Vanessa Derenji Ferreira de Mello

Dietary fatty acids and cardiovascular disease: an epidemiological approach.

The quality of dietary fat in relation to cardiovascular disease forms the basis of the diet-heart hypothesis. Current recommendations on dietary fat now emphasise quality rather than quantity. The focus of this review is to summarise the results from prospective cohort studies on dietary fat and cardiovascular disease outcomes. Relatively few prospective cohort studies have found an association between dietary fat quality and cardiovascular disease, partly because of limitations in estimating dietary intake. Saturated and trans fatty acids have increased cardiovascular risk in several studies. Both n-6 and n-3 polyunsaturated fatty acids have been associated with lower cardiovascular risk. Within the n-6 series, linoleic acid seems to decrease cardiovascular risk. Within the n-3 series the long-chain fatty acids (eicosapentaenoic and docosahexaenoic acids) are associated with decreased risk for especially fatal coronary outcomes, whereas the role of alpha-linolenic acid is less clear. Dietary fat quality also influences the activity of enzymes involved in the desaturation of fatty acids in the body. Serum desaturase indices have been consistently associated with adverse cardiovascular outcomes. Data from metabolic and clinical studies reinforce findings from observational studies supporting recommendations to replace saturated and trans fat with unsaturated fat in the prevention of cardiovascular disease.

Effect of weight loss on cytokine messenger RNA expression in peripheral blood mononuclear cells of obese subjects with the metabolic syndrome

Inflammation is associated with obesity, the metabolic syndrome, and diabetes. No data are available on the effect of weight reduction on the gene expression of cytokines in immune cells in obesity and the metabolic syndrome. We assessed how long-term weight loss affects expression of cytokines in peripheral blood mononuclear cells (PBMCs) in individuals with impaired glucose metabolism and the metabolic syndrome. Data from 34 subjects randomized to either a weight reduction or a control group for a 33-week period were analyzed. The messenger RNA (mRNA) expression of interleukins (ILs) in PBMCs was measured using real-time polymerase chain reaction. Measures of insulin and glucose metabolism (intravenous and oral glucose tolerance tests), body composition, and circulating adipokines and inflammatory markers were also assessed. Weight reduction resulted in a decrease in the mRNA expression of IL-1beta (IL1B), IL-1 receptor antagonist, and tumor necrosis factor alpha (P < .001) and an increase in expression of IL-6 (IL6) and IL-8 (P < .01). The increase in IL6 expression was associated with a decrease in fasting glycemia (r = -0.53, P < .01). Interestingly, the decrease in IL1B expression was correlated with an increase in insulin sensitivity index (r = -0.68, P < .01). In general, a decrease in circulating levels of adipokines and inflammatory markers was also observed after weight loss. Weight loss altered gene expression of cytokines related to inflammation and the immune response in PBMCs. Changes in IL6 mRNA expression were associated with changes in fasting glycemia. The decrease in IL-1 receptor antagonist expression after weight loss and the strong correlation between the decrease in IL1B expression and the increase in insulin sensitivity suggest a contribution of these genes to insulin-resistant states found in obesity and the metabolic syndrome.

Insulin Secretion and Its Determinants in the Progression of Impaired Glucose Tolerance to Type 2 Diabetes in Impaired Glucose-Tolerant Individuals: The Finnish Diabetes Prevention Study

OBJECTIVE We investigated the effect of early-phase insulin secretion on the incidence of type 2 diabetes in individuals with impaired glucose tolerance (IGT) participating in the Finnish Diabetes Prevention Study (DPS). We examined how a lifestyle intervention affected early-phase insulin secretion (ratio of total insulin area under the curve [AUC] and total glucose AUC [AIGR] from 0 to 30 min) during a 4-year follow-up intervention trial and whether AIGR0–30 response was modified by insulin sensitivity (IS) and obesity. RESEARCH DESIGN AND METHODS A total of 443 participants with IGT originally randomized to a lifestyle intervention or control group were studied. IS and AIGR0–30 were estimated from an oral tolerance glucose test administered annually during the 4-year follow-up trial and were related to the risk of diabetes onset over a 6-year follow-up. RESULTS Lifestyle intervention resulted in higher IS (P = 0.02) and lower unadjusted AIGR0–30 (P = 0.08) during the 4-year follow-up. A higher IS and a lower BMI during the follow-up were associated with a lower unadjusted AIGR0–30 during the follow-up, independently of study group (P < 0.001). A greater increase in IS on the median cutoff point of a 0.69 increase was associated with higher IS-adjusted AIGR0–30 during the follow-up (P = 0.002). In multivariate models, IS and IS-adjusted AIGR0–30 were both inversely associated with diabetes incidence (P < 0.001). Participants who progressed to type 2 diabetes were more obese and had lower IS and Matsuda IS index-AIGR0–30 than nonprogressors. CONCLUSIONS Our results indicate that the reduction in the risk of developing type 2 diabetes after lifestyle intervention is related to the improvement of IS along with weight loss. Improved IS may also have beneficial effects on preservation of β-cell function.

