Dietary Anthocyanins Mitigate High-Fat Diet-Induced Hippocampal Inflammation in Mice.

BACKGROUND: Obesity and consumption of high-fat diets (HFD) are associated with intestinal permeabilization and increased paracellular transport of endotoxins, which can promote neuroinflammation. Inflammation can affect the hypothalamic pituitary adrenal (HPA) axis, which controls responses to stress and downregulates the brain-derived neurotrophic factor (BDNF), which can promote anxiety and depression, conditions frequently found in obesity. We previously showed that consumption of anthocyanins (AC) mitigate HFD-induced insulin resistance, intestinal permeability, and inflammation. OBJECTIVES: This study investigated if a dietary supplementation with a cyanidin- and delphinidin-rich extract (CDRE) could counteract HFD/obesity-induced hippocampal inflammation in mice. METHODS: C57BL/6J male mice were fed for 14 wk on one of the following diets: 1) a control diet containing 10% total calories from fat (C), 2) a control diet supplemented with 40 mg AC/kg body weight (BW) (CAC), 3) a HFD containing 60% total calories from fat (lard) (HF), or 4) the HFD supplemented with 2, 20, or 40 mg AC/kg BW (HFA2, HFA20, and HFA40, respectively). In plasma and in the hippocampus, parameters of neuroinflammation and the underlying cause (endotoxemia) and consequences (alterations to the HPA and BDNF downregulation) were measured. RESULTS: Consumption of the HFD caused endotoxemia. Accordingly, hippocampal Tlr4 mRNA levels were 110% higher in the HF group, which were both prevented by CDRE supplementation. Consumption of the HFD also caused: 1) microgliosis and increased expression of genes involved in neuroinflammation, that is, Iba-1, Nox4, Tnfα, and Il-1ß, 2) alterations of HPA axis regulation, that is, with low expression of mineralocorticoid (MR) and glucocorticoid (GR) receptors; and 3) decreased Bdnf expression. Supplementation of HFD-fed mice with CDRE mitigated neuroinflammation, microgliosis, and MR and BDNF decreases. CONCLUSIONS: CDRE supplementation mitigates the negative effects associated with HFD consumption and obesity in mouse hippocampus, in part by decreasing inflammation, improving glucocorticoid metabolism, and upregulating BDNF.

Natural Products and Diabetes: (-)-Epicatechin and Mechanisms Involved in the Regulation of Insulin Sensitivity.

Type 2 diabetes (T2D) is a disease that occurs when cells do not respond normally to insulin, a condition called insulin resistance, which leads to high blood glucose levels. Although it can be treated pharmacologically, dietary habits beyond carbohydrate restriction can be highly relevant in the management of T2D. Emerging evidence supports the possibility that natural products (NPs) could contribute to managing blood glucose or counteract the undesirable effects of hyperglycemia and insulin resistance. This chapter summarizes the relevant preclinical evidence involving the flavonoid (-)-epicatechin (EC) in the optimization of glucose homeostasis, reducing insulin resistance and/or diabetes-associated disorders. Major effects of EC are observed on (i) intestinal functions, including digestive enzymes, glucose transporters, microbiota, and intestinal permeability, and (ii) redox homeostasis, including oxidative stress and inflammation. There is still a need for further clinical studies to confirm the in vitro and rodent data, allowing recommendations for EC, particularly in prediabetic and T2D patients. The collection of similar data and the lack of clinical evidence for EC is also applicable to other NPs.

(-)-Epicatechin and Anthocyanins Modulate GLP-1 Metabolism: Evidence from C57BL/6J Mice and GLUTag Cells.

