by inhibiting intestinal cholesterol absorption, interfering micellar cholesterol formation, and attenuating cholesterol synthesis. As such, A. indica flower extract has potential for developing into nutraceutical product for prevention of hypocholesterolemia.

Potential of Intestine-Selective FXR Modulation for Treatment of Metabolic Disease.

Farnesoid X receptor controls bile acid metabolism, both in the liver and intestine. This potent nuclear receptor not only maintains homeostasis of its own ligands, i.e., bile acids, but also regulates glucose and lipid metabolism as well as the immune system. These findings have led to substantial interest for FXR as a therapeutic target and to the recent approval of an FXR agonist for treating primary biliary cholangitis as well as ongoing clinical trials for other liver diseases. Given that FXR biology is complex, including moderate expression in tissues outside of the enterohepatic circulation, temporal expression of isoforms, posttranscriptional modifications, and the existence of several other bile acid-responsive receptors such as TGR5, clinical application of FXR modulators warrants thorough understanding of its actions. Recent findings have demonstrated remarkable physiological effects of targeting FXR specifically in the intestine (iFXR), thereby avoiding systemic release of modulators. These include local effects such as improvement of intestinal barrier function and intestinal cholesterol turnover, as well as systemic effects such as improvements in glucose homeostasis, insulin sensitivity, and nonalcoholic fatty liver disease (NAFLD). Intriguingly, metabolic improvements have been observed with both an iFXR agonist that leads to production of enteric Fgf15 and increased energy expenditure in adipose tissues and antagonists by reducing systemic ceramide levels and hepatic glucose production. Here we review the recent findings on the role of intestinal FXR and its targeting in metabolic disease.

Coffee prevents fatty liver disease induced by a high-fat diet by modulating pathways of the gut-liver axis.

Coffee consumption is inversely associated with the risk of non-alcoholic fatty liver disease (NAFLD). A gap in the literature still exists concerning the intestinal mechanisms that are involved in the protective effect of coffee consumption towards NAFLD. In this study, twenty-four C57BL/6J mice were divided into three groups each receiving a standard diet, a high-fat diet (HFD) or an HFD plus decaffeinated coffee (HFD+COFFEE) for 12 weeks. Coffee supplementation reduced HFD-induced liver macrovesicular steatosis (P<0·01) and serum cholesterol (P<0·001), alanine aminotransferase and glucose (P<0·05). Accordingly, liver PPAR- α (P<0·05) and acyl-CoA oxidase-1 (P<0·05) as well as duodenal ATP-binding cassette (ABC) subfamily A1 (ABCA1) and subfamily G1 (ABCG1) (P<0·05) mRNA expressions increased with coffee consumption. Compared with HFD animals, HFD+COFFEE mice had more undigested lipids in the caecal content and higher free fatty acid receptor-1 mRNA expression in the duodenum and colon. Furthermore, they showed an up-regulation of duodenal and colonic zonulin-1 (P<0·05), duodenal claudin (P<0·05) and duodenal peptide YY (P<0·05) mRNA as well as a higher abundance of Alcaligenaceae in the faeces (P<0·05). HFD+COFFEE mice had an energy intake comparable with HFD-fed mice but starting from the eighth intervention week they gained significantly less weight over time. Data altogether showed that coffee supplementation prevented HFD-induced NAFLD in mice by reducing hepatic fat deposition and metabolic derangement through modification of pathways underpinning liver fat oxidation, intestinal cholesterol efflux, energy metabolism and gut permeability. The hepatic and metabolic benefits induced by coffee were accompanied by changes in the gut microbiota.

Egg phospholipids exert an inhibitory effect on intestinal cholesterol absorption in mice.