Expression of ghrelin gene in peripheral blood mononuclear cells and plasma ghrelin concentrations in patients with metabolic syndrome.

OBJECTIVE We examined the expression of ghrelin and ghrelin receptors in peripheral blood mononuclear cells (PBMCs) and evaluated the effect of weight loss or exercise on plasma ghrelin concentrations in subjects with the metabolic syndrome. DESIGN AND METHODS Data from 75 overweight/obese subjects randomized to a weight loss, aerobic exercise, resistance exercise or control group for a 33-week intervention period were analysed. The plasma ghrelin concentrations and indices of insulin and glucose metabolism were assessed, and mRNA expression of ghrelin, its receptors and various cytokines in PBMCs was studied using real-time PCR. RESULTS Ghrelin and GH secretagogue receptor 1b were expressed in PBMCs of subjects with metabolic syndrome. Ghrelin gene expression correlated positively with the expressions of tumour necrosis factor-alpha (P<0.001), interleukin-1beta (P<0.001) and interleukin-6 (P=0.026) during the study, but was not associated with the plasma ghrelin concentration. Genotype-specific ghrelin gene expression in PBMCs was found for the -604G/A and the -501A/C polymorphisms in the ghrelin gene. At baseline, the plasma ghrelin levels were associated with fasting serum insulin concentrations, insulin sensitivity index and high-density lipoprotein cholesterol. However, longitudinally weight, BMI or waist circumference and acute insulin response in i.v. glucose tolerance test were stronger predictors of the ghrelin concentration. Plasma ghrelin did not change over the study period in the weight reduction group, but it tended to decrease in the control group (P=0.050). CONCLUSIONS Ghrelin mRNA expression in PBMCs suggests an autocrine role for ghrelin within an immune microenvironment. Moderate long-term weight loss may prevent a decline in ghrelin concentration over time in individuals with metabolic syndrome.

Healthy Nordic diet downregulates the expression of genes involved in inflammation in subcutaneous adipose tissue in individuals with features of the metabolic syndrome

BACKGROUND Previously, a healthy Nordic diet (ND) has been shown to have beneficial health effects close to those of Mediterranean diets. OBJECTIVE The objective was to explore whether the ND has an impact on gene expression in abdominal subcutaneous adipose tissue (SAT) and whether changes in gene expression are associated with clinical and biochemical effects. DESIGN Obese adults with features of the metabolic syndrome underwent an 18- to 24-wk randomized intervention study comparing the ND with the control diet (CD) (the SYSDIET study, carried out within Nordic Centre of Excellence of the Systems Biology in Controlled Dietary Interventions and Cohort Studies). The present study included participants from 3 Nordic SYSDIET centers [Kuopio (n = 20), Lund (n = 18), and Oulu (n = 18)] with a maximum weight change of ±4 kg, highly sensitive C-reactive protein concentration <10 mg/L at the beginning and the end of the intervention, and baseline body mass index (in kg/m²) <38. SAT biopsy specimens were obtained before and after the intervention and subjected to global transcriptome analysis with Gene 1.1 ST Arrays (Affymetrix). RESULTS Altogether, 128 genes were differentially expressed in SAT between the ND and CD (nominal P < 0.01; false discovery rate, 25%). These genes were overrepresented in pathways related to immune response (adjusted P = 0.0076), resulting mainly from slightly decreased expression in the ND and increased expression in the CD. Immune-related pathways included leukocyte trafficking and macrophage recruitment (e.g., interferon regulatory factor 1, CD97), adaptive immune response (interleukin32, interleukin 6 receptor), and reactive oxygen species (neutrophil cytosolic factor 1). Interestingly, the regulatory region of the 128 genes was overrepresented for binding sites for the nuclear transcription factor κB. CONCLUSION A healthy Nordic diet reduces inflammatory gene expression in SAT compared with a control diet independently of body weight change in individuals with features of the metabolic syndrome.