BACKGROUND: Generated in intestinal L cells through cleavage of proglucagon (Gcg), glucagon-like peptide 1 (GLP-1) is secreted and rapidly inactivated by dipeptidyl peptidase IV (DPP-IV). GLP-1 regulates insulin secretion and overall glucose homeostasis. The capacity of dietary bioactives to increase GLP-1 circulating levels, and therefore increase insulin secretion and glucose metabolism, has gained significant interest of late. OBJECTIVES: We evaluated the effects of (-)-epicatechin (EC) and different anthocyanins (ACs) and AC metabolites on GLP-1 metabolism in mice and on GLUTag cells. METHODS: We fed 6-week-old C57BL/6J male mice a control diet or a control diet supplemented with either 40 mg AC or 20 mg EC/kg body weight for 14 weeks (AC) or 15 weeks (EC). Intestinal mRNA levels of Gcg and Dpp-iv were measured. In vitro, GLUTag cells were incubated in the presence or absence of different ACs, the AC metabolite protocatechuic acid (PCA), and EC. GLP-1 secretion and the main pathways involved in its release were assessed. RESULTS: Long-term supplementation with EC or AC increased mouse GLP-1 plasma concentrations (55% and 98%, respectively; P < 0.05). In mice, 1) EC and AC increased Gcg mRNA levels in the ileum (91%) and colon (41%), respectively (P < 0.05); and 2) AC lowered ileum Dpp-iv mRNA levels (35%), while EC decreased plasma DPP-IV activity (15%; P < 0.05). In GLUTag cells, 1) cyanidin, delphinidin, PCA, and EC increased GLP-1 secretion (53%, 33%, 53%, and 68%, respectively; P < 0.05); and 2) cyanidin, delphinidin, EC, and PCA increased cyclin adenosine monophosphate levels (25-50%; P < 0.05) and activated protein kinase A (PKA; 100%, 50%, 80%, and 86%, respectively; P < 0.05). CONCLUSIONS: In mice, EC and ACs regulated different steps in GLP-1 regulation, leading to increased plasma GLP-1. Cyanidin, delphinidin, PCA, and EC promoted GLP-1 secretion from GLUTag cells by activating the PKA-dependent pathway. These findings support the beneficial actions of these flavonoids in sustaining intestinal and glucose homeostasis through the modulation of the GLP-1 metabolism.

(-)-Epicatechin and the comorbidities of obesity.

Obesity has major adverse consequences on human health contributing to the development of, among others, insulin resistance and type 2 diabetes, cardiovascular disease, non-alcoholic fatty liver disease, altered behavior and cognition, and cancer. Changes in dietary habits and lifestyle could contribute to mitigate the development and/or progression of these pathologies. This review will discuss current evidence on the beneficial actions of the flavan-3-ol (-)-epicatechin (EC) on obesity-associated comorbidities. These benefits can be in part explained through EC's capacity to mitigate several common events underlying the development of these pathologies, including: i) high circulating levels of glucose, lipids and endotoxins; ii) chronic systemic inflammation; iii) tissue endoplasmic reticulum and oxidative stress; iv) insulin resistance; v) mitochondria dysfunction and vi) dysbiosis. The currently known underlying mechanisms and cellular targets of EC's beneficial effects are discussed. While, there is limited evidence from human studies supplementing with pure EC, other studies involving cocoa supplementation in humans, pure EC in rodents and in vitro studies, support a potential beneficial action of EC on obesity-associated comorbidities. This evidence also stresses the need of further research in the field, which would contribute to the development of human dietary strategies to mitigate the adverse consequences of obesity.

(-)-Epicatechin and its metabolites prevent palmitate-induced NADPH oxidase upregulation, oxidative stress and insulin resistance in HepG2 cells.

While diets rich in fruit and vegetables can decrease the risk for type 2 diabetes (T2D), diets rich in fat and carbohydrates can increase it. The flavanol-3-ol (-)-epicatechin (EC) can improve insulin sensitivity both in humans and animal models of T2D. NADPH oxidases and oxidative stress can contribute to the development of insulin resistance. This study investigated the capacity of EC and EC metabolites (ECM) to downregulate NADPH oxidases and oxidative stress, and its association to an improvement of insulin sensitivity. This was studied in in vivo (high fat-fed mice) and in vitro (HepG2 cells) conditions of hepatic lipid overload. EC decreased NOX3/NOX4 liver expression and mitigated oxidative stress in high fat-fed mice. In HepG2 cells, incubation with palmitate increased: i) lipid deposition, ii) NOX3/NOX4 expression, iii) NADPH oxidase activity, and iv) oxidative stress; promoting v) the activation of redox-sensitive kinases (JNK and IKK), and vi) impaired insulin responses. Physiological concentrations of EC and ECM, and NADPH oxidase inhibitors (apocynin, VAS2870) prevented all those deleterious effects of palmitate. The obtained results points to NADPH oxidases as an important target in the capacity of EC to improve insulin sensitivity in conditions of liver lipid overload, as those associated with Western-style diets.

