Chicory, a typical vegetable in Mediterranean diet, exerts a therapeutic role in established atherosclerosis in apolipoprotein E-deficient mice

Impact of thermal processing on polyphenols, carotenoids, glucosinolates, and ascorbic acid in fruit and vegetables and their cardiovascular benefits

Bioactive compounds in fruit and vegetables have a positive impact on human health by reducing oxidative stress, inflammation, and the risk of chronic diseases such as cancer, cardiovascular (CV) diseases, and metabolic disorders. However, some fruit and vegetables must be heated before consumption and thermal processes can modify the amount of nutraceuticals, that is, polyphenols, carotenoids, glucosinolates, and ascorbic acid, that can increase or decrease in relation to different factors such as type of processing, temperature, and time but also the plant part (e.g., flower, leaf, tuber, and root) utilized as food. Another important aspect is related to the bioaccessibility and bioavailability of nutraceuticals. Indeed, the key stage of nutraceutical bioefficiency is oral bioavailability, which involves the release of nutraceuticals from fruit and vegetables in gastrointestinal fluids, the solubilization of nutraceuticals and their interaction with other components of gastrointestinal fluids, the absorption of nutraceuticals by the epithelial layer, and the chemical and biochemical transformations into epithelial cells. Several studies have shown that thermal processing can enhance the absorption of nutraceuticals from fruit and vegetable. Once absorbed, they reach the blood vessels and promote multiple biological effects (e.g., antioxidant, anti-inflammatory, antihypertensive, vasoprotective, and cardioprotective). In this review, we described the impact of different thermal processes (such as boiling, steaming and superheated steaming, blanching, and microwaving) on the retention/degradation of bioactive compounds and their health-promoting effects after the intake. We then summarized the impact of heating on the absorption of nutraceuticals and the biological effects promoted by natural compounds in the CV system to provide a comprehensive overview of the potential impact of thermal processing on the CV benefits of fruit and vegetables.

Edible wild plants, chicory and purslane, alleviated diabetic testicular dysfunction, and insulin resistance via suppression 8OHdg and oxidative stress in rats

Testicular dysfunction is a prevalent health problem frequently reported in individuals with diabetes mellitus (DM). Oxidative-inflammatory reactions, hormonal and spermatic abnormalities often accompany this illness. Herbal remedies "particularly wild plants" including chicory (Chicorium Intybus) and purslane (Portulaca Oleracea) are emerging as popular agents for people dealing with these issues due to their ability to act as antioxidants, reduce inflammation, and exhibit antidiabetic effects. According to the collected data, the daily administration of chicory (Ch) seed-extract (250 mg/kg) or purslane (Pu) seed-extract (200 mg/kg) to streptozotocin (STZ)-induced diabetic rats (50 mg/kg) for 30 days resulted in the normalization of fasting blood glucose (FBG), serum fructosamine, insulin levels, and insulin resistance (HOMA-IR), as well as reducing lipid peroxidation end-product malondialdehyde (MDA) level, aldehyde oxidase (AO) and xanthene oxidase (XO) activities. While caused a considerable improvement in glutathione (GSH) content, superoxide dismutase (SOD), catalase (CAT) activity, and total antioxidant capacity (TAC) when compared to diabetic rats. Ch and Pu extracts had a substantial impact on testicular parameters including sperm characterization, testosterone level, vimentin expression along with improvements in body and testis weight. They also mitigated hyperlipidemia by reducing total lipids (TL), total cholesterol (TC) levels, and low-density lipoprotein cholesterol (LDL-C), while increasing high-density lipoprotein cholesterol (HDL-C). Furthermore, oral administration of either Ch or Pu notably attuned the elevated proinflammatory cytokines as tumor necrotic factor (TNF-α), C-reactive protein (CRP), and Interleukin-6 (IL-6) together with reducing apoptosis and DNA damage. This was achieved through the suppression of DNA-fragmentation marker 8OHdG, triggering of caspase-3 immuno-expression, and elevation of Bcl-2 protein. The histological studies provided evidence supporting the preventive effects of Ch and Pu against DM-induced testicular dysfunction. In conclusion, Ch and Pu seed-extracts mitigate testicular impairment during DM due to their antihyperglycemic, antilipidemic, antioxidant, anti-inflammatory, and antiapoptotic properties.

Dietary non-starch polysaccharides impair immunity to enteric nematode infection

BACKGROUND

The influence of diet on immune function and resistance to enteric infection and disease is becoming ever more established. Highly processed, refined diets can lead to inflammation and gut microbiome dysbiosis, whilst health-promoting dietary components such as phytonutrients and fermentable fibres are thought to promote a healthy microbiome and balanced mucosal immunity. Chicory (Cichorium intybus) is a leafy green vegetable rich in fibres and bioactive compounds that may promote gut health.