Endothelial dysfunction and serum fatty acid composition in patients with type 2 diabetes mellitus

The aim of this study was to evaluate the possible association between serum fatty acids composition and endothelial dysfunction in patients with type 2 diabetes mellitus. A cross-sectional study was conducted with 125 normo- or microalbuminuric type 2 diabetes mellitus patients with serum creatinine <1.5 mg/dL. Serum fatty acids composition (gas chromatography), serum levels of endothelin-1 (ET-1) (enzyme-linked immunosorbent assay), fibrinogen, serum C-reactive protein, lipids, homeostasis model assessment resistance index (HOMA-R), and 24-hour urinary albumin excretion rate were measured. Serum levels of ET-1 were positively correlated with saturated fatty acids (r = 0.257, P = .025) and negatively correlated with polyunsaturated fatty acids (PUFAs) (r = -0.319, P = .005). Serum ET-1 levels were also positively correlated with systolic blood pressure, waist circumference, total cholesterol levels, triglycerides, and HOMA-R. In multiple linear regression models, only saturated fatty acids (R(2) = 0.317, P = .002) or PUFAs (R(2) = 0.314, P = .001) remained associated with ET-1 levels. Models were adjusted for systolic blood pressure, HOMA-R, waist circumference, triglycerides, body mass index, and smoking habit. The serum total PUFA levels showed an inverse correlation with urinary albumin excretion rate (r = -0.248, P = .012). In conclusion, in type 2 diabetes mellitus patients, the serum fatty acids composition was independently related to endothelial function evaluated by serum ET-1. Saturated fatty acids were associated with endothelial dysfunction (high levels of ET-1), whereas PUFAs had a protective role in endothelial function.

Relevance of vitamin D receptor target genes for monitoring the vitamin D responsiveness of primary human cells.

Vitamin D3 has transcriptome- and genome-wide effects and activates, via the binding of its metabolite 1α,25-dihydroxyvitamin D3 to the transcription factor vitamin D receptor (VDR), several hundred target genes. Using samples from a 5-month vitamin D3 intervention study (VitDmet), we recently reported that the expression of 12 VDR target genes in peripheral blood mononuclear cells (PBMCs) as well as 12 biochemical and clinical parameters of the study participants are significantly triggered by vitamin D3. In this study, we performed a more focused selection of further 12 VDR target genes and demonstrated that changes of their mRNA expression in PBMCs of VitDmet subjects significantly correlate with alterations of 25-hydroxyvitamin D3 serum levels. Network and self-organizing map analysis of these datasets together with that of the other 24 parameters was followed by relevance calculations and identified changes in parathyroid hormone serum levels and the expression of the newly selected genes STS, BCL6, ITGAM, LRRC25, LPGAT1 and TREM1 as well as of the previously reported genes DUSP10 and CD14 as the most relevant parameters for describing vitamin D responsiveness in vivo. Moreover, parameter relevance ranking allowed the segregation of study subjects into high and low responders. Due to the long intervention period the vitamin D response was not too prominent on the level of transcriptional activation. Therefore, we performed in the separate VitDbol trial a short-term but high dose stimulation with a vitamin D3 bolus. In PBMCs of VitDbol subjects we observed direct transcriptional effects on the selected VDR target genes, such as an up to 2.1-fold increase already one day after supplementation onset. In conclusion, both long-term and short-term vitamin D3 supplementation studies allow monitoring the vitamin D responsiveness of human individuals and represent new types of human in vivo vitamin D3 investigations.