BACKGROUND/OBJECTIVESConsumption of cholesterol-rich foods, such as eggs, has a minimal effect on circulating cholesterol levels in healthy humans. To gain insight, we investigated whether phospholipids rich in eggs (EPL) interfere with intestinal cholesterol absorption in vivo.MATERIALS/METHODSTo investigate the acute effect of EPL on intestinal cholesterol absorption, male C57BL/6J mice were orally administered with 6, 11, or 19 mg of EPL for three days. We also tested the effect of chronic EPL consumption on cholesterol metabolism in the small intestine and the liver in mice with diet-induced hypercholesterolemia. Male C57BL/6J mice were fed a high fat/high cholesterol (HF/HC; 35% fat, 0.25% cholesterol, w/w) diet for 4 weeks to induce hypercholesterolemia, and subsequently the mice were either fed 0, 0.4 or 0.8% (w/w) of EPL for 6 weeks.RESULTSIntestinal cholesterol absorption was significantly decreased by the highest dose of acute EPL administration compared to control. Chronic EPL supplementation did not significantly alter intestinal cholesterol absorption nor plasma levels of total cholesterol and low-density lipoprotein cholesterol. In the small intestine and the liver, EPL supplementation minimally altered the expression of genes which regulate cellular cholesterol levels.CONCLUSIONAlthough chronic EPL consumption was not able to counteract hypercholesterolemia in HF/HC-fed mice, acute EPL administration decreased intestinal cholesterol absorption. This study provides in vivo evidence that acute administration of PLs in eggs prevent cholesterol absorption in the intestine, suggesting a mechanism for a minimal effect of egg consumption on circulating cholesterol levels.

Intestine-Specific Overexpression of LDLR Enhances Cholesterol Excretion and Induces Metabolic Changes in Male Mice.

Roux-en-Y gastric bypass (RYGB) surgery is one of the most effective treatment options for severe obesity and related comorbidities, including hyperlipidemia, a well-established risk factor of cardiovascular diseases. Elucidating the molecular mechanisms underlying the beneficial effects of RYGB may facilitate development of equally effective, but less invasive, treatments. Recent studies have revealed that RYGB increases low-density lipoprotein receptor (LDLR) expression in the intestine of rodents. Therefore, in this study we first examined the effects of RYGB on intestinal cholesterol metabolism in human patients, and we show that they also exhibit profound changes and increased LDLR expression. We then hypothesized that the upregulation of intestinal LDLR may be sufficient to decrease circulating cholesterol levels. To this end, we generated and studied mice that overexpress human LDLR specifically in the intestine. This perturbation significantly affected intestinal metabolism, augmented fecal cholesterol excretion, and induced a reciprocal suppression of the machinery related to luminal cholesterol absorption and bile acid synthesis. Circulating cholesterol levels were significantly decreased and, remarkably, several other metabolic effects were similar to those observed in RYGB-treated rodents and patients, including improved glucose metabolism. These data highlight the importance of intestinal cholesterol metabolism for the beneficial metabolic effects of RYGB and for the treatment of hyperlipidemia.

Small Heterodimer Partner and Fibroblast Growth Factor 19 Inhibit Expression of NPC1L1 in Mouse Intestine and Cholesterol Absorption

The nuclear receptor subfamily 0 group B member 2 (NR0B2, also called SHP) is expressed at high levels in the liver and intestine. Postprandial fibroblast growth factor 19 (human FGF19, mouse FGF15) signaling increases the transcriptional activity of SHP. We studied the functions of SHP and FGF19 in the intestines of mice, including their regulation of expression of the cholesterol transporter NPC1L1 )NPC1-like intracellular cholesterol transporter 1) and cholesterol absorption. We performed histologic and biochemical analyses of intestinal tissues from C57BL/6 and SHP-knockout mice and performed RNA-sequencing analyses to identify genes regulated by SHP.The effects of fasting and refeeding on intestinal expression of NPC1L1 were examined in C57BL/6, SHP-knockout, and FGF15-knockout mice. Mice were given FGF19 daily for 1 week; fractional cholesterol absorption, cholesterol and bileacid (BA) levels, and composition of BAswere measured. Intestinal organoids were generated from C57BL/6 and SHP-knockout mice, and cholesterol uptake was measured. Luciferase reporter assays were performed with HT29 cells. We found that the genes that regulate lipid and ion transport in intestine, including NPC1L1, were up-regulated and that cholesterol absorption was increased in SHP-knockout mice compared with C57BL/6 mice. Expression of NPC1L1 was reduced in C57BL/6 mice after refeeding after fasting but not in SHP-knockout or FGF15-knockout mice. SHP-knockout mice had altered BA composition compared with C57BL/6 mice. FGF19 injection reduced expression of NPC1L1, decreased cholesterol absorption, and increased levels of hydrophilic BAs, including tauro-α- and -β-muricholic acids; these changes were not observed in SHP-knockout mice. SREBF2 (sterol regulatory element binding transcription factor 2), which regulates cholesterol, activated transcription of NPC1L1. FGF19 signaling led to phosphorylation of SHP, which inhibited SREBF2 activity. Postprandial FGF19 and SHP inhibit SREBF2, which leads to repression of intestinal NPC1L1 expression and cholesterol absorption. Strategies to increase FGF19 signaling to activateSHP might be developed for treatment of hypercholesterolemia.