RESULTS

Unexpectedly, we here show that incorporation of chicory into semisynthetic AIN93G diets renders mice susceptible to infection with enteric helminths. Mice fed a high level of chicory leaves (10% dry matter) had a more diverse gut microbiota, but a diminished type-2 immune response to infection with the intestinal roundworm Heligmosomoides polygyrus. Furthermore, the chicory-supplemented diet significantly increased burdens of the caecum-dwelling whipworm Trichuris muris, concomitant with a highly skewed type-1 immune environment in caecal tissue. The chicory-supplemented diet was rich in non-starch polysaccharides, particularly uronic acids (the monomeric constituents of pectin). In accordance, mice fed pectin-supplemented AIN93G diets had higher T. muris burdens and reduced IgE production and expression of genes involved in type-2 immunity. Importantly, treatment of pectin-fed mice with exogenous IL-25 restored type-2 responses and was sufficient to allow T. muris expulsion.

CONCLUSIONS

Collectively, our data suggest that increasing levels of fermentable, non-starch polysaccharides in refined diets compromises immunity to helminth infection in mice. This diet-infection interaction may inform new strategies for manipulating the gut environment to promote resistance to enteric parasites.

Protocatechuic acid boosts continual efferocytosis in macrophages by derepressing KLF4 to transcriptionally activate MerTK

Macrophages clear apoptotic cells through a process called continual efferocytosis. We found that protocatechuic acid (PCA), a polyphenolic compound abundant in fruits and vegetables, increased the continual efferocytic capacity of macrophages and inhibited the progression of advanced atherosclerosis. PCA reduced the intracellular amounts of microRNA-10b (miR-10b) by promoting its secretion in extracellular vesicles, which led to an increase in the abundance of the miR-10b target Krüppel-like factor 4 (KLF4). In turn, KLF4 transcriptionally induced the gene encoding Mer proto-oncogene tyrosine kinase (MerTK), an efferocytic receptor for the recognition of apoptotic cells, resulting in increased continual efferocytic capacity. However, in naive macrophages, the PCA-induced secretion of miR-10b did not affect KLF4 and MerTK protein abundance or efferocytic capacity. In mice, oral administration of PCA increased continual efferocytosis in macrophages residing in the peritoneal cavities, thymi, and advanced atherosclerotic plaques through the miR-10b-KLF4-MerTK pathway. In addition, pharmacological inhibition of miR-10b with antagomiR-10b also increased the efferocytic capacity of efferocytic but not naive macrophages in vitro and in vivo. Together, these data describe a pathway that promotes continual efferocytosis in macrophages through miR-10b secretion and a KLF4-dependent increase in MerTK abundance, which can be activated by dietary PCA and which has implications for understanding the regulation of continual efferocytosis in macrophages.

The Influence of Polyphenols on Atherosclerosis Development

Polyphenols have attracted tremendous attention due to their pro-health properties, including their antioxidant, anti-inflammatory, antibacterial and neuroprotective activities. Atherosclerosis is a vascular disorder underlying several CVDs. One of the main risk factors causing atherosclerosis is the type and quality of food consumed. Therefore, polyphenols represent promising agents in the prevention and treatment of atherosclerosis, as demonstrated by in vitro, animal, preclinical and clinical studies. However, most polyphenols cannot be absorbed directly by the small intestine. Gut microbiota play a crucial role in converting dietary polyphenols into absorbable bioactive substances. An increasing understanding of the field has confirmed that specific GM taxa strains mediate the gut microbiota-atherosclerosis axis. The present study explores the anti-atherosclerotic properties and associated underlying mechanisms of polyphenols. Moreover, it provides a basis for better understanding the relationship between dietary polyphenols, gut microbiota, and cardiovascular benefits.

Re-Visiting Antioxidant Therapy in Murine Advanced Atherosclerosis with Brussels Chicory, a Typical Vegetable in Mediterranean Diets

