Yearly attained adherence to Mediterranean diet and incidence of diabetes in a large randomized trial

BACKGROUND

Several large observational prospective studies have reported a protection by the traditional Mediterranean diet against type 2 diabetes, but none of them used yearly repeated measures of dietary intake. Repeated measurements of dietary intake are able to improve subject classification and to increase the quality of the assessed relationships in nutritional epidemiology. Beyond observational studies, randomized trials provide stronger causal evidence. In the context of a randomized trial of primary cardiovascular prevention, we assessed type 2 diabetes incidence according to yearly repeated measures of compliance with a nutritional intervention based on the traditional Mediterranean diet.

METHODS

PREDIMED (''PREvención con DIeta MEDiterránea'') was a Spanish trial including 7447 men and women at high cardiovascular risk. We assessed 3541 participants initially free of diabetes and originally randomized to 1 of 3 diets: low-fat diet (n = 1147, control group), Mediterranean diet supplemented with extra virgin olive (n = 1154) or Mediterranean diet supplemented with mixed nuts (n = 1240). As exposure we used actual adherence to Mediterranean diet (cumulative average), yearly assessed with the Mediterranean Diet Adherence Screener (scoring 0 to 14 points), and repeated up to 8 times (baseline and 7 consecutive follow-up years). This score was categorized into four groups: < 8, 8-< 10, 10- < 12, and 12-14 points. The outcome was new-onset type 2 diabetes.

RESULTS

Multivariable-adjusted hazard ratios from time-varying Cox models were 0.80 (95% confidence interval, 0.70-0.92) per + 2 points in Mediterranean Diet Adherence Screener (linear trend p = .001), and 0.46 (0.25-0.83) for the highest (12-14 points) versus the lowest (< 8) adherence. This inverse association was maintained after additionally adjusting for the randomized arm. Age- and sex-adjusted analysis of a validated plasma metabolomic signature of the Mediterranean Diet Adherence Screener (constituted of 67 metabolites) in a subset of 889 participants also supported these results.

CONCLUSIONS

Dietary intervention trials should quantify actual dietary adherence throughout the trial period to enhance the benefits and to assist results interpretation. A rapid dietary assessment tool, yearly repeated as a screener, was able to capture a strong inverse linear relationship between Mediterranean diet and type 2 diabetes. Trial registration ISRCTN35739639.

Systemic biomarkers for the preclinical diagnosis of dementia

Background

As a consequence of aging and the age-related cardiovascular risk, both of them closely associated to neurodegenerative diseases, dementia has become one of the major public health concerns for governments and the scientific and medical communities. Up to date, there isn't any front-line screening tool implemented at a population level. In this regard, we aim to assess the association of several systemic biomarkers related to neuroinflammation [lactate dehydrogenase (LDH), complement component 3, C-reactive protein, alpha-1-antitrypsin, alpha-2-macroglobulin (α2M) and pancreatic prohormone], lipid metabolism [apolipoprotein E, 24S-hydroxycholesterol], and neuronal integrity [tau protein], with dementia risk in an adult-elderly population at high cardiovascular risk.

Methods

We designed a case-cohort study nested in the PREDIMED cohort (110 incident cases of dementia, 251 non-cases). Participants were at high risk for cardiovascular disease (CVD), but had no clinical CVD neither dementia at the time of enrolment. Inclusion criteria were an age of 55-80 years old and the presence of diabetes type 2 or at least 3 cardiovascular risk factors (smoking, overweight or obesity, hypertension, dyslipidemia, and family history of premature CVD). We used Cox proportional hazard models to estimate hazard ratios (HR) of the association between these nine plasma biomarkers and dementia risk adjusted for several covariates.

Results

Dementia cases were older, presented higher levels of fasting glucose and were more likely to have type 2 diabetes. The prevalence of dyslipidemia and smoking in patients with dementia was lower. Dementia cases had higher levels of LDH and α2M. Higher LDH levels were associated with a higher risk of developing dementia after adjustment (HR = 1.19).

