DNA methylation risk score for type 2 diabetes is associated with gestational diabetes

BACKGROUND

Gestational diabetes mellitus (GDM) and type 2 diabetes mellitus (T2DM) share many pathophysiological factors including genetics, but whether epigenetic marks are shared is unknown. We aimed to test whether a DNA methylation risk score (MRS) for T2DM was associated with GDM across ancestry and GDM criteria.

METHODS

In two independent pregnancy cohorts, EPIPREG (n = 480) and EPIDG (n = 32), DNA methylation in peripheral blood leukocytes was measured at a gestational age of 28 ± 2. We constructed an MRS in EPIPREG and EPIDG based on CpG hits from a published epigenome-wide association study (EWAS) of T2DM.

RESULTS

With mixed models logistic regression of EPIPREG and EPIDG, MRS for T2DM was associated with GDM: odd ratio (OR)[95% CI]: 1.3 [1.1-1.8], P = 0.002 for the unadjusted model, and 1.4 [1.1-1.7], P = 0.00014 for a model adjusted by age, pre-pregnant BMI, family history of diabetes and smoking status. Also, we found 6 CpGs through a meta-analysis (cg14020176, cg22650271, cg14870271, cg27243685, cg06378491, cg25130381) associated with GDM, and some of their methylation quantitative loci (mQTLs) were related to T2DM and GDM.

CONCLUSION

For the first time, we show that DNA methylation marks for T2DM are also associated with GDM, suggesting shared epigenetic mechanisms between GDM and T2DM.

Epigenome wide association study in peripheral blood of pregnant women identifies potential metabolic pathways related to gestational diabetes

Gestational diabetes mellitus (GDM) increases the risk of developing metabolic disorders in both pregnant women and their offspring. Factors such as nutrition or the intrauterine environment may play an important role, through epigenetic mechanisms, in the development of GDM. The aim of this work is to identify epigenetic marks involved in the mechanisms or pathways related to gestational diabetes. A total of 32 pregnant women were selected, 16 of them with GDM and 16 non-GDM. DNA methylation pattern was obtained from Illumina Methylation Epic BeadChip, from peripheral blood samples at the diagnostic visit (26-28 weeks). Differential methylated positions (DMPs) were extracted using ChAMP and limma package in R 2.9.10, with a threshold of FDR <0.05, deltabeta >|5|% and B >0. A total of 1.141 DMPs were found, and 714 were annotated in genes. A functional analysis was performed, and we found 23 genes significantly related to carbohydrate metabolism. Finally, a total of 27 DMPs were correlated with biochemical variables such as glucose levels at different points of oral glucose tolerance test, fasting glucose, cholesterol, HOMAIR and HbA1c, at different visits during pregnancy and postpartum. Our results show that there is a differentiated methylation pattern between GDM and non-GDM. Furthermore, the genes annotated to the DMPs could be implicated in the development of GDM as well as in alterations in related metabolic variables.

Changes in Oxidative Stress and Intestinal Permeability during Pregnancy in Women with Gestational Diabetes Mellitus Treated with Metformin or Insulin and Healthy Controls: A Randomized Controlled Trial

Both oxidative stress and intestinal permeability are increased in hyperglycemic situations and have been shown to be reduced by metformin in type 2 diabetes mellitus (T2DM) patients. The aim of this study was to elucidate the effect of metformin on oxidative stress and intestinal permeability in women with gestational diabetes mellitus (GDM) treated with metformin compared to those treated with insulin and healthy controls. A total of 120 women were included from August 2016 to February 2022: 41 received metformin (MET group), 38 received insulin (INS group), and 41 were healthy controls. Baseline and antenatal visits were carried out at 25.4 ± 4.8 and 36.1 ± 0.8 weeks of pregnancy, respectively. Advanced oxidation protein products (AOPPs), total antioxidant capacity (TAC), and zonulin levels were measured at every visit. Zonulin levels from baseline to prepartum visit increased significantly in both healthy controls (0.6 ± 0.9 to 1.2 ± 1.7 ng/mL, p = 0.004) and the INS group (0.4 ± 0.3 to 0.6 ± 0.5 ng/mL, p = 0.034) but did not significantly change in the MET group (0.4 ± 0.4 to 0.5 ± 0.4 ng/mL, p = 0.202). However, TAC and AOPP levels significantly increased in women with GDM, both in the INS and MET groups but not in the healthy controls. In conclusion, in our population, metformin has been shown to avoid an increase in intestinal permeability but failed to avoid an increase in oxidative stress related to hyperglycemia.

Pediatric Type 1 Diabetes: Is Age at Onset a Determining Factor in Advanced Hybrid Closed-Loop Insulin Therapy?

BACKGROUND

The integration of continuous glucose monitoring systems with insulin infusion pumps has shown improved glycemic control, with improvements in hyperglycemia, hypoglycemia, Hb1Ac, and greater autonomy in daily life. These have been most studied in adults and there are currently not many articles published in the pediatric population that establish their correlation with age of debut.

METHODS

Prospective, single-study. A total of 28 patients (mean age 12 ± 2.43 years, 57% male, duration of diabetes 7.84 ± 2.46 years) were included and divided into two groups according to age at T1D onset (≤4 years and >4 years). Follow-up for 3 months, with glucometric variables extracted at different cut-off points after the start of the closed-loop (baseline, 1 month, 3 months).

RESULTS

Significant improvement was evidenced at 1 month and 3 months after closed-loop system implantation, with better glycemic control in the older age group at baseline at TIR (74.06% ± 6.37% vs. 80.33% ± 7.49% at 1 month, p < 0.003; 71.87% ± 6.58% vs. 78.75% ± 5.94% at 3 months, p < 0.009), TAR1 (18.25% ± 4.54% vs. 14.33% ± 5.74% at 1 month, p < 0.006; 19.87% ± 5.15% vs. 14.67% ± 4. 36% at 3 months, p < 0.009) and TAR2 (4.75% ± 2.67% vs. 2.75% ± 1.96% at 1 month, p = 0.0307; 5.40% ± 2.85% vs. 3% ± 2.45% at 3 months, p < 0.027).

CONCLUSIONS

the use of automated systems such as the MiniMedTM780G system brings glucometric results closer to those recommended by consensus, especially in age at T1D onset >4 years. However, the management in pediatrics continues to be a challenge even after the implementation of these systems, especially in terms of hyperglycemia and glycemic variability.

Epigenetic Marks as Predictors of Metabolic Response to Bariatric Surgery: Validation from an Epigenome Wide Association Study

Little is known about the potential role of epigenetic marks as predictors of the resolution of obesity-related comorbidities after bariatric surgery. In this study, 20 patients were classified according to the metabolic improvement observed 6 months after sleeve gastrectomy, based on the diagnosis of metabolic syndrome, into responders if metabolic syndrome reversed after bariatric surgery (n = 10) and non-responders if they had metabolic syndrome bariatric surgery (n = 10). Blood DNA methylation was analyzed at both study points using the Infinium Methylation EPIC Bead Chip array-based platform. Twenty-six CpG sites and their annotated genes, which were previously described to be associated with metabolic status, were evaluated. Cg11445109 and cg19469447 (annotated to Cytochrome P450 2E1 (CYP2E1) gene) were significantly more hypomethylated in the responder group than in the non-responder group at both study points, whilst cg25828445 (annotated to Nucleolar Protein Interacting With The FHA Domain Of MKI67 Pseudogene 3 (NIFKP3) gene) showed to be significantly more hypermethylated in the non-responder group compared to the responder group at both study points. The analysis of the methylation sites annotated to the associated genes showed that CYP2E1 had 40% of the differentially methylated CpG sites, followed by Major Histocompatibility Complex, Class II, DR Beta 1 (HLA-DRB1) (33.33%) and Zinc Finger Protein, FOG Family Member 2 (ZFPM2) (26.83%). Cg11445109, cg19469447 and cg25828445 could have a role in the prediction of metabolic status and potential value as biomarkers of response to bariatric surgery.