Brussels chicory, a typical vegetable in Mediterranean diets, has been recently reported to stabilize advanced atherosclerotic plaques in the brachiocephalic artery of apoE-deficient (Apoe-/-) mice. Herein, we investigated whether Brussels chicory can stabilize advanced plaques in the aorta via improving oxidative stress. Thirty week old Apoe-/- mice were fed the AIN-93G diet or supplemented with 0.5% freeze-dried Brussels chicory for twenty weeks. Aortic plaque size and stability, aortic relaxation, monocyte adhesion to aortic endothelium, free radicals, and enzymatic and non-enzymatic factors involved in free radical production and elimination in aorta and serum were measured. Brussels chicory consumption did not alter aortic plaque size, however, it stabilized aortic plaques, promoted aortic relaxation, and also inhibited monocyte adhesion to aortic endothelium. Moreover, this administration reduced oxidized LDL (ox-LDL) and 4-hydroxynonenal (4-HNE) content in aortic plaques, associated with inhibited aortic NADPH oxidase (NOX) and uncoupled endothelial nitric oxide synthase (eNOS)-mediated free radical production. However, Brussels chicory consumption did not appreciably alter aortic and serum superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) activities, aortic glutathione (GSH), as well as serum non-enzymatic antioxidants, such as bilirubin, uric acid, and GSH. Collectively, improved oxidative stress might contribute to the atheroprotective effect of Brussels chicory, supporting the prospect of the antioxidant therapy in advanced atherosclerosis progression.

Brussels Chicory Stabilizes Unstable Atherosclerotic Plaques and Reshapes the Gut Microbiota in Apoe-/- Mice

BACKGROUND

Adherence to a Mediterranean dietary pattern can protect against atherosclerosis in part by reducing intestinal permeability and gut microbial LPS production. Brussels chicory, a typical Mediterranean vegetable, has been shown to inhibit the formation of early-stage atherosclerosis in mice.

OBJECTIVES

We evaluated whether Brussels chicory affects advanced atherosclerosis progression, intestinal permeability, and gut microbial LPS production.

METHODS

Thirty-week-old male apoE-deficient mice with unstable atherosclerotic plaques in the brachiocephalic artery were fed the AIN-93G diet alone (control) or supplemented with 0.5% freeze-dried Brussels chicory for 20 wk. Plaque volume and features of plaque stability, plaque macrophage polarization, fecal and serum LPS concentrations, serum lipid profiles and inflammation-related cytokines, and gut microbial profiles were measured.

RESULTS

Compared with the control treatment, Brussels chicory consumption did not significantly change plaque volume and serum lipid profiles. However, it increased plaque stability (P < 0.05), as evidenced by reduced necrotic core size (42.3%), and increased fibrous cap thickness (55.0%) and collagen content (68.4%). Moreover, Brussels chicory consumption reduced intestinal permeability (56.3%), fecal and serum LPS concentrations (52.2% and 39.4%), serum IL1β and TNFα (52.0% and 33.8%), promoted plaque macrophage polarization towards the M2-like phenotype, and altered gut microbial composition, the latter indicated by increased relative abundance of certain members of the Ruminococcaceae family, such as Ruminiclostridium_9, Ruminiclostridium_5, and Intestinimonas (P < 0.05). Spearman correlation analyses further showed that these bacterial genera were significantly correlated with intestinal permeability, fecal and serum LPS, serum proinflammatory cytokines, and several features of plaque stability.

CONCLUSIONS

Brussels chicory might help stabilize atherosclerotic plaques in mice by reducing intestinal permeability and gut microbial LPS production. This study provides a promising approach to slow the progression of atherosclerosis.

Dietary supplementation of inulin alleviates metabolism disorders in gestational diabetes mellitus mice via RENT/AKT/IRS/GLUT4 pathway

BACKGROUND

Gestational diabetes mellitus (GDM) has significant short and long-term health consequences for both the mother and child. There is limited but suggestive evidence that inulin could improve glucose tolerance during pregnancy. This study assessed the effect of inulin on glucose homeostasis and elucidated the molecular mechanisms underlying the inulin-induced antidiabetic effects during pregnancy.

METHOD

Female C57BL/6 mice were randomized to receive either no treatment, high-dose inulin and low-dose inulin for 7 weeks with measurement of biochemical profiles. A real-time² (RT²) profiler polymerase chain reaction (PCR) array involved in glycolipid metabolism was measured.

RESULTS

Inulin treatment facilitated glucose homeostasis in a dose-dependent manner by decreasing fasting blood glucose, advanced glycation end products and total cholesterol, and improving glucose tolerance. Suppressing resistin (RETN) expression was observed in the inulin treatment group and the expression was significantly correlated with fasting blood glucose levels. The ratios of p-IRS to IRS and p-Akt to Akt in liver tissue and the ratio of p-Akt to Akt in adipose tissue as well as the expression level of GLUT4 increased significantly after inulin treatment.

CONCLUSIONS

Our findings indicated improvement of glucose and lipid metabolism by inulin was to activate glucose transport through the translocation of GLUT4 which was mediated by insulin signaling pathway repairment due to decreased expression of RETN and enhanced phosphorylation of IRS and Akt in GDM mice.