Seroprevalence of a "new" bacterium, Simkania negevensis, in renal transplant recipients and in hemodialysis patients.

BACKGROUND: Simkania negevensis is an obligate intracellular bacterium belonging to the family Simkaniaceae in the Chlamydiales order. It is considered an ubiquitous microorganism and aquatic environments may be involved as a source of infection for humans. It was just isolated in samples from domestic water supplies and from mains water supplies, like spa water or swimming pool water, confirming its ability to resist to the common chlorination treatments. Evidence indicates a possible role of the microorganism in respiratory tract infections, in gastroenteric disorders and in the pathogenesis of cardiovascular disease, furthermore it has hypothesized that it could play a role in lung transplant rejection. Prevalence and possible effects in nephrology are unknown. METHODS: We examined the occurrence of Simkania negevensis in two differents populations, both characterized by a high susceptibility to infectious complications: 105 hemodialysis patients, 105 renal transplant recipients and 105 healthy subjects through the IgG and IgA response to Simkania negevensis in their sera. Serum antibodies to Simkania negevensis were detected by a homemade ELISA performed according to the Kahane's protocol. Furthermore water samples from hemodialytic circuit were collected, to evaluate Simkania negevensis resistance to usual treatment of disinfection. RESULTS: Our results were unexpected, showing a higher seroprevalence of antibodies against Simkania negevensis in the hemodialysis patients, compared to renal transplant patients (IgG 22% vs 9% - IgA 9% vs 3%). S. negevensis was isolated in all water samples analyzed. CONCLUSIONS: Our study detected for the first time the occurrence of S. negevensis in hemodialysis and in renal transplant patients. Our findings suggest that water used in hemodialysis could be one of the possible sources of S. negevensis infection, without clinical involvement risk for patients.

The PI3K/Akt pathway is involved in procyanidin-mediated suppression of human colorectal cancer cell growth.

Colorectal cancer (CRC) has the third highest incidence worldwide. Epidemiological studies showed that the consumption of fruit and vegetables containing procyanidins (PCA), polymers of flavan-3-ols, is associated with lower CRC risk. However, the molecular mechanisms supporting this positive association are unclear. This study investigated the capacity of PCA with different degrees of polymerization to reduce CRC cell growth, characterizing the underlying mechanisms. Compared to the monomer ((-)-epicatechin) and the trimer, the hexamer (Hex) was the most active at reducing CRC cell viability. Hex caused a concentration- (2.5-50 µM) and time- (24-72 h) dependent decrease in the viability of six human CRC cell lines in culture. Hex caused CRC apoptotic Caco-2 cell death within 24 h, as evidenced by caspase 3 and caspase 9 activation, DNA fragmentation, and changes in nuclear morphology/staining. Hex-induced apoptosis occurs through the mitochondrial pathway, as evidenced by an increased Bad mitochondrial translocation, and cytochrome c release from the mitochondria to the cytosol. Hex also arrested the Caco-2 cell cycle at G2 /M phase and upregulated genes involved in autophagy. Mechanistically, in Caco-2 cells Hex inhibited the PI3K/Akt signaling pathway, causing the downstream downregulation of proteins involved in the regulation of cell survival (Bad, GSK-3ß). Accordingly, the Akt inhibitor MKK-2206 decreased Bad and GSK-3ß phosphorylation. MKK-2206 decreased cell growth, having an additive effect with Hex. In conclusion, our results show that large PCA can inhibit CRC cell growth via the Akt kinase pathway, demonstrating a mechanism to explain the epidemiological evidence linking PCA-rich diets with lower CRC risk. © 2016 Wiley Periodicals, Inc.

