CD36 is involved in lycopene and lutein uptake by adipocytes and adipose tissue cultures

The low-density lipoprotein receptor contributes to carotenoid homeostasis by regulating tissue uptake and fecal elimination

OBJECTIVE

Carotenoids are lipophilic plant molecules with antioxidant properties. Some carotenoids such as β-carotene also serve as vitamin A precursors, playing a key role in human health. Carotenoids are transported in lipoproteins with other lipids such as cholesterol, however, the mechanisms responsible for carotenoid storage in tissues and their non-enzymatic elimination remain relatively unexplored. The goal of this study was to examine the contribution of the low-density lipoprotein receptor (LDLR) in the bodily distribution and disposal of carotenoids.

METHODS

We employed mice lacking one or both carotenoid-cleaving enzymes as suitable models for carotenoid accumulation. We examined the contribution of LDLR in carotenoid distribution by crossbreeding these mice with Ldlr-/- mice or overexpressing LDLR in the liver.

RESULTS

Our results show that LDLR plays a dual role in carotenoid homeostasis by simultaneously favoring carotenoid storage in the liver and adipose tissue while facilitating their fecal elimination.

CONCLUSIONS

Our results highlight a novel role of the LDLR in carotenoid homeostasis, and unveil a previously unrecognized disposal pathway for these important bioactive molecules.

Characterization of the interindividual variability of lutein and zeaxanthin concentrations in the adipose tissue of healthy male adults and identification of combinations of genetic variants associated with it

Lutein (L) and zeaxanthin (Z) are involved in visual function and could prevent age-related macular degeneration and chronic diseases and improve cognitive performances. Adipose tissue is the main storage site for these xanthophylls (Xanth). The factors affecting their concentrations in this tissue remain poorly understood but in animal models, genetic variations in apolipoprotein E and β-carotene oxygenase 2 have been associated with adipose tissue L concentration. Therefore, the aims of this study were to better characterize the interindividual variability of adipose tissue Xanth concentration and to identify single nucleotide polymorphisms (SNPs) associated with it. Periumbilical subcutaneous adipose tissue samples were collected on 6 occasions in 42 healthy adult males and L and Z concentrations were measured by HPLC. Participants had their whole genome genotyped and the associations of 3589 SNPs in 49 candidate genes with the concentrations of L and Z were measured. Mean L and Z concentrations were 281 ± 27 and 150 ± 14 nmol g-1 proteins, respectively. There was no significant correlation between plasma and adipose tissue Xanth concentrations, although the correlation for L approached significance (Pearson's r = 0.276, p = 0.077). Following univariate filtering, 109 and 97 SNPs were then entered into a partial least squares regression analysis to identify the combination of SNPs that explained best adipose tissue concentration of L and Z, respectively. A combination of 7 SNPs in ELOVL5, PPARG, ISX and ABCA1, explained 58% of the variability in adipose tissue L concentration while 11 SNPs located in or near PPARG, ABCA1, ELOVL5, CXCL8, IRS1, ISX, MC4R explained 53% of the variance in adipose tissue Z concentration. This suggests that some genetic variations influence the concentrations of these Xanth in adipose tissue and could therefore indirectly influence the health effects of these compounds. Clinical Trial Registry: https://ClinicalTrials.gov registration number NCT02100774.

Effect of microencapsulated canthaxanthin and apo-ester on egg yolk color and antioxidant capacity in laying hens

This study was conducted to evaluate the effects of common canthaxanthin (CC) or microencapsulated canthaxanthin (MC) combined with apo-ester (AE) on productive performance, egg yolk color and antioxidant capacity in laying hens. A total of 270 Hyline Brown laying hens at 56 wk of age were allocated to 3 groups with 6 replicates, and fed a wheat-soybean meal basal diet or the same diet supplemented with CC+AE or MC+AE at 5 mg/kg feed for each supplement. The productive performance was not affected by dietary treatments. The 2 test groups had higher (P < 0.05) yolk color score in fresh eggs than the control group, but the yolk color score of CC+AE group significantly declined (P < 0.05) with time, and a slight decline was also observed in the MC+AE group at 36 d. The MC+AE group had higher (P < 0.05) yolk color score of fried and boiled eggs than the other 2 groups. Higher (P < 0.05) feed canthaxanthin concentration was found in the MC+AE group at the end of experiment, which also had higher yolk canthaxanthin concentration in fresh eggs at 24 and 36 d as well as in fried, boiled and stored (4°C and 25°C) eggs. The 2 test groups had higher (P < 0.05) total antioxidant capacity in serum than the control group, and lower (P < 0.05) MDA content was observed in the MC+AE group. The mRNA level of cluster determinant 36 in jejunum was increased by the 2 test groups, and the same increase was also found in liver only in the MC+AE group. In conclusion, MC was more efficient in promoting yolk color and antioxidant capacity than CC when combined with AE.

Cluster of Differentiation 36 (CD36) Preferentially Mediates Intestinal Absorption of Dietary Z-Astaxanthin and Especially 9-Z-Isomer via Higher Binding Affinity

Variances in the biological functions of astaxanthin geometric isomers (i.e., all-E, Z) are related to their intestinal absorption, but the mechanism of isomer absorption mediated by transporters remains unclear. Here, models of in vitro cell overexpression, in situ intestinal perfusion, and in vivo mouse inhibition were employed to investigate the impact of cluster of differentiation 36 (CD36) on the absorption of astaxanthin isomers. Cells overexpressing CD36 notably enhanced the uptake of Z-astaxanthin, particularly the 9-Z-isomer (47.76%). The absorption rate and permeability of Z-astaxanthin surpassed that of the all-E-isomer by the in situ model. Furthermore, the addition of the CD36-specific inhibitor sulfo-N-succinimidyl oleate significantly reduced the absorption of Z-astaxanthin in the mouse duodenum and jejunum, especially the 9-Z-isomer (57.66%). Molecular docking and surface plasmon resonance techniques further validated that 9-Z-astaxanthin binds to more amino acids of CD36 with higher affinity and in a fast-binding, fast-dissociating mode, thus favoring transport. Our findings elucidate, for the first time, the mechanism of the CD36-mediated transmembrane transport of astaxanthin geometric isomers.

Association of Candidate Single-Nucleotide Polymorphism Genotypes With Plasma and Skin Carotenoid Concentrations in Adults Provided a Lycopene-Rich Juice

BACKGROUND

Carotenoids are fat-soluble phytochemicals with biological roles, including ultraviolet protective functions in skin. Spectroscopic skin carotenoid measurements can also serve as a noninvasive biomarker for carotenoid consumption. Single-nucleotide polymorphisms (SNPs) in metabolic genes are associated with human plasma carotenoid concentrations; however, their relationships with skin carotenoid concentrations are unknown.

OBJECTIVES

The objective of this study was to determine the relationship between 13 candidate SNPs with skin and plasma carotenoid concentrations before and after a carotenoid-rich tomato juice intervention.

METHODS

In this randomized, controlled trial, participants (n = 80) were provided with lycopene-rich vegetable juice providing low (13.1 mg), medium (23.9 mg), and high (31.0 mg) daily total carotenoid doses for 8 wk. Plasma carotenoid concentrations were measured by high-pressure liquid chromatography, and skin carotenoid score was assessed by reflection spectroscopy (Veggie Meter) at baseline and the end-of-study time point. Thirteen candidate SNPs in 5 genes (BCO1, CD36, SCARB1, SETD7, and ABCA1) were genotyped from blood using PCR-based assays. Mixed models tested the effects of the intervention, study time point, interaction between intervention and study time point, and SNP genotype on skin and plasma carotenoids throughout the study. Baseline carotenoid intake, body mass index, gender, and age are covariates in all models.

RESULTS

The genotype of CD36 rs1527479 (P = 0.0490) was significantly associated with skin carotenoid concentrations when baseline and the final week of the intervention were evaluated. Genotypes for BCO1 rs7500996 (P = 0.0067) and CD36 rs1527479 (P = 0.0018) were significant predictors of skin carotenoid concentrations in a combined SNP model.