Terpene Lactucopicrin Limits Macrophage Foam Cell Formation by a Reduction of Lectin-Like Oxidized Low-Density Lipoprotein Receptor-1 in Lipid Rafts

SCOPE

Sustained inflammation promotes macrophage foam cell formation by promoting cholesterol influx and impairing cholesterol efflux. Terpene lactucopicrin, affluent in vegetables of the Asteraceae family (e.g., chicory, curly escarole, and lettuce) can inhibit atherogenesis in mice. However, it remains unknown whether and how lactucopicrin regulates macrophage foam cell formation.

METHODS AND RESULTS

Lactucopicrin at physiologically reachable concentrations inhibits oxidized low-density lipoprotein (oxLDL)-induced foam cell formation in inflammatory mouse bone marrow derived macrophages established by 50 pg mL^-1 of LPS, reachable level in patients with metabolic endotoxemia. This effect is not due to modulation of cholesterol efflux, but reliant on a reduction in lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1)-mediated cholesterol influx. Mechanistically, lactucopicrin does not affect LOX-1 expression, cellular oxidative stress, and exocytosis, known mechanisms regulating LOX-1 function in cholesterol influx. Strikingly, lactucopicrin selectively decreases LOX-1 content in lipid rafts, an effect responsible for the lactucopicrin effect on cholesterol influx. Moreover, ApoE^-/- mice fed a high fat diet supplemented with lactucopicrin for 12 weeks display fewer macrophage foam cells within atherosclerotic plaques relative to the control mice.

CONCLUSION

Lactucopicrin limits macrophage foam cell formation through a reduction of LOX-1 distribution in lipid rafts, thus contributing to its atheroprotective effect.

Impact of protocatechuic acid on high fat diet-induced metabolic syndrome sequelae in rats

The study aimed to assess the possible protective impact of protocatechuic acid (PCA) on high fat diet (HFD)-induced metabolic syndrome (Mets) sequelae in rats. Forty-two male Sprague-Dawley (SD) rats were randomly grouped as follows: CTR group; PCA group; HFD group; HFD-PCA group and HFD-MET group. Rats were fed on standard diet or HFD for 14 weeks. HFD-fed rats exhibited significant decreases in food intake and adiponectin (ADP) level; yet, body weight and anthropometrical parameters were significantly increased. Moreover, insulin sensitivity was impaired as indicated by significant elevation in glucose AUC during oral glucose tolerance test (OGTT), fasting serum glucose, fasting serum insulin and homeostasis model assessment of insulin resistance (HOMA-IR) index. Furthermore, chronic HFD feeding elicited significant increases in serum lipid profile and free fatty acids (FFAs) with concomitant hepatic steatosis. Additionally, serum C-reactive protein (CRP), interleukin 1b (Il-1b) and monocyte chemoattractant protein 1(MCP-1) levels were increased. Also, HFD-fed rats exhibited an increase in MDA level, while superoxide dismutase (SOD) and glutathione (GSH) activities were decreased. Moreover, the insulin-signaling pathway was markedly impaired in soleus muscles as indicated by a decrease in insulin-induced AKT phosphorylation. Histopathologically, adipose tissues showed significant increase in adipocyte size. Also, flow cytometry analysis of adipose tissue confirmed a significant increase in the percentage of number of CD68+ cells. PCA administration succeeded to attenuate HFD-induced obesity, insulin resistance, oxidative stress and inflammation. In conclusion, PCA administration could protect against HFD-induced Mets, possibly via its hypoglycemic, insulin-sensitizing, anti-oxidant and anti-inflammatory effects.

Low Oral Bioavailability and Partial Gut Microbiotic and Phase II Metabolism of Brussels/Witloof Chicory Sesquiterpene Lactones in Healthy Humans

Free and glycosylated sesquiterpene lactones (SLs), which are abundant in leafy vegetables including Brussels/witloof chicory, possess health-promoting effects in vivo. However, the pharmacokinetics of dietary source of SLs remain largely unknown. In this open-label and single-dose trial, sixteen healthy volunteers consumed 150 g of Brussels/witloof chicory juice containing 48.77 μmol SLs in 5 min. Blood, urine, and fecal samples were collected before and after chicory consumption in 24 h. No SLs were detected in the serum, urine, and fecal samples before chicory consumption in all of the participants. Chicory consumption increased lactucin, 11β,13-dihydrolactucin, and their glucuronide/sulfate conjugates, rather than lactucopicrin and 11β,13-dihydrolactucopicrin, as well as glycosylated SLs in biological samples. The peak concentration of total SLs in serum reached 284.46 nmol/L at 1 h, while, in urine, this peak was 220.3 nmol between 2 and 6 h. The recovery of total SLs in blood, urine, and feces was 7.03%, 1.13%, and 43.76% of the ingested dose, respectively. Human fecal suspensions with intestinal microbiota degraded glycosylated SLs in chicory, and converted lactucopicrin and 11β,13-dihydrolactucopicrin to lactucin and 11β,13-dihydrolactucin, respectively. Collectively, Brussels/witloof chicory SLs are poorly bioavailable and they undergo partial gut microbial and phase II metabolism in humans.