Epigenetic marks associated with gestational diabetes mellitus across two time points during pregnancy

An adverse intrauterine or periconceptional environment, such as hyperglycemia during pregnancy, can affect the DNA methylation pattern both in mothers and their offspring. In this study, we explored the epigenetic profile in maternal peripheral blood samples through pregnancy to find potential epigenetic biomarkers for gestational diabetes mellitus (GDM), as well as candidate genes involved in GDM development. We performed an epigenome-wide association study in maternal peripheral blood samples in 32 pregnant women (16 with GDM and 16 non-GDM) at pregnancy week 24-28 and 36-38. Biochemical, anthropometric, and obstetrical variables were collected from all the participants. The main results were validated in an independent cohort with different ethnic origin (European = 307; South Asians = 165). Two hundred and seventy-two CpGs sites remained significantly different between GDM and non-GDM pregnant women across two time points during pregnancy. The significant CpG sites were related to pathways associated with type I diabetes mellitus, insulin resistance and secretion. Cg01459453 (SELP gene) was the most differentiated in the GDM group versus non-GDM (73.6 vs. 60.9, p = 1.06E-11; FDR = 7.87E-06). Three CpG sites (cg01459453, cg15329406, and cg04095097) were able to discriminate between GDM cases and controls (AUC = 1; p = 1.26E-09). Three differentially methylated positions (DMPs) were replicated in an independent cohort. To conclude, epigenetic marks during pregnancy differed between GDM cases and controls suggesting a role for these genes in GDM development. Three CpGs were able to discriminate GDM and non-GDM groups with high specificity and sensitivity, which may be biomarker candidates for diagnosis or prediction of GDM.

Higher β cell death in pregnant women, measured by DNA methylation patterns of cell-free DNA, compared to new-onset type 1 and type 2 diabetes subjects: a cross-sectional study

Diabetes is a metabolic disorder of glucose homeostasis in which β cell destruction occurs silently and is detected mainly when symptoms appear. In the last few years, it has emerged a great interest in developing markers capable of detecting pancreatic β cell death focused on improving early diagnosis and getting a better treatment response, mainly in type 1 diabetes. But other types of diabetes would also benefit from early detection of β cell death. Differentially methylated circulating DNA is being studied as minimally invasive biomarker of cell death. We aimed to explore whether the unmethylated/methylated ratio of the insulin and amylin genes might be a good biomarker of β cell death in different types of diabetes. A lower index ∆Ct indicates a higher rate of β-cell death. Plasma samples from subjects without diabetes, pregnant women, pregnant with gestational diabetes (GDM), type 1 diabetes and type 2 diabetes were analyzed. A qPCR reaction with specific primers for both methylated and unmethylated fragments of insulin and amylin genes were carried out. Pregnant women, GDM and non- GDM, showed a higher β-cell death for both markers (∆INS = 3.8 ± 2.1 and ∆Amylin = 8.5 ± 3.6), whereas T1D presented lower rate (∆INS = 6.2 ± 2.1 and ∆Amylin = 10.7 ± 2.9) comparable to healthy subjects. The insulin methylation index was associated with the newborn birth weight (r = 0.46; p = 0.033) and with insulin resistance (r = -0.533; p = 0.027) in the GDM group. The higher rate of β-cell death was observed in pregnant women independently of their metabolic status. These indexes could be a good indicator of β cell death in processes caused by defects on insulin secretion, insulin action, or both.

Impact of the Gestational Diabetes Diagnostic Criteria during the Pandemic: An Observational Study

OBJECTIVE

To analyze the effect of applying alternative diagnostic criteria for gestational diabetes mellitus (GDM) during the COVID-19 pandemic on GDM prevalence and obstetrical and perinatal outcomes, in comparison to usual diagnostic approaches.

METHODS

Data from women referred to GDM diagnosis from 1 September to 30 November 2019 were retrospectively collected (2019-group). The same data from the same period in 2020 were prospectively collected (2020-group). In both cases, a two-step diagnostic approach was used, the first step being a screening test (1 h 50 goral glucose tolerance test, OGTT). In 2019 it was followed by a 100 gr OGTT for diagnosis. In 2020, this was replaced by a blood test for the measurement of plasma glucose and HbA1c, according to alternative GDM diagnostic criteria during the COVID-19 pandemic.

RESULTS

From 237 women in the 2019 group, 40 (16.9%) were diagnosed with GDM, while from 255 women in the 2020 group, 37 (14.5%) had GDM (p = 0.470). More women in the 2020 group, in comparison to the 2019 group, were nulligravid (41.9% vs. 47.2%, p = 0.013), had a personal history of GDM (11.4% vs. 4.6%, p = 0.013) and had macrosomia in previous pregnancies (10.2% vs. 2.1%, p = 0.001). Obstetrical and perinatal outcomes were similar when comparing women with GDM to non-GDM women in the 2019 and 2020 groups and between GDM women and non-GDM women.

CONCLUSION

In a Spanish population, GDM prevalence during the COVID-19 pandemic using the alternative diagnostic criteria was similar to that found in 2019 using the usual diagnostic criteria. Despite women referred for GDM diagnosis during the pandemic having more GDM risk factors, obstetrical and perinatal outcomes were comparable to those observed before the pandemic.

Epigenetic Biomarkers of Transition from Metabolically Healthy Obesity to Metabolically Unhealthy Obesity Phenotype: A Prospective Study

Background: Identifying those parameters that could potentially predict the deterioration of metabolically healthy phenotype is a matter of debate. In this field, epigenetics, in particular DNA methylation deserves special attention. Results: The aim of the present study was to analyze the long-term evolution of methylation patterns in a subset of metabolically healthy subjects in order to search for epigenetic markers that could predict the progression to an unhealthy state. Twenty-six CpG sites were significantly differentially methylated, both at baseline and 11-year follow-up. These sites were related to 19 genes or pseudogenes; a more in-depth analysis of the methylation sites of these genes showed that CYP2E1 had 50% of the collected CpG sites differently methylated between stable metabolically healthy obesity (MHO) and unstable MHO, followed by HLA-DRB1 (33%), ZBTB45 (16%), HOOK3 (14%), PLCZ1 (14%), SLC1A1 (12%), MUC2 (12%), ZFPM2 (12.5%) and HLA-DQB2 (8%). Pathway analysis of the selected 26 CpG sites showed enrichment in pathways linked to th1 and th2 activation, antigen presentation, allograft rejection signals and metabolic processes. Higher methylation levels in the cg20707527 (ZFPM2) could have a protective effect against the progression to unstable MHO (OR: 0.21, 95%CI (0.067–0.667), p < 0.0001), whilst higher methylation levels in cg11445109 (CYP2E1) would increase the progression to MUO; OR: 2.72, 95%CI (1.094–6.796), p < 0.0014; respectively). Conclusions: DNA methylation status is associated with the stability/worsening of MHO phenotype. Two potential biomarkers of the transition to an unhealthy state were identified and deserve further investigation (cg20707527 and cg11445109). Moreover, the described differences in methylation could alter immune system-related pathways, highlighting these pathways as therapeutic targets to prevent metabolic deterioration in MHO patients.

Relationship between environmental temperature and the diagnosis and treatment of gestational diabetes mellitus: An observational retrospective study

INTRODUCTION

Environmental temperature has been described to affect plasma glucose levels after oral glucose tolerance testing (OGTT).

AIMS

We evaluated the relationship between seasons and environmental temperature and gestational diabetes mellitus (GDM) diagnosis and treatment.

METHODS

We analyzed data from 2374 women retrospectively. GDM was diagnosed in 473 patients by a 100-g OGTT. OGTT results and needing of insulin therapy were evaluated in relation to seasons and environmental temperature (mean temperature and temperature change) the day of the OGTT and the preceding 14 and 28 days.

RESULTS

We found significant seasonal differences in the percentage of GDM: 24.4% in summer vs. 15.6% in autumn (p < 0.01). The odds ratio (OR) for being diagnosed with GDM was 1.78 in summer relative to autumn, after controlling for age. A higher mean temperature the day of the OGTT and the preceding 14 and 28 days increased the risk of being diagnosed with GDM the months in which temperature was rising (March-August) but not the months in which temperature was decreasing (September-February). We observed a negative correlation between temperature and fasting glucose and a positive correlation with post-load glucose. Neither the season nor the environmental temperature affected the risk of requiring insulin therapy.

