👤 Francisco Jose Tinahones

In this study, we investigated gene expression related to cholesterol efflux receptors in individuals at high cardiovascular risk undergoing Mediterranean dietary interventions. Through transcriptomic analysis, we examined samples from two randomized controlled trials: PREDIMED and PREDIMED-Plus, with 151 and 89 elderly adults, respectively. Blood cells were isolated at baseline and after a 12-month intervention. In the PREDIMED trial, participants followed different Mediterranean diets: one supplemented with extra-virgin olive oil (traditional Mediterranean diet enriched with extra-virgin olive oil [MedDiet-EVOO]), another with nuts (MedDiet enriched with nuts MedDiet-Nuts [MedDiet-Nuts]), and a low-fat control diet. The PREDIMED-Plus trial compared an energy-reduced Mediterranean diet (Er-MedDiet) with physical activity to an ad libitum Mediterranean diet. Over time, mild but significant upregulation of genes like ATP binding cassette subfamily A member 1 (ABCA1), retinoid X receptor alpha (RXRA), retinoid X receptor beta (RXRB), and Nuclear Receptor Subfamily 1 Group H Member 3 (NR1H3) was observed in response to MedDiet-EVOO, MedDiet-Nuts, and Er-MedDiet. Notably, RXRA expression was higher in both MedDiet-EVOO and MedDiet-Nuts compared to the control diet. Differences in gene expression, particularly RXRA, ATP binding cassette subfamily G member 1 (ABCG1), NR1H3, and Peroxisome Proliferator Activated Receptor Delta (PPARD), were evident between MedDiet-Nuts and the control diet. In the PREDIMED-Plus trial, no significant differences in gene expression were found between dietary groups. Principal component analysis (PCA) and linear discriminant analysis (LDA) showed overlapping gene expression profiles across different Mediterranean diet interventions. In conclusion, our study highlights the cardiovascular health benefits of long-term adherence to a Mediterranean diet, both normocaloric and hypocaloric, primarily reflected by mild upregulation of cholesterol efflux-related genes-specifically involving RXRA, RXRB, ABCA1, ABCG1, Nuclear Receptor Subfamily 1 Group H Member 2(NR1H2), and PPARD-among elderly adults at high cardiovascular risk. This suggests a potential mechanism by which these diets may exert cardiovascular protective effects. Show less

Glucose-dependent insulinotropic peptide (GIP) has a central role in glucose homeostasis through its amplification of insulin secretion; however, its physiological role in adipose tissue is unclear. Our objective was to define the function of GIP in human adipose tissue in relation to obesity and insulin resistance. GIP receptor (GIPR) expression was analyzed in human sc adipose tissue (SAT) and visceral adipose (VAT) from lean and obese subjects in 3 independent cohorts. GIPR expression was associated with anthropometric and biochemical variables. GIP responsiveness on insulin sensitivity was analyzed in human adipocyte cell lines in normoxic and hypoxic environments as well as in adipose-derived stem cells obtained from lean and obese patients. GIPR expression was downregulated in SAT from obese patients and correlated negatively with body mass index, waist circumference, systolic blood pressure, and glucose and triglyceride levels. Furthermore, homeostasis model assessment of insulin resistance, glucose, and G protein-coupled receptor kinase 2 (GRK2) emerged as variables strongly associated with GIPR expression in SAT. Glucose uptake studies and insulin signaling in human adipocytes revealed GIP as an insulin-sensitizer incretin. Immunoprecipitation experiments suggested that GIP promotes the interaction of GRK2 with GIPR and decreases the association of GRK2 to insulin receptor substrate 1. These effects of GIP observed under normoxia were lost in human fat cells cultured in hypoxia. In support of this, GIP increased insulin sensitivity in human adipose-derived stem cells from lean patients. GIP also induced GIPR expression, which was concomitant with a downregulation of the incretin-degrading enzyme dipeptidyl peptidase 4. None of the physiological effects of GIP were detected in human fat cells obtained from an obese environment with reduced levels of GIPR. GIP/GIPR signaling is disrupted in insulin-resistant states, such as obesity, and normalizing this function might represent a potential therapy in the treatment of obesity-associated metabolic disorders. Show less