The Impact of Dietary Supplementation of Whole Foods and Polyphenols on Atherosclerosis

The purpose of this review is to highlight current research on the benefits of supplementation with foods with a diverse polyphenol composition, including fruits, vegetables, nuts, grains, oils, spices, and teas in blunting atherosclerosis. We searched PubMed for publications utilizing whole food or polyphenols prepared from whole foods in Apolipoprotein E (ApoE) or Low-Density Lipoprotein Receptor (LDLR) knockout mice, and identified 73 studies in which plaque was measured. The majority of the studies reported a reduction in plaque. Nine interventions showed no effect, while three using Agaricus blazei mushroom, HYJA-ri-4 rice variety, and safrole-2', 3'-oxide (SFO) increased plaque. The mechanisms by which atherosclerosis was reduced include improved lipid profile, antioxidant status, and cholesterol clearance, and reduced inflammation. Importantly, not all dietary interventions that reduce plaque showed an improvement in lipid profile. Additionally, we found that, out of 73 studies, only 9 used female mice and only 6 compared both sexes. Only one study compared the two models (LDLR vs. ApoE), showing that the treatment worked in one but not the other. Not all supplementations work in both male and female animals, suggesting that increasing the variety of foods with different polyphenol compositions may be more effective in mitigating atherosclerosis.

In vitro differentiation induction of embryonal carcinoma stem cells into insulin-producing cells by Cichorium intybus L. leaf extract

ETHNOPHARMACOLOGICAL RELEVANCE

Medicinal herb Cichorium intybus L. (chicory) has been used traditionally for the treatment of various diseases, including diabetes. One of the promising therapeutic options to treat diabetes is replacing the degenerative pancreatic β cells by stem cell-derived IPCs (insulin-producing cells).

AIM OF THE STUDY

By the combination of cell therapy as a modern approach and traditional medicine, the current study was designed to evaluate the effects of chicory leaf extract (LE) on the differentiation potential of P19 EC cells (an embryonal carcinoma stem cell line) into IPCs.

MATERIALS AND METHODS

The plant (voucher no. 4567) were collected and deposited in the herbarium of Shahrekord University. In vitro experiments were designed to compare the effects of various concentrations of LE on the differentiation potential of P19 EC cells.

RESULTS

The differentiated cells showed morphological characteristics of pancreatic β cells. They could also synthesized and secreted insulin when exposed to glucose. Moreover, the cells expressed specific proteins and genes of mature pancreatic β cells.

CONCLUSIONS

In conclusion, LE as a natural herbal extract was efficiently able to induce the differentiation of P19 EC cells into the clusters similar to pancreatic islets with the molecular, cellular and functional characteristics of mature β cells.

Targeting Foam Cell Formation in Atherosclerosis: Therapeutic Potential of Natural Products

Foam cell formation and further accumulation in the subendothelial space of the vascular wall is a hallmark of atherosclerotic lesions. Targeting foam cell formation in the atherosclerotic lesions can be a promising approach to treat and prevent atherosclerosis. The formation of foam cells is determined by the balanced effects of three major interrelated biologic processes, including lipid uptake, cholesterol esterification, and cholesterol efflux. Natural products are a promising source for new lead structures. Multiple natural products and pharmaceutical agents can inhibit foam cell formation and thus exhibit antiatherosclerotic capacity by suppressing lipid uptake, cholesterol esterification, and/or promoting cholesterol ester hydrolysis and cholesterol efflux. This review summarizes recent findings on these three biologic processes and natural products with demonstrated potential to target such processes. Discussed also are potential future directions for studying the mechanisms of foam cell formation and the development of foam cell-targeted therapeutic strategies.

