Serum 25-Hydroxyvitamin D, Vitamin D Receptor, and Vitamin-D-Binding Protein Gene Polymorphisms and Risk of Dementia Among Older Adults With Prediabetes

BACKGROUND

The association between vitamin D and dementia risk in those with prediabetes remains uncertain. We aimed to evaluate the association of serum 25-hydroxyvitamin D (25OHD) with incident dementia among older adults with prediabetes, and examine whether apolipoprotein E (APOE) genotypes, vitamin D receptor (VDR), and vitamin-D-binding protein (VDBP) gene polymorphisms may modify this association.

METHODS

A total of 34 237 participants aged ≥60 with prediabetes (HbA1c <6.5% and ≥5.7%) and without dementia at baseline were included from the UK Biobank. Serum 25-hydroxyvitamin D (25OHD) was measured using chemiluminescent immunoassay method. The primary outcome was incident all-cause dementia. Secondary outcomes included incident Alzheimer's disease (AD) and vascular dementia, respectively. The VDR and VDBP gene polymorphisms included single nucleotide polymorphisms of rs7975232, rs1544410, rs2228570, rs731236, and rs7041, rs4588, respectively.

RESULTS

During a median follow-up of 11.8 years, 941 (2.7%) participants developed incident all-cause dementia. Overall, serum 25OHD was inversely associated with all-cause dementia (per standard deviation increment, adjusted hazard ratio: 0.82; 95% confidence interval: 0.75, 0.89). Similar trends were found for incident AD and vascular dementia. Furthermore, there was a stronger inverse relationship between serum 25OHD and all-cause dementia among VDR rs7975232 C allele noncarriers (p-interaction < 0.05). However, APOE Ɛ4, other VDR, and VDBP gene polymorphisms did not significantly modify the relation of serum 25OHD with incident all-cause dementia (all p-interactions >.05).

CONCLUSIONS

There was an inverse association between serum 25OHD and incident dementia among older adults with prediabetes, especially in VDR rs7975232 AA allele carriers.

The clinical relevance of a polygenic risk score for type 2 diabetes mellitus in the Korean population

The clinical utility of a type 2 diabetes mellitus (T2DM) polygenic risk score (PRS) in the East Asian population remains underexplored. We aimed to examine the potential prognostic value of a T2DM PRS and assess its viability as a clinical instrument. We first established a T2DM PRS for 5490 Korean individuals using East Asian Biobank data (269,487 samples). Subsequently, we assessed the predictive capability of this T2DM PRS in a prospective longitudinal study with baseline data and data from seven additional follow-ups. Our analysis showed that the T2DM PRS could predict the transition of glucose tolerance stages from normal glucose tolerance to prediabetes and from prediabetes to T2DM. Moreover, T2DM patients in the top-decile PRS group were more likely to be treated with insulin (hazard ratio = 1.69, p value = 2.31E-02) than were those in the remaining PRS groups. T2DM PRS values were significantly high in the severe diabetes subgroup, characterized by insulin resistance and β -cell dysfunction (p value = 0.0012). The prediction models with the T2DM PRS had significantly greater Harrel's C-indices than did corresponding models without it. By utilizing prospective longitudinal study data and extensive clinical risk factor information, our analysis provides valuable insights into the multifaceted clinical utility of the T2DM PRS.

Genome-wide association study of blood lipid levels in Southern Han Chinese adults with prediabetes

Background

Dyslipidemia is highly prevalent among individuals with prediabetes, further exacerbating their cardiovascular risk. However, the genetic determinants underlying diabetic dyslipidemia in Southern Han Chinese remain largely unexplored.

Methods

We performed a genome-wide association study (GWAS) of blood lipid traits in 451 Southern Han Chinese adults with prediabetes. Fasting plasma lipids, including triglycerides (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C) were assayed. Genotyping was conducted using the Precision Medicine Diversity Array and Gene Titan platform, followed by genotype imputation using IMPUTE2 with the 1000 Genomes Project (Phase 3, Southern Han Chinese) as reference. Single nucleotide polymorphisms (SNPs) associated with lipid levels were identified using mixed linear regression, with adjustment for covariates.

Results

We identified 58, 215, 74 and 81 novel SNPs associated with TG, TC, HDL-C and LDL-C levels, respectively (P < 5×10-5). Several implicated loci were located in or near genes involved in lipid metabolism, including SRD5A2, PCSK7, PITPNC1, IRX3, BPI, and LBP. Pathway enrichment analysis highlighted lipid metabolism and insulin secretion.

Conclusion

This first GWAS of dyslipidemia in Southern Han Chinese with prediabetes identified novel genetic variants associated with lipid traits. Our findings provide new insights into genetic mechanisms underlying heightened cardiovascular risk in the prediabetic stage. Functional characterization of implicated loci is warranted.