CONCLUSIONS

There is a higher prevalence of GDM diagnosis at warmer seasons and at rising temperatures the 2-4 weeks prior to the OGTT. The impact of temperature is different between fasting and post-load glucose.

Association between variation of circulating 25-OH vitamin D and methylation of secreted frizzled-related protein 2 in colorectal cancer

BACKGROUNDS

Colorectal cancer (CRC) results from the accumulation of epigenetic and genetic changes in colon cells during neoplasic transformation, which the activation of Wingless (Wnt) signaling pathway is a common mechanism for CRC initiation. The Wnt pathway is mainly regulated by Wnt antagonists, as secreted frizzled-related protein (SFRP) family. Indeed, SFRP2 is proposed as a noninvasive biomarker for CRC diagnosis. Vitamin D also antagonizes Wnt signaling in colon cancers cells. Several studies showed that vitamin D was able to alter DNA methylation, although this mechanism is not yet clear. Therefore, the aim of this study was to find an association between circulating 25-OH vitamin D (30th percentile of vitamin D) and the SFRP2 methylation.

METHODS

A total of 67 CRC patients were included in the study. These patients were subdivided into two groups based on their 30th percentile vitamin D (20 patients were below, and 47 participants were above the 30th percentile of vitamin D). We investigated the SFRP2 methylation in peripheral blood mononuclear cells (PBMCs), visceral adipose tissue (VAT), CRC tumor tissue, and adjacent tumor-free area. We also determined the relationship between SFRP2 methylation and methylation of carcinogenic and adipogenic genes. Finally, we tested the effect of vitamin D on the SFRP2 methylation in human colorectal carcinoma cell lines 116 (HCT116) and studied the association of neoadjuvant therapy under the 30th percentile vitamin D with SFRP2 promoter methylation.

RESULTS

SFRP2 methylation in tumor area was decreased in patients who had higher levels of vitamin D. SFRP2 promoter methylation was positively correlated in tumor area with insulin and homeostasis model assessment of insulin resistance (HOMA-IR) but negatively correlated with HDL-c. SFRP2 methylation was also correlated with T cell lymphoma invasion and metastasis 1 (TIAM1) methylation in tumor area and CCAAT/enhancer-binding protein alpha (C/EBPα) in VAT. Treatment with vitamin D did not affect SFRP2 methylation in HCT116 cell line. Finally, neoadjuvant treatment was correlated with higher circulating 25-OH vitamin D and SFRP2 methylation under linear regression model.

CONCLUSION

Our results showed that higher circulating vitamin D is associated with low SFRP2 promoter methylation. Therefore, our results could suggest that vitamin D may have an epigenetic effect on DNA methylation. Finally, higher vitamin D could contribute to an improvement response to neoadjuvant treatment.

Association between the APOA2 rs3813627 Single Nucleotide Polymorphism and HDL and APOA1 Levels Through BMI

Background: The interaction between obesity and genetic traits on high density lipoprotein (HDL) levels has been extensively studied. The variance of serum HDL has a strong genetic heritability, although the studied variant only explains a small part of this variation. The goal of this study was to investigate the associations between the apolipoprotein type 2 (APOA2) rs3813627 single nucleotide polymorphism (SNP) and anthropometric and biochemical variables, though body mass index (BMI). Methods: This study included 153 subjects (91 overweight/obese (BMI³25 kg/m²) and 62 non-obese individuals (BMI < 25 kg/m²)). The APOA2 rs3813627 SNP was selected and genotyped. Genotype analysis was performed to analyze the associations between APOA2 SNPs and anthropometric and biochemical variables through BMI. Results: The APOA2 rs3813627 TT genotype was associated with low HDL levels in comparison with the APOA2 rs3813627 GG and GT genotype in overweight/obese individuals, but not in the non-obese subjects (p < 0.05). The same trend was observed in the apolipoprotein type 1 (APOA1) protein levels (p < 0.05). Correlation analysis revealed a negative correlation between HDL and APOA1 levels and APOA2 rs3813627 SNP under recessive model (p < 0.05). The odds ratio for low HDL levels was 3.76 and 3.94 for low APOA1 levels. The mediation analysis of APOA2 rs3813627 SNP through BMI showed a full mediation on HDL and partial mediation on APOA1 levels (p < 0.05). Bioinformatic analysis showed that rs3813627 lies in the APOA2 promoter and overlaps motifs for several bound transcription factors. Conclusion: On the basis of these data, the APOA2 rs3813627 SNP is associated with low HDL and APOA1 levels susceptibility, and this effect was mediated by an increased BMI.

Novel SFRP2 DNA Methylation Profile Following Neoadjuvant Therapy in Colorectal Cancer Patients with Different Grades of BMI

The relationship between body weight and different cancers is now well-recognized and among such cancers, colorectal cancer (CRC) is reported most frequently. Our group recently published findings, through an epigenome-wide association study, suggesting that body mass index (BMI) could act as a relevant risk factor in the CRC. In addition, aberrant SFRP2 methylation is one of the major mechanisms for Wnt signaling activation in CRC. Conversely, neoadjuvant chemo-radiotherapy appears to alter the rectal cancer epigenome. This study was aimed to evaluate the effect of obesity, measured by BMI, on the methylation of SFRP2 in tumor samples of patients with CRC. Non-treated CRC patients and CRC patients treated with pre-operative neoadjuvant therapy from 2011 to 2013 were included and classified by BMI < 25.0 kg/m² and BMI > 25.0 kg/m². SFRP2 DNA methylation in tumor samples was measured by pyrosequencing. Our findings suggest a possible interaction between SFRP2 methylation levels and BMI in CRC tumor samples. The correlation of SFRP2 hypomethylation with an elevated BMI was stronger within the non-treated CRC patient group than within the treated CRC patient group. We have successfully demonstrated that the beneficial association of tumor SFRP2 hypomethylation is dependent on patient BMI in non-treated CRC, suggesting a possible tumor suppressor role for SFRP2 in overweight and obese patients. Additional studies of clinical pathologies would be necessary to strengthen these preliminary results.

Altered Adipose Tissue DNA Methylation Status in Metabolic Syndrome: Relationships Between Global DNA Methylation and Specific Methylation at Adipogenic, Lipid Metabolism and Inflammatory Candidate Genes and Metabolic Variables

Metabolic syndrome (MetS) has been postulated to increase the risk for type 2 diabetes, cardiovascular disease and cancer. Adipose tissue (AT) plays an important role in metabolic homeostasis, and AT dysfunction has an active role in metabolic diseases. MetS is closely related to lifestyle and environmental factors. Epigenetics has emerged as an interesting landscape to evaluate the possible interconnection between AT and metabolic disease, since it can be modulated by environmental factors and metabolic status. The aim of this study was to determine whether MetS has an impact on the global DNA methylation pattern and the DNA methylation of several genes related to adipogenesis (PPARG, PPARA), lipid metabolism (RXRA, SREBF2, SREBF1, SCD, LPL, LXRb), and inflammation (LRP1 C3, LEP and TNF) in visceral adipose tissue. LPL and TNF DNA methylation values were significantly different in the control-case comparisons, with higher and lower methylation respectively in the MetS group. Negative correlations were found between global DNA methylation (measured by LINE-1 methylation levels) and the metabolic deterioration and glucose levels. There were associations among variables of MetS, BMI, and HOMA-IR with DNA methylation at several CpG positions for the studied genes. In particular, there was a strong positive association between serum triglyceride levels (TG) with PPARA and LPL methylation levels. TNF methylation was negatively associated with the metabolic worsening and could be an important factor in preventing MetS occurrence according to logistic regression analysis. Therefore, global DNA methylation and methylation at specific genes related to adipogenesis, lipid metabolism and inflammation are related to the etiology of MetS and might explain in part some of the features associated to metabolic disorders.

Decreased blood pressure is related to changes in NF-kB promoter methylation levels after bariatric surgery

BACKGROUND

Obesity is characterized by a chronic, low-grade inflammation, and bariatric surgery is proposed as an effective treatment for reducing the obesity-related co-morbidities. Epigenetic modifications could be involved in the metabolic improvement after surgery.