(-)-Epicatechin improves insulin sensitivity in high fat diet-fed mice.

Obesity constitutes a major public health concern, being frequently associated with type 2 diabetes (T2D). Evidence from studies in humans and experimental animals suggest that consumption of the flavan-3-ol (-)-epicatechin (EC) and of EC-rich foods may improve insulin sensitivity. To further understand the potential benefits of dietary EC consumption on insulin resistance, this study investigated the capacity of EC supplementation to prevent high fat diet (HFD)-induced insulin resistance in mice. To assess the underlying mechanisms, the effects of HFD and EC consumption on the activation of the insulin cascade and of its negative modulators were evaluated. HFD consumption for 15 w caused obesity and insulin resistance in C57BL/6J mice as evidenced by high fasted and fed plasma glucose and insulin levels, and impaired ITT and GTT tests. This was associated with alterations in the activation of components of the insulin-triggered signaling cascade (insulin receptor, IRS1, ERK1/2, Akt) in adipose and liver tissues. EC supplementation prevented/ameliorated all these parameters. EC acted improving insulin sensitivity in the HFD-fed mice in part through a downregulation of the inhibitory molecules JNK, IKK, PKC and protein tyrosine phosphatase 1B (PTP1B). Thus, the above results suggest that consumption of EC-rich foods could constitute a dietary strategy to mitigate obesity-associated insulin resistance.

(-)-Epicatechin in the prevention of tumor necrosis alpha-induced loss of Caco-2 cell barrier integrity.

An increased permeability of the intestinal barrier is proposed as a major event in the pathophysiology of inflammatory bowel diseases (IBD). Tumor necrosis alpha (TNFα) plays a central role in IBD pathogenesis, in part promoting tight function (TJ) barrier dysfunction. Food extracts enriched in (-)-epicatechin (EC) prevent the development or improve the progression of IBD in animal models. This study investigated the capacity of EC to inhibit TNFα-induced permeabilization of Caco-2 cell monolayers, characterizing the underlying mechanisms. Caco-2 cells differentiated into intestinal epithelial cells were incubated in the absence/presence of TNFα, with or without the addition of 0.5-5 µM EC. TNFα triggered cell monolayer permeabilization, decreasing transepithelial electrical resistance (TEER) and increasing the paracellular transport of fluorescein sulfonic acid. The permeabilizing effects of TNFα were not due to Caco-2 cell apoptosis as evaluated by DNA fragmentation, caspase 3 and 9 activation, and cell morphology. EC prevented TNFα-triggered Caco-2 monolayer permeabilization and acted inhibiting the associated: (i) NADPH oxidase (NOX)-mediated increased oxidant production, (ii) NF-κB (IκBα phosphorylation, p50 and RelA nuclear transport, and nuclear NF-κB-DNA binding) and ERK1/2 activation, (iii) increased myosin light kinase expression, and decreased TJ protein ZO-1 levels. In summary, EC prevented TNFα-mediated Caco-2 cell barrier permeabilization in part through the inhibition of NOX/NF-κB activation and downstream TJ disruption. Diets rich in EC could contribute to ameliorate IBD-associated increased intestinal permeability.

Waist circumference and dual-energy X-ray absorptiometry measures of overall and central obesity are similarly associated with systemic oxidative stress in women.

Growing evidence suggests that overall and abdominal obesity might lead to oxidative stress (OxS), which, in turn, plays a key role in the pathogenesis of a wide spectrum of diseases. In this study, for the first time, we compared the correlations of indirect, i.e. anthropometric, and direct, by dual energy X-ray absorptiometry (DXA), measures of body fat with circulatory OxS markers in women. To address this issue, we assessed central and total body fat mass (FM) by DXA, and serum levels of advanced oxidation protein products (AOPP), thiols and hydroperoxides in 275 healthy women (age 21-65 years; body mass index [BMI] 21.1-32.0 kg/m(2); waist circumference [WC] 60.1-109.9 cm). Among the markers considered in the study, only hydroperoxides levels, i.e. by-products of lipid peroxidation, were significantly (p < 0.05 for all) and positively correlated to body fat accumulation after controlling for confounding factors. In particular, this marker was found to be similarly associated with DXA-derived total FM, total FM % and trunk FM as well as with WC. Of note, hydroperoxides appeared to be correlated with abdominal but not with general obesity, as classified according to standard WC and BMI cut-offs, respectively. In conclusion, taken together our data demonstrated that, at least in women, the measurement of body FM by DXA has no advantage over the simpler and cheaper WC with regard to their associations with systemic OxS markers. Moreover, WC emerged as a superior potential predictor of OxS compared to the other most commonly used anthropometric measures (including BMI and waist to hip ratio).