The mechanisms involved in the progression to overt diabetes in pre-obese subjects remain unclear. Therefore, a nontargeted evaluation of differences in the protein abundance of visceral adipose tissue (VAT) obtained from pre-obese diabetic subjects and pre-obese subjects showing normal glucose tolerance may provide novel insights on the molecular processes involved in the progression to overt diabetes in pre-obesity. Diabetic patients showed increased VAT abundance of glutathione S-transferase Mu 2, peroxiredoxin-2, antithrombin-III, apolipoprotein A-IV, Ig κ chain C region, mitochondrial aldehyde dehydrogenase and actin, and decreased abundance of annexin-A1, retinaldehyde dehydrogenase-1, and vinculin, compared with their non-diabetic counterparts. These proteins are involved in cytoskeleton function and structure, oxidative stress, inflammation and retinoid metabolism. The presence of diabetes influences the VAT abundance of several proteins. Hence, the proteins identified here could be considered candidate molecules in future studies addressing the role that VAT dysfunction plays in the development of type 2 diabetes. Show less

Munc18c is associated with glucose metabolism and could play a relevant role in obesity. However, little is known about the regulation of Munc18c expression. We analyzed Munc18c gene expression in human visceral (VAT) and subcutaneous (SAT) adipose tissue and its relationship with obesity and insulin. We evaluated 70 subjects distributed in 12 non-obese lean subjects, 23 overweight subjects, 12 obese subjects and 23 nondiabetic morbidly obese patients (11 with low insulin resistance and 12 with high insulin resistance). The lean, overweight and obese persons had a greater Munc18c gene expression in adipose tissue than the morbidly obese patients (p<0.001). VAT Munc18c gene expression was predicted by the body mass index (B = -0.001, p = 0.009). In SAT, no associations were found by different multiple regression analysis models. SAT Munc18c gene expression was the main determinant of the improvement in the HOMA-IR index 15 days after bariatric surgery (B = -2148.4, p = 0.038). SAT explant cultures showed that insulin produced a significant down-regulation of Munc18c gene expression (p = 0.048). This decrease was also obtained when explants were incubated with liver X receptor alpha (LXRα) agonist, either without (p = 0.038) or with insulin (p = 0.050). However, Munc18c gene expression was not affected when explants were incubated with insulin plus a sterol regulatory element-binding protein-1c (SREBP-1c) inhibitor (p = 0.504). Munc18c gene expression in human adipose tissue is down-regulated in morbid obesity. Insulin may have an effect on the Munc18c expression, probably through LXRα and SREBP-1c. Show less

Several epidemiological studies have related an increase of lipids in the postprandial state to an individual risk for the development of CVD, possibly due to the increased plasma levels of TAG and fatty acids (FA) through enzymes of FA metabolism. The interaction between nutrition and the human genome determines gene expression and metabolic response. The aim of the present study was to evaluate the influence of a fat overload on the gene mRNA levels of lipogenic regulators in peripheral blood mononuclear cells (PBMC) from patients with the metabolic syndrome. The study included twenty-one patients with criteria for the metabolic syndrome who underwent a fat overload. Measurements were made before and after the fat overload of anthropometric and biochemical variables and also the gene mRNA levels of lipogenic factors. The main results were that the fat overload led to an increased mRNA levels of sterol regulatory element binding protein-1 (SREBP1), retinoid X receptor α (RXRα) and liver X receptor α (LXRα) in PBMC, and this increase was associated with the FA synthase (FASN) mRNA levels. We also found that TAG levels correlated with FASN mRNA levels. In addition, there was a positive correlation of SREBP1 with RXRα and of LXRα with the plasma lipoperoxide concentration. The fat overload led to an increase in regulators of lipogenesis in PBMC from patients with the metabolic syndrome. Show less

Apolipoprotein C-III (APOC3) is a component of triglyceride rich lipoproteins, and SstI polymorphism has been associated with hypertriglyceridemia. Apolipoprotein A-I (APOA1) is the major component of HDL and MspI polymorphism has been associated with APOA1 and HDL-C levels. Thus, we study the influence of these polymorphisms in the postprandial response in metabolic syndrome (MS). 73 MS patients and 21 healthy subjects underwent a fat overload, with measurements of their fasting and postprandial lipid profile. The APOC3 SstI and the APOA1MspI polymorphisms were genotyped. No significant differences were found in the lipid profile with respect to the MspI genotype. Patients with the S2S2 APOC3 genotype had significantly higher fasting and postprandial triglyceride levels and postprandial APOC3 and chylomicron-triglyceride levels compared with the other SstI APOC3 genotypes. Homozygosity for the minor allele of the APOC3 SstI polymorphism was associated to a worse postprandial response in MS patients. Show less