CONCLUSIONS

These novel associations between SNPs and skin carotenoid concentrations expand on the understanding of how genetic variation affects interindividual variation in skin carotenoid phenotypes in humans. This trial was registered at clinicaltrials.gov as NCT03202043.

Exploring the lutein therapeutic potential in steatotic liver disease: mechanistic insights and future directions

The global prevalence of Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD) is increasing, now affecting 25%-30% of the population worldwide. MASLD, characterized by hepatic steatosis, results from an imbalance in lipid metabolism, leading to oxidative stress, lipoperoxidation, and inflammation. The activation of autophagy, particularly lipophagy, alleviates hepatic steatosis by regulating intracellular lipid levels. Lutein, a carotenoid with antioxidant and anti-inflammatory properties, protects against liver damage, and individuals who consume high amounts of lutein have a lower risk of developing MASLD. Evidence suggests that lutein could modulate autophagy-related signaling pathways, such as the transcription factor EB (TFEB). TFEB plays a crucial role in regulating lipid homeostasis by linking autophagy to energy metabolism at the transcriptional level, making TFEB a potential target against MASLD. STARD3, a transmembrane protein that binds and transports cholesterol and sphingosine from lysosomes to the endoplasmic reticulum and mitochondria, has been shown to transport and bind lutein with high affinity. This protein may play a crucial role in the uptake and transport of lutein in the liver, contributing to the decrease in hepatic steatosis and the regulation of oxidative stress and inflammation. This review summarizes current knowledge on the role of lutein in lipophagy, the pathways it is involved in, its relationship with STARD3, and its potential as a pharmacological strategy to treat hepatic steatosis.

Effect of tomato, tomato-derived products and lycopene on metabolic inflammation: from epidemiological data to molecular mechanisms

The goal of this narrative review is to summarise the current knowledge and limitations related to the anti-inflammatory effects of tomato, tomato-derived products and lycopene in the context of metabolic inflammation associated to cardiometabolic diseases. The potential of tomato and tomato-derived product supplementation is supported by animal and in vitro studies. In addition, intervention studies provide arguments in favour of a limitation of metabolic inflammation. This is also the case for observational studies depicting inverse association between plasma lycopene levels and inflammation. Nevertheless, current data of intervention studies are mixed concerning the anti-inflammatory effect of tomato and tomato-derived products and are not in favour of an anti-inflammatory effect of pure lycopene in humans. From epidemiological to mechanistic studies, this review aims to identify limitations of the current knowledge and gaps that remain to be filled to improve our comprehension in contrasted anti-inflammatory effects of tomato, tomato-derived products and pure lycopene.

Cluster-determinant 36 (CD36) mediates intestinal absorption of dietary astaxanthin and affects its secretion

The functional activity of dietary astaxanthin is closely related to its absorption, and the absorption of dietary carotenoids mainly mediated by transmembrane transport protein (TTP) has become the mainstream research direction in recent years. However, the main TTP mediating astaxanthin absorption and its potential mechanisms are still unclear. Hence, based on the preliminary screening results, this study aims to elucidate the role of cluster-determinant 36 (CD36) mediating astaxanthin absorption from the perspective of expression levels through in vitro cell model, in situ single-pass intestinal perfusion model and in vivo mice model. The results showed that astaxanthin uptake was significantly increased by 45.13% in CD36 overexpressing cells and decreased by 20.92% in the case of sulfo-N-succinimidyl oleate (SSO) inhibition. A similar trend also appeared in the duodenum and jejunum by in situ model. Moreover, astaxanthin uptake in the small intestine of CD36 knockout mice was significantly reduced by 88.22%. Furthermore, the inhibition or knockout of CD36 suppressed the expression of other transporters (SR-BI and NPC1L1). Interestingly, CD36 was also involved in the downstream secretion pathway, which is manifested by interfering with the expression of related proteins (ERK1/2, MTP, ApoB48, and ApoAI). Therefore, these results indicate the important role of CD36 in astaxanthin transmembrane transport for the first time, providing vital exploration way for the absorption of dietary fat-soluble substances.

Preterm Pigs Fed Donor Human Milk Have Greater Liver β-Carotene Concentrations than Pigs Fed Infant Formula

BACKGROUND

Milk carotenoids may support preterm infant health and neurodevelopment. Infants fed human milk often have higher blood and tissue carotenoid concentrations than infants fed carotenoid-containing infant formula (IF). Donor human milk (DHM) is a supplement to mother's own milk, used to support preterm infant nutrition.

OBJECTIVES

We tested whether tissue and plasma β-carotene concentrations would be higher in preterm pigs fed pasteurized DHM versus premature IF.

METHODS

This is a secondary analysis of samples collected from a study of the effects of enteral diet composition on necrotizing enterocolitis incidence. Preterm pigs received partial enteral feeding of either DHM (n = 7) or premature IF (n = 7) from 2 to 7 d of age. The diets provided similar β-carotene (32 nM), but DHM had higher lutein, zeaxanthin, and lycopene, whereas IF had higher total vitamin A. Plasma, liver, and jejunum carotenoid and vitamin A concentrations were measured by HPLC-PDA. Jejunal expression of 12 genes associated with carotenoid and lipid metabolism were measured.

RESULTS

Liver β-carotene concentrations were higher in DHM- than IF-fed piglets (23 ± 4 compared with 16 ± 2 μg/g, respectively, P = 0.0024), whereas plasma and jejunal β-carotene concentrations were similar between diets. Liver vitamin A stores were higher in piglets fed IF than DHM (50.6 ± 10.1 compared with 30.9 ± 7.2 μg/g, respectively, P=0.0013); however, plasma vitamin A was similar between groups. Plasma, liver, and jejunum concentrations of lutein, zeaxanthin, and lycopene were higher with DHM than IF feeding. Relative to piglets fed DHM, jejunal low density lipoprotein receptor (Ldlr) expression was higher (61%, P = 0.018) and cluster determinant 36 (Cd36) expression (-27%, P = 0.034) was lower in IF-fed piglets.

CONCLUSIONS

Preterm pigs fed DHM accumulate more liver β-carotene than IF-fed pigs. Future studies should further investigate infant carotenoid bioactivity and bioavailability.

Pharmacological potentials of lycopene against aging and aging-related disorders: A review

Aging and aging-related chronic disorders are one of the principal causes of death worldwide. The prevalence of these disorders is increasing gradually and globally. Considering this unwavering acceleration of the global burden, seeking alternatives to traditional medication to prevent the risk of aging disorders is needed. Among them, lycopene, a carotenoid, is abundant in many fruits and vegetables, including tomatoes, grapefruits, and watermelons, and it has a unique chemical structure to be a potent antioxidant compound. This nutraceutical also possesses several anti-aging actions, including combating aging biomarkers and ameliorating several chronic disorders. However, no systematic evaluation has yet been carried out that can comprehensively elucidate the effectiveness of lycopene in halting the course of aging and the emergence of chronic diseases linked to aging. This review, therefore, incorporates previous pre-clinical, clinical, and epidemiological studies on lycopene to understand its potency in treating aging disorders and its role as a mimic of caloric restriction. Lycopene-rich foods are found to prevent or attenuate aging disorders in various research. Based on the evidence, this review suggests the clinical application of lycopene to improve human health and alleviate the prevalence of aging and aging disorders.