Protocatechuic acid from chicory is bioavailable and undergoes partial glucuronidation and sulfation in healthy humans

Protocatechuic acid exerts multiple health-promoting effects such as anticancer, anti-atherosclerosis, and neuroprotection in animal models. While protocatechuic acid produced in the lower gastrointestinal tract by microbial catabolism of several flavonoids is bioavailable, the pharmacokinetics of protocatechuic acid has not been evaluated so far in humans following its oral consumption. In this open-label and single-dose pharmacokinetic trial, 16 healthy adults followed a low-phytochemical diet for three days. Next, after overnight fasting, participants consumed 150 g of chicory containing 248 μmol of protocatechuic acid. Blood, urine, and fecal samples were collected before and up to 24 hr after chicory consumption. Protocatechuic acid in the free and glucuronide/sulfate-conjugated forms was almost undetectable in serum, urine, and fecal samples before chicory consumption. Chicory consumption increased the levels of protocatechuic acid and its glucuronide/sulfate conjugates in biological samples. The maximum serum concentrations of protocatechuic acid in the free-, glucuronide-, and sulfate-conjugated forms were 3,273, 519, and 340 nmol/L, respectively. The recovery of total protocatechuic acid in blood circulation, urine, and feces was 23.79%, 12.17%, and 12.79% of the ingested dose, respectively. Moreover, glucuronide and sulfate conjugates of protocatechuic acid made up 34.79%, 60.15%, and 72.70% of its total recovery in blood circulation, urine, and feces, respectively. Collectively, protocatechuic acid from chicory is bioavailable and undergoes partial glucuronidation and sulfation in human adults, and its regular consumption may exert health-promoting effects.

Polydatin attenuates atherosclerosis in apolipoprotein E-deficient mice: Role of reverse cholesterol transport

BACKGROUND

Polydatin has been recently shown to possess extensive cardiovascular pharmacological activities. However, its protective effect against atherosclerosis in vivo remains poorly understood. The aim of the present study was to evaluate the potential effects of polydatin on high fat diet (HFD)-induced atherosclerosis using ApoE^-/- mice, and explore the underlying mechanisms involved, especially focusing on reverse cholesterol transport (RCT) regulation.

METHODS

after 12 weeks treatment, serum samples, mouse aorta, liver, peritoneal macrophages were collected to determine lipid profiles, atherosclerotic lesions, hepatic steatosis, foam cell formation and expression of related molecules. RAW264.7 macrophages were used to study cholesterol efflux.

RESULTS

Polydatin improved serum lipid profiles, attenuated atherosclerosis and hepatic steatosis. Furthermore, polydatin may facilitate RCT by stimulating cholesterol efflux through ATP-binding cassette transporters (ABC) A1, ABCG1 and scavenger receptor class B type I (SR-BI) in macrophages, increasing serum levels of high density lipoprotein and apolipoprotein A-I, promoting of SR-BI-mediated cholesterol uptake of liver, increasing secretion of cholesterol into bile by ABCG5/ABCG8 and improving cholesterol metabolism by CYP7A1 pathway. Polydatin also regulated the protein expressions of hepatic fatty acid synthase and peroxisome proliferator-activated receptor-α. Additionally, polydatin reduced hepatic and aortic reactive oxygen species generation, normalized activities of antioxidant enzymes and increased protein expressions of NADPH-oxidase (NOX) 2 and NOX4 in liver. Polydatin also prevented hepatic and aortic inflammation as evidenced by the reduced macrophage infiltration and mRNA expressions of tumor necrosis factor-α and interleukin-6 in both aorta and liver.

CONCLUSION

These findings indicated that polydatin can inhibit atherosclerosis through enhancement of overall RCT. In addition, anti-oxidative and anti-inflammatory effect of polydatin may also contribute to its inhibitory effects on atherosclerosis.

Salusin-α attenuates hepatic steatosis and atherosclerosis in high fat diet-fed low density lipoprotein receptor deficient mice

Salusin-α is an endogenous bioactive peptide and likely to prevent atherosclerosis. But its protective effect against atherosclerosis in vivo remains poorly understood. The aim of the present study was to determine the potential effects of salusin-α on atherosclerosis and its associated metabolic disorders in high fat diet (HFD)-fed low density lipoprotein receptor deficient (LDLr^-/-) mice, and also explore the possible underlying mechanisms involved. Our data showed that after 12 weeks treatment, salusin-α ameliorated HFD-induced weight gain, hyperlipidemia, and serum levels of interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α). Salusin-α suppressed HFD-induced hepatic steatosis and regulated gene expression of fatty acid synthase, acetyl coenzyme A carboxylase-α, peroxisome proliferator-activated receptor-α, camitine palmitoyltransferase-1α and CYP7A1 in liver. Salusin-α reduced atherosclerotic plaque area and macrophage foam cell formation. Salusin-α prevented hepatic and aortic inflammation as evidenced by the reduced macrophage recruitment and mRNA expression of IL-6 and TNF-α in both liver and aorta. Salusin-α also reduced hepatic and aortic oxidative stress by normalizing activities of antioxidant enzymes in liver and suppressing reactive oxygen species generation and protein expressions of NADPH-oxidase (NOX) 2 and NOX4 in both liver and aorta. Our present data suggest that salusin-α could reduce hepatic steatosis and atherosclerosis via its pleiotropic effects, including amelioration of lipid profiles, regulation of some key molecules involved in lipid metabolism in liver, anti-oxidative effect and anti-inflammatory action.