Single-Cell Transcriptome Profiling of Pancreatic Islets From Early Diabetic Mice Identifies Anxa10 for Ca2+ Allostasis Toward β-Cell Failure

Type 2 diabetes is a progressive disorder denoted by hyperglycemia and impaired insulin secretion. Although a decrease in β-cell function and mass is a well-known trigger for diabetes, the comprehensive mechanism is still unidentified. Here, we performed single-cell RNA sequencing of pancreatic islets from prediabetic and diabetic db/db mice, an animal model of type 2 diabetes. We discovered a diabetes-specific transcriptome landscape of endocrine and nonendocrine cell types with subpopulations of β- and α-cells. We recognized a new prediabetic gene, Anxa10, that was induced by and regulated Ca2+ influx from metabolic stresses. Anxa10-overexpressed β-cells displayed suppression of glucose-stimulated intracellular Ca2+ elevation and potassium-induced insulin secretion. Pseudotime analysis of β-cells predicted that this Ca2+-surge responder cluster would proceed to mitochondria dysfunction and endoplasmic reticulum stress. Other trajectories comprised dedifferentiation and transdifferentiation, emphasizing acinar-like cells in diabetic islets. Altogether, our data provide a new insight into Ca2+ allostasis and β-cell failure processes.

ARTICLE HIGHLIGHTS

The transcriptome of single-islet cells from healthy, prediabetic, and diabetic mice was studied. Distinct β-cell heterogeneity and islet cell-cell network in prediabetes and diabetes were found. A new prediabetic β-cell marker, Anxa10, regulates intracellular Ca2+ and insulin secretion. Diabetes triggers β-cell to acinar cell transdifferentiation.

A low-inflammatory diet is associated with a lower incidence of diabetes: role of diabetes-related genetic risk

BACKGROUND

Whether a low-inflammatory diet relates to type 2 diabetes risk remains unclear. We examined the association between a low-inflammatory diet and risk of type 2 diabetes among normoglycemic and prediabetic participants. We also explored whether a low-inflammatory diet modifies genetic risk for type 2 diabetes.

METHODS

Among 142,271 diabetes-free UK Biobank participants (aged 39-72 years), 126,203 were normoglycemic and 16,068 were prediabetic at baseline. Participants were followed for up to 15 years to detect incident type 2 diabetes. At baseline, dietary intake was assessed with a 24-h dietary record. An inflammatory diet index (IDI) was generated based on high-sensitivity C-reactive protein levels and was a weighted sum of 34 food groups (16 anti-inflammatory and 18 pro-inflammatory). Participants were grouped into tertiles corresponding to inflammatory level (low, moderate, and high) based on IDI scores. Prediabetes at baseline was defined as HbA1c 5.7-6.4% in diabetes-free participants. Incident type 2 diabetes and age of onset were ascertained according to the earliest recorded date of type 2 diabetes in the Primary Care and Hospital inpatient data. A diabetes-related genetic risk score (GRS) was calculated using 424 single-nucleotide polymorphisms. Data were analyzed using Cox regression and Laplace regression.

RESULTS

During follow-up (median 8.40 years, interquartile range 6.89 to 11.02 years), 3348 (2.4%) participants in the normoglycemia group and 2496 (15.5%) in the prediabetes group developed type 2 diabetes. Type 2 diabetes risk was lower in normoglycemic (hazard ratio [HR] = 0.71, 95% confidence interval [CI] 0.65, 0.78) and prediabetic (HR = 0.81, 95% CI 0.73, 0.89) participants with low IDI scores compared to those with high IDI scores. A low-inflammatory diet may prolong type 2 diabetes onset by 2.20 (95% CI 1.67, 2.72) years among participants with normoglycemia and 1.11 (95% CI 0.59, 1.63) years among participants with prediabetes. In joint effect analyses, normoglycemic or prediabetes participants with low genetic predisposition to type 2 diabetes and low IDI scores had a significant 74% (HR = 0.26, 95% CI 0.21, 0.32) or 51% (HR = 0.49, 95% CI 0.40, 0.59) reduction in type 2 diabetes risk compared to those with high genetic risk plus high IDI scores. There were significant additive and multiplicative interactions between IDI and GRS in relation to type 2 diabetes risk in the normoglycemia group.

CONCLUSIONS

A low-inflammatory diet is associated with a decreased risk of type 2 diabetes and may delay type 2 diabetes onset among participants with normal blood glucose or prediabetes. A low-inflammatory diet might significantly mitigate the risk of genetic factors on type 2 diabetes development.

