Long-term administration of resveratrol at low doses improves neurocognitive performance as well as cerebral blood flow and modulates the inflammatory pathways in the brain.

There is an increasing prevalence of coincident cerebrovascular deficiency and cognitive dysfunction with aging. Increased oxidative stress as well as inflammation that occurs with aging are associated with the impairment of cerebral vascularization. Interestingly, Resveratrol (RSV), a natural phytoalexin, is known to be a strong antioxidant and possesses anti-inflammatory properties. Collectively, these observations strongly suggest that RSV could protect against cerebral vascularization defect and then improves the decline cognitive function associated with aging. In order to test this hypothesis, we investigated the effect of a long-term RSV treatment (1.25 mg/day for 5 months) on cognitive performances of animals that we have allowed to age normally. Then, we further analyzed the gene expression profile and the cerebral blood flow in the brain. By means of novel object recognition (NOR) test, we observed that RSV enhanced NOR performances of aged rats. In addition, RSV enhanced cerebral blood flow during NOR task in aged rats. Using microarrays experiments, we also showed that several pathways related to inflammation and oxidative stress (Eicosanoid signaling, MIF-mediated innate immunity, NF-kB signaling, TNFR2 signaling, IL6 signaling, Production of nitric oxide and ROS) were down-regulated in the brain of RSV treatments rats compared to control rats. In conclusion, these results support that a long-term treatment with RSV improves cognitive performance in the elderly male rat model. This effect is associated with an increase in cerebral blood flow and a decrease in the expression of several pro-inflammatory pathways in the brain.

Resveratrol-mediated glycemic regulation is blunted by curcumin and is associated to modulation of gut microbiota.

The polyphenols resveratrol (RSV) and curcumin (Cur) are phytoalexines and natural antibiotics with numerous pharmacological functions and metabolic impacts. Recent evidences show a broad control of gut microbiota by polyphenols which could influence glycemic regulation. The aim of this work is to estimate the respective effect of RSV and Cur alone or in association on the control of glycemia and on gut microbiota. A 5-week chronic treatment of hyperglycemic mice with RSV and/or Cur resulted in a differential effect on glucose tolerance test and modified gut microbiome. We precisely identified groups of bacteria representing a specific signature of the glycemic effect of RSV. Inferred metagenomic analysis and metabolic pathway prediction showed that the sulfur and branched-chain amino-acid (BCAA) metabolic activities are tightly correlated with the efficacy of RSV for the control of glycaemia. The impact on BCAA metabolism was further validated by serum metabolomics analysis. Altogether, we show that polyphenols specifically impact gut microbiota and corresponding metabolic functions which could be responsible for their therapeutic role.

In Vitro Cocktail Effects of PCB-DL (PCB118) and Bulky PCB (PCB153) with BaP on Adipogenesis and on Expression of Genes Involved in the Establishment of a Pro-Inflammatory State.

(1) Objective: Highlight the in vitro effects of 3T3-L1 cell exposure to polychlorinated biphenyls (PCB118 and 153) or benzo(a)pyrene (BaP) alone or as a cocktail on adipogenesis (ADG) by focusing on changes in lipid metabolism and inflammatory-related genes expression (INFG) and ADG-related genes expression (ADGG); (2) Results: Treatment from the early stage of cell differentiation by BaP alone or in combination with PCBs decreased the expression of some of the ADGG (PPARγGlut-4, FAS, Lipin-1a, Leptin, and Adiponectin). BaP enhanced the INFG, especially MCP-1 and TNFα. Co-exposure to BaP and PCB153 showed a synergistic effect on TNFα and IL6 expression. Treatment with BaP and PCBs during only the maturation period up-regulated the INFG (IL6, TNFα, CXCL-10 & MCP-1). PCB118 alone also enhanced TNFα, CXCL-10, and PAI-1 expression. The change in MCP-1 protein expression was in agreement with that of the gene. Finally, the BaP-induced up-regulation of the xenobiotic responsive element (XRE)-controlled luciferase activity was impaired by PCB153 but not by PCB118; (3) Conclusion: BaP and PCBs down-regulate a part of ADGG and enhance INFG. The direct regulatory effect of PCBs on both ADGG and INFG is usually rather lower than that of BaP and synergistic or antagonistic cocktail effects are clearly observed.

The Transcriptional Effects of PCB118 and PCB153 on the Liver, Adipose Tissue, Muscle and Colon of Mice: Highlighting of Glut4 and Lipin1 as Main Target Genes for PCB Induced Metabolic Disorders.