2,3,4′,5-tetrahydroxystilbene-2-O-β-d-glycoside attenuates atherosclerosis in apolipoprotein E-deficient mice: role of reverse cholesterol transport

The aim of this study was to evaluate the potential effects of 2,3,4′,5-tetrahydroxystilbene-2-O-β-d-glucoside (TSG) on the development of atherosclerotic plaque in ApoE−/− mice, and explore the mechanisms involved. Our data showed that after 8 weeks of treatment, TSG ameliorated serum levels of total cholesterol, triglyceride, and low density lipoprotein cholesterol, and increased serum levels of high density lipoprotein cholesterol in ApoE−/− mice. TSG suppressed hepatic steatosis, the formation of atherosclerotic lesions, and the formation of macrophage foam cells in ApoE−/− mice. Moreover, TSG improved the expressions of hepatic SR-BI, ABCG5, and CYP7A1, and up-regulated the protein expressions of aortic ABCA1 and ABCG1. An in-vitro study showed that TSG promoted macrophage cholesterol efflux and increased the protein expressions of ABCA1 and ABCG1. Our findings provide evidence for a positive role of TSG in preventing atherosclerosis by promoting reverse cholesterol transport. These effects may be achieved by stimulating cholesterol efflux through ABCA1 and ABCG1, promoting SR-BI-mediated cholesterol uptake in the liver, increasing secretion of cholesterol into bile by ABCG5, and improving cholesterol metabolism by the CYP7A1 pathway. In addition, antioxidative and anti-inflammatory effects of TSG may also contribute to its inhibitory effects on atherosclerosis. Further study is needed to investigate whether other potential mechanisms are involved in TSG-mediated atheroprotection.

Chicory inulin ameliorates type 2 diabetes mellitus and suppresses JNK and MAPK pathways in vivo and in vitro

SCOPE

Chicory inulin is a naturally occurring fructan that is conducive to glucose and lipid metabolism in patients with diabetes mellitus. This study aims to investigate the mechanism by which chicory inulin improves glucolipid metabolism in diabetic conditions.

METHODS AND RESULTS

Rats were injected with streptozotocin and fed with high fat diet to induce diabetes, and then administrated with different doses of chicory inulin for 8 weeks. The glycometabolism and lipid metabolism parameters were determined, the activity of insulin receptor substrate (IRS) and mitogen-activated protein kinase (MAPK) pathways were examined by western blot. The effect of chicory inulin on glucose uptake of myoblast and hepatocyte were also measured in vitro. Data were analyzed by student's t-test or one-way analysis of variance followed by the Bonferroni post-hoc testing. The results showed that chicory inulin improved glucolipid metabolism, and it activated IRS but suppressed the MAPK pathways in vivo and in vitro.

CONCLUSION

Our study demonstrates that chicory inulin, as a nutritional supplement, may be beneficial for the patients with type 2 diabetes mellitus, and the metabolism-modulatory effect seems to be related with the inhibition of JNK and P38 MAPK pathways.

Quercetin protects against atherosclerosis by inhibiting dendritic cell activation

SCOPE

Quercetin is a typical flavonol with atheroprotective effects, but the effect of quercetin on dendritic cell (DC) maturation in relation to atherosclerosis has not yet been clearly defined. Thus, we investigated whether quercetin can inhibit DC maturation and evaluated its potential value in atherosclerosis progression in ApoE^-/- mice.

METHODS AND RESULTS

Quercetin consumption inhibited DC activation, inflammatory response and suppressed the progression of atherosclerosis in ApoE^-/- mice. Subsequently, quercetin treatment inhibited the phenotypic and functional maturation of DCs, as evidenced not only by downregulation of CD80, CD86, MHC-II, IL-6 and IL-12 but also by a reduction in the ability to stimulate T cell allogeneic proliferation. Finally, an in vitro study demonstrated that quercetin inhibited DC maturation via upregulation of Dabs, which then downregulated the Src/PI3K/Akt-NF-κB-inflammatory pathways.

CONCLUSIONS

Our data indicate that quercetin attenuates atherosclerosis progression by regulating DC activation via Dab2 protein expression.