Prediabetic HbA1c and Cortical Atrophy: Underlying Neurobiology

OBJECTIVE

To investigate the relationship between blood glycated hemoglobin (HbA1c) and cerebral cortical thickness (CT) and identify potential cellular mechanisms involved.

RESEARCH DESIGN AND METHODS

A cohort of 30,579 adults age 45 to 81 (mean ± SD: 64 ± 7.5) years with available data on brain MRI and blood HbA1c levels was analyzed. The relationship between HbA1c and CT was probed using independent spatial profiles of cell-specific gene expression. Lastly, a genome-wide association study was conducted on the shared variance between HbA1c and CT.

RESULTS

The HbA1c-CT association was noncontinuous, emerging negatively within the prediabetic range (39.6 mmol/mol). This association was strongest in brain regions with higher expression of genes specific to excitatory neurons and lower expression of genes specific to astrocytes and microglia. A significant locus implicated mitochondrial maintenance and ATP generation.

CONCLUSIONS

Effective glycemia control at prediabetic levels is warranted to preserve brain health and prevent prediabetes-related neurobiologic perturbations.

Rare Variant in Metallothionein 1E Increases the Risk of Type 2 Diabetes in a Chinese Population

OBJECTIVE

To uncover novel targets for the treatment of type 2 diabetes (T2D) by investigating rare variants with large effects in monogenic forms of the disease.

RESEARCH DESIGN AND METHODS

We performed whole-exome sequencing in a family with diabetes. We validated the identified gene using Sanger sequencing in additional families and diabetes- and community-based cohorts. Wild-type and variant gene transgenic mouse models were used to study the gene function.

RESULTS

Our analysis revealed a rare variant of the metallothionein 1E (MT1E) gene, p.C36Y, in a three-generation family with diabetes. This risk allele was associated with T2D or prediabetes in a community-based cohort. MT1E p.C36 carriers had higher HbA1c levels and greater BMI than those carrying the wild-type allele. Mice with forced expression of MT1E p.C36Y demonstrated increased weight gain, elevated postchallenge serum glucose and liver enzyme levels, and hepatic steatosis, similar to the phenotypes observed in human carriers of MT1E p.C36Y. In contrast, mice with forced expression of MT1E p.C36C displayed reduced weight and lower serum glucose and serum triglyceride levels. Forced expression of wild-type and variant MT1E demonstrated differential expression of genes related to lipid metabolism.

CONCLUSIONS

Our results suggest that MT1E could be a promising target for drug development, because forced expression of MT1E p.C36C stabilized glucose metabolism and reduced body weight, whereas MT1E p.C36Y expression had the opposite effect. These findings highlight the importance of considering the impact of rare variants in the development of new T2D treatments.

Identification of MicroRNAs Associated with Prediabetic Status in Obese Women

MicroRNAs (miRNAs) recently emerged as means of communication between insulin-sensitive tissues to mediate diabetes development and progression, and as such they present a valuable proxy for epigenetic alterations associated with type 2 diabetes. In order to identify miRNA markers for the precursor of diabetes called prediabetes, we applied a translational approach encompassing analysis of human plasma samples, mouse tissues and an in vitro validation system. MiR-652-3p, miR-877-5p, miR-93-5p, miR-130a-3p, miR-152-3p and let-7i-5p were increased in plasma of women with impaired fasting glucose levels (IFG) compared to those with normal fasting glucose and normal glucose tolerance (NGT). Among these, let-7i-5p and miR-93-5p correlated with fasting blood glucose levels. Human data were then compared to miRNome data obtained from islets of Langerhans and adipose tissue of 10-week-old female New Zealand Obese mice, which differ in their degree of hyperglycemia and liver fat content. Similar to human plasma, let-7i-5p was increased in adipose tissue and islets of Langerhans of diabetes-prone mice. As predicted by the in silico analysis, overexpression of let-7i-5p in the rat β-cell line INS-1 832/12 resulted in downregulation of insulin signaling pathway components (Insr, Rictor, Prkcb, Clock, Sos1 and Kcnma1). Taken together, our integrated approach highlighted let-7i-5p as a potential regulator of whole-body insulin sensitivity and a novel marker of prediabetes in women.

Cardiovascular and microvascular outcomes according to vitamin D level and genetic variants among individuals with prediabetes: a prospective study

BACKGROUND

Whether serum vitamin D mediate vascular diseases in prediabetic populations remains unclear. This study aimed to determine the associations between circulating 25-hydroxyvitamin D [25(OH)D] levels and vitamin D receptor (VDR) polymorphisms with the risk of macrovascular complications, including myocardial infarction and stroke, and microvascular complications such as diabetic nephropathy and retinopathy, among adults with prediabetes.