Maternal High-Fat Diet Consumption in Sprague Dawley Rats Compromised the Availability and Altered the Tissue Distribution of Lutein in Neonatal Offspring

Lutein, the most abundant carotenoid in the infant eye and brain, is critical for their visual and cognitive development. Due to its lipophilic nature, a high adiposity may affect the tissue distribution of lutein. The aim of the study was to determine the impacts of a maternal high-fat diet (HFD) consumption on the status of lutein in the neonatal offspring. Female Sprague Dawley rats (n = 6) were fed a normal fat diet (NFD) or a HFD for 8 weeks before mating, and they were switched to an NFD or an HFD containing the same concentration of lutein ester during gestation and lactation. Rat pups (n = 7/group/time) were euthanized on postnatal day 2 (P2), P6, P11, and P20 for measuring tissue lutein concentrations. No significant difference in maternal lutein intake was found between the two groups. At both P6 and P11, a significantly lower lutein concentration was noted in the milk samples separated from the stomach of HFD pups than the concentration in the samples from the NFD pups; the HFD group showed a significantly lower lutein concentration in the liver. At P11, the HFD pups exhibited a significantly lower lutein concentration in the eye, brain, and brown adipose tissue accompanied with a significantly higher lutein concentration and mass in the visceral white adipose tissue. The study was the first to provide evidence that maternal HFD consumption resulted in a compromised availability and altered distribution of lutein in the neonatal offspring.

CD36 AFFECTS CHICKEN CARCASS, SKIN YELLOWNESS Detection of CD36 gene polymorphism associated with chicken carcass traits and skin yellowness

Investigations into the association between chicken traits and genetic variations provide helpful breeding information to improve production performance and economic benefits in chickens. The single nucleotide polymorphism technique is an important method in agricultural molecular breeding. In this study, we detected 11 SNPs in the CD36 gene, 2 SNPs (g.-1974 A>G, g.-1888 T>C) located in the 5' flanking regions, 8 SNPs (g.23496 G>A, g.23643 C>T, g.23931 T>C, g.23937 G>A, g.31256 C>A, g.31258 C>T, g.31335 C>T, g.31534 A>C) located in the intron region, 1 SNPs (g.23743 G>T) located in the exon region and it belongs to synonymous mutation. In SNPs g.23743 G>T, the abdominal fat weight and abdominal fat weight rate of the GG genotype were lower than that of the TT genotype. In SNPs g.23931 T>C, the full-bore weight rate and half-bore weight rate of the TT genotype were higher compared with the CC genotype. And the SNPs g.-1888 T>C, g.23496 G>A, g.23643 C>T, g.31335 C>T and g.31534 A>C were significantly associated with skin yellowness traits, the cloacal skin yellowness before slaughter of the TT genotype was higher than that of the TC and CC genotype in SNPs g.-1888 T>C. Furthermore, 3 haplotypes of the above eleven SNPs were calculated and they correlated with heart weight, stomach weight, wing weight, leg skin yellowness and shin skin yellowness before slaughter. Finally, the CD36 expression profile displayed the expression pattern of CD36 mRNA variation in different tissues.

Identification of candidate genes associated with skin yellowness in yellow chickens

The yellow color of the skin is an important economic trait for yellow chickens. Low and non-uniform skin yellowness would reduce economic efficiency. However, the regulatory mechanism of chicken skin yellowness has not been fully elucidated. In this study, we evaluated the skin yellowness of 819 chickens by colorimeter and digital camera, which are from the same batch and the same age of 2 pure lines with significant differences in skin yellowness. A total of 982 candidate differential expressed genes (DEGs) were detected in duodenal tissue by RNA-seq analysis for high and low yellowness chickens. Among the DEGs, we chose fatty acid translocase (CD36) gene and identified a single nucleotide polymorphism (SNP) upstream of the CD36 gene that was significantly associated with skin yellowness at multiple parts of the chicken, and its different genotypes had significant effects on the promoter activity of the CD36 gene. These findings will help to further elucidate the molecular mechanism of chicken skin yellowness and is helpful for improving chicken skin yellowness.

In-Season Consumption of Locally Produced Tomatoes Decreases Cardiovascular Risk Indices

Tomatoes are widely consumed worldwide at any time of the year. However, depending on the variety, they have a characteristic season. We evaluated the consequences metabolic of consumption of Ekstasis tomatoes from different geographical origin and in different seasons in Fischer 344 rats. The hepatic gene expression of key enzymes in lipid metabolism was also evaluated. Animals were classified in three photoperiods (L6, L12, and L18) and in three treatments (vehicle: VH; local tomato: LT; and non-local tomato: nLT). We measured serum metabolic parameters and the gene expression of liver enzymes related to lipid metabolism (Acc1, Cpt1a, Had, Fas1, Srebp-1c, Fatp5, Cd36). LT consumption in season decreased cardiovascular risk 1 and coefficient atherogenic by 1.81 (p = 0.031) and in L6 decreased TAG and glucose (p = 0.046; p = 0.024). The L18-LT animals had decreased total cholesterol (p = 0.029) and gene expression of Srebp1-c (p = 0.022) but increased expression of Acc1 (p = 0.032). The treatments significantly affected the expression of Acc1 and Fas1 in the liver and the levels of serum TAG and glucose. A significant effect of photoperiod on serum concentration of glucose, insulin, HOMA index, and on the hepatic expression of Srep1-c, Fas1, and Acc1 was observed.

Bioactive dietary components-Anti-obesity effects related to energy metabolism and inflammation

Obesity is the result of the long-term energy imbalance between the excess calories consumed and the few calories expended. Reducing the intake of energy dense foods (fats, sugars), and strategies such as fasting and caloric restriction can promote body weight loss. Not only energy in terms of calories, but also the specific composition of the diet can affect the way the food is absorbed and how its energy is stored, used or dissipated. Recent research has shown that bioactive components of food, such as polyphenols and vitamins, can influence obesity and its pathologic complications such as insulin resistance, inflammation and metabolic syndrome. Individual micronutrients can influence lipid turnover but for long-term effects on weight stability, dietary patterns containing several micronutrients may be required. At the molecular level, these molecules modulate signaling and the expression of genes that are involved in the regulation of energy intake, lipid metabolism, adipogenesis into white, beige and brown adipose tissue, thermogenesis, lipotoxicity, adipo/cytokine synthesis, and inflammation. Higher concentrations of these molecules can be reached in the intestine, where they can modulate the composition and action of the microbiome. In this review, the molecular mechanisms by which bioactive compounds and vitamins modulate energy metabolism, inflammation and obesity are discussed.

A review of recent progress in improving the bioavailability of nutraceutical-loaded emulsions after oral intake

Increasing awareness of the health benefits of specific constituents in fruits, vegetables, cereals, and other whole foods has sparked a broader interest in the potential health benefits of nutraceuticals. Many nutraceuticals are hydrophobic substances, which means they must be encapsulated in colloidal delivery systems. Oil-in-water emulsions are one of the most widely used delivery systems for improving the bioavailability and bioactivity of these nutraceuticals. The composition and structure of emulsions can be designed to improve the water dispersibility, physicochemical stability, and bioavailability of the encapsulated nutraceuticals. The nature of the emulsion used influences the interfacial area and properties of the nutraceutical-loaded oil droplets in the gastrointestinal tract, which influences their digestion, as well as the bioaccessibility, metabolism, and absorption of the nutraceuticals. In this article, we review recent in vitro and in vivo studies on the utilization of emulsions to improve the bioavailability of nutraceuticals. The findings from this review should facilitate the design of more efficacious nutraceutical-loaded emulsions with increased bioactivity.

Recent insights into vitamin D, adipocyte, and adipose tissue biology

Several studies bring strong evidence for an active role of vitamin D and its metabolites in physiological adipocyte and adipose tissue processes in adulthood. This role includes effects of vitamin D on key adipose tissue and adipocyte biology parameters, including adipogenesis, energy metabolism, and inflammation. Interestingly, recent data also point to a role of maternal vitamin D deficiency in adipocyte and adipose tissue metabolic programming in offspring. This review summarizes the current state of knowledge on the biological effect of vitamin D on adipocyte/adipose tissue physiology.

Bioavailability evaluation of the intestinal absorption and liver accumulation of torularhodin using a rat postprandial model

Torularhodin, as a new functional carotenoid, possesses great application potential in disease intervention. However, its absorption process and corresponding mechanism have not been studied. In this study, a rat postprandial model was established to explore the absorption and mechanism of torularhodin by investigating the bioavailability of torularhodin in different tissues, the expression of related enzymes and several transporters in the intestine. The results showed that torularhodin entered the intestine faster from micelles (45.21 ± 2.61% was absorbed in the duodenum), and part of it was metabolized into retinol in the anterior segment of the intestine. The expression of genes indicated that absorption of torularhodin in the intestine might require transporter CD36 and SR-B1. The special structure and target organ might be speculated to be the main reason for the low bioavailability of torularhodin in the serum and liver. The results could lay a theoretical foundation for the chemical modification, carrier and subsequent development of torularhodin.