OBJECTIVE

The main aim of this study was to evaluate whether DNA methylation pattern from genes related to inflammation and insulin response is associated with the metabolic improvement after bariatric surgery in morbidly obese patients and if these changes depend on the surgical procedure.

SETTING

University hospital, Spain.

METHODS

We studied 60 severely obese patients; 31 underwent Roux-en-Y gastric bypass and 29 underwent laparoscopic sleeve gastrectomy. All patients were examined before and at 6 months after bariatric surgery. DNA methylation profile of genes related to the inflammatory response and insulin sensitivity was measured by pyrosequencing.

RESULTS

The promoter methylation levels of the NFKB1 gene were increased significantly after surgery (2.16 ± .9 versus 2.8 ± 1.03). The decrease in blood pressure, both systolic and diastolic, after surgery was significantly associated with the changes in the promoter methylation levels of the NFKB1 gene (β = -.513, P = .003 and β = -.543, P = .004, respectively). A decrease in inflammation status, measured by high sensitivity C-reactive protein values, was associated with changes in SLC19A1 methylation levels.

CONCLUSION

Our study shows for the first time an association between NFKB1 methylation levels and blood pressure after bariatric surgery, highlighting the possible function of this gene in the regulation of arterial pressure. Regarding SLC19A1, this gene could position as a potential target linking inflammation and insulin resistance.

Adipose tissue inflammation and VDR expression and methylation in colorectal cancer

Background

Lack of vitamin D (VD) has been associated with colorectal cancer (CRC). VD has anti-inflammatory effects and regulates several cellular pathways by means of its receptor, including epigenetic modifications. Adipose tissue dysfunction has been related to low-grade inflammation, which is related to diseases like cancer. The aim of this study was to explore the relationship between serum 25-hydroxyvitamin D (25(OH)D), adipose tissue gene expression of VD receptor (VDR), pro-inflammatory markers, and the epigenetic factor DNA methyltransferase 3a (DNMT3A) as well as VDR promoter methylation in CRC.

Methods

Blood and visceral adipose tissue from 57 CRC and 50 healthy control subjects were collected. CRC subjects had lower serum 25(OH)D levels and higher VDR gene expression, and these were negatively correlated in the CRC group.

Results

Adipose tissue NFκB1, IL6, and IL1B gene expression were higher in the CRC subjects than in the control subjects. 25(OH)D correlated negatively with NFκB1 and CRP. In turn, CRP correlated positively with NFκB1, IL6, IL1B, and VDR gene expression as well as NFκB1 that correlated positively with IL6 and IL1B. DNMT3A mRNA was negatively correlated with serum 25(OH)D and positively correlated with VDR DNA methylation. VDR DNA methylation at position 4 had lower levels in the CRC group. Global NFκB1 methylation at dinucleotide 3 was lower in the CRC group.

Conclusion

Our results suggest that adipose tissue may be a key factor in CRC development. The low 25(OH)D levels and high adipose tissue VDR expression in CRC may, at least in part, mediate this relationship by modifying adipose tissue DNA methylation and promoting inflammation.

Electronic supplementary material

The online version of this article (10.1186/s13148-018-0493-0) contains supplementary material, which is available to authorized users.

The role of vitamin D and VDR in carcinogenesis: Through epidemiology and basic sciences

In the last two decades vitamin D (VD) research has demonstrated new extraskeletal actions of this pre-hormone, suggesting a protective role of this secosteroid in the onset, progression and prognosis of several chronic noncommunicable diseases, such as cardiovascular disease, diabetes mellitus or cancer. Regarding carcinogenesis, both preclinical and epidemiological evidence available show oncoprotective actions of VD and its receptor, the VDR. However, in late neoplastic stages the VD system (VDS) seems to be less functional, which appears to be due to an epigenetic silencing of the system. In preclinical experimental studies, VD presents oncoprotective actions through modulation of inflammation, cell proliferation, cell differentiation, angiogenesis, invasive and metastatic potential, apoptosis, miRNA expression regulation and modulation of the Hedgehog signalling pathway. Moreover, epidemiological evidence points towards an oncoprotective role of vitamin D and VDR in colorectal cancer. This association is more controversial with breast, ovarian and prostate cancers, although with a few adverse effects. Nonetheless, we should consider other factors to determine the benefit of increased serum concentration of VD. Much of the epidemiological evidence is still inconclusive, and we will have to wait for new, better-designed ongoing RCTs and their results to discern the real effect of vitamin D in cancer risk reduction and therapy. The objective of this literature review is to offer an up-to-date analysis of the role of the VD and VDR, in the onset, progression and prognosis of all types of cancer. We further discuss the available literature and suggest new hypotheses and future challenges in the field of VD research.

No effect of different bariatric surgery procedures on LINE-1 DNA methylation in diabetic and nondiabetic morbidly obese patients

BACKGROUND

Bariatric surgery (BS) is proposed as a highly effective therapy for reducing weight and improving obesity-related co-morbidities. The molecular mechanisms involved in the metabolic improvement after BS are not completely resolved. Epigenetic modifications could have an important role.

OBJECTIVE

The aim of this study was to evaluate the effect of different BS procedures (Roux-en-Y gastric bypass and laparoscopic sleeve gastrectomy) on global DNA methylation (long interspersed nucleotide element 1 [LINE-1]) in a group of nondiabetic and diabetic severely obese patients.

SETTING

University hospital, Spain.

METHODS

This study included 60 patients (30 nondiabetic and 30 diabetic severely obese patients) undergoing BS: 31 patients underwent Roux-en-Y gastric bypass and 29 underwent laparoscopic sleeve gastrectomy. Before and 6 months post-BS, anthropometric data, blood pressure, and metabolic parameters were determined. LINE-1 DNA methylation was quantified by pyrosequencing. We used the methylation levels of tumor necrosis factor-α as a control gene promoter.

RESULTS

There were no differences between LINE-1 methylation levels at baseline and at 6 months after surgery (66.3±1.6 versus 66.2±2.06). Likewise, there was no statistically significant difference on LINE-1 methylation levels when we stratified according to metabolic status (diabetic versus nondiabetic), nor was there regarding the BS procedure. A strong correlation was shown between LINE-1 methylation levels and weight at baseline both in diabetic and nondiabetic obese patients (r = .486; P<.001). Tumor necrosis factor-α methylation levels increased significantly after BS in the group of diabetic obese patients.

CONCLUSION

After BS, global LINE-1 methylation is not modified in the short term. More studies are required to determine if LINE-1 is a stable epigenetic marker, or, on the contrary, if it is susceptible to modification by external factors such as changes in lifestyle or a surgical intervention.

Genome-Wide Association Study of the Modified Stumvoll Insulin Sensitivity Index Identifies BCL2 and FAM19A2 as Novel Insulin Sensitivity Loci

Genome-wide association studies (GWAS) have found few common variants that influence fasting measures of insulin sensitivity. We hypothesized that a GWAS of an integrated assessment of fasting and dynamic measures of insulin sensitivity would detect novel common variants. We performed a GWAS of the modified Stumvoll Insulin Sensitivity Index (ISI) within the Meta-Analyses of Glucose and Insulin-Related Traits Consortium. Discovery for genetic association was performed in 16,753 individuals, and replication was attempted for the 23 most significant novel loci in 13,354 independent individuals. Association with ISI was tested in models adjusted for age, sex, and BMI and in a model analyzing the combined influence of the genotype effect adjusted for BMI and the interaction effect between the genotype and BMI on ISI (model 3). In model 3, three variants reached genome-wide significance: rs13422522 (NYAP2; P = 8.87 × 10(-11)), rs12454712 (BCL2; P = 2.7 × 10(-8)), and rs10506418 (FAM19A2; P = 1.9 × 10(-8)). The association at NYAP2 was eliminated by conditioning on the known IRS1 insulin sensitivity locus; the BCL2 and FAM19A2 associations were independent of known cardiometabolic loci. In conclusion, we identified two novel loci and replicated known variants associated with insulin sensitivity. Further studies are needed to clarify the causal variant and function at the BCL2 and FAM19A2 loci.