Effects of (-)-epicatechin on hepatic triglyceride metabolism.

(-)-Epicatechin (EC) consumption is associated with an improvement of hyperlipemia and other metabolic changes linked to obesity and western-style diets. This work investigated the effects of EC on triglyceride (TG) metabolism both in vivo, where mice were supplemented with EC (2 and 20 mg EC per kg body weight), and in vitro, when human HepG2 hepatocytes were incubated in the presence of EC and the main EC metabolites found in human plasma. Increased hepatic TG levels were only observed after 24 weeks supplementation with EC (20 mg per kg body weight), with a preserved liver structure and absence of inflammation or oxidative stress. EC caused increased expression of diacylglycerol acyltransferases (DGAT2), key enzymes in TG synthesis, and the upregulation of PPARα, which promotes free fatty acid (FFA) oxidation. On the other hand, incubation of HepG2 cells in the presence of high concentrations of EC (1-10 µM) did not affect TG deposition nor DGAT2 expression. In summary, in mouse liver, EC upregulated mechanisms that can neutralize the potential toxicity of FFA, i.e. TG synthesis and FFA ß-oxidation. Results in mouse liver and HepG2 cells stress the safety of EC in terms of TG metabolism and development of hepatopathies in doses within the limits given by a rational time and dose for human consumption.

Factors driving the inter-individual variability in the metabolism and bioavailability of (poly)phenolic metabolites: A systematic review of human studies.

This systematic review provides an overview of the available evidence on the inter-individual variability (IIV) in the absorption, distribution, metabolism, and excretion (ADME) of phenolic metabolites and its determinants. Human studies were included investigating the metabolism and bioavailability of (poly)phenols and reporting IIV. One hundred fifty-three studies met the inclusion criteria. Inter-individual differences were mainly related to gut microbiota composition and activity but also to genetic polymorphisms, age, sex, ethnicity, BMI, (patho)physiological status, and physical activity, depending on the (poly)phenol sub-class considered. Most of the IIV has been poorly characterised. Two major types of IIV were observed. One resulted in metabolite gradients that can be further classified into high and low excretors, as seen for all flavonoids, phenolic acids, prenylflavonoids, alkylresorcinols, and hydroxytyrosol. The other type of IIV is based on clusters of individuals defined by qualitative differences (producers vs. non-producers), as for ellagitannins (urolithins), isoflavones (equol and O-DMA), resveratrol (lunularin), and preliminarily for avenanthramides (dihydro-avenanthramides), or by quali-quantitative metabotypes characterized by different proportions of specific metabolites, as for flavan-3-ols, flavanones, and even isoflavones. Future works are needed to shed light on current open issues limiting our understanding of this phenomenon that likely conditions the health effects of dietary (poly)phenols.

Anthocyanins and their metabolites promote white adipose tissue beiging by regulating mitochondria thermogenesis and dynamics.