β-Carotene stimulates browning of 3T3-L1 white adipocytes by enhancing thermogenesis via the β3-AR/p38 MAPK/SIRT signaling pathway

BACKGROUND

Natural compounds with medicinal properties are part of a strategic trend in the treatment of obesity. The vitamin A agent, β-carotene, is a well-known carotenoid, and its numerous functions in metabolism have been widely studied. The activation of thermogenesis by stimulating white fat browning (beiging) has been identified as a treatment for obese individuals.

PURPOSE

The current study was undertaken to unveil the browning activity of β-carotene in 3T3-L1 white adipocytes.

METHODS

The effects of β-carotene were evaluated in 3T3-L1 white adipocytes, and gene/protein expressions were determined by performing quantitative real-time PCR, immunoblot analysis, immunofluorescence assessment, and molecular docking techniques.

RESULTS

β-carotene strikingly increased the expression levels of brown-fat-specific marker proteins (UCP1, PRDM16, and PGC-1α) and beige-fat-specific genes (Cd137, Cidea, Cited1, andTbx1) in 3T3-L1 cells. Exposure to β-carotene also elevated the expressions of key adipogenic transcription factors C/EBPα and PPARγ in white adipocytes but decreased the expressions of lipogenic marker proteins ACC and FAS. Moreover, lipolysis and fat oxidation were regulated by β-carotene via upregulation of ATGL, pHSL, ACOX, and CPT1. In addition, molecular docking studies revealed β-carotene activation of the adenosine A2A receptor and β3-AR. β-Carotene increased the expressions of mitochondrial biogenic markers, stimulated the β3-AR and p38 MAPK signaling pathways and its downstream signaling molecules (SIRTs and ATF2), thereby inducing browning.

CONCLUSIONS

Taken together, our results indicate the potential of β-carotene as a natural-source therapeutic anti-obesity agent.

Carotenoid transporter CD36 expression depends on hypoxia-inducible factor-1α in mouse soleus muscles

Dietary β-carotene induces muscle hypertrophy and prevents muscle atrophy in red slow-twitch soleus muscles, but not in white fast-twitch extensor digitorum longus (EDL) muscles and gastrocnemius muscles. However, it remains unclear why these beneficial effects of β-carotene are elicited in soleus muscles. To address this issue, we focused on carotenoid transporters in skeletal muscles. In mice, Cd36 mRNA levels were higher in red muscle than in white muscle. The siRNA-mediated knockdown of CD36 decreased β-carotene uptake in C2C12 myotubes. In soleus muscles, CD36 knockdown inhibited β-carotene-induced increase in muscle mass. Intravenous injection of the hypoxia marker pimonidazole produced more pimonidazole-bound proteins in soleus muscles than in EDL muscles, and the hypoxia-inducible factor-1 (HIF-1) α protein level was higher in soleus muscles than in EDL muscles. In C2C12 myotubes, hypoxia increased the expression of CD36 and HIF-1α at the protein and mRNA levels, and HIF-1α knockdown reduced hypoxia-induced increase in Cd36 mRNA level. In soleus muscles, HIF-1α knockdown reduced Cd36 mRNA level. These results indicate that CD36 is predominantly involved in β-carotene-induced increase in soleus muscle mass of mice. Furthermore, we demonstrate that CD36 expression depends on HIF-1α in the soleus muscles of mice, even under normal physiological conditions.

Carotenoids in Milk and the Potential for Dairy Based Functional Foods

Carotenoids are a family of over 1100 known natural pigments synthesized by plants, algae, fungi and bacteria. Dietary intake of carotenoids is necessary for mammals as they cannot be synthesized in the body. In cows, the nature of the diet consumed strongly influences the composition of milk produced and this includes carotenoid concentration and profile. Fresh forage is the richest source of carotenoids for cows. The main carotenoids identified in forages are lutein, β-carotene, zeaxanthin and epilutein. Manipulating cow feed via carotenoid supplementation increases the carotenoid content of bovine milk. In humans, carotenoids have anti-oxidant, anti-inflammatory and provitamin A activity. Lutein is a major carotenoid in human milk and the brain tissue of adults and infants. Lutein and zeaxanthin are linked to improved eye health and cognitive function. Traditionally for humans, fruit and vegetables have been the main source of carotenoid intake. Functional foods present an opportunity to incorporate these naturally occurring compounds into milk products for added health benefits, widening the range of dietary sources of carotenoids. We offer an overview of the literature to date on carotenoid-fortified dairy products and infant formula. This review will describe and summarize the key mechanisms by which the carotenoid profile of bovine milk can be manipulated. We present findings on the origin and role of carotenoids in bovine and human milk, outline factors that impact the carotenoid content of milk, evaluate carotenoid-fortified milk products and discuss the associated challenges, such as bioaccessibility and stability.

From carotenoid intake to carotenoid blood and tissue concentrations - implications for dietary intake recommendations

There is uncertainty regarding carotenoid intake recommendations, because positive and negative health effects have been found or are correlated with carotenoid intake and tissue levels (including blood, adipose tissue, and the macula), depending on the type of study (epidemiological vs intervention), the dose (physiological vs supraphysiological) and the matrix (foods vs supplements, isolated or used in combination). All these factors, combined with interindividual response variations (eg, depending on age, sex, disease state, genetic makeup), make the relationship between carotenoid intake and their blood/tissue concentrations often unclear and highly variable. Although blood total carotenoid concentrations <1000 nmol/L have been related to increased chronic disease risk, no dietary reference intakes (DRIs) exist. Although high total plasma/serum carotenoid concentrations of up to 7500 nmol/L are achievable after supplementation, a plateauing effect for higher doses and prolonged intake is apparent. In this review and position paper, the current knowledge on carotenoids in serum/plasma and tissues and their relationship to dietary intake and health status is summarized with the aim of proposing suggestions for a "normal," safe, and desirable range of concentrations that presumably are beneficial for health. Existing recommendations are likewise evaluated and practical dietary suggestions are included.

Study on the bioavailability of stevioside-encapsulized lutein and its mechanism

This study aims to develop novel lutein nanoparticles encapsulized by stevioside (LUT-STE, 165 ± 2 nm average particles size) and systematically evaluate its bioavailability. Multiple spectroscopy and NMR analyses showed lutein and stevioside could interact through hydrogen bonds, CHπ interaction and van der Waals forces. Molecular docking simulation showed lutein was well distributed in the hydrophobic cavity of stevioside. Analyzed by Caco-2 cellular models, the transported amount of LUT-STE was 2.39 times that of lutein in 120 min with a P_app (B → A)/P_app (A → B) value of 0.63 ± 0.04. Nystatin and dynasore significantly reduced the cellular uptake of LUT-STE by 41.3% and 57.7%, respectively. Compared with free lutein, LUT-STE increased the C_max in mice plasma by 5.01-fold and promoted the accumulation in multiple organs. LUT-STE promoted the protein expressions of CD36, NPC1L1 and PPARγ in both cell and animal models. In conclusion, stevioside entrapment significantly promote the bioavailability of lutein through multiple transmembrane pathways.