Epidemiological studies have associated environmental exposure to polychlorinated biphenyls (PCBs) with an increased risk of type 2 diabetes; however, little is known about the underlying mechanisms involved in the metabolic side-effects of PCB. Our study evaluated the transcriptional effects of a subchronic exposure (gavage at Day 0 and Day 15 with 10 or 100 µmol/Kg bw) to PCB118 (dioxin-like PCB), PCB153 (non-dioxin-like PCB), or an equimolar mixture of PCB118 and PCB153 on various tissues (liver, visceral adipose tissue, muscle, and colon) in mice. Our results showed that a short-term exposure to PCB118 and/or PCB153 enhanced circulating triglyceride levels but did not affect glycemia. Among the studied tissues, we did not observe any modification of the expression of inflammation-related genes, such as cytokines or chemokines. The main transcriptional effects were observed in visceral adipose and liver tissues. We found a downregulation of lipin1 and glut4 expression in these two target organs. In adipose tissue, we also showed a downregulation of Agpat2, Slc25a1, and Fasn. All of these genes are involved in lipid metabolism and insulin resistance. In muscles, we observed an induction of CnR1 and Foxo3 expression, which may be partly involved in PCB metabolic effects. In summary, our results suggest that lipin1 and glut4, notably in adipose tissue, are the main targeted genes in PCB-induced metabolic disorders, however, further studies are required to fully elucidate the mechanisms involved.

Resveratrol increases glucose induced GLP-1 secretion in mice: a mechanism which contributes to the glycemic control.

Resveratrol (RSV) is a potent anti-diabetic agent when used at high doses. However, the direct targets primarily responsible for the beneficial actions of RSV remain unclear. We used a formulation that increases oral bioavailability to assess the mechanisms involved in the glucoregulatory action of RSV in high-fat diet (HFD)-fed diabetic wild type mice. Administration of RSV for 5 weeks reduced the development of glucose intolerance, and increased portal vein concentrations of both Glucagon-like peptid-1 (GLP-1) and insulin, and intestinal content of active GLP-1. This was associated with increased levels of colonic proglucagon mRNA transcripts. RSV-mediated glucoregulation required a functional GLP-1 receptor (Glp1r) as neither glucose nor insulin levels were modulated in Glp1r-/- mice. Conversely, levels of active GLP-1 and control of glycemia were further improved when the Dipeptidyl peptidase-4 (DPP-4) inhibitor sitagliptin was co-administered with RSV. In addition, RSV treatment modified gut microbiota and decreased the inflammatory status of mice. Our data suggest that RSV exerts its actions in part through modulation of the enteroendocrine axis in vivo.

CYP1A1 induction in the colon by serum: involvement of the PPARα pathway and evidence for a new specific human PPREα site.

BACKGROUND: We previously showed that blood serum induced cytochrome P450 1A1 (CYP1A1) monooxygenase expression in vitro. OBJECTIVE: Our purpose was (i) to identify the molecular mechanism involved and (ii) to characterize the inducer compound(s) in serum involved at least in part. METHODS: Serum was fractionated on hydrophobic columns. PPARα involvement was demonstrated by gene reporter assays, DNA mutagenesis and EMSA. Gene expression was evaluated by qRT-PCR. Serum samples were analyzed using HS-SPME-GC-MS. RESULTS: The inductive effect of serum did not depend on the AhR pathway and was enhanced by cotransfection of PPARα cDNA. Mutations in the PPAR response elements of the CYP1A1 gene promoter suppressed this effect. One of the PPRE sites appeared highly specific for human PPARα, an unreported PPRE property. A link was found between CYP1A1 inducibility and serum hydrophobic compounds. Characterization of sera showed that hexanal, a metabolite produced by peroxidation of linoleic acid, was involved in CYP1A1 induction by serum, possibly along with other serum entities. CONCLUSION: We demonstrate that serum induces CYP1A1 via the PPARα pathway and that hexanal is one of the serum inducers. The two PPRE sites within the CYP1A1 promoter are functional and one of them is specific for PPARα.

Polycyclic aromatic hydrocarbons potentiate high-fat diet effects on intestinal inflammation.