The nutrigenetic influence of the interaction between dietary vitamin E and TXN and COMT gene polymorphisms on waist circumference: a case control study

Background

Abdominal obesity (AO) is a common modifiable risk factor for certain non-communicable diseases associated with enhanced oxidative stress (OS). The objective of this work was to investigate whether the interaction between antioxidant vitamin intake and OS-related polymorphisms modulates gene-associated anthropometry in a Spanish population.

Methods

A total of 246 subjects with AO, and 492 age and gender matched non-AO subjects were included in the study. Anthropometric, biochemical, and OS parameters, and antioxidant dietary intake data were assessed using validated procedures. DNA from white blood cells was isolated and the genotype of seven polymorphisms from genes involved in OS (pro-oxidant and antioxidant) were analyzed using the SNPlex system. The effects of the c.-793T > C polymorphism on promoter activity and thus thioredoxin (TXN) activity were examined using reporter assays.

Results

The AO group had higher 8-Oxo-2′-deoxyguanosine levels and took in less vitamin A and vitamin E compared to the non-AO group. Logistic regression analysis revealed that the rs2301241 polymorphism in TXN and rs740603 in catechol-O-methyltransferase (COMT) were associated with waist circumference (WC) and AO. Moreover, these polymorphisms were more strongly associated with variations in WC in subjects with low vitamin E intakes. A promoter assay revealed that the T to C conversion at c.-793 (rs2301241) induced a more than two fold increase in reporter gene expression.

Conclusions

WC is associated both with dietary vitamin E intake and genetic variants of TXN and COMT suggesting that existence of a complex nutrigenetic pathway that involves regulation of AO.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-015-0652-4) contains supplementary material, which is available to authorized users.

Type 2 diabetes mellitus in relation to global LINE-1 DNA methylation in peripheral blood: a cohort study

In the last years, epigenetic processes have emerged as a promising area of complex diseases research. DNA methylation measured in Long Interspersed Nucleotide Element 1 (LINE-1) sequences has been considered a surrogate marker for global genome methylation. New findings have suggested the potential involvement of epigenetic mechanisms in Type 2 diabetes (T2DM) as a crucial interface between the effects of genetic predisposition and environmental influences. Our study evaluated whether global DNA methylation predicted increased risk from T2DM or other carbohydrate metabolism disorders in a cohort study. We used a prospective cohort intervention study and a control group. We collected phenotypic, anthropometric, biochemical, and nutritional information from all subjects. Global LINE-1 DNA methylation was quantified by pyrosequencing technology. Subjects that did not improve their carbohydrate metabolism status showed lower levels of global LINE-1 DNA methylation (63.9 ± 1.7 vs. 64.7 ± 2.4) and they practiced less intense physical activity (5.8% vs. 21.5%). Logistic regression analyses showed a significant association between LINE-1 DNA methylation and metabolic status after adjustment for sex, age, BMI, and physical activity. Our study showed that lower LINE-1 DNA methylation levels were associated with a higher risk metabolic status worsening, independent of other classic risk factors. This finding highlights the potential role for epigenetic biomarkers as predictors of T2DM risk or other related metabolic disorders.

Changes in thyroid function with age: results from the Pizarra population-based longitudinal study

BACKGROUND

Results of studies examining the influence of age on thyroid function and TSH levels, in the absence of thyroid disease, remain controversial. The aim of this study was to determine the course of thyroid function over 11 years in a population with normal thyroid function.

METHODS

This is a population-based prospective study started in 1995-1997 (first phase), and reassessed 6 (second phase) and 11 years later (third phase).

RESULTS

The TSH and FT4 in the third phase were significantly increased (p=0.001 and p=0.001, respectively), with the values being higher particularly from the age of 50 years. In those persons with a baseline TSH≥1.2 and <3 μIU/mL, the OR of having a TSH of 3-5 μIU/mL in the third phase was 6.10 (p=0.004). In those with a baseline TSH≥3 and ≤5 μIU/mL, the OR of having a TSH of 3-5 μIU/mL in the third phase was 20.8 (p<0.0001). Similar results were found for FT4.

CONCLUSION

In a population free of clinical thyroid disease, TSH and FT4 values rise over the years. This increase occurs in all age groups, but depends mainly on the basal concentrations of TSH and FT4.

Polymorphisms in endothelin system genes, arsenic levels and obesity risk

BACKGROUND/OBJECTIVES

Obesity has been linked to morbidity and mortality through increased risk for many chronic diseases. Endothelin (EDN) system has been related to endothelial function but it can be involved in lipid metabolism regulation: Receptor type A (EDNRA) activates lipolysis in adipocytes, the two endothelin receptors mediate arsenic-stimulated adipocyte dysfunction, and endothelin system can regulate adiposity by modulating adiponectin activity in different situations and, therefore, influence obesity development. The aim of the present study was to analyze if single nucleotide polymorphisms (SNPs) in the EDN system could be associated with human obesity.

SUBJECTS/METHODS

We analyzed two samples of general-population-based studies from two different regions of Spain: the VALCAR Study, 468 subjects from the area of Valencia, and the Hortega Study, 1502 subjects from the area of Valladolid. Eighteen SNPs throughout five genes were analyzed using SNPlex.

RESULTS

We found associations for two polymorphisms of the EDNRB gene which codifies for EDN receptor type B. Genotypes AG and AA of the rs5351 were associated with a lower risk for obesity in the VALCAR sample (p=0.048, OR=0.63) and in the Hortega sample (p=0.001, OR=0.62). Moreover, in the rs3759475 polymorphism, genotypes CT and TT were also associated with lower risk for obesity in the Hortega sample (p=0.0037, OR=0.66) and in the VALCAR sample we found the same tendency (p=0.12, OR=0.70). Furthermore, upon studying the pooled population, we found a stronger association with obesity (p=0.0001, OR=0.61 and p=0.0008, OR=0.66 for rs5351 and rs3759475, respectively). Regarding plasma arsenic levels, we have found a positive association for the two SNPs studied with obesity risk in individuals with higher arsenic levels in plasma: rs5351 (p=0.0054, OR=0.51) and rs3759475 (p=0.009, OR=0.53).

CONCLUSIONS

Our results support the hypothesis that polymorphisms of the EDNRB gene may influence the susceptibility to obesity and can interact with plasma arsenic levels.

Modifications of the homeostasis model assessment of insulin resistance index with age

The aim of the study was to analyze the association between aging and insulin resistance estimated by the homeostasis model assessment of insulin resistance (HOMA-IR). This work involved two studies: (1) the Di@bet.es study is a cross-sectional study including 4,948 subjects, comprising a representative sample of the adult Spanish population; (2) the Pizarra study is a population-based cohort study undertaken in Pizarra (Spain), in which 1,051 subjects were evaluated at baseline and 714 completed the 6-year follow-up study. Study variables included a clinical and demographic structured survey, a lifestyle survey, a physical examination, and an oral glucose tolerance test in subjects without diabetes. In the Di@bet.es study overall, an increase occurred in blood glucose until the age of 50, after which it remained stable (data adjusted for gender, body mass index, abnormal glucose regulation [AGR]). The HOMA-IR increased significantly with age (p = 0.01), due to a higher prevalence of obesity (p < 0.0001) and AGR (p < 0.001). In non-obese subjects without AGR, HOMA-IR values were not modified with age (p = 0.30), but they were with body mass index (p < 0.001). In the Pizarra study, the HOMA-IR was significantly lower after 6-year follow-up in the whole study population. Subjects with a HOMA-IR level higher than the 75th percentile at baseline were more likely to develop diabetes (OR 2.2, 95 % CI 1.2-3.9; p = 0.007) than subjects with a lower HOMA-IR. We concluded that age per se did not increase HOMA-IR levels, changes that might be related to higher rates of obesity and AGR in older subjects. The HOMA-IR was associated with an increased risk of developing type 2 diabetes 6 years later.

Night-time sleep duration and the incidence of obesity and type 2 diabetes. Findings from the prospective Pizarra study

BACKGROUND

Several recent studies have related short sleep duration with different health problems, though the results related with the risk of obesity and type 2 diabetes (T2D) are far from conclusive. The aim of this study was to investigate the association between night-time sleep duration and the incidence of obesity and T2D in a prospective study with a follow-up of 11 years.