Lactobacillus plantarum LRCC 5273 isolated from Kimchi ameliorates diet-induced hypercholesterolemia in C57BL/6 mice

This study was designed to select potent cholesterol-lowering probiotic strains on HepG2 cell and investigate the effect of selected strain, Lactobacillus plantarum LRCC 5273 and LRCC 5279 in hypercholesterolemic mice. In the results, LP5273 group showed significantly reduced total and LDL cholesterol compared to HCD group. In addition to significantly up-regulated hepatic mRNA expression of LXR-α and CYP7A1, intestinal LXR-α and ABCG5 were significantly up-regulated in LP5273 group. With activation of hepatic and intestinal LXR-α and its target genes, fecal cholesterol and bile acid excretion were increased in LP5273 fed mice. These results suggest that LP5273 ameliorates hypercholesterolemia in mice through the activation of hepatic and intestinal LXR-α, resulting in enhancement of fecal cholesterol and bile acids excretion in the small intestine. The results of present study suggest mechanistic evidences for hypocholesterolemic effects of L. plantarum spp., and may contribute to future researches for prevention of hypercholesterolemia and cardiovascular disease.

NPC1L1-dependent intestinal cholesterol absorption requires ganglioside GM3 in membrane microdomains

Intestinal cholesterol absorption is a key regulator of systemic cholesterol homeostasis. Excessive dietary cholesterol and its intestinal uptake lead to hypercholesterolemia, a major risk factor for cardiovascular disease. Intestinal cholesterol uptake is mediated by Niemann-Pick C1-like 1 (NPC1L1), a transmembrane protein localized in membrane microdomains (lipid rafts) enriched in gangliosides and cholesterol. The roles of gangliosides, such as monosialodihexosylganglioside (GM3) and its synthesizing enzyme GM3 synthase (GM3S), in NPC1L1-dependent cholesterol uptake have not been examined previously. Here, we examined NPC1L1-dependent cholesterol uptake in a cell model as well as in wild-type and apoE-deficient mice fed normal or high-cholesterol diets. We showed that NPC1L1-dependent cholesterol uptake was impaired in GM3S-deficient cells and that GM3S deficiency promoted resistance to hypercholesterolemia in both wild-type and apoE-deficient mice fed the high-cholesterol but not the normal diet. Our findings suggest that GM3 and related gangliosides are essential for NPC1L1-mediated intestinal cholesterol absorption and are potential targets for hypercholesterolemia therapy.

Trimethylamine N-Oxide: A Link among Diet, Gut Microbiota, Gene Regulation of Liver and Intestine Cholesterol Homeostasis and HDL Function.