Lycopene: A Critical Review of Digestion, Absorption, Metabolism, and Excretion

Lycopene is a non-provitamin A carotenoid that exhibits several health benefits. Epidemiological data support a correlation between lycopene intake and the attenuation of several chronic diseases, including certain types of cancers and cardiovascular diseases. It is currently unknown whether the beneficial effects are from the native structure of lycopene or its metabolic derivatives: lycopenals, lycopenols, and lycopenoic acids. This literature review focuses on the current research on lycopene digestion, absorption, metabolism, and excretion. This review primarily focuses on in vivo studies because of the labile nature and difficulty of studying carotenoids within in vitro experimental models. The studies presented address tissue accumulation of lycopene, the modification of bioavailability due to genetic and dietary factors, and lycopene cleavage by the enzymes ß-carotene oxygenase 1 (BCO1) and ß-carotene oxygenase 2 (BCO2). The current literature suggests that the majority of lycopene is cleaved eccentrically by BCO2, yet further research is needed to probe the enzymatic cleavage activity at the tissue level. Additionally, results indicate that single nucleotide polymorphisms and dietary fat influence lycopene absorption and thus modify its health effects. Further research exploring the metabolism of lycopene, the mechanisms related to its health benefits, and optimal diet composition to increase the bioavailability is required.

The Remedial Potential of Lycopene in Pancreatitis through Regulation of Autophagy

Autophagy is an evolutionarily conserved process that degrades damaged organelles and recycles macromolecules to support cell survival. However, in certain disease states, dysregulated autophagy can play an important role in cell death. In pancreatitis, the accumulation of autophagic vacuoles and damaged mitochondria and premature activation of trypsinogen are shown in pancreatic acinar cells (PACs), which are the hallmarks of impaired autophagy. Oxidative stress mediates inflammatory signaling and cytokine expression in PACs, and it also causes mitochondrial dysfunction and dysregulated autophagy. Thus, oxidative stress may be a mediator for autophagic impairment in pancreatitis. Lycopene is a natural pigment that contributes to the red color of fruits and vegetables. Due to its antioxidant activity, it inhibited oxidative stress-induced expression of cytokines in experimental models of acute pancreatitis. Lycopene reduces cell death through the activation of 5′-AMP-activated protein kinase-dependent autophagy in certain cells. Therefore, lycopene may ameliorate pancreatitis by preventing oxidative stress-induced impairment of autophagy and/or by directly activating autophagy in PACs.

Lycopene as a Natural Antioxidant Used to Prevent Human Health Disorders

Lycopene, belonging to the carotenoids, is a tetraterpene compound abundantly found in tomato and tomato-based products. It is fundamentally recognized as a potent antioxidant and a non-pro-vitamin A carotenoid. Lycopene has been found to be efficient in ameliorating cancer insurgences, diabetes mellitus, cardiac complications, oxidative stress-mediated malfunctions, inflammatory events, skin and bone diseases, hepatic, neural and reproductive disorders. This review summarizes information regarding its sources and uses amongst different societies, its biochemistry aspects, and the potential utilization of lycopene and possible mechanisms involved in alleviating the abovementioned disorders. Furthermore, future directions with the possible use of this nutraceutical against lifestyle-related disorders are emphasized. Its protective effects against recommended doses of toxic agents and toxicity and safety are also discussed.

Systemic and Adipose Tissue Redox Status in Sprague-Dawley Rats Fed Normal- and High-Fat Diets Supplemented with Lycopene

Dietary patterns high in fat influence local and systemic oxidative stress through adipose tissue (AT) accrual and increased reactive oxygen species generation. Lycopene, a carotenoid with antioxidant functionality, may mitigate excess oxidative stress, yet the lipophilic nature of this compound may limit its functionality if sequestered by AT. Thus, it is critical to elucidate whether lycopene's efficacy is limited based on adiposity. The purpose of this study was to investigate the influence of lycopene-supplemented normal- and high-fat diets on systemic and AT redox status. Male Sprague-Dawley rats (n = 18) were fed a 30% normal-fat (NFD) or 60% high-fat (HFD) purified diet supplemented with 100 mg of lycopene/day. Body weight and visceral AT mass, as well as serum and AT lycopene, lipid peroxides, and antioxidant capacity (AC), were assessed after 3, 7, and 10 weeks of supplementation. At week 10, AT mass was significantly higher (P = .028) in the HFD group, yet there were no significant differences in serum or AT lycopene concentrations or lipid peroxides between groups. Additionally, AT in the HFD group exhibited significantly greater lipophilic AC (27.6% higher, P = .031). Results suggest that excess adiposity did not negatively influence circulating lycopene, nor did it limit its antioxidant functionality.

Carotenoids and carotenoid conversion products in adipose tissue biology and obesity: Pre-clinical and human studies

Antiobesity activities of carotenoids and carotenoid conversion products (CCPs) have been demonstrated in pre-clinical studies, and mechanisms behind have begun to be unveiled, thus suggesting these compounds may help obesity prevention and management. The antiobesity action of carotenoids and CCPs can be traced to effects in multiple tissues, notably the adipose tissues. Key aspects of the biology of adipose tissues appear to be affected by carotenoid and CCPs, including adipogenesis, metabolic capacities for energy storage, release and inefficient oxidation, secretory function, and modulation of oxidative stress and inflammatory pathways. Here, we review the connections of carotenoids and CCPs with adipose tissue biology and obesity as revealed by cell and animal intervention studies, studies addressing the role of endogenous retinoid metabolism, and human epidemiological and intervention studies. We also consider human genetic variability influencing carotenoid and vitamin A metabolism, particularly in adipose tissues, as a potentially relevant aspect towards personalization of dietary recommendations to prevent or manage obesity and optimize metabolic health. 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.

The macular carotenoids: A biochemical overview

Among the more than 750 carotenoids identified in nature, only lutein, zeaxanthin, meso-zeaxanthin, and their oxidative metabolites are selectively accumulated in the macula lutea region of the human retina. These retinal carotenoids are collectively referred to as the macular pigment (MP) and are obtained only through dietary sources such as green leafy vegetables and yellow and orange fruits and vegetables. Lutein- and zeaxanthin-specific binding proteins (StARD3 and GSTP1, respectively) mediate the highly selective uptake of MP into the retina. Meso-zeaxanthin is rarely present in the diet, and its unique presence in the human eye results from metabolic conversion from dietary lutein by the RPE65 enzyme. The MP carotenoids filter high-intensity, short-wavelength visible light and are powerful antioxidants in a region vulnerable to light-induced oxidative stress. This review focuses on MP chemistry, absorption, metabolism, transport, and distribution with special emphasis on animal models used for MP study. 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.

Anti-Obesity Effect of Carotenoids: Direct Impact on Adipose Tissue and Adipose Tissue-Driven Indirect Effects

This review summarizes current knowledge on the biological relevance of carotenoids and some of their metabolites in obesity management. The relationship between carotenoids and obesity is considered in clinical studies and in preclinical studies. Adipose tissue is a key organ in obesity etiology and the main storage site for carotenoids. We thus first describe carotenoid metabolism in adipocyte and adipose tissue and the effects of carotenoids on biological processes in adipose tissue that may be linked to obesity management in in vitro and preclinical studies. It is also now well established that the brain is strongly involved in obesity processes. A section is accordingly devoted to the potential effect of carotenoids on obesity via their direct and/or adipose tissue-driven indirect biological effects on the brain.

Mechanisms of Carotenoid Intestinal Absorption: Where Do We Stand?

A growing literature is dedicated to the understanding of carotenoid beneficial health effects. However, the absorption process of this broad family of molecules is still poorly understood. These highly lipophilic plant metabolites are usually weakly absorbed. It was long believed that β-carotene absorption (the principal provitamin A carotenoid in the human diet), and thus all other carotenoid absorption, was driven by passive diffusion through the brush border of the enterocytes. The identification of transporters able to facilitate carotenoid uptake by the enterocytes has challenged established statements. After a brief overview of carotenoid metabolism in the human upper gastrointestinal tract, a focus will be put on the identified proteins participating in the transport and the metabolism of carotenoids in intestinal cells and the regulation of these processes. Further progress in the understanding of the molecular mechanisms regulating carotenoid intestinal absorption is still required to optimize their bioavailability and, thus, their health effects.

Single Nucleotide Polymorphisms in β-Carotene Oxygenase 1 are Associated with Plasma Lycopene Responses to a Tomato-Soy Juice Intervention in Men with Prostate Cancer

BACKGROUND

Human plasma and tissue lycopene concentrations are heterogeneous even when consuming controlled amounts of tomato or lycopene.