MATERIAL AND METHODS

The study comprised 1145 people evaluated in 1997-1998 and re-evaluated after 6 years and 11 years. At the three study points, subjects without known diabetes mellitus (KDM) were given an oral glucose tolerance test (OGTT). Anthropometric and biochemical variables were measured. The subjects were asked about their number of hours of night-time sleep.

RESULTS

After adjustment, the OR of becoming obese was significantly higher in subjects who slept ≤ 7 hours per night, at both the 6-year follow-up (OR = 1.99; 95% CI = 1.12-3.55) and the 11-year follow-up (OR = 2.73; 95% CI = 1.47-5.04). The incidence of T2D at the 6-year follow-up in subjects without T2D at baseline was higher in those who slept ≤ 7 hours per night (OR = 1.96; 95% CI = 1.10-3.50). However, this association was not independent of obesity, weight gain or abnormal glucose regulation at baseline. At the 11-year follow-up however there was no association between night-time sleep duration and the incidence of T2D.

CONCLUSIONS

The incidence of obesity over the 11-year follow-up increased in subjects with fewer hours of night-time sleep. The incidence of T2D according to the hours of night-time sleep depended on obesity and the carbohydrate metabolism phenotype.

Methylation levels of the SCD1 gene promoter and LINE-1 repeat region are associated with weight change: an intervention study

SCOPE

Epigenetic processes may be affected by environmental factors. DNA methylation measured in LINE-1 elements (LINE-1, long interspersed nucleotide element-1) correlates with LINE-1 DNA methylation. Variations in stearoyl CoA desaturase (SCD) activity (a key enzyme in the fatty acid metabolism) may be involved in various processes that can lead to diseases such as obesity. We evaluated whether changes in diet after a nutritional intervention would be associated with changes in LINE-1 DNA methylation and/or specific methylation of SCD1 gene promoter.

METHODS AND RESULTS

DESIGN

Prospective cohort intervention study with a control group. We recorded phenotypic, anthropometric, biochemical, and nutritional information at baseline and 1 year later. DNA methylation was quantified by pyrosequencing. LINE-1 DNA methylation and SCD1 gene promoter methylation levels were similar at the beginning of the study in both populations, whereas after a year these levels were higher in the control group (p < 0.001). In the intervention group, those subjects who lost weight showed higher levels of SCD1 gene promoter methylation after the intervention. Subjects with lower adherence to a Mediterranean diet experienced larger changes in LINE-1 methylation.

CONCLUSION

DNA methylation levels were associated with weight change and with adherence to a Mediterranean diet.

Impact of obesity-related genes in Spanish population

Background

The objective was to investigate the association between BMI and single nucleotide polymorphisms previously identified of obesity-related genes in two Spanish populations. Forty SNPs in 23 obesity-related genes were evaluated in a rural population characterized by a high prevalence of obesity (869 subjects, mean age 46 yr, 62% women, 36% obese) and in an urban population (1425 subjects, mean age 54 yr, 50% women, 19% obese). Genotyping was assessed by using SNPlex and PLINK for the association analysis.

Results

Polymorphisms of the FTO were significantly associated with BMI, in the rural population (beta 0.87, p-value <0.001). None of the other SNPs showed significant association after Bonferroni correction in the two populations or in the pooled analysis. A weighted genetic risk score (wGRS) was constructed using the risk alleles of the Tag-SNPs with a positive Beta parameter in both populations. From the first to the fifth quintile of the score, the BMI increased 0.45 kg/m² in Hortega and 2.0 kg/m² in Pizarra. Overall, the obesity predictive value was low (less than 1%).

Conclusion

The risk associated with polymorphisms is low and the overall effect on BMI or obesity prediction is minimal. A weighted genetic risk score based on genes mainly acting through central nervous system mechanisms was associated with BMI but it yields minimal clinical prediction for the obesity risk in the general population.

Polymorphisms in the SCD1 gene are associated with indices of stearoyl CoA desaturase activity and obesity: a prospective study

SCOPE

The serum fatty acid (FA) composition is influenced by dietary fat and the endogenous production of FAs. Stearoyl CoA desaturase 1 (SCD1) is the rate-limiting enzyme catalyzing the synthesis of MUFAs from saturated FAs. Variations in SCD1 activity have been associated with obesity, diabetes, or inflammation. We evaluated the associations between genetic variation of the SCD1 gene, SCD1 activity, intake of oil, and obesity in a population-based prospective study in southern Spain.

METHODS AND RESULTS

We collected phenotypic, metabolic, nutritional, and genetic information. The type of dietary fat was assessed from samples of cooking oil taken from the participants' kitchens and analyzed by GC. A total of nine single nucleotide polymorphisms (SNPs) of the SCD1 gene were analyzed by SNPlex technology. We found a significant association between SCD1 genetic variation and enzyme activity in four of nine polymorphisms studied. An interaction between rs10883463 and olive oil intake on the [18:1/18:0] desaturase index was found (p = 0.009). We also showed that genetic variations in the SCD1 gene were associated with obesity.

CONCLUSION

Our results show a relationship between genetic variation of the SCD1 gene, enzyme activity, and the risk of obesity, an association that is not independent of the type of oil consumed.

Factors determining weight gain in adults and relation with glucose tolerance

OBJECTIVE

Modifications in lifestyle, diet and certain clinical events are major contributors for the high prevalence of obesity. The aim of this study was to assess factors associated with weight gain in a population of Spanish adults.

DESIGN

The study was undertaken in two population-based cohorts from the north and the south of Spain (baseline and after 6 years). The Asturias Study, in the north, included 1034 persons aged 30-75 years, of whom 701 were reassessed. The Pizarra Study, in the south, included 1226 persons aged 18-65 years, of whom 783 were re-evaluated. Both studies involved a nutritional questionnaire, a physical examination and an oral glucose tolerance test (OGTT).

RESULTS

During the follow-up, 32.3% of the participants lost weight, 34.5% gained fewer than 4 kg and 33.2% gained more than 4 kg. Weight gain was greater in persons younger than 50 years and in those with an initial body mass index below 30. Weight gain was associated with a greater incidence of type 2 diabetes mellitus (T2DM) and abnormal glucose tolerance, whereas weight loss in persons with these disorders was associated with a normal OGTT 6 years later. Persons who took less exercise and those who reported a higher daily calorie intake experienced greater weight gain.

CONCLUSION

The longitudinal changes in weight affect the development of T2DM and abnormal glucose tolerance. The weight is a dynamic phenomenon affected by several social customs.

Metabolically healthy but obese, a matter of time? Findings from the prospective Pizarra study

BACKGROUND

Prospective longitudinal studies evaluating the relevance of "Metabolically Healthy but Obese" (MHO) phenotype at risk for type 2 diabetes mellitus (T2D) and cardiovascular diseases are few and results are contradictory.

METHODS

As a representative of the general population, 1051 individuals were evaluated in 1997-1998 and re-evaluated after 6 years and 11 years. Subjects without known T2D were given an oral glucose tolerance test. Anthropometric and biochemical variables were measured. Four sets of criteria were considered to define MHO subjects besides body mass index ≥30 kg/m(2): A: Homeostatic Model of Assessment-Insulin Resistance Index (HOMA-IR) <90th percentile; B: HOMA-IR <90th percentile, high-density lipoprotein cholesterol >40 mg/dL in men and high-density lipoprotein cholesterol >50 mg/dL in women, triglycerides <150 mg/dL, fasting glucose <110 mg/dL, and blood pressure ≤140/90 mm Hg; C: HOMA-IR <90th percentile, triglycerides <150 mg/dL, fasting glucose <110 mg/dL, and blood pressure ≤140/90 mm Hg; D: HOMA-IR <90th percentile, triglycerides <150 mg/dL, and fasting glucose <110 mg/dL. Subjects with T2D at baseline were excluded from the calculations of incidence of T2D.