We demonstrate that intestinal inflammation caused by high-fat diet is increased by the environmental contaminant benzo[a]pyrene. Our in vivo results indicate that a high-fat diet (HFD) induces a pre-diabetic state in mice compared with animals fed normal chow. HFD increased IL-1betamRNA concentration in the jejunum, colon, and liver, and TNFalpha was increased in the colon and strongly increased in the liver. HFD also increased the expression of other genes related to type 2 diabetes, such as the uncoupling protein UCP2, throughout the bowel and liver, but not in the colon. The treatment of HFD with BaP enhanced the expression of IL-1beta in the liver and TNFalpha throughout the bowel and in the liver. Adding BaP to the diet also caused a significant decrease in the expression of the incretin glucagon-like peptide 1, which plays an important role in insulin secretion. Our results suggest that intestinal inflammation may be involved in the onset of type 2 diabetes and that chronic exposure to environmental polycyclic aromatic hydrocarbons can increase the risk of type 2 diabetes by inducing pro-inflammatory cytokine production.

Integrin alphavbeta6 mediates HT29-D4 cell adhesion to MMP-processed fibrinogen in the presence of Mn2+.

Mn(2+) was found to induce adhesion of HT29-D4 adenoma carcinoma cells to fibrinogen (Fb). This was independent of the expression of the beta3 integrin subunit and involved endogenous alphavbeta6 but not alphavbeta5 integrin. Thus, addition of Mn(2+) led to a change in integrin alphavbeta6 specificity. Furthermore, Mn(2+) was found to strongly activate the extracellular signal-regulated kinase/mitogen-activated protein kinase (ERK/MAPK) pathway in the HT29-D4 cell line. As a MAPK inhibitor strongly reduced the Mn(2+)-induced cell adhesion to Fb, it is suggested that a link between MAPK activation and cell adhesion to Fb exists. Both expression and activity of matrix metalloproteinase-9 (MMP-9) were enhanced by Mn(2+) and this led to Fb processing. MMP inhibitors prevented Mn(2+)-mediated cell adhesion to Fb, leading us to suggest that Mn(2+) promoted convergent changes in integrin alphavbeta6 conformation and Fb structure through activation of ERK/MAPK and MMP-9. Finally, we found that Mn(2+) and activators of the ERK pathway cooperated in HT29-D4 cell adhesion to Fb. Such a process may be involved in bone metastasis of some cancer cells.

Cytokine-induced upregulation of NF-kappaB, IL-8, and ICAM-1 is dependent on colonic cell polarity: implication for PKCdelta.

As described for a long time, carcinoma-derived Caco-2 cells form a polarized epithelium in culture, whereas HT29-D4 cells are nonpolarized and undifferentiated but can form a polarized monolayer when cultured in a galactose-supplemented medium. Using NF-kappaB translocation and IL-8 and ICAM-1 gene activation as an index, we have studied the relationship between the differentiation state and the cell response to cytokines. We found that differentiated Caco-2 and HT29-D4 cells were responsive to both cytokines TNFalpha- and IL-1beta-mediated activation of NF-kappaB but that undifferentiated HT29-D4 cells were unresponsive to IL-1beta. However, the expression of endogenous ICAM-1 and IL-8 genes was upregulated by these cytokines in either cell lines differentiated or not. Upregulation of ICAM-1 gene occurred when IL-1beta or TNFalpha was added to the basal, but not apical surface of the differentiated epithelia. Finally, it appeared that in polarized HT29-D4 cells, the IL-1beta-induced translocation of NF-kappaB was connected to PKCdelta translocation.

Insulin-like growth factor-1 downregulates nuclear factor kappa B activation and upregulates interleukin-8 gene expression induced by tumor necrosis factor alpha.

Pretreatment of HT29-D4 epithelial adenocarcinoma colic cells with des-IGF-1 upregulated TNF alpha-mediated activation of IL-8 expression at different levels (protein, mRNA, and hnRNA). RNA transcription but not RNA stabilization was found to be involved. In this cell line, cooperation of NF-kappa B with other factors appeared essential for IL-8 expression. Indeed, TNF alpha-induced NF-kappa B translocation was not sufficient to support enhancement of the transcription and des-IGF-1 did not promote but partly inhibited both the TNF alpha-induced NF-kappa B activation and I kappa B alpha degradation through a PI-3K-dependent pathway. A CCAAT/enhancer binding protein (C/EBP) site located on the IL-8 gene enhancer cooperated with a NF-kappa B binding site and led to the upregulation of IL-8 expression. Binding of C/EBP alpha to this sequence disappeared in IGF-1 treated cells. This event may be important for the cross-talk between IGF-1- and TNF alpha-mediated pathways leading to the control of inflammatory processes and the decision concerning apoptosis or cell survival.