Recent evidence, including massive gene-expression analysis and a wide-variety of other multi-omics approaches, demonstrates an interplay between gut microbiota and the regulation of plasma lipids. Gut microbial metabolism of choline and l-carnitine results in the formation of trimethylamine (TMA) and concomitant conversion into trimethylamine-N-oxide (TMAO) by liver flavin monooxygenase 3 (FMO3). The plasma level of TMAO is determined by the genetic variation, diet and composition of gut microbiota. Multiple studies have demonstrated an association between TMAO plasma levels and the risk of atherothrombotic cardiovascular disease (CVD). We aimed to review the molecular pathways by which TMAO production and FMO3 exert their proatherogenic effects. TMAO may promote foam cell formation by upregulating macrophage scavenger receptors, deregulating enterohepatic cholesterol and bile acid metabolism and impairing macrophage reverse cholesterol transport (RCT). Furthermore, FMO3 may promote dyslipidemia by regulating multiple genes involved in hepatic lipogenesis and gluconeogenesis. FMO3 also impairs multiple aspects of cholesterol homeostasis, including transintestinal cholesterol export and macrophage-specific RCT. At least part of these FMO3-mediated effects on lipid metabolism and atherogenesis seem to be independent of the TMA/TMAO formation. Overall, these findings have the potential to open a new era for the therapeutic manipulation of the gut microbiota to improve CVD risk.

Insulin increases cholesterol uptake, lipid droplet content, and apolipoprotein B secretion in CaCo-2 cells by upregulating SR-BI via a PI3K, AKT, and mTOR-dependent pathway.

CaCo-2 cells were cultured to postconfluency in Transwell filters and stimulated with glucose (25 mM) in the presence or absence of insulin (100 nM) at their basolateral surface. SR-BI mRNA and protein levels were quantified by quantitative reverse transcription-PCR and immunoblot, respectively. Polarized localization of SR-BI was determined by cell surface proteins biotinylation and streptavidin precipitation. Activities of PI3K, AKT, mTOR, and SR-BI were pharmacologically antagonized. Cholesterol uptake was assessed by NBD-cholesterol incorporation. Apolipoprotein (apo) B concentration was quantified by ELISA. Subcellular localization of neutral lipids (BODIPY) and SR-BI (immunofluorescence) was determined by confocal microscopy. In polarized CaCo-2 cells, insulin increased SR-BI at the mRNA and protein levels. SR-BI was exclusively present at apical cell surface, as indicated by biotinylation and confocal microscopy analysis. Glucose did not modify SR-BI abundance or subcellular localization. Effects of insulin on SR-BI levels were abrogated by PI3K, AKT, or mTOR pharmacological antagonism. Cholesterol uptake, neutral lipid abundance, and apo B secretion were increased by insulin in CaCo-2 cells, and these effects were prevented by SR-BI pharmacological antagonism with block lipid transport-1. insulin promotes cholesterol uptake, intracellular lipid store, and apo B-containing lipoproteins secretion by SR-BI-dependent mechanisms in a model of human intestinal epithelium.

A0030 The difference of anti-hypertensive drugs between KOREA and JAPAN

Objectives: Anti-hypertensive drugs are used for hypertensive patients around the world. Methods: We examined the anti-hypertensive drugs between KOREA and JAPAN. Results: The usual dose of Amlodipine (Ca antagonist) is 5 mg in both countries. But the dose of Irbesartan (Angiotensin II receptor antagonist; ARB) is different. Korean irbesartan has 150 mg and 300 mg tablets, and about 30% Korean patients are taking 300 mg. The maximam recommended dose is 300 mg in Korea, is higher than 200 mg in Japan. The Ca antagonist/ARB combination product is equivalent. The Ca antagonist/statin combination product is approved in both countries, but the dose of statin is different. Rosuvastatin has 5 mg, 10 mg and 20 mg tablets, and Atorvastatin has 10 mg, 20 mg and 40 mg tablets in Korea. In contrast, Rosuvastatin has 2.5 mg and 5 mg tablets, and Atorvastatin has 5 mg and 10 mg tablets in Japan. The maximam recommended dose of statin is higher in Korea than one in Japan. The dose of ezetimibe (intestinal cholesterol transporter inhibitor) is not different 10 mg once daily in both countries. Conclusion: Compared to anti-hypertensive and anti-hyperlipidemic drugs, ARB and statin are regulated. The recommended dose of drugs depends on the effectiveness and safety in process of each examination approval.

