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.

Can we trust untargeted metabolomics? Results of the metabo-ring initiative, a large-scale, multi-instrument inter-laboratory study

The metabo-ring initiative brought together five nuclear magnetic resonance instruments (NMR) and 11 different mass spectrometers with the objective of assessing the reliability of untargeted metabolomics approaches in obtaining comparable metabolomics profiles. This was estimated by measuring the proportion of common spectral information extracted from the different LCMS and NMR platforms. Biological samples obtained from 2 different conditions were analysed by the partners using their own in-house protocols. Test #1 examined urine samples from adult volunteers either spiked or not spiked with 32 metabolite standards. Test #2 involved a low biological contrast situation comparing the plasma of rats fed a diet either supplemented or not with vitamin D. The spectral information from each instrument was assembled into separate statistical blocks. Correlations between blocks (e.g., instruments) were examined (RV coefficients) along with the structure of the common spectral information (common components and specific weights analysis). In addition, in Test #1, an outlier individual was blindly introduced, and its identification by the various platforms was evaluated. Despite large differences in the number of spectral features produced after post-processing and the heterogeneity of the analytical conditions and the data treatment, the spectral information both within (NMR and LCMS) and across methods (NMR vs. LCMS) was highly convergent (from 64 to 91 % on average). No effect of the LCMS instrumentation (TOF, QTOF, LTQ-Orbitrap) was noted. The outlier individual was best detected and characterised by LCMS instruments. In conclusion, untargeted metabolomics analyses report consistent information within and across instruments of various technologies, even without prior standardisation.

Independent positive association of plasma β-carotene concentrations with adiponectin among non-diabetic obese subjects

PURPOSE

Many epidemiological studies find an inverse correlation between carotenoids intake or carotenoids plasma concentrations and body mass index (BMI), insulin resistance or metabolic syndrome in the general population. However, it is not clear whether these relationships occur in obese population.

METHODS

We conducted a cross-sectional study in 108 obese non-diabetic patients.

RESULTS

There was an inverse correlation between plasma levels of pro-vitamin A carotenoids (α-carotene, β-carotene and β-cryptoxanthin) and both BMI and insulin resistance (estimated by the HOMA-IR). No correlation between plasma concentrations of lycopene or lutein/zeaxanthin and BMI or insulin resistance was found. The inverse association between the three pro-vitamin A carotenoids and HOMA-IR disappeared after adjustment for BMI and waist circumference. Interestingly, we identified a positive association between concentrations of β-carotene and adiponectin in plasma that was independent of sex, age, smoking status, BMI and waist circumference. To our knowledge, such association has never been described in obese patients.

CONCLUSION

These results suggest the existence of a favourable effect of β-carotene on insulin sensitivity in obese individuals that could involve a positive regulation of adiponectin, either directly or via its pro-vitamin A activity. The demonstration of the potential benefits of β-carotene towards insulin sensitivity would open the way to dietary strategies to prevent metabolic syndrome.

The Medi-RIVAGE study: reduction of cardiovascular disease risk factors after a 3-mo intervention with a Mediterranean-type diet or a low-fat diet

BACKGROUND

Epidemiologic studies link Mediterranean-type diets to a low incidence of cardiovascular disease; however, few dietary intervention studies have been undertaken, especially in primary prevention.

OBJECTIVES

In the Mediterranean Diet, Cardiovascular Risks and Gene Polymorphisms (Medi-RIVAGE) study, the effects of a Mediterranean-type diet (Med group) or a low-fat diet (low-fat group) on risk factors were evaluated in 212 volunteers (men and women) with moderate risk factors for cardiovascular disease.

DESIGN

After the 3-mo dietary intervention, changes in many risk factors were evaluated. Dietary questionnaires and plasma nutritional markers were used to test compliance.

RESULTS

Although the dietary goals were only partially reached, changes in dietary habits were observed in both groups (n = 169): protein, carbohydrate, and fiber intakes increased and fat quality (decreased saturated fat and increased monounsaturated or polyunsaturated fat) improved. BMI, total and triacylglycerol-rich lipoprotein (TRL) cholesterol, triacylglycerols, TRL triacylglycerols, apolipoproteins A-I and B, insulinemia, glycemia, and the homeostasis model assessment score were significantly lower after 3 mo. The reductions in total cholesterol, triacylglycerols, and insulinemia remained significant after adjustment for BMI. There was a trend for a diet-by-time interaction for LDL cholesterol (P = 0.09). Our data predicted a 9% reduction in cardiovascular disease risk with the low-fat diet and a 15% reduction with this particular Mediterranean diet.