METHODS

Participants with prediabetes in UK Biobank were included (N = 56,387). Multivariable dose-response and Cox proportion models were used to explore the relationship of serum 25(OH)D status and the risks of vascular complications. The interaction of VDR polymorphisms with serum 25(OH)D level on risks of vascular events was also assessed.

RESULTS

During a median follow-up of 12 years, higher levels of 25(OH)D were significantly and nonlinearly associated with a lower risk of macrovascular diseases among prediabetic individuals. The adjusted hazard ratios (95% confidential interval) of serum 25(OH)D levels of ≥ 75.0 nmol/L versus < 25 nmol/L were 0.75 (0.63-0.88) for myocardial infarction, 0.74 (0.55-1.00) for stroke, 1.02 (0.60-1.74) for diabetic nephropathy, and 1.30 (0.92-1.84) for diabetic retinopathy, respectively. The rs2228570 (FokI) polymorphisms significantly interacted with 25(OH)D on incident myocardial infarction (P-interaction = 0.042) and stroke (P-interaction = 0.033). The individuals with serum 25(OH)D level of 50.0-74.9 nmol/L and rs2228570 (FokI) homozygotes had the lowest risks of vascular complications.

CONCLUSIONS

Lower serum 25(OH)D levels are significantly and nonlinearly associated with an increased risk of cardiocerebrovascular diseases in prediabetic individuals, with VDR polymorphisms of rs2228570 (FokI) modify such associations. Monitoring a safe 25(OH)D concentration is suggested to prevent the vascular complications for prediabetes.

The lncOb rs10487505 polymorphism impairs insulin sensitivity and glucose tolerance in children and adolescents with obesity

OBJECTIVE

Leptin plays a key role in the regulation of body weight and other endocrine systems. Recently, impairment of leptin gene transcription due to genetic variations in a long noncoding RNA (lncOb) has been described. This retrospective study aims to characterize the clinical and metabolic phenotype of children and adolescents with obesity who were homozygous for the lncOb rs10487505 leptin lowering allele.

METHODS

Enrolled children underwent an anthropometrical evaluation, biochemical assessment, and genotyping for lncOb rs10487505. Plasma leptin levels were assessed in 150 participants. A total of 434 patients were included and divided into two groups according to rs10487505 recessive inheritance (CC vs. GG/GC).

RESULTS

Children who were homozygous for the C allele showed higher fasting insulin (p = 0.01), homeostasis model assessment of insulin resistance (p = 0.01), lower whole-body insulin sensitivity index (p = 0.02), and lower disposition index (p = 0.03). Moreover, CC patients presented with a higher prevalence of prediabetes (9.3% vs. 3.4%, p = 0.04) and a 2.9-fold (95% CI: 1.1-7.9, p = 0.04) higher risk of prediabetes compared with G-carriers independently from confounders. Leptin plasma levels were significantly lower in the CC group (p = 0.002). Hormone levels correlated with BMI z score (r = 0.19, p = 0.04), fasting insulin (r = -0.34, p < 0.0001), homeostasis model assessment of insulin resistance (r = -0.33, p < 0.0001), and disposition index (r = 0.20, p = 0.04).

CONCLUSIONS

The lncOb rs10487505 polymorphism affects leptin circulating levels, worsens insulin resistance, and heightens the risk of prediabetes in children and adolescents with obesity.

Analysis of mRNA-miRNA-lncRNA differential expression in prediabetes/type 2 diabetes mellitus patients as potential players in insulin resistance

Introduction

Type 2 diabetes mellitus (T2DM) is a major global health concern. It usually develops gradually and is frequently preceded by undetectable pre-diabetes mellitus (pre-DM) stage. The purpose of this study was to identify a novel set of seven candidate genes associated with the pathogenesis of insulin resistance (IR) and pre-DM, followed by their experimental validation in patients' serum samples.

Methods

We used the bioinformatics tools and through a two-step process, we first identified and verified two mRNA candidate genes linked to insulin resistance molecular pathogenesis. Second, we identified a non-coding RNAs related to the selected mRNAs and implicated in the insulin resistance molecular pathways followed by pilot study for the RNA panel differential expression in 66 patients with T2DM, 49 individuals with prediabetes and 45 matched controls using real time PCR.

Results

The levels of expression of TMEM173 and CHUK mRNAs, hsa-miR (-611, -5192, and -1976) miRNAs gradually increased from the healthy control group to the prediabetic group, reaching their maximum levels in the T2DM group (p <10-3), whereas the levels of expression of RP4-605O3.4 and AC074117.2 lncRNAs declined gradually from the healthy control group to the prediabetic group, reaching their lowest levels in the T2DM group (p <10-3). TMEM173, CHUK mRNAs, hsa_miR (-611 & -1976) and RP4-605O3.4 lncRNA were useful in distinguishing insulin resistant from insulin sensitive groups. miR_611 together with RP4-605O3.4 exhibited significant difference in good versus poor glycemic control groups.