RESULTS

The baseline prevalence of MHO phenotype varied between 3.0% and 16.9%, depending on the set of criteria chosen. Metabolically nonhealthy obese subjects were at highest risk for becoming diabetic after 11 years of follow-up (odds ratio = 8.20; 95% confidence interval = 2.72-24.72; P < .0001). In MHO subjects the risk for becoming diabetic was lower than in metabolically nonhealthy obese subjects, but this risk remained significant (odds ratio = 3.13; 95% confidence interval = 1.07-9.17; P = .02). In subjects who lost weight during the study, the association between MHO phenotype and T2D incidence disappeared, even after adjusting for HOMA-IR.

CONCLUSIONS

The results suggest that MHO is a dynamic concept that should be taken into account over time. As a clinical entity, it may be questionable.

Hypovitaminosis D and incidence of obesity: a prospective study

The aim of this study was to assess the relationship between obesity and vitamin D status cross-sectionally, the relationship between obesity and the incidence of hypovitaminosis D prospectively and inversely the relationship between vitamin D status and incidence of obesity in a population-based cohort study in Spain. At baseline (1996-1998), 1226 subjects were evaluated and follow-up assessments were performed in 2002-2004 and 2005-2007, participants undergoing an interview and clinical examination with an oral glucose tolerance test. At the second visit, 25-hydroxyvitamin D and intact parathyroid hormone concentrations were also measured. Prevalence of obesity at the three visits was 28.1, 36.2 and 39.5%, respectively. The prevalence of vitamin D deficiency (25-hydroxyvitamin D ≤ 20 ng/ml (≤ 50 nmol/l)) was 34.7%. Neither obesity at baseline (OR=0.98, 95% CI: 0.69-1.40, P=0.93) nor the development of obesity between baseline and the second evaluation (OR=0.80, 95% CI: 0.48-1.33, P=0.39) were significantly associated with vitamin D status. In subjects who were non-obese (BMI <30 kg/m²) at the second evaluation, 25-hydroxyvitamin D values ≤ 17 ng/ml (≤ 42.5 nmol/l) were significantly associated with an increased risk of developing obesity in the next 4 years (OR=2.35, 95% CI: 1.03-5.4, P=0.040 after diverse adjustments). We conclude that vitamin D deficiency is associated with an increased risk of developing obesity.

C-reactive protein and incidence of type 2 diabetes in the Pizarra study

AIM

To determine the association between serum levels of high-sensitivity C-reactive protein (hs-CRP) and the incidence of type 2 diabetes in a prospective cohort from southern Spain (Pizarra study).

MATERIALS AND METHODS

The study formed part of the Pizarra cohort study, a prospective study started in 1995 with a follow-up of 11 years. Anthropometric and metabolic variables were measured at baseline and at 6 years and 11 years of follow-up. All subjects underwent an oral glucose tolerance test. Serum levels of TNFα and its receptors, hs-CRP, IL-6, leptin, adiponectin and FABP4 were measured at 6 years of follow-up.

RESULTS

After adjusting for age, sex and obesity, subjects with levels of hs-CRP> 2.9 mg/L in the second study (2003-4) had a higher risk of developing type 2 diabetes by the third study (2008-9) (OR = 7.97; 95% CI = 1.72-36.89; P = 0.008), and subjects with adiponectin levels > 13.2 mg/L had a lower risk of developing type 2 diabetes (OR = 0.23, P = 0.02). High values of hs-CRP and high values of adiponectin were associated positively (OR = 8.26; 95% CI = 1.84-37.19; P = 0.006) and negatively (OR = 0.17; 95% CI = 0.04-0.69; P = 0.01), respectively, with the risk of having HbA1c ≥ 6.5% at 11 years of follow-up.

CONCLUSIONS

Subjects with high serum hs-CRP levels and low serum adiponectin levels have a higher risk of developing type 2 diabetes within five years.

White rice consumption and risk of type 2 diabetes

BACKGROUND & AIM

Recent studies suggest that white rice consumption increases risk of diabetes.

AIM

to assess the association between white rice intake and the incidence of diabetes in a population from Southern Spain.

METHODS

A population-based cohort study was undertaken in Pizarra, Spain. At baseline and follow-up, participants underwent an interview and a standardized clinical examination which included an oral glucose tolerance test in those subjects without known diabetes. Incidence and odds ratio (OR) for diabetes were calculated. Multivariate analysis was performed using stepwise logistical regression.

RESULTS

Thirty eight percent of subjects reported rice consumption 2-3 times a week, 58.5% once or less a week, and 3.6% no rice consumption. In subjects who reported rice intake 2-3 times a week, incidence of diabetes after 6 years follow-up was 12.0%, and in those who reported once or less a week, 20.2% (p = 0.04, non adjusted). Subjects who ate rice frequently had lower risk to develop diabetes 6 years later (OR = 0.43, p = 0.04; adjusted for age, sex, obesity, and presence of impaired fasting glucose and/or impaired glucose tolerance at baseline).

CONCLUSIONS

A negative association was found between white rice intake in the way it is consumed in Southern Spain, and the 6 years incidence of diabetes.

Common variants of the liver fatty acid binding protein gene influence the risk of type 2 diabetes and insulin resistance in Spanish population

Summary

The main objective was to evaluate the association between SNPs and haplotypes of the FABP1-4 genes and type 2 diabetes, as well as its interaction with fat intake, in one general Spanish population. The association was replicated in a second population in which HOMA index was also evaluated.

Methods

1217 unrelated individuals were selected from a population-based study [Hortega study: 605 women; mean age 54 y; 7.8% with type 2 diabetes]. The replication population included 805 subjects from Segovia, a neighboring region of Spain (446 females; mean age 52 y; 10.3% with type 2 diabetes). DM2 mellitus was defined in a similar way in both studies. Fifteen SNPs previously associated with metabolic traits or with potential influence in the gene expression within the FABP1-4 genes were genotyped with SNPlex and tested. Age, sex and BMI were used as covariates in the logistic regression model.

Results

One polymorphism (rs2197076) and two haplotypes of the FABP-1 showed a strong association with the risk of DM2 in the original population. This association was further confirmed in the second population as well as in the pooled sample. None of the other analyzed variants in FABP2, FABP3 and FABP4 genes were associated. There was not a formal interaction between rs2197076 and fat intake. A significant association between the rs2197076 and the haplotypes of the FABP1 and HOMA-IR was also present in the replication population.

Conclusions

The study supports the role of common variants of the FABP-1 gene in the development of type 2 diabetes in Caucasians.

Polymorphisms of the UCP2 gene are associated with body fat distribution and risk of abdominal obesity in Spanish population

BACKGROUND

Increased accumulation of fat results from an imbalance between energy expenditure and intake, being modulated by different environmental and genetic factors. Uncoupling proteins (UCPs) are mitochondrial carrier proteins able to spend energy generating heat. Therefore, variations in these genes are good candidates as potential modulators of body fat accumulation. Our aim was to investigate the possible association of genetic variations of the gene codifying the UCP2 protein with obesity and fat distribution.

DESIGN

We performed a cross-sectional study in 2367 individuals from two population-based studies from different regions of Spain. The Hortega Study included 1436 individuals (693 women) 21-85 years old, and the Pizarra Study included 931 individuals (584 women) 18-65 years old. We evaluated three polymorphisms of the UCP2 gene.

RESULTS

The TT genotype of the rs660339 polymorphism and the AA genotype of the rs659366 polymorphism of the UCP2 gene were significantly associated with higher waist circumference in the Hortega Study. Furthermore, subjects carrying both genotypes (TT+AA) also showed higher central adiposity compared with other genotypes. This association was also present in the Pizarra Study. Moreover, in the pooled population, we found a stronger association with waist circumference. Even, we found association with BMI. Furthermore, rs659366 polymorphism was associated with the risk of abdominal obesity (P= 0·04: OR = 1·3; CI = 1·01-1·67).

CONCLUSIONS

Polymorphisms of the UCP2 gene (rs660339 and rs659366) were associated with central obesity. This study shows association between the UCP2 gene and the susceptibility to obesity and body fat distribution in a south European population.