High-fat diet (HFD) consumption and excess nutrient availability can cause alterations in mitochondrial function and dynamics. We previously showed that anthocyanins (AC) decreased HFD-induced body weight gain and fat deposition. This study investigated: i) the capacity of AC to mitigate HFD-induced alterations in mitochondrial dynamics, biogenesis, and thermogenesis in mouse subcutaneous white adipose tissue (sWAT), and ii) the underlying mechanisms of action of cyanidin-3-O-glucoside (C3G), delphinidin-3-O-glucoside (D3G), and their gut metabolites on mitochondria function/dynamics in 3T3-L1 adipocytes treated with palmitate. Mice were fed control or HFD diets, added or not with 40 mg AC/kg body weight (BW). Compared to control and AC-supplemented mice, HFD-fed mice had fewer sWAT mitochondria that presented alterations of their architecture. AC supplementation prevented HFD-induced decrease of proteins involved in mitochondria biogenesis (PPARγ, PRDM16 and PGC-1α), and thermogenesis (UCP-1), and decreased AMPK phosphorylation. AC supplementation also restored the alterations in sWAT mitochondrial dynamics (Drp-1, OPA1, MNF-2, and Fis-1) and mitophagy (BNIP3L/NIX) caused by HFD consumption. In mature 3T3-L1, C3G, D3G, and their metabolites protocatechuic acid (PCA), 4-hydroxybenzaldehyde (HB), and gallic acid (GA) differentially affected palmitate-mediated decreased cAMP, PKA, AMPK, and SIRT-1 signaling pathways. C3G, D3G, and metabolites also prevented palmitate-mediated decreased expression of PPARγ, PRDM16, PGC-1α, and UCP1. Results suggest that consumption of select AC, i.e. cyanidin and delphinidin, could promote sWAT mitochondriogenesis and improve mitochondria dynamics in the context of HFD/obesity-induced dysmetabolism in part by regulating PKA, AMPK, and SIRT-1 signaling pathways.

Bone mass density selectively correlates with serum markers of oxidative damage in post-menopausal women.

BACKGROUND: Post-menopausal osteoporosis (PO) affecting a large fraction of elderly women, is triggered by the decline in 17ß-estradiol (E2) level. Experimental studies in animal models and cell cultures have suggested that the fall in E2 might contribute to developing oxidative stress (OS) which in turn is believed to play an important role in PO pathogenesis. The scarcity of human studies focusing on this issue prompted us to investigate the effects of the reproductive and post-reproductive phase of women's life on OS and bone health. METHODS: Serum parameters of oxidative challenge (lipid hydroperoxides and protein advanced oxidation products) and antioxidant defence (total serum antioxidants levels) along with bone mineral density (BMD) at femoral neck and lumbar spine were assessed in a sample of 191 women (98 pre- and 93 post-menopausal, of whom 30 osteoporotic). RESULTS: Pearson's correlation analysis unveiled that spinal BMD was negatively correlated with lipid hydroperoxides in overall postmenopausal subsample (r=-0.251, p=0.012), while no significant link between these two variables was detected in women in reproductive age (r=-0.022, p=0.833). Noteworthy, stepwise multiple regression analysis showed that the association found in post-menopausal women retained significance after adjusting for potential confounding factors (p=0.001). CONCLUSIONS: Our data showed that markers of oxidative challenge are associated with bone loss in women in post-menopausal status. We suggest that menopause-related estrogen withdrawal might contribute to make bone more vulnerable to oxidative injury thereby increasing the risk of PO development.

Accumulation of central fat correlates with an adverse oxidative balance in non-obese postmenopausal women.

The aim of the present study was to investigate whether accumulation of central fat is correlated with systemic oxidative stress (OxS) in non-obese apparently healthy postmenopausal women. Serum parameters of OxS (hydroperoxides and non-enzymatic antioxidants) along with body fat distribution, as assessed by dual-energy-X-ray absorptiometry (DXA), were evaluated in 134 non-obese postmenopausal women. Multiple regression analysis showed that central (trunk) fat significantly correlated with both markers of OxS independently of confounding factors (i.e. BMI, smoking, age, hypertension, legs and arms fat mass). In specific, the standardized regression coefficient was positive for hydroperoxides (ß = 0.324, p < 0.05) and negative for antioxidants (ß = -0.495, p < 0.01) level. In conclusion, the current data showed that the increase in central fat is an independent predictor of OxS condition among non-obese women in postmenopausal status. The possible pro-oxidant effects of the excess in central adiposity might be more harmful among post- than among pre-menopausal women, due to the postulated ability of E2 to contrast oxidative challenge and the related diseases.

Anthocyanin actions at the gastrointestinal tract: Relevance to their health benefits.