Chicoric Acid Ameliorates Lipopolysaccharide-Induced Oxidative Stress via Promoting the Keap1/Nrf2 Transcriptional Signaling Pathway in BV-2 Microglial Cells and Mouse Brain

As a major nutraceutical component of a typical Mediterranean vegetable chicory, chicoric acid (CA) has been well-documented due to its excellent antioxidant and antiobesity bioactivities. In the current study, the effects of CA on lipopolysaccharide (LPS)-stimulated oxidative stress in BV-2 microglia and C57BL/6J mice and the underlying molecular mechanisms were investigated. Results demonstrated that CA significantly reversed LPS-elicited cell viability decrease, mitochondrial dysfunction, activation of NFκB and MAPK stress pathways, and inflammation responses via balancing cellular redox status. Furthermore, molecular modeling study demonstrated that CA could insert into the pocket of Keap1 and up-regulated Nrf2 signaling and, thus, transcriptionally regulate downstream expressions of antioxidant enzymes including HO-1 and NQO-1 in both microglial cells and ip injection of LPS-treated mouse brain. These results suggested that CA attenuated LPS-induced oxidative stress via mediating Keap1/Nrf2 transcriptional pathways and downstream enzyme expressions, which indicated that CA has great potential as a nutritional preventive strategy in oxidative stress-related neuroinflammation.

Established atherosclerosis might be a prerequisite for chicory and its constituent protocatechuic acid to promote endothelium-dependent vasodilation in mice

SCOPE

Chicory (Cichorium intybus L. var. foliosum, Belgian endive), a typical Mediterranean vegetable, and its constituent protocatechuic acid (PCA) can inhibit established atherosclerosis progression. We thus investigated whether chicory can improve vascular relaxation, a critical pathway for combating atherosclerosis, and whether PCA is a contributor to a chicory-induced effect.

METHODS AND RESULTS

Apolipoprotein E-deficient (ApoE-/- ) mice with established atherosclerosis and C57BL/6J mice without atherosclerosis were fed an AIN-93G diet, or AIN-93G plus 0.5% freeze-dried chicory or 0.003% PCA for 1 wk. In ApoE-/- mice, both chicory and PCA consumption increased endothelium-dependent vasodilation and endothelial nitric oxide synthase (eNOS) activity independent of eNOS and phospho-eNOS Ser1177 and Thr495 protein expression. Chicory- or PCA-induced eNOS activities were associated with increased vascular tetrahydrobiopterin (BH4 ) levels that result from reduced BH4 oxidation partially through preventing eNOS uncoupling. In C57BL/6J mice, neither chicory nor PCA consumption affected endothelium-dependent vasodilation and eNOS activity. Notably, in vitro studies showed that PCA increases eNOS activity in mouse aortic endothelial cells in co-culture with macrophage foam cells, but not in aortic endothelial cells alone.

CONCLUSIONS

Chicory improves eNOS-mediated endothelium-dependent vasodilation by increasing BH4 levels in mice with established atherosclerosis, which might be partially ascribed to its constituent PCA.

Effect of Cichorium intybus L. on the expression of hepatic NF-κB and IKKβ and serum TNF-α in STZ- and STZ+ niacinamide-induced diabetes in rats

BACKGROUND

Inflammation is an early event in the development of diabetes type 2 (T2D). Cichorium intybus L. (chicory) possesses anti-inflammatory action. We compared the anti-inflammatory aspect of aqueous chicory seed extract (CSE) in early and late stage T2D in rats.

METHODS

Wistar albino rats were divided into nine final groups (n = 6). Three main groups consisted of non-diabetic (Control), early stage diabetes (ET2D; niacinamide/streptozotocin, i.e., NIA/STZ), and late stage diabetes (LT2D; STZ). Within each main group, a subgroup was treated with CSE (125 mg/kg; i.p.); within each diabetic group (STZ and NIA/STZ) a subgroup received metformin (100 mg/kg; i.p.); another subgroup in STZ group received aspirin (120 mg/kg; oral). After 21 days, fasting blood glucose (FBS), insulin, and TNF-α level were measured in serum; IKKβ and NF-κB (p65) mRNA and protein expression were evaluated by real time PCR and Western blotting; p65 DNA binding activity was determined by ELISA, in liver tissue.

RESULTS

The mRNA and protein expression levels of IKKβ, and P65 genes increased in both stages of T2D (p < 0.01); CSE decreased their expression (p < 0.001, mRNAs; p < 0.05, proteins). The increased DNA-binding capacity of NF-κB (p < 0.0001) in diabetes was lowered by CSE (p < 0.001). The effect of CSE was limited to ET2D requiring insulin.

CONCLUSIONS

The anti-inflammatory action of CSE is due to a direct modulation of cytokine expression. The dependency of chicory action on the presence of insulin indicates its usefulness in the early stages of diabetes and for the purpose of preventing and delaying diabetes onset.