OBJECTIVES

Our objective is to determine whether single nucleotide polymorphisms (SNPs) in or near known or putative carotenoid metabolism genes [β-carotene 15,15' monooxygenase 1 (BCO1), scavenger receptor class B type 1 (SCARB1), ATP-binding cassette transporter subfamily A member 1 (ABCA1), microsomal triglyceride transfer protein (MTTP), apolipoprotein B-48, elongation of very long chain fatty acids protein 2 (ELOVL2), and ATP-binding cassette subfamily B member 1 (ABCB1), and an intergenic superoxide dismutase 2, mitochondrial-associated SNP] are predictive of plasma lycopene responses to steady state tomato juice consumption.

METHODS

Secondary linear regression analyses of data from a dose-escalation study of prostate cancer patients [n = 47; mean ± SEM age: 60 ± 1 y; BMI (in kg/m2): 32 ± 1] consuming 0, 1, or 2 cans of tomato-soy juice/d (163 mL/can; 20.6 mg lycopene 1.2 mg β-carotene/can) for 24 ± 0.7 d before prostatectomy were conducted to explore 11 SNP genotype effects on the change in plasma lycopene and plasma and prostate tissue concentrations of lycopene, β-carotene, phytoene, and phytofluene.

RESULTS

Two BCO1 SNP genotypes were significant predictors of the change in plasma lycopene, with SNP effects differing in magnitude and direction, depending on the level of juice intake (rs12934922 × diet group P = 0.02; rs6564851 × diet group P = 0.046). Further analyses suggested that plasma β-carotene changes were predicted by BCO1 rs12934922 (P < 0.01), prostate lycopene by trending interaction and main effects of BCO1 SNPs (rs12934922 × diet group P = 0.09; rs12934922 P = 0.02; rs6564851 P = 0.053), and prostate β-carotene by BCO1 SNP interaction and main effects (rs12934922 × diet group P = 0.01; rs12934922 P < 0.01; rs7501331 P = 0.02).

CONCLUSIONS

In conclusion, SNPs in BCO1 and other genes may modulate human plasma and prostate tissue responses to dietary lycopene intake and warrant validation in larger, human controlled feeding intervention and cohort studies. Genetic variants related to carotenoid metabolism may partially explain heterogeneous human blood and tissue responses and may be critical covariates for population studies and clinical trials. This trial was registered at clinicaltrials.gov as NCT01009736.

Carotenoid Content in Human Colostrum is Associated to Preterm/Full-Term Birth Condition

Factors such as lactation stage and premature and small-for-gestational conditions could lead to great inter-individual variability in the carotenoid content of human milk. The aim was to analyze the carotenoid content in colostrum and mature milk of preterm (PT) and full-term (FT) mothers to establish whether they are significantly different and, if so, the stage of lactation when the differences are established. Samples of blood, colostrum, and mature milk were collected from Spanish donating mothers who gave birth to PT or FT infants. Carotenoids from serum and milk samples were analyzed by HPLC-atmospheric pressure chemical ionization (APCI)-MS. Quantitatively, colostrum from PT mothers presented lower total carotenoid content when compared to that from FT mothers. The only exception was lutein, where levels were not different. The transition from colostrum to mature milk makes observed differences in the carotenoid content disappear, since there were no variances between PT and FT groups for both individual and total carotenoid content. The premature birth condition affects the quantitative carotenoid composition of the colostrum but has no effect on the lutein content. This fact could be related to the significant role of this xanthophyll in the development of infant retina and feasibly to cognitive function.

Genetic factors involved in the bioavailability of tomato carotenoids

PURPOSE OF REVIEW

To provide an update on the genetic factors recently associated with the interindividual variability of tomato carotenoid bioavailability.

RECENT FINDINGS

Several clinical studies have demonstrated that the main carotenoids found in tomatoes (lycopene, phytoene, phytofluene, β-carotene, lutein) all display relatively large interindividual variabilities of their bioavailability, with coefficients of variations more than 70%. The bioavailability of the parent molecules, and the blood/tissue appearance of their metabolites, is modulated by numerous proteins, involved in intestinal absorption and metabolism, blood lipoprotein transport or tissue uptake. Several single nucleotide polymorphisms (SNPs) have been associated with the interindividual variability of lycopene, lutein and β-carotene bioavailability, with six genes consistently shared between the three carotenoids, and in particular one SNP in ELOVL fatty acid elongase 2. The effects of the genetic variants taken separately are relatively low, that is each variant is usually associated with only a few percentage of the variability but multivariate analyses suggest that the additive effect of several genetic variants can explain a significant fraction of tomato carotenoid bioavailability.

SUMMARY

Additional studies are needed to improve our knowledge of the genetic determinants of tomato carotenoid bioavailability but progress in this field could one day allow nutritionists to provide more personalized dietary recommendations.

Phytoene and Phytofluene Isolated from a Tomato Extract are Readily Incorporated in Mixed Micelles and Absorbed by Caco-2 Cells, as Compared to Lycopene, and SR-BI is Involved in their Cellular Uptake

SCOPE

Absorption mechanisms of phytoene (PT) and phytofluene (PTF) are poorly known. The main objectives of the study are to measure their micellization and intestinal cell uptake efficiencies and to compare them to those of commonly consumed carotenoids. Other objectives are to assess the involvement of protein(s) in their cellular uptake and whether they compete with other carotenoids for micellization and cellular uptake.

METHODS AND RESULTS

Tomato-extract-purified PT and PTF, mainly present as cis-isomers, are much better incorporated in synthetic mixed micelles than pure all-trans lycopene. PT impairs lycopene micellization (-56%, P < 0.05) while PT and PTF do not significantly affect the micellization of other carotenoids, and vice versa. At low concentration, Caco-2 PTF uptake is higher (P < 0.05) than that of PT and lycopene (29%, 21%, and not detectable). SR-BI, but not CD36 neither NPC1L1, is involved in PT and PTF uptake. PT and PTF impair (p < 0.05) β-carotene uptake (-13 and -22%, respectively).

CONCLUSIONS

The high bioaccessibility of PT and PTF can be partly explained by their high micellization efficiency, which is likely due to their natural cis isomerization and/or to their high molecular flexibility. SR-BI is involved in their cellular uptake, which can explain competitions with other carotenoids.

Tomato Juice Supplementation Influences the Gene Expression Related to Steatosis in Rats

The objective of this work was to identify the effect of tomato juice on the expression of genes and levels of metabolites related to steatosis in rats. Male Sprague Dawley rats (8 weeks-old) were grouped (6 rats/group) in four experimental groups: NA (normal diet and water), NL (normal diet and tomato juice), HA (high-fat diet and water), and HL (high-fat diet and tomato juice). After an intervention period of 5 weeks, rats were sacrificed and biochemical parameters, biomarkers of oxidative stress, liver metabolites, and gene expression were determined. Although the H diet provoked dislipemia related to steatosis, no changes in isoprostanes or liver malondialdehyde (MDA) were observed. Changes in the gene expression of the HA group were produced by the high consumption of fat, whereas the consumption of tomato juice had different effects, depending on the diet. In the NL group, the genes involved in β-oxidation were upregulated, and in groups NL and HL upregulation of CD36 and downregulation of APOB and LPL were observed. In addition, in the HL group the accumulation of lycopene upregulated the genes FXR and HNF4A, which have been suggested as preventive factors in relation to steatosis. Regarding the metabolomics study, intake of tomato juice stimulated the biosynthesis of glutathione and amino acids of the transulfurization pathway, increasing the levels of metabolites related to the antioxidant response.