Apolipoprotein A5 is a key gene controlling VLDL synthesis and hydrolysis and is the target of the main pharmacological agent to lower triglycerides (fibrates). We hypothesised that variability in the promoter of the APOA5 gene may affect the individual response to fibrate therapy, in both the fasting and postprandial states. We selected 50 subjects with the metabolic syndrome who also had important increase in fasting triglycerides. A subgroup of 36 patients underwent lipid-lowering treatment with 160 mg/day of fenofibrate (Secalip) for 3 months. The participants underwent a 60 g fat overload with a commercial preparation, after which we assessed the influence of the -1131T>C APOA5 SNP on the postprandial response. Compared with non-carriers, the C allele carriers had significantly higher triglyceride levels at baseline (54.87%), and at 3h (61.08%) and 4h (68.35%). Other lipid parameters were not affected by the APOA5 genotype. Our results indicate that carriers of the -1131C allele had a better response to fenofibrate treatment (reduction in triglyceride levels of 40.33% at baseline, P=0.018; and postprandially, 37.64% at 3h, P=0.028 and 42.58% at 4h after the high-fat meal, P=0.018) than wild-type subjects (30.91% decrease at baseline, P<0.001; and 26.61% at 3h P=0.005 and 22.95% at 4h P=0.033 after the high-fat meal). Thus, the treatment for patients with the metabolic syndrome and elevated plasma triglyceride levels may vary according to whether they carry the APOA5 -1131T>C polymorphism. Show less

The apolipoprotein AI-CIII-AIV cluster has been associated with the response to a urate-lowering diet, and polymorphisms in the apolipoprotein CIII gene have been associated with hyperuricemia and hypertriglyceridemia. We assessed the influence of polymorphisms in the apolipoprotein AI-CIII-AIV cluster on the response to a urate-lowering diet in patients with hyperuricemia. A urate-lowering diet was followed for 2 weeks by 64 men with hyperuricemia. Plasma concentrations of triglycerides, cholesterol, glucose, and uric acid, and the uric acid clearance and 24-hour uric acid urinary excretory fraction were measured before and after the diet. The data were analyzed in association with the polymorphisms of the apolipoprotein AI-CIII-AIV gene cluster. After the urate-lowering diet, the plasma levels of triglycerides, cholesterol, glucose, and uric acid and 24-hour uric acid excretion all fell significantly. Paired sample ANOVA showed that the decrease was mainly due to the diet, except for the plasma triglycerides, which were influenced by allele X2 of the XmnI polymorphism of the apolipoprotein AI gene. The response of the biological variables to a urate-lowering diet was mainly influenced by diet. Changes in triglycerides were also influenced by the apolipoprotein AI XmnI polymorphism (p = 0.04), suggesting a gene-diet interaction (p = 0.03). Show less

Studies have shown that hyperuricaemia is independently related to the insulin resistance syndrome and that polymorphisms of the apolipoprotein AI-CIII-AIV cluster are also related to insulin resistance. To study the prevalence of polymorphisms of the apolipoprotein AI-CIII-AIV cluster in persons with gout and to determine whether these polymorphisms contribute to the pathophysiology of gout or to altered lipid concentrations. Plasma cholesterol, triglycerides, uric acid, VLDL, LDL, IDL, and HDL triglycerides, cholesterol, and the renal excretion of uric acid were measured in 68 patients with gout with gout and 165 healthy subjects. Polymorphisms were studied by amplification and RFLP in all subjects, using XmnI and MspI in the apolipoprotein AI gene and SstI in the apolipoprotein CIII gene. The A allele at position -75 bp in the apolipoprotein AI gene was more common in patients with gout than in controls (p = 0.01). Levels of cholesterol, triglycerides, uric acid, basal glycaemia, and HDL cholesterol were higher in the patients (p<0.001). In the patients there was also an interaction between mutations at the two polymorphic loci studied in the apolipoprotein AI gene (p = 0.04). An absence of the mutation at position -75 bp of the apolipoprotein AI gene resulted in increased plasma triglyceride levels. Gouty patients have an altered allelic distribution in the apolipoprotein AI-CIII-AIV cluster, which could lead to changes in levels of lipoproteins. This is not caused by a single mutation but rather by a combination of different mutations. Show less