Thyroid hormone levels predict the change in body weight: a prospective study

BACKGROUND

Different studies, mostly cross-sectional, have found an association between low levels of thyroid hormones, even within the normal range, and a greater body mass index. The aim of this study was to determine the association between thyroid function and the risk for obesity.

MATERIALS AND METHODS

In this population-based prospective study, measurements were made of anthropometric parameters, thyroid hormone function and urinary iodine in a cohort of the Pizarra Study (n = 937), and repeated 6 years later (n = 784). At the second point, measurements were also made of leptin and adiponectin.

RESULTS

Among the persons who were not obese at the start of the study, the odds ratio (OR) of becoming obese for those in the fourth quartile (Q(4)) for free triiodothyronine (FT3) (versus those in Q(1)) was 2·94 (1·46-5·90) (P = 0·005). The OR of becoming obese in persons in Q(4) of FT4 (versus those in Q(1)) was 3·06 (1·23-7·43) (P = 0·01). Those persons in Q(4) of weight gain had a higher FT3 at the 6-year follow-up than those whose weight gain was in Q(1) (P < 0·001). Leptin correlated with thyrotropin (β = 0·58, P = 0·001) and the FT4 (β = -1·12, P = 0·005). Adiponectin correlated with FT3 (r = -0·24, P < 0·001). The urinary iodine correlated negatively with both the BMI (β = -0·08, P = 0·01) and the increase in weight (β = -0·08, P = 0·04).

CONCLUSIONS

The changes in the thyroid hormones could be the consequence, rather than the cause, of the increase in weight. The same pathophysiological mechanisms that induce obesity might also be modifying the thyroid hormone pattern.

[Validation of the FINDRISC (FINnish Diabetes RIsk SCore) for prediction of the risk of type 2 diabetes in a population of southern Spain. Pizarra Study]

BACKGROUND AND OBJECTIVE

The aim of this study was to validate the ability of the Finnish Diabetes Risk Score (FINDRISC) to predict the risk of DM2 in a population of south-eastern Spain (Pizarra Study).

SUBJECTS AND METHODS

The Pizarra Study is a population-based prospective study developed in the town of Pizarra (Málaga). The first phase of the study was conducted in 1997-1998, including 1051 individuals aged 18-65 years randomly selected from the municipal census of the town. In 2003-2004 the subjects participating in the first study were reassessed. 824 individuals completed the second phase of the study (78.4%). All participants without known diabetes underwent an oral glucose tolerance test both at baseline and follow-up. We evaluated the ability of the FINDRISC to detect undiagnosed DM2 (first phase: cross-sectional study) and in predicting the incidence of DM2 (second phase: cohort study).

RESULTS

The test showed good results both to detect undiagnosed DM2 (ROC-AUC 0.74) and to predict incident DM2 (ROC-AUC 0.75). The best prediction of risk of incident DM2 was found in those subjects with fasting glucose >100mg/dl and a FINDRISC ≥9 (OR: 19.37; 95%IC: 8,86-42,34; P<.0001).

CONCLUSIONS

The results of our study show that FINDRISC can be a useful tool to detect subjects at high risk of diabetes in this population.

High resolution melting curve analysis of DNA samples isolated by different DNA extraction methods

BACKGROUND

High resolution melting is a post-PCR-based method for detecting DNA sequence variation by measuring changes in the melting of a DNA duplex. Melting of double-stranded DNA molecules is influenced by several factors. We evaluated the influence of the DNA isolation method in the melting curve analysis to detect genetic variations.

METHODS

We isolated DNA from whole blood of 547 subjects by two different methods: Maxwell 16 Instrument and DNA FlexiGene Kit. A fragment of 159 bp was amplified and analyzed by high resolution melting. Those samples that showed a different melting curve pattern were sequenced.

RESULTS

Of the samples extracted with the Maxwell 16 Instrument, 42% showed variation compared with 0.18% of the samples extracted with DNA FlexiGene Kit. After sequencing, we showed that all samples extracted with the Maxwell 16 Instrument were false positive except one, which coincided with the only sample that showed variation in those extracted with the DNA FlexiGene Kit.

CONCLUSION

The method used to extract DNA is an important factor to consider in the analysis of melting curves obtained by high resolution melting, as it may influence the melting behaviour of the samples, giving false positive results in the detection of genetic variants.

Dietary polyunsaturated fatty acids may increase plasma LDL-cholesterol and plasma cholesterol concentrations in carriers of an ABCG1 gene single nucleotide polymorphism: study in two Spanish populations

BACKGROUND

ABCG1 mediates cellular cholesterol transport, but there is very little known about the influence of ABCG1 polymorphisms on human plasma lipoprotein cholesterol concentrations or on the interactions of these polymorphisms with diet.

OBJECTIVE

Our objective was to investigate whether interactions between PUFA intake and ABCG1 polymorphisms modulate associations with plasma total cholesterol (TC), LDL- and HDL-cholesterol in two Spanish populations.

METHODS

We grounded our investigation on two general population-based studies: the Hortega study (population A) and the Pizarra study (population B). Participants included 1178 individuals (50.0% women, age range 21-85 years) and 763 individuals (66% women, age range 23-73 years) from populations A and B, respectively, without lipid lowering drugs. Subjects were genotyped for ABCG1 variants. Biochemical measurements were taken by standard procedures. Dietary intakes were estimated with a validated questionnaire.

RESULTS

In population A, the A allele homozygotes of SNP rs4148102 had higher TC and LDLc concentrations in subjects on a high PUFA diet than did the carriers of the G allele (242.1 ± 38.9 vs. 198.0 ± 36.0mg/dL, p = 0.003, and 149.8 ± 37.9 vs. 111.4 ± 32.1mg/dL, p = 0.005, respectively), and significant gene-diet interactions were observed (p=0.020 and p = 0.013, respectively). In population B, similar differences in TC and LDLc concentrations were also found in association with this SNP under a high PUFA diet (253.2±24.9 vs. 197.7 ± 39.9 mg/dL, p = 0.009, and 171.8 ± 20.5 vs. 120.4 ± 34.2mg/dL, p = 0.004, respectively), but the gene-diet interactions observed were not significant (p = 0.379 and p = 0.422, respectively). In the pooled populations, differences in the TC and LDLc concentrations increased (246.8 ± 32.9 vs. 198.0 ± 37.5, p = 6 × 10(-5), and 159.0±32.6 vs. 114.3 ± 33.1, p = 3 × 10(-5), respectively), and significant gene-diet interactions were maintained (p = 0.006 and p = 0.003, respectively).

CONCLUSION

In two Spanish populations, the ABCG1 polymorphism rs4148102 was associated with variations in plasma lipoprotein cholesterol concentrations in subjects with high PUFA intakes. Carriers of the AA genotype consuming high PUFA diet showed higher plasma LDLc concentrations.

ELOVL6 genetic variation is related to insulin sensitivity: a new candidate gene in energy metabolism

Background

The elongase of long chain fatty acids family 6 (ELOVL6) is an enzyme that specifically catalyzes the elongation of saturated and monounsaturated fatty acids with 12, 14 and 16 carbons. ELOVL6 is expressed in lipogenic tissues and it is regulated by sterol regulatory element binding protein 1 (SREBP-1).

Objective

We investigated whether ELOVL6 genetic variation is associated with insulin sensitivity in a population from southern Spain.

Design

We undertook a prospective, population-based study collecting phenotypic, metabolic, nutritional and genetic information. Measurements were made of weight and height and the body mass index (BMI) was calculated. Insulin resistance was measured by homeostasis model assessment. The type of dietary fat was assessed from samples of cooking oil taken from the participants' kitchens and analyzed by gas chromatography. Five SNPs of the ELOVL6 gene were analyzed by SNPlex.

Results

Carriers of the minor alleles of the SNPs rs9997926 and rs6824447 had a lower risk of having high HOMA_IR, whereas carriers of the minor allele rs17041272 had a higher risk of being insulin resistant. An interaction was detected between the rs6824447 polymorphism and the intake of oil in relation with insulin resistance, such that carriers of this minor allele who consumed sunflower oil had lower HOMA_IR than those who did not have this allele (P = 0.001).

Conclusions

Genetic variations in the ELOVL6 gene were associated with insulin sensitivity in this population-based study.