Conclusions

Higher LDH plasma levels are associated with a higher risk of dementia incidence in population at high cardiovascular risk.

Key messages

Higher levels of LDH are associated with higher risk of dementia incidence among adult-elderly individuals with a high cardiovascular risk profile. The early detection of this biomarker could enable an early intervention and to delay, or perhaps even prevent, the onset of clinical symptoms.

Levels of β-klotho determine the thermogenic responsiveness of adipose tissues: involvement of the autocrine action of FGF21

Fibroblast growth factor-21 (FGF21) is a hormonal regulator of metabolism; it promotes glucose oxidation and the thermogenic capacity of adipose tissues. The levels of β-klotho (KLB), the co-receptor required for FGF21 action, are decreased in brown (BAT) and white (WAT) adipose tissues during obesity, diabetes, and lipodystrophy. Reduced β-klotho levels have been proposed to account for FGF21 resistance in these conditions. In this study, we explored whether downregulation of β-klotho affects metabolic regulation and the thermogenic responsiveness of adipose tissues using mice with total (KLB-KO) or partial (KLB-heterozygotes) ablation of β-klotho. We herein show that KLB gene dosage was inversely associated with adiposity in mice. Upon cold exposure, impaired browning of subcutaneous WAT and milder alterations in BAT were associated with reduced KLB gene dosage in mice. Cultured brown and beige adipocytes from mice with total or partial ablation of the KLB gene showed reduced thermogenic responsiveness to β3-adrenergic activation by treatment with CL316,243, indicating that these effects were cell-autonomous. Deficiency in FGF21 mimicked the KLB-reduction-induced impairment of thermogenic responsiveness in brown and beige adipocytes. These results indicate that the levels of KLB in adipose tissues determine their thermogenic capacity to respond to cold and/or adrenergic stimuli. Moreover, an autocrine action of FGF21 in brown and beige adipocytes may account for the ability of the KLB level to influence thermogenic responsiveness.NEW & NOTEWORTHY Reduced levels of KLB (the obligatory FGF21 co-receptor), as occurring in obesity and type 2 diabetes, reduce the thermogenic responsiveness of adipose tissues in cold-exposed mice. Impaired response to β3-adrenergic activation in brown and beige adipocytes with reduced KLB occurs in a cell-autonomous manner involving an autocrine action of FGF21.

Transcriptional response to a Mediterranean diet intervention exerts a modulatory effect on neuroinflammation signaling pathway

Background: The Traditional Mediterranean Diet (TMD) is known to have beneficial effects on several chronic diseases. However, data concerning the whole transcriptome modulation of the TMD are scarce.Objective: We aimed to explore the effects of the TMD on the whole transcriptome of individuals at high cardiovascular risk.Methods: Thirty-four participants at high cardiovascular risk were randomly assigned to a TMD enriched with extra-virgin olive oil (TMD + VOO), mixed nuts (TMD + Nuts), or a control diet based on low-fat diet recommendations. A microarray analysis in circulating peripheral blood mononuclear cells of the participants was conducted before and after 3 months of the intervention. The association of changes in gene expression was modeled into canonical pathways by conducting an untargeted functional analysis with the Ingenuity Pathway Analysis^® (IPA). Effects were considered significant when the absolute z-score values were ≥2.0 and the logarithm P (adjusted by the Benjamini-Hochberg procedure [BH]) values were ≥1.30.Results: According to IPA, interventions with TMD + Nuts, TMD + VOO, and control diet downregulated neuroinflammation, triggering receptor expressed on myeloid cells 1 , and cholecystokinin/gastrin-mediated signaling pathways, respectively. The gene expression among these pathways included cytokines, T-cell activation receptors, nuclear factor kappa β/inflammasome components, pro-inflammatory enzymes and cell cycle regulators.Conclusion: The current findings suggest that the TMD enriched with mixed nuts or VOO downregulate transcriptomic pathways, including those related to neuroinflammation, which could influence development of neurodegenerative diseases. Our data should be corroborated in other tissue cells, such as neurons and glial cells. The PREDIMED trial was registered at https://www.controlled-trials.com (ISRCTN35739639).