Discussion

The presented study provides an insight about this RNA based STING/NOD/IR associated panel that could be used for PreDM-T2DM diagnosis and also as a therapeutic target based on the differences of its expression level in the pre-DM and T2DM stages.

Salivary telomere length and the risks of prediabetes and diabetes among middle-aged and older adults: findings from the Health and Retirement Study

AIM

To assess the association of telomere length (TL) with prediabetes/diabetes and to explore the potential factors affecting TL among individuals with prediabetes/diabetes by weight status.

METHODS

This study included 3,379 eligible adults (aged 45-85 years, males: 42%) from the US Health and Retirement Study in 2008. TL was assayed using quantitative PCR of saliva (T/S ratio). Linear and nonlinear associations between TL and prediabetes/diabetes were assessed using the logistic regression and restricted cubic spline model, respectively, adjusting for TL-plate numbers, age, sex, race, body mass index, lifestyles, diabetes medications, and cardiometabolic parameters (blood pressure, C-reactive protein, and total cholesterol). Multiple linear regression was used for testing any factors associated with TL.

RESULTS

Among 3,379 participants, 868 (25.7%) had prediabetes with a mean TL of 1.34 ± 0.37 (T/S ratio) and 858 (25.4%) had diabetes with a mean TL of 1.36 ± 0.43 (T/S ratio). Neither linear nor nonlinear association of TL with prediabetes/diabetes was significant by weight status. Age was negatively associated with TL in both normal-weight (β = - 0.002, p = 0.025) and overweight/obese (β = - 0.002, p = 0.006) prediabetes, but non-significant in normal-weight and overweight/obese diabetes. BMI and cardiometabolic parameters were not associated with TL in prediabetes/diabetes by weight status.

CONCLUSIONS

Salivary TL was not associated with prediabetes/diabetes among the US middle-aged and older adults. Further longitudinal studies are required to establish the link between TL and diabetes development and to identify potential factors affecting TL shortening, particularly in normal-weight diabetic patients.

ABCA1 C69T Gene Polymorphism Association with Dysglycemia in Saudi Prediabetic Adults

Studies suggest that ATP-binding cassette transporter A1 (ABCA1 C69T) polymorphism is associated with a decreased incidence of type 2 diabetes mellitus (T2DM) and that there is an association between ABCA1 C69T polymorphism and the risk of dyslipidemia in diabetic individuals. However, other studies contradict these suggestions. Therefore, we aimed to investigate the prevalence of ABCA1 C69T (rs1800977) gene polymorphism in a representative sample of the Saudi population not previously diagnosed with diabetes and its possible association with dyslipidemia and dysglycemia. A cross-sectional design was used to recruit nondiabetic adults of both genders from the Saudi population in Jeddah by employing a stratified, two-stage cluster sampling method. A total of 650 people (337 men and 313 women) were recruited. Demographic, dietary, and lifestyle variables, as well as medical history and family history of chronic diseases, were collected using a predesigned questionnaire. Fasting blood samples were taken for the determination of fasting plasma glucose (FPG), glycated hemoglobin (HbA1c), and lipids profile, which were followed by a 1-h oral glucose tolerance test (OGTT). Real-time PCR technology was used to determine the ABCA1 C69T gene SNP (rs1800977). The T allele of ABCA1 C69T (rs1800977) was very frequent (TT in 44.9% and CT in 43.7%). There was a trend toward significance for a higher dysglycemia percentage in people with CT and TT genotypes (25.7%, and 23.3%, respectively) compared with CC genotypes (16.2%). In addition, FPG and 1-h plasma glucose were significantly higher in people with both TT and CT genotypes compared to CC genotypes. However, T allele was not associated with any dysregulation of lipid parameters.

Can miR-145-5p be used as a marker in diabetic patients?