CONCLUSION

After a 3-mo intervention, both diets significantly reduced cardiovascular disease risk factors to an overall comparable extent.

The Medi-RIVAGE study (Mediterranean Diet, Cardiovascular Risks and Gene Polymorphisms): rationale, recruitment, design, dietary intervention and baseline characteristics of participants

OBJECTIVE

To report the rationale, recruitment, design, dietary intervention and baseline characteristics of participants in the Medi-RIVAGE study (Mediterranean Diet, Cardiovascular Risks and Gene Polymorphisms).

DESIGN

A randomised, parallel trial comparing a new nutritional programme with a conventional programme.

SETTING

Centre for Detection and Prevention of Arteriosclerosis, Timone University Hospital, Marseille, France, and collaborating teams.

SUBJECTS

Two hundred and twelve male and female volunteers with at least one cardiovascular risk factor.

INTERVENTION

A Mediterranean-type diet characterised mainly by the quality of fatty acids, amount of fish, vegetable foodstuffs and fibre was proposed and compared with a usually prescribed, low-fat/cholesterol diet. Body mass index, fasting lipids and lipoproteins, apolipoproteins, glucose, insulin and homocysteine were the main outcome measures. Gene polymorphisms of interest were determined.

RESULTS

Characteristics of men in the two arms were comparable with regard to sociodemographic variables, and clinical and biological cardiovascular risk factors. There were few differences between the groups of women (cholesterol-related parameters, P<0.05). There was no difference between arms in allelic distribution of the gene polymorphisms studied. Saturated fat and protein intakes were high while carbohydrate and fibre intakes were low, but with no difference between arms. Overall, the nutritional markers were comparable in both arms with few exceptions. Correlations between nutritional intakes and plasma nutrient levels ranged from 0.19 (beta-carotene) to 0.47 (folate).

CONCLUSIONS

The comparability of the two arms is notable and warrants a low risk of biases. Current diet departs from the traditional Mediterranean one. The assessment of nutritional intake is validated by correlations obtained between dietary intake and relevant biomarkers. This will be important to estimate participant compliance and to analyse intervention data.

Effect of Tomato Product Consumption on the Plasma Status of Antioxidant Microconstituents and on the Plasma Total Antioxidant Capacity in Healthy Subjects

OBJECTIVES

to identify the plasma antioxidant microconstituents mainly affected by tomato product consumption, to check whether tomato product consumption can affect antioxidant status, and to identify tomato-product antioxidant-microconstituents mainly involved in the effect of these products on oxidative stress.

DESIGN

Medium-term dietary supplementation study.

SETTING

Human Nutrition Laboratory, Clermont-Ferrand, France.

SUBJECTS

Twenty healthy young (20 < years < 40), non obese (18 < BMI (kg/m2) < 25), females were recruited by advertisement. All of them completed the study.

INTERVENTION

The usual diet of the subjects was supplemented for three weeks with 96 g/day tomato puree. The volunteers then avoided tomato-product-rich foods for a subsequent three-week period.

MEASURES OF OUTCOME

Fasting blood samples were collected the day before supplementation, the day after the supplementation period, and the day after the depletion period. The status of several antioxidant microconstituents (plasma microconstituent concentrations), and the antioxidant status (plasma total antioxidant capacity) were assessed.

RESULTS

Supplementation with tomato puree significantly increased plasma lycopene, beta-carotene and lutein. Conversely it did not significantly affect plasma vitamin C and E, plasma antioxidant trace metals (Cu, Zn and Se), and plasma total antioxidant capacity. Avoidance of tomato-product-rich foods for three weeks significantly (p < 0.05) decreased plasma lycopene, beta-carotene, lutein and vitamin C, as well as plasma total antioxidant capacity. Plasma total antioxidant capacity, as measured by chemiluminescence, was positively related (p < 0.05) to the status of lycopene, vitamin C and beta-carotene.

CONCLUSIONS

Tomato product consumption can affect not only the lycopene status, but also that of other antioxidant microconstituents (beta-carotene and lutein). Lycopene, but also beta-carotene, are apparently the main tomato microconstituents responsible for the effect of tomato products on antioxidant status.