Plasma cholesterol-lowering activity of piperine is mediated by inhibition on cholesterol absorption via down-regulation of intestinal ACAT2 and MTP

Piperine is the major pungent ingredient in black and white peppers. The present study investigated plasma cholesterol-lowering activity of piperine and associated underlying mechanism in hypercholesterolemia hamsters. Thirty-two hamsters were assigned into four groups receiving one of four diets namely a non-cholesterol diet (NCD), a high-cholesterol diet (HCD), and the two HCD diets containing 0.03% (PL) and 0.06% (PH) piperine, respectively, for 6 weeks. Results showed that PL and PH diets significantly reduced plasma total cholesterol (TC) by 16–17%, and non-high-density lipoprotein cholesterol (non-HDL-C) by 24–25%, respectively. This was accompanied by 84–109% increase in fecal excretion of neutral sterols with down-regulation on gene expression of intestinal Niemann-Pick C1-like 1 protein (NPC1L1), acyl-CoA:cholesterol acyltransferase 2 (ACAT2), and microsomal triacylglycerol transport protein (MTP). It was concluded that plasma TC-lowering activity of piperine was mediated by reducing the intestinal cholesterol absorption via inhibition on gene expression of intestinal NPC1L1, ACAT and MTP.

Searching for high-binding peptides to bile acid for inhibition of intestinal cholesterol absorption using principal component analysis

We previously proposed a new method for exploring functional peptides using both spot-synthesis peptide libraries and principal component analysis (PCA). Here, we applied these methods to determine if high-binding 6-mer peptides can be used on bile acid for the inhibition of intestinal cholesterol absorption. We used a binding assay of 512 basal 4-mer peptides to bile acid, and from these selected high-binding and low-binding peptides. PCA was performed on data from both these binding groups and many physicochemical variables of the 512 peptides tested, and then through this, the variables were reduced to two principal components (PCs). The peptides were plotted on the PCA chart, and we identified distinct clusters of high- and low-binding regions. These PCA regions were applied to 6-mer random peptides, and we identified 6-mer peptides with high and low binding capacity to bile acid. We confirmed that the average fluorescence intensity of high-binding peptides was 3.0-fold higher than that of low-binding peptides. We succeeded in identifying 6-mer peptides with high and low-binding affinity based on the PCA analysis of 4-mer peptides. These results were compared and discussed with regard to those acquired by our previous computational analysis based on neural networks.

A LIMA1 variant promotes low plasma LDL cholesterol and decreases intestinal cholesterol absorption

A LIMA1 variant promotes low plasma LDL cholesterol and decreases intestinal cholesterol absorption

Effect of the prebiotic fiber inulin on cholesterol metabolism in wildtype mice

Dietary non-digestible carbohydrates are perceived to improve health via gut microbiota-dependent generation of products such as short-chain fatty acids (SCFA). In addition, SCFA are also precursors for lipid and cholesterol synthesis potentially resulting in unwanted effects on lipid metabolism. Inulin is a widely used model prebiotic dietary fiber. Inconsistent reports on the effects of inulin on cholesterol homeostasis have emerged in humans and preclinical models. To clarify this issue, the present study aimed to provide an in-depth characterization of the effects of short-chain (sc)- and long-chain (lc)- inulin on cholesterol synthesis, absorption and elimination in mice. Feeding wildtype C57BL/6J mice diets supplemented with 10% (w/w) of either sc- or lc-inulin for two weeks resulted in approximately 2.5-fold higher fecal SCFA levels (P < 0.01) compared with controls, but had no significant effects on plasma and liver lipids. Subtle shifts in fecal and plasma bile acid species were detected with beta-muricholic acid increasing significantly in plasma of the inulin fed groups (1.7-fold, P < 0.05). However, neither sc-inulin nor lc-inulin affected intestinal cholesterol absorption, mass fecal cholesterol excretion or trans-intestinal cholesterol excretion (TICE). Combined, our data demonstrate that sc- and lc-inulin have no adverse effects on cholesterol metabolism in mice despite increased generation of SCFA.