A global perspective on carotenoids: Metabolism, biotechnology, and benefits for nutrition and health

Carotenoids are lipophilic isoprenoid compounds synthesized by all photosynthetic organisms and some non-photosynthetic prokaryotes and fungi. With some notable exceptions, animals (including humans) do not produce carotenoids de novo but take them in their diets. In photosynthetic systems carotenoids are essential for photoprotection against excess light and contribute to light harvesting, but perhaps they are best known for their properties as natural pigments in the yellow to red range. Carotenoids can be associated to fatty acids, sugars, proteins, or other compounds that can change their physical and chemical properties and influence their biological roles. Furthermore, oxidative cleavage of carotenoids produces smaller molecules such as apocarotenoids, some of which are important pigments and volatile (aroma) compounds. Enzymatic breakage of carotenoids can also produce biologically active molecules in both plants (hormones, retrograde signals) and animals (retinoids). Both carotenoids and their enzymatic cleavage products are associated with other processes positively impacting human health. Carotenoids are widely used in the industry as food ingredients, feed additives, and supplements. This review, contributed by scientists of complementary disciplines related to carotenoid research, covers recent advances and provides a perspective on future directions on the subjects of carotenoid metabolism, biotechnology, and nutritional and health benefits.

4,4'-diaponeurosporene, a C30 carotenoid, effectively activates dendritic cells via CD36 and NF-κB signaling in a ROS independent manner

Carotenoids could be divided into C30 carotenoids and C40 carotenoids. The immune functions of C40 carotenoids had been extensively researched, while those of C30 carotenoids still remain unclear. In this study, the immune functions of a biosynthetic C30 carotenoid, 4,4'-diaponeurosporene (Dia), were identified on dendritic cells (DCs). DCs treated with 1 μM Dia for 24 h showed morphologic and phenotypic characteristics of mature state and had an increased production of IL-6, IL-10, IL-12p70 and TNFα, while β-carotene had a suppressive effect on DCs maturation. Moreover, Dia promoted antigen uptake of DCs in vitro and increased the quantity of antigen loaded DCs in mesenteric lymph nodes (MLN). Dia-treated DCs also had an enhanced ability to stimulate T cell proliferation and Th1 polarization. Further researches showed that Dia activated DCs via CD36 as well as ERK, JNK, and NF-κB signals in a reactive oxygen species (ROS) independent manner.

Host-related factors explaining interindividual variability of carotenoid bioavailability and tissue concentrations in humans

Carotenoid dietary intake and their endogenous levels have been associated with a decreased risk of several chronic diseases. There are indications that carotenoid bioavailability depends, in addition to the food matrix, on host factors. These include diseases (e.g. colitis), life-style habits (e.g. smoking), gender and age, as well as genetic variations including single nucleotide polymorphisms that govern carotenoid metabolism. These are expected to explain interindividual differences that contribute to carotenoid uptake, distribution, metabolism and excretion, and therefore possibly also their association with disease risk. For instance, digestion enzymes fostering micellization (PNLIP, CES), expression of uptake/efflux transporters (SR-BI, CD36, NPC1L1), cleavage enzymes (BCO1/2), intracellular transporters (FABP2), secretion into chylomicrons (APOB, MTTP), carotenoid metabolism in the blood and liver (LPL, APO C/E, LDLR), and distribution to target tissues such as adipose tissue or macula (GSTP1, StARD3) depend on the activity of these proteins. In addition, human microbiota, e.g. via altering bile-acid concentrations, may play a role in carotenoid bioavailability. In order to comprehend individual, variable responses to these compounds, an improved knowledge on intra-/interindividual factors determining carotenoid bioavailability, including tissue distribution, is required. Here, we highlight the current knowledge on factors that may explain such intra-/interindividual differences.

4,4'-Diaponeurosporene-Producing Bacillus subtilis Increased Mouse Resistance against Salmonella typhimurium Infection in a CD36-Dependent Manner

Deficient mucosal innate immunity is a hallmark of infectious diarrhea, such as Salmonella typhimurium (S. typhimurium)-induced gastroenteritis. Here, we report that oral administration of a 4,4′-diaponeurosporene-producing Bacillus subtilis (B.s-Dia) could improve mice mucosal immunity, as showed by an increased resistance against S. typhimurium infection. Intragastric administration of B.s-Dia for 7 days could increase the secretion of CCL20 by intestinal epithelial cells (IECs) and then recruit more dendritic cells. Meanwhile, the number of CD8αα⁺ intraepithelial lymphocytes, which play a critical role in downregulating immune responses, was also reduced, probably as a consequence of the decrease of IEC-derived TGFβ. Further study showed that CD36 played a critical role in B.s-Dia-induced immune enhancement, as blocking CD36 signal with a specific antagonist, sulfo-N-succinimidyl oleate, led to the inability of B.s-Dia to enhance mucosal innate immunity.

Lycopene and tomato powder supplementation similarly inhibit high-fat diet induced obesity, inflammatory response, and associated metabolic disorders

SCOPE

Several studies have linked the high intake of lycopene or tomatoes products with lower risk for metabolic diseases. The aim of the present study was to evaluate and to compare the effect of lycopene and tomato powder on obesity-associated disorders.

METHODS AND RESULTS

Male C57BL/J6 mice were assigned into four groups to receive: control diet (CD), high fat diet (HFD), high fat diet supplemented with lycopene or with tomato powder (TP) for 12 weeks. In HFD condition, lycopene and TP supplementation significantly reduced adiposity index, organ, and relative organ weights, serum triglycerides, free fatty acids, 8-iso-prostaglandin GF2α and improved glucose homeostasis, but did not affect total body weight. Lycopene and TP supplementation prevented HFD-induced hepatosteatosis and hypertrophy of adipocytes. Lycopene and TP decreased HFD-induced proinflammatory cytokine mRNA expression in the liver and in the epididymal adipose tissue. The anti-inflammatory effect of lycopene and TP was related to a reduction in the phosphorylation levels of IκB, and p65, and resulted in a decrease of inflammatory proteins in adipose tissue.

CONCLUSION

These results suggest that lycopene or TP supplementation display similar beneficial health effects that could be particularly relevant in the context of nutritional approaches to fight obesity-associated pathologies.

Dietary calcium impairs tomato lycopene bioavailability in healthy humans

Lycopene (LYC) bioavailability is relatively low and highly variable, because of the influence of several factors. Recent in vitro data have suggested that dietary Ca can impair LYC micellarisation, but there is no evidence whether this can lead to decreased LYC absorption efficiency in humans. Our objective was to assess whether a nutritional dose of Ca impairs dietary LYC bioavailability and to study the mechanism(s) involved. First, in a randomised, two-way cross-over study, ten healthy adults consumed either a test meal that provided 19-mg (all-E)-LYC from tomato paste or the same meal plus 500-mg calcium carbonate as a supplement. Plasma LYC concentration was measured at regular time intervals over 7 h postprandially. In a second approach, an in vitro digestion model was used to assess the effect of increasing Ca doses on LYC micellarisation and on the size and zeta potential of the mixed micelles produced during digestion of a complex food matrix. LYC bioavailability was diminished by 83 % following the addition of Ca in the test meal. In vitro, Ca affected neither LYC micellarisation nor mixed micelle size but it decreased the absolute value of their charge by 39 %. In conclusion, a nutritional dose of Ca can impair dietary LYC bioavailability in healthy humans. This inhibition could be due to the fact that Ca diminishes the electrical charge of micelles. These results call for a thorough assessment of the effects of Ca, or other divalent minerals, on the bioavailability of other carotenoids and lipophilic micronutrients.

Combinations of bio-active dietary constituents affect human white adipocyte function in-vitro

Background

Specific bio-active dietary compounds modulate numerous metabolic processes in adipose tissue (AT), including pre-adipocyte proliferation and differentiation. AT dysfunction, rather than an increased fat mass per se, is strongly associated with the development of insulin resistance and is characterized by impaired adipogenesis, hypertrophic adipocytes, inflammation, and impairments in substrate metabolism. A better understanding of mechanisms underlying AT dysfunction may provide new strategies for the treatment of obesity-associated metabolic diseases. Here we evaluated the role of (all-E)-lycopene (Lyc), eicosapentaenoic acid (EPA) or trans-resveratrol (Res) and combinations thereof on human white adipocyte function.