Anthocyanins (AC) are flavonoids abundant in the human diet, which consumption has been associated to several health benefits, including the mitigation of cardiovascular disease, type 2 diabetes, non-alcoholic fatty liver disease, and neurological disorders. It is widely recognized that the gastrointestinal (GI) tract is not only central for food digestion but actively participates in the regulation of whole body physiology. Given that AC, and their metabolites reach high concentrations in the intestinal lumen after food consumption, their biological actions at the GI tract can in part explain their proposed local and systemic health benefits. In terms of mechanisms of action, AC have been found to: i) inhibit GI luminal enzymes that participate in the absorption of lipids and carbohydrates; ii) preserve intestinal barrier integrity and prevent endotoxemia, inflammation and oxidative stress; iii) sustain goblet cell number, immunological functions, and mucus production; iv) promote a healthy microbiota; v) be metabolized by the microbiota to AC metabolites which will be absorbed and have systemic effects; and vi) modulate the metabolism of GI-generated hormones. This review will summarize and discuss the latest information on AC actions at the GI tract and their relationship to overall health benefits.

Curcumin Mitigates TNFα-Induced Caco-2 Cell Monolayer Permeabilization Through Modulation of NF-κB, ERK1/2, and JNK Pathways.

SCOPE: This work studies the capacity of curcumin to inhibit tumor necrosis alpha (TNFα)-induced inflammation, oxidative stress, and loss of intestinal barrier integrity, characterizing the underlying mechanisms. METHODS AND RESULTS: Caco-2 cell monolayers are incubated with TNFα (10 ng mL-1 ), in the absence or presence of curcumin. TNFα causes an increase in interleukin (IL)-6 and IL-8 release, which is inhibited by curcumin in a dose-dependent manner (half-maximal inhibitory concentration (IC50 ) = 3.4 µM for IL-6). Moreover, TNFα leads to: i) increased intercellular adhesion molecule 1 (ICAM-1) and NLRP3 inflammasome expression; ii) increased cell monolayer permeability and decreased levels of tight junction proteins; iii) increased cellular and mitochondrial oxidant production; iv) decreased mitochondrial membrane potential and complex I-III activity; v) activation of redox-sensitive pathways, i.e., nuclear factor-kappa B (NF-κB), extracellular signal-regulated kinase 1/2 (ERK1/2), and c-Jun N-terminal kinases (JNK); and vi) increased myosin light-chain kinase (MLCK) expression and phosphorylation levels of myosin light-chain protein MLC. Curcumin (2-8 µM) inhibits all these TNFα-triggered undesirable outcomes, mostly showing dose-dependent effects. CONCLUSION: The inhibition of NF-κB, ERK1/2, and JNK activation could be in part involved in the capacity of curcumin to mitigate intestinal inflammation, oxidant production, activation of redox-sensitive pathways, and prevention of monolayer permeabilization. These results support an action of dietary curcumin in sustaining gastrointestinal tract physiology.

Supplementation with cyanidin and delphinidin mitigates high fat diet-induced endotoxemia and associated liver inflammation in mice.

Consumption of high fat diets (HFD) and the associated metabolic endotoxemia can initiate liver inflammation and lipid deposition that with time can progress to non-alcoholic fatty liver disease (NAFLD). We previously observed that 14 weeks supplementation with the anthocyanidins cyanidin and delphinidin mitigated HFD-induced metabolic endotoxemia and liver insulin resistance, steatosis, inflammation and oxidative stress. This work investigated if a 4-week supplementation of mice with a cyanidin- and delphinidin-rich extract (CDRE) could mitigate or reverse HFD (60% calories from lard fat)-induced liver steatosis and inflammation. After a first 4-weeks period on the HFD, mice showed increased endotoxemia and activation of liver proinflammatory signaling cascades. Supplementation with CDRE between weeks 4 and 8 did not mitigate liver steatosis or the altered lipid and glucose plasma levels. However, CDRE supplementation reverted HFD-induced metabolic endotoxemia, in parallel with the mitigation of the overexpression of hepatic TLR2 and TLR4, and of the activation of: (i) NF-κB, (ii) AP-1 and upstream mitogen-activated kinases p38 and ERK1/2, and (iii) HIF-1. Thus, even a short-term consumption of cyanidin and delphinidin could help mitigate the adverse consequences, i.e. metabolic endotoxemia and associated liver inflammation, triggered by the regular consumption of diets rich in fat.