Effects of Calcium Bentonite on High Blood Cholesterol Level

Background : Calcium bentonite has been known to decrease high blood cholesterol level. This study aimed to explore whether a local calcium bentonite from West Java, Indonesia, had effect on lowering total blood cholesterol level. Methods : A laboratory experimental study was carried out on thirty adult male Wistar rats’ at Laboratory animals, Department of Pharmacology and Therapy, Universitas Padjadjaran in 2012. The rats were divided into five groups with six rats in each group, consisting of group I (negative control) with standard diet and distilled water, group II (positive control) with high lipid diet and distilled water, group III with high lipid diet and ezetimibe 0.18 g/rat/day, groups IV with high lipid diet and calcium bentonite 0.25 g/rat/day, group V with high lipid diet and calcium bentonite 0.5 g/rat/day. Ezetimibe as was used as this was an inhibitory agent of intestinal cholesterol absorption. Blood cholesterol levels were measured and analyzed using analysis of variance and Tukey’s post-hoc test. Results : Oral calcium bentonite at 0.25 g/rat/day and 0.5 g/rat/day significantly decrease total blood cholesterol level relative to the positive control group, 31.68% (p=0.018) and 32.87% (p=0.006) respectively, but its effect is inferior to ezetimibe 62.83% (p=0.000). Conclusions : Local calcium bentonite from West Java, Indonesia, has a significant lowering effect, however, the effect is less comparing to ezetimibe.

The Impact of Egg Nutrient Composition and Its Consumption on Cholesterol Homeostasis.

Nutrient deficiencies and excess are involved in many aspects of human health. As a source of essential nutrients, eggs have been used worldwide to support the nutritional needs of human societies. On the other hand, eggs also contain a significant amount of cholesterol, a lipid molecule that has been associated with the development of cardiovascular diseases. Whether the increase of egg consumption will lead to elevated cholesterol absorption and disruption of cholesterol homeostasis has been a concern of debate for a while. Cholesterol homeostasis is regulated through its dietary intake, endogenous biosynthesis, utilization, and excretion. Recently, some research interests have been paid to the effects of egg consumption on cholesterol homeostasis through the intestinal cholesterol absorption. Nutrient components in eggs such as phospholipids may contribute to this process. The goals of this review are to summarize the recent progress in this area and to discuss some potential benefits of egg consumption.

Chronic Activation of Liver X Receptor Sensitizes Mice to High Cholesterol Diet-Induced Gut Toxicity.

Cholesterol is essential for numerous biologic functions and processes, but an excess of intracellular cholesterol can be toxic. Intestinal cholesterol absorption is a major determinant of plasma cholesterol level. The liver X receptor (LXR) is a nuclear receptor known for its activity in cholesterol efflux and reverse cholesterol transport. In this study, we uncovered a surprising function of LXR in intestinal cholesterol absorption and toxicity. Genetic or pharmacologic activation of LXRα-sensitized mice to a high-cholesterol diet (HCD) induced intestinal toxicity and tissue damage, including the disruption of enterocyte tight junctions, whereas the same HCD caused little toxicity in the absence of LXR activation. The gut toxicity in HCD-fed LXR-KI mice may have been accounted for by the increased intestinal cholesterol absorption and elevation of enterocyte and systemic levels of free cholesterol. The increased intestinal cholesterol absorption preceded the gut toxicity, suggesting that the increased absorption was not secondary to tissue damage. The heightened sensitivity to HCD in the HCD-fed LXRα-activated mice appeared to be intestine-specific because the liver was not affected despite activation of the same receptor in this tissue. Moreover, heightened sensitivity to HCD cannot be reversed by ezetimibe, a Niemann-Pick C1-like 1 inhibitor that inhibits intestinal cholesterol absorption, suggesting that the increased cholesterol absorption in LXR-activated intestine is mediated by a mechanism that has yet to be defined.