Methods

In-vitro differentiating human pre-adipocytes were treated with EPA, Lyc and Res or their combinations for 14 days. The effects on intracellular lipid droplet (LD) accumulation, secreted anti- and pro-inflammatory cyto-/adipokines (e.g. adiponectin, IL-6, IL-8/CXCL-8 and MCP-1/CCL2) and on gene expression of markers of adipocyte differentiation and substrate metabolism (e.g. PPAR-gamma, C/EBP-alpha, GLUT-4, FAS, ATGL, HSL, and PLIN-1) were measured by fluorescent microscopy (Cellomics™), multi-parametric LiquiChip® technology and quantitative RT-PCR, respectively.

Results

Treatment of differentiating adipocytes for 14 days with the combination of Lyc/Res and EPA/Res resulted in significantly inhibited LD formation (~ -25 and -20%, respectively) compared to the effects of the single compounds. These morphological changes were accompanied by increased mRNA levels of the adipogenic marker PPAR-gamma and the lipase ATGL and by decreased expression levels of lipogenic markers (LPL, FAS, GLUT-4) and the LD-covering protein PLIN-1. In addition, a blunted adipocyte secretion of pro-inflammatory cytokines (IL-6 and MCP-1) and adiponectin was observed following treatment with these compounds.

Conclusion

The combination of the dietary bio-actives Lyc and EPA with Res might influence adipocyte function by affecting the balance between adipogenic, lipogenic and lipolytic gene expression, resulting in a reduced LD storage and a less inflammatory secretion profile. Taken together, our results indicate that combinations of dietary compounds may be beneficial for the prevention and treatment of metabolic disorders via effects on human white adipocyte function.

Electronic supplementary material

The online version of this article (doi:10.1186/s12986-016-0143-5) contains supplementary material, which is available to authorized users.

Cardiovascular benefits of lycopene: fantasy or reality?

Epidemiological evidence indicates that high consumption of tomatoes and tomato-based products reduces the risk of chronic diseases such as CVD and cancer. Such potential benefits are often ascribed to high concentrations of lycopene present in tomato products. Mainly from the results of in vitro studies, potential biological mechanisms by which carotenoids could protect against heart disease and cancer have been suggested. These include cholesterol reduction, inhibition of oxidation processes, modulation of inflammatory markers, enhanced intercellular communication, inhibition of tumourigenesis and induction of apoptosis, metabolism to retinoids and antiangiogenic effects. However, with regard to CVD, results from intervention studies gave mixed results. Over fifty human intervention trials with lycopene supplements or tomato-based products have been conducted to date, the majority being underpowered. Many showed some beneficial effects but mostly on non-established cardiovascular risk markers such as lipid peroxidation, DNA oxidative damage, platelet activation and inflammatory markers. Only a few studies showed improvement in lipid profiles, C reactive protein and blood pressure. However, recent findings indicate that lycopene could exert cardiovascular protection by lowering HDL-associated inflammation, as well as by modulating HDL functionality towards an antiatherogenic phenotype. Furthermore, in vitro studies indicate that lycopene could modulate T lymphocyte activity, which would also inhibit atherogenic processes and confer cardiovascular protection. These findings also suggest that HDL functionality deserves further consideration as a potential early marker for CVD risk, modifiable by dietary factors such as lycopene.

Dietary beta-carotene and lutein metabolism is modulated by the APOE genotype

The human apolipoprotein E (APOE) genotype has been suggested to interact with nutrient metabolism particularly with lipid soluble vitamins. Plasma carotenoid levels are determined by numerous dietary and genetic factors with high inter-individual variation; however, the APOE genotype has not been systematically examined so far. Our aim was to investigate the effect of the APOE genotype on dietary carotenoid metabolism with special regard to transcriptional regulation of carotenoid absorption, cleavage and adipocyte fat storage. We supplemented targeted replacement mice expressing human APOE3 and APOE4 isoforms with dietary beta-carotene (BC) and lutein (LUT) for 8 weeks. Plasma BC and adipose tissue BC and LUT levels were in trend lower in APOE4 than APOE3 mice, while hepatic expression of the beta-carotene oxygenases BCO1 and BCO2 was significantly higher. In contrast to the liver, mRNA levels of proteins involved in carotenoid absorption and cleavage in the small intestinal mucosa as well as of adipogenic markers in the adipose tissue were not different between APOE3 and APOE4 mice. Our data suggest that the hepatic carotenoid cleavage activity is higher in APOE4 mice partially reducing the circulation and extra-hepatic accumulation of intact carotenoids as compared to APOE3. Therefore we suggest considering the APOE genotype as modulator of carotenoid status in the future. © 2016 BioFactors, 42(4):388-396, 2016.

Absorption and Distribution Kinetics of the 13C-Labeled Tomato Carotenoid Phytoene in Healthy Adults

BACKGROUND

Phytoene is a tomato carotenoid that may contribute to the apparent health benefits of tomato consumption. Although phytoene is a less prominent tomato carotenoid than lycopene, it is a major carotenoid in various human tissues. Phytoene distribution to plasma lipoproteins and tissues differs from lycopene, suggesting the kinetics of phytoene and lycopene differ.

OBJECTIVE

The objective of this study was to characterize the kinetic parameters of phytoene absorption, distribution, and excretion in adults, to better understand why biodistribution of phytoene differs from lycopene.

METHODS

Four adults (2 males, 2 females) maintained a controlled phytoene diet (1-5 mg/d) for 42 d. On day 14, each consumed 3.2 mg (13)C-phytoene, produced using tomato cell suspension culture technology. Blood samples were collected at 0, 1-15, 17, 21, and 24 h and 2, 3, 4, 7, 10, 14, 17, 21, and 28 d after (13)C-phytoene consumption. Plasma-unlabeled and plasma-labeled phytoene concentrations were determined using ultra-HPLC-quadrupole time-of-flight-mass spectrometry, and data were fit to a 7-compartment carotenoid kinetic model using WinSAAM 3.0.7 software.

RESULTS

Subjects were compliant with a controlled phytoene diet, consuming a mean ± SE of 2.5 ± 0.6 mg/d, resulting in a plasma unlabeled phytoene concentration of 71 ± 14 nmol/L. A maximal plasma (13)C-phytoene concentration of 55.6 ± 5.9 nM was achieved 19.8 ± 9.2 h after consumption, and the plasma half-life was 2.3 ± 0.2 d. Compared with previous results for lycopene, phytoene bioavailability was nearly double at 58% ± 19%, the clearance rate from chylomicrons was slower, and the rates of deposition into and utilization by the slow turnover tissue compartment were nearly 3 times greater.

CONCLUSIONS

Although only differing from lycopene by 4 double bonds, phytoene exhibits markedly different kinetic characteristics in human plasma, providing insight into metabolic processes contributing to phytoene enrichment in plasma and tissues compared with lycopene. This trial was registered at clinicaltrials.gov as NCT01692340.

Carotenoids in Adipose Tissue Biology and Obesity

Cell, animal and human studies dealing with carotenoids and carotenoid derivatives as nutritional regulators of adipose tissue biology with implications for the etiology and management of obesity and obesity-related metabolic diseases are reviewed. Most studied carotenoids in this context are β-carotene, cryptoxanthin, astaxanthin and fucoxanthin, together with β-carotene-derived retinoids and some other apocarotenoids. Studies indicate an impact of these compounds on essential aspects of adipose tissue biology including the control of adipocyte differentiation (adipogenesis), adipocyte metabolism, oxidative stress and the production of adipose tissue-derived regulatory signals and inflammatory mediators. Specific carotenoids and carotenoid derivatives restrain adipogenesis and adipocyte hypertrophy while enhancing fat oxidation and energy dissipation in brown and white adipocytes, and counteract obesity in animal models. Intake, blood levels and adipocyte content of carotenoids are reduced in human obesity. Specifically designed human intervention studies in the field, though still sparse, indicate a beneficial effect of carotenoid supplementation in the accrual of abdominal adiposity. In summary, studies support a role of specific carotenoids and carotenoid derivatives in the prevention of excess adiposity, and suggest that carotenoid requirements may be dependent on body composition.