Cyanidin and delphinidin restore colon physiology in high fat diet-fed mice: Involvement of TLR-4 and redox-regulated signaling.

Consumption of high fat diets (HFD) mimics a modern or "Western style" diet pattern and can impair intestinal barrier integrity, leading to endotoxemia and associated unhealthy conditions. This study investigated if supplementation with an anthocyanin (cyanidin and delphinidin glucosides)-rich extract (CDRE) could revert or mitigate HFD-induced alterations of colonic physiology in part through the regulation of Toll-Like Receptor 4 (TLR-4)- and redox-regulated signaling. C57BL/6J male mice were fed for 4 weeks with a control or an HFD. Then, mice were divided in four groups fed either control or HFD, or these diets supplemented with CDRE for the subsequent 4 weeks. After 8 weeks on the HFD we observed in the colon: i) disruption of tight junction structure and function; ii) increased TLR-4 expression; iii) increased NADPH oxidase NOX1 expression, and iv) activation of redox-sensitive and TLR-4-triggered pathways, i.e. NF-κB, ERK1/2, JNK1/2, PI3K/Akt. All these events were prevented or reverted by CDRE supplementation. Supporting the relevance of CDRE-mediated downregulation of TLR-4 on its colon beneficial effect; in vitro (Caco-2 cell monolayers), cyanidin, delphinidin and their metabolites protocatechuic and gallic acid, mitigated lipopolysaccharide (LPS)-induced monolayer permeabilization by restoring tight junction structure and dynamics and preventing lipid/protein oxidation. The CDRE also mitigated HFD-mediated alterations in parameters of goblet cell differentiation and function, including the downregulation of markers of goblet cell differentiation (Klf4), and intestinal mucosa healing (Tff3). Results show that a short-term supplementation with cyanidin and delphinidin, protect from HFD-induced alterations in colon physiology in part through the modulation of TLR-4- and redox-regulated signaling.

(-)-Epicatechin mitigates anxiety-related behavior in a mouse model of high fat diet-induced obesity.

Mounting evidence demonstrates that consumption of high fat diet (HFD) and subsequent development of obesity leads to alterations in cognition and mood. While obesity can affect brain function, consumption of select dietary bioactives may help prevent obesity-related cognitive decline. This study investigated the capacity of the dietary flavonoid (-)-epicatechin (EC) to mitigate HFD-induced obesity-associated alterations in memory and mood. Healthy 8-week old male C57BL/6J mice were maintained on either a control diet (10 kCal% from fat) or a HFD (45 kCal% from fat) and were supplemented with EC at 2 or 20 mg/kg body weight (B.W.) for a 24 week period. Between week 20 and 22, anxiety-related behavior, recognition memory, and spatial memory were measured. Underlying mechanisms were assessed by measuring the expression of selected genes in the hippocampus and by 16S rRNA sequencing and metabolomic analysis of the gut microbiota. 24 weeks of HFD feeding resulted in obesity, which was not affected by EC supplementation. HFD-associated increase in anxiety-related behavior was mitigated by EC in a dose-response manner and was accompanied by increased hippocampal brain-derived neurotrophic factor (BDNF), as well as partial or full restoration of glucocorticoid receptor, mineralocorticoid receptor and 11ß-hydroxysteroid dehydrogenase type 1 (11ß-HSD1) expression. Higher EC dosage (20 mg/kg B.W.) also restored aberrant Lactobacillus and Enterobacter abundance altered by HFD and/or the associated obesity. Together, these results demonstrate how EC mitigates anxiety-related behaviors, revealing a connection between BDNF- and glucocorticoids-mediated signaling. Our findings link changes in the hippocampus and the gut microbiota in a context of HFD-induced obesity and anxiety.