Lipid-lowering effects of Coffea arabica pulp aqueous extract in Caco-2 cells and hypercholesterolemic rats

BackgroundCoffea arabica pulp (CP) is the first by-product obtained from coffee berries during coffee processing. The major constituents of CP, including chlorogenic acid, caffeine, and epicatechin exhibit anti-hyperlipidemic effects in in vitro and in vivo models. Whether Coffea arabica pulp aqueous extract (CPE) has a lipid-lowering effect remains unknown. PurposeThis study examined the effect of CPE on cholesterol absorption, and identified the mechanisms involved in lowered cholesterol in in vitro and in vivo models. MethodsUptake of [3H]-cholesterol micelles and the mode of CPE inhibition were determined using human intestinal Caco-2 cells, and subsequently, confirmed using isolated rat jejunal loops. In addition, the 12-week high-fat diet-induced hypercholesterolemic rats (HF) received either CPE (1000 mg/kg BW), a sole and high dose which was selected because it contained approximately 12 mg of CGA that was previously shown to have lipid-lowering effects, or ezetimibe (10 mg/kg BW), a cholesterol inhibitor. The rats were divided into HF, HF ++ CPE, and HF ++ ezetimibe groups for the next 12 weeks. Normal rats received a normal diet (ND) and CPE (ND + CPE). Body weights and lipid profiles were evaluated. Cholesterol transporter, Niemann–Pick C1-Like 1 (NPC1L1), protein expression and liver X receptor alpha (LXRα) mRNA expression were determined. In vitro micellar complex properties were also investigated. ResultsCPE inhibited [3H]-cholesterol micelle transport in Caco-2 cells and rat jejunal loops in a dose-dependent, non-competitive manner partly by decreasing membrane NPC1L1 expression. Congruently, CPE and its major constituents activated LXRα which, in turn, down-regulated NPC1L1. Furthermore, CPE interfered with physicochemical characteristics of cholesterol mixed micelles. These data were consistent with decreased body weight and slowed body weight gain and improved lipid profiles by CPE in hypercholesterolemic rats while no change occurred in these parameters in normal rats. Down-regulated intestinal NPC1L1 expression mediated by increased LXRα mRNA were also observed in HF ++ CPE and ND + CPE rats. ConclusionCPE has a cholesterol-lowering effect in in vitro and in vivo via inhibition of intestinal cholesterol absorption by down-regulating NPC1L1 mediated LXRα activation and interfering with micellar complex formation. Accordingly, CPE could be developed as nutraceutical product to prevent dyslipidemia-induced obesity and insulin resistance.

Overexpression of transforming growth factor β induced factor homeobox 1 represses NPC1L1 and lowers markers of intestinal cholesterol absorption

Background and aimsTransforming growth factor β induced factor homeobox 1 (TGIF1) is a transcriptional repressor that limits the response to transforming growth factor ß signaling and also represses transcription independent of this pathway. Recently, we found higher serum cholesterol levels and more hepatic lipid accumulation in mice lacking Tgif1, and showed that TGIF1 can repress the expression of Soat2, the gene encoding the cholesterol esterifying enzyme acyl-Coenzyme A:cholesterol acyltransferase 2. Although there is evidence that TGIF1 plays a role in lipid metabolism, its role in this metabolic pathway is not fully characterized. Here we investigate whether overexpression of TGIF1 affects intestinal cholesterol absorption. Methods and resultsTGIF1 was found to repress human and mouse Niemann-Pick C1 like 1 (Npc1l1) promoter activity in intestinal Caco2 cells. We also found TGIF1 to be able to oppose the induction of the promoter activity by sterol regulatory element binding protein 2 and hepatocyte nuclear factor 1α and 4α. To validate these effects of TGIF1 in vivo, we generated transgenic mice specifically overexpressing TGIF1 in the intestine (Villin-Tgif1). We observed lower intestinal expression levels of Npc1l1 that was associated with lower expression of ATP-binding cassette transporter (Abc) a1, Abcg5, and Abcg8. Villin-Tgif1 mice fed regular chow or a high-fat diet had lower levels of markers of intestinal cholesterol absorption than wild types. ConclusionsWe suggest TGIF1 as a new player in intestinal cholesterol metabolism.