In the light of emerging global epidemics of type 2 diabetes mellitus significant efforts are continuing to discover novel biomarkers for early detection of the disease. Since miRNAs play an important role in both the initiation and progress of many pathologic processes such as diabetes, in this study we aimed to evaluate expression level of plasma miR-145-5p in diabetics and pre-diabetics in comparison to the control group and assess its use as a biomarker in diagnosis of T2D. The plasma level of miR-145-5p was assessed in three groups including 20 prediabetic patients, 20 T2D patients and 20 healthy controls using RT-qPCR. Biochemical parameters were also measured by the auto-analyzer. Expression level of miR-145-5p was down-regulated in the prediabetics and the T2D patients compared to the controls. In the control group miR-145-5p showed a borderline correlation with FBS (p = .06), while in the prediabetic group miR-145 showed a significant negative correlation with FBS and finally in the T2D patients miR-145 was negatively correlated with HbA1c and TC and showed a negative borderline correlation with FBS. The ROC analysis indicated a significant ability for miR-145-5p in discriminating between the diabetics and pre-diabetics from the healthy subjects. Our results demonstrated that the miR-145-5p expression level is deregulated in the diabetics and the prediabetics. Furthermore miR-145-5p displayed a significant ability to discriminate the diabetics from the healthy subjects. These results suggest that miR-145-5p may be a useful biomarker for the diagnosis of T2DM.

Alterations in Microbiota and Metabolites Related to Spontaneous Diabetes and Pre-Diabetes in Rhesus Macaques

Spontaneous type 2 diabetes mellitus (T2DM) macaques are valuable resources for our understanding the pathological mechanism of T2DM. Based on one month’s fasting blood glucose survey, we identified seven spontaneous T2DM macaques and five impaired glucose regulation (IGR) macaques from 1408 captive individuals. FPG, HbA1c, FPI and IR values were significant higher in T2DM and IGR than in controls. 16S rRNA sequencing of fecal microbes showed the significantly greater abundance of Oribacterium, bacteria inhibiting the production of secondary bile acids, and Phascolarctobacterium, bacteria producing short-chain fatty acids was significantly lower in T2DM macaques. In addition, several opportunistic pathogens, such as Mogibacterium and Kocuria were significantly more abundant in both T2DM and IGR macaques. Fecal metabolites analysis based on UHPLC-MS identified 50 differential metabolites (DMs) between T2DM and controls, and 26 DMs between IGR and controls. The DMs were significantly enriched in the bile acids metabolism, fatty acids metabolism and amino acids metabolism pathways. Combining results from physiochemical parameters, microbiota and metabolomics, we demonstrate that the imbalance of gut microbial community leading to the dysfunction of glucose, bile acids, fatty acids and amino acids metabolism may contribute to the hyperglycaemia in macaques, and suggest several microbes and metabolites are potential biomarkers for T2DM and IGR macaques.

Circulating miR-148b-3p and miR-27a-3p can be potential biomarkers for diagnosis of pre-diabetes and type 2 diabetes: integrating experimental and in-silico approaches

BACKGROUND

In view of the growing global prevalence of type 2 diabetes (T2D), detection of prediabetes and type 2 diabetes in the early stages is necessary to reduce the risk of developing diabetes, prevent the progression of the disease, and dysfunction of different organs. Since miRNAs are involved in the initiation and progression of numerous pathogenic processes, including diabetes, in the present study, we aimed to investigate the expression of miR-148b-3p and miR-27a-3p in prediabetic and T2D patients and to evaluate the diagnostic potential of these miRNAs.

METHODS

We evaluated the expression of miR-148b-3p and miR-27a-3p in the plasma of three groups: 20 prediabetic patients, 20 T2D patients, and 20 healthy controls. The biochemical parameters were determined by the auto-analyzer. The possible target genes of these miRNAs were identified using an in-silico approach.

RESULTS

Our results showed that, as compared to the healthy controls, there was a significant up regulation and down regulation in the expression of miR-148b-3p and miR-27a-3p in the T2D patients, respectively. The results of receiver operating characteristic curve analysis also suggested that miR-148b-3p acted successfully in discriminating the prediabetic and diabetic patients from the control group. According to in-silico analysis, miRs influence biological pathways involved in T2DM development, such as insulin signaling.

CONCLUSIONS

The miR148b-3p and miR-27a-3p expression levels were deregulated in diabetes and pre-diabetes. Furthermore, miR-148b-3p showed significant ability in discriminating between diabetic and healthy individuals, suggesting a potential diagnostic use of miR-148b-3p in the detection of T2D.