Glucose Metabolism Effects of Vitamin D in Prediabetes: The VitDmet Randomized Placebo-Controlled Supplementation Study

Epidemiological evidence suggests a role for vitamin D in type 2 diabetes prevention. We investigated the effects of vitamin D3 supplementation on glucose metabolism and inflammation in subjects with prediabetes. A 5-month randomized, double-blind, placebo-controlled intervention with three arms (placebo, 40 μg/d, or 80 μg/d vitamin D3) was carried out among sixty-eight overweight (BMI 25–35) and aging (≥60 years) subjects from Finland, with serum 25-hydroxyvitamin D3 [25(OH)D3] < 75 nmol/L and either impaired fasting glucose or impaired glucose tolerance. Analyses included 66 subjects who completed the trial. Glucose metabolism was evaluated by fasting and 2-hour oral glucose tolerance test-derived indices and glycated hemoglobin. Inflammation was evaluated by high-sensitive C-reactive protein and five cytokines. Although a dose-dependent increase in serum 25(OH)D3 over the supplementation period was observed (P trend < 0.001), there were no other statistically significant differences in changes in the 13 glucose homeostasis indicators between the study groups other than increase in the 120 min glucose concentration (P trend = 0.021) and a decreasing trend both in 30 min plasma insulin (P trend = 0.030) and glycated hemoglobin (P trend = 0.024) concentrations. A borderline statistically significant decreasing trend in interleukin-1 receptor antagonist concentration was observed (P = 0.070). Vitamin D3 supplementation does not improve glucose metabolism in ageing subjects with prediabetes but may have modest anti-inflammatory effects.

Long-term effect of a chicken-based diet versus enalapril on albuminuria in type 2 diabetic patients with microalbuminuria.

OBJECTIVE In short-term studies, the replacement of red meat in the diet with chicken reduced the urinary albumin excretion rate (UAER) and improved lipid profile in type 2 diabetic patients with diabetic nephropathy. The present study sought to assess these effects over a long-term period, comparing the effects of a chicken-based diet (CD) versus enalapril on renal function and lipid profile in microalbuminuric type 2 diabetic patients. DESIGN This was a randomized, open-label, controlled clinical trial with a follow-up of 1 year. SETTING The trial involved outpatients with type 2 diabetes attending a clinic of the Division of Endocrinology at a tertiary-care hospital. PATIENTS Twenty-eight microalbuminuric patients completed the study and were evaluated. INTERVENTIONS Patients were randomized to an experimental diet (CD plus active placebo) or to treatment with enalapril (10 mg/day plus usual diet). MAIN OUTCOME MEASURES The main outcome measure was UAER (according to immunoturbidimetry). Blood pressure, anthropometric indices, and compliance were also evaluated monthly. The glomerular filtration rate ((51)Cr-EDTA), and lipid, glycemic, and nutritional indices, were measured at baseline and quarterly. RESULTS The UAER was reduced after CD (n = 13; from 62.8 [range, 38.4 to 125.1] to 49.1 [range, 6.2 to 146.5] microg/min; P < .001) and after enalapril (n = 15; from 55.8 [range, 22.6 to 194.3] to 23.1 [range, 4.0 to 104.9] microg/min; P < .001), and this was already significant at month 4. The reduction in UAER after CD (32%; 95% confidence interval, 6.7% to 57.6%) and after enalapril treatment (44.7%; 95% confidence interval, 28.3% to 61.1%; P = .366) were not significantly different. CONCLUSIONS The CD and the angiotensin-converting enzyme inhibitor enalapril promoted a similar reduction of UAER in patients with type 2 diabetes and microalbuminuria in a 12-month follow-up period.

Role of dietary lipids in diabetic nephropathy.

The aim of the present study was to review the possible role of dietary lipids in diabetic nephropathy (DN), taking into account associated abnormalities of serum lipids and interaction of dietary and genetic aspects. Dietary lipids may have an important role in the development and progression of DN. The fat diet composition has been associated with DN, particularly with microalbuminuria, serum lipids abnormalities, and endothelial function. However, the beneficial effect of fat intake modification for these patients is not fully established, especially regarding hard outcomes, such as DN incidence and progression, kidney failure, and death. Moreover, genetic factors may influence the response of serum lipids to fat intake. The identification of specific genetic polymorphisms associated with this interaction could allow adoption of individual nutritional strategies in DN.