Histopathological and Ultrastructural Changes after Electroporation in Pig Liver Using Parallel-Plate Electrodes and High-Performance Generator

Irreversible electroporation (IRE) has gained attention as a new non-thermal therapy for ablation with important benefits in terms of homogeneous treatment and fast recovery. In this study, a new concept of high voltage generator is used, enabling irreversible electroporation treatment in large tissue volume using parallel plates. Unlike currently available generators, the proposed versatile structure enables delivering high-voltage high-current pulses. To obtain homogeneous results, 3-cm parallel-plates electrodes have also been designed and implemented. IRE ablation was performed on six female pigs at 2000 V/cm electric field, and the results were analysed after sacrifice three hours, three days and seven days after ablation. Histopathological and ultrastructural studies, including transmission and scanning electron microscopy, were carried out. The developed high-voltage generator has proved to be effective for homogeneous IRE treatment using parallel plates. The destruction of the membrane of the hepatocytes and the alterations of the membranes of the cellular organelles seem incompatible with cell death by apoptosis. Although endothelial cells also die with electroporation, the maintenance of vascular scaffold allows repairing processes to begin from the third day after IRE as long as the blood flow has not been interrupted. This study has opened new direction for IRE using high performance generators and highlighted the importance of taking into account ultrastructural changes after IRE by using electron microscopy analysis.

DNA Methylation and High-Density Lipoprotein Functionality-Brief Report: The REGICOR Study (Registre Gironi del Cor)

OBJECTIVE

The function of high-density lipoproteins (HDLs) may better reflect their atheroprotective role, compared with HDL-cholesterol levels. The association between DNA methylation and HDL function has not yet been established.

APPROACH AND RESULTS

We designed an epigenome-wide association study including 645 individuals from the REGICOR study (Registre Gironi del Cor). We determined DNA methylation from peripheral blood cells using the HumanMethylation450 array. We analyzed HDL functionality by determining HDL cholesterol efflux capacity and HDL inflammatory index. We discovered 3 methylation sites located in HOXA3, PEX5, and PER3 related to cholesterol efflux capacity and 1 located in GABRR1 related to HDL inflammatory index. Using a candidate gene approach, we also found 2 methylation sites located in CMIP related to cholesterol efflux capacity.

CONCLUSIONS

We identified 6 potential loci associated with HDL functionality in HOXA3, PEX5, PER3, CMIP, and GABRR1. Additional studies are warranted to validate these findings in other populations.

Olive oil phenolic compounds and high-density lipoprotein function

PURPOSE OF REVIEW

The functional capacities of high-density lipoproteins (HDLs) reflect the physiological role of the particle better than the quantity of HDL cholesterol. Owing to its phenolic compounds, the consumption of virgin olive oil has emerged as a promising therapy to promote these capacities. This review highlights the human studies that explain these benefits and explores some possible mechanisms.

RECENT FINDINGS

The consumption of olive oil phenolic compounds increased the ability of HDLs to pick up cholesterol excess in peripheral cells (the cholesterol efflux capacity). Olive oil phenolic compounds have also been shown to improve HDL antioxidant capacities and some anti-inflammatory traits. These changes respond to an improvement of HDL oxidative status and composition.

SUMMARY

Novel strategies to increase HDL functional capacities are in demand from clinicians. The attainment of a fully-functional HDL through dietary or lifestyle changes is a priority in cardiovascular research. Within this context, the consumption of virgin olive oil, because of its phenolic compounds, may be a relevant protective approach. Further studies in large-scale, randomized controlled trials are, however, required to confirm these effects in HDL functionality.