[Mechanism of Huangjing Qianshi Decoction in treatment of prediabetes based on network pharmacology and molecular docking]

This study analyzed the molecular mechanism of Huangjing Qianshi Decoction(HQD) in the treatment of prediabetes based on network pharmacology and molecular docking. The active components of HQD were identified and screened based on Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform(TCMSP, http://Lsp.nwu.edu.cn/tcmsp.php) and then the targets of the components and the genes related to prediabetes were retrieved, followed by identifying the common targets of the decoction and the disease. The medicinal component-target network was constructed by Cytoscape to screen key components. The protein-protein interaction(PPI) network was established by STRING and hub genes were identified by Cytoscape-CytoNCA, followed by Gene Ontology(GO) term enrichment and Kyoto Encyclopedia of Genes and Genomes(KEGG) of the hub genes with R-clusterProfi-ler. Thereby, the possible signaling pathways were predicted and the molecular mechanism was deduced. A total of 79 active components of HQD and 785 diabetes-related targets of the components were screened out. The hub genes mainly involved the GO terms of tricarboxylic acid cycle, peptide binding, amide binding, hydrolase activity, and kinase activity regulation, and the KEGG pathways of AGE-RAGE signaling pathway, TNF signaling pathway, AMPK signaling pathway, IL-17 signaling pathway, and insulin signaling pathway. Western blot result showed that HQD-containing serum significantly reduced the expression of AKT1, AGE, and RAGE proteins in insulin resistance model cells. HQD's treatment of prediabetes is characterized by multiple pathways, multiple targets, and multiple levels. The main mechanism is that the components zhonghualiaoine, baicalein, kaempferol, and luteolin act on AKT1 and inhibit the AGE-RAGE axis.

Genetic Variants Relate to Fasting Plasma Glucose, 2-Hour Postprandial Glucose, Glycosylated Hemoglobin, and BMI in Prediabetes

Diabetes mellitus (DM) is a chronic disease that seriously threatens human health. Prediabetes is a stage in the progression of DM. The level of clinical indicators including fasting plasma glucose (FPG), 2-h postprandial glucose (2hPG), and glycosylated hemoglobin (HbA1C) are the diagnostic markers of diabetes. In this genome-wide association study (GWAS), we aimed to investigate the association of genetic variants with these phenotypes in Hainan prediabetes. In this study, we recruited 451 prediabetes patients from the residents aged ≥18 years who participated in the National Diabetes Prevalence Survey of the Chinese Medical Association in 2017. The GWAS of FPG, 2hPG, HbA1C, and body mass index (BMI) in prediabetes was analyzed with a linear model using an additive genetic model with adjustment for age and sex. We identified that rs13052524 in MRPS6 and rs62212118 in SLC5A3 were associated with 2hPG in Hainan prediabetes (p = 4.35 × 10^-6, p = 4.05 × 10^-6, respectively). Another six variants in the four genes (LINC01648, MATN1, CRAT37, and SLCO3A1) were related to HbA1C. Moreover, rs11142842, rs1891298, rs1891299, and rs11142843 in TRPM3/TMEM2 and rs78432036 in MLYCD/OSGIN1 were correlated to BMI (all p < 5 × 10^-6). This study is the first to determine the genome-wide association of FPG, 2hPG, and HbA1C, which emphasizes the importance of in-depth understanding of the phenotypes of high-value susceptibility gene markers in the diagnosis of prediabetes.

14-weeks combined exercise epigenetically modulated 118 genes of menopausal women with prediabetes

BACKGROUND

Pre-diabetes precedes Diabetes Mellitus (DM) disease and is a critical period for hyperglycemia treatment, especially for menopausal women, considering all metabolic alterations due to hormonal changes. Recently, the literature has demonstrated the role of physical exercise in epigenetic reprogramming to modulate the gene expression patterns of metabolic conditions, such as hyperglycemia, and prevent DM development. In the present study, we hypothesized that physical exercise training could modify the epigenetic patterns of women with poor glycemic control.

METHODS

48 post-menopause women aged 60.3 ± 4.5 years were divided according to their fasting blood glucose levels into two groups: Prediabetes Group, PG (n=24), and Normal Glucose Group, NGG (n=24). All participants performed 14 weeks of physical exercise three times a week. The Infinium Methylation EPIC BeadChip measured the participants' Different Methylated Regions (DMRs).

RESULTS

Before the intervention, the PG group had 12 DMRs compared to NGG. After the intervention, five DMRs remained different. Interestingly, when comparing the PG group before and after training, 118 DMRs were found. The enrichment analysis revealed that the genes were related to different biological functions such as energy metabolism, cell differentiation, and tumor suppression.

CONCLUSION

Physical exercise is a relevant alternative in treating hyperglycemia and preventing DM in post-menopause women with poor glycemic control.

Plasma miR-21 as a potential predictor in prediabetic individuals with a positive family history of type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is a heritable metabolic perturbation, rapidly growing across the world. Primary recognition of susceptible individuals with a family history of type 2 diabetes (FHD) in the prediabetes stage could delay the onset of T2DM or reduce complications induced by diabetes. This study aims to evaluate the expression levels of miR-21, miR-126 as noninvasive predictive biomarkers in individuals with genetic predisposition and investigate the correlation of miRNAs and cardiometabolic risk factors. Our study demonstrated that miR-21 expression has a notable elevate in both groups of T2DM and pre-T2DM. miR-21 expression was distinguished in the pre-T2DM and T2DM from the nondiabetic individuals by ROC curve analysis with AUC of 0.77 (95% CI 0.65-0.90; p = 0.0004) and AUC of 0.78 (95% CI 0.64-0.92; p = 0.0042), respectively. The relative gene expression of miR-126 was nearly equal among groups. miR-21 expression was positively associated with glycosylated hemoglobin (HbA1c), fasting blood sugar (FBS), and triglyceride (TG) and might have diagnostic value for T2DM and pre-T2DM. This study has revealed that the expression level of miR-21 can be considered as a non-invasive and rapid tool for distinguishing pre-T2DM and T2DM counterparts from healthy individuals.

TCF7L2 gene associated postprandial triglyceride dysmetabolism- a novel mechanism for diabetes risk among Asian Indians

AIM

TCF7L2 gene is believed to increase the risk of T2DM by its effects on insulin secretion. However, the exact mechanism of this enhanced risk is not clearly known. While TCF7L2 gene has been shown to affect lipid metabolism, these effects have remained largely unexplored in the context of diabetes risk.

METHODS

Postprandial lipid responses to a standardized fat challenge test were performed in 620 Asian Indian subjects (310 with NGT and 310 with T2DM/prediabetes) and compared between the risk and wild genotypes of the rs7903146 TCF7L2 gene. In 30 subjects scheduled to undergo abdominal surgery (10 each with NGT, Prediabetes and T2DM), adipocyte TCF7L2 gene expression was also performed by real time qPCR and confirmed by protein expression in western blot.

RESULTS

T allele of rs7903146 TCF7L2 gene was confirmed as the risk allele for T2DM (OR=1.8(1.2-2.74), p=0.005). TT+CT genotypes of rs7903146 TCF7L2 gene showed significantly higher 4hrTg (p<0.01), TgAUC (p<0.01), peakTg (p<0.01) as well as higher postprandial plasma glucose (p=.006) levels and HOMA-IR (p=0.03) and significantly lower adiponectin levels (p=0.02) as compared to CC genotype. The expression of TCF7L2 gene in VAT was 11-fold higher in prediabetes group as compared to NGT (P<0.01) and 5.7-fold higher in T2DM group as compared to NGT group(P=0.003) and was significantly associated with PPTg and glucose levels.

CONCLUSION

There is significant PPTg dysmetabolism associated with the risk allele of rs7903146 polymorphism as well as adipocyte expression of TCF7L2 gene. Significant upregulation of TCF7L2 gene expression in VAT that correlates with PPTg and glycaemia is also seen in Asian Indians with glucose intolerance. Modulation of PPTg metabolism by TCF7L2 gene and the resultant PPHTg may be a novel mechanism that contributes to its diabetes risk in them.

A Genome-Wide Association Study of Prediabetes Status Change

We conducted the first genome-wide association study of prediabetes status change (to diabetes or normal glycaemia) among 900 White participants of the Atherosclerosis Risk in Communities (ARIC) study. Single nucleotide polymorphism (SNP)-based analysis was performed by logistic regression models, controlling for age, gender, body mass index, and the first 3 genetic principal components. Gene-based analysis was conducted by combining SNP-based p values using effective Chi-square test method. Promising SNPs (p < 1×10-5) and genes (p < 1×10-4) were further evaluated for replication among 514 White participants of the Framingham Heart Study (FHS). To accommodate familial correlations, generalized estimation equation models were applied for SNP-based analyses in the FHS. Analysis results across ARIC and FHS were combined using inverse-variance-weighted meta-analysis method for SNPs and Fisher's method for genes. We robustly identified 5 novel genes that are associated with prediabetes status change using gene-based analyses, including SGCZ (ARIC p = 9.93×10-6, FHS p = 2.00×10-3, Meta p = 3.72×10-7) at 8p22, HPSE2 (ARIC p = 8.26×10-19, FHS p = 5.85×10-3, Meta p < 8.26×10-19) at 10q24.2, ADGRA1 (ARIC p = 1.34×10-5, FHS p = 1.13×10-3, Meta p = 2.88×10-7) at 10q26.3, GLB1L3 (ARIC p = 3.71×10-6, FHS p = 4.51×10-3, Meta p = 3.16×10-7) at 11q25, and PCSK6 (ARIC p = 6.51×10-6, FHS p = 1.10×10-2, Meta p = 1.25×10-6) at 15q26.3. eQTL analysis indicated that these genes were highly expressed in tissues related to diabetes development. However, we were not able to identify any novel locus in single SNP-based analysis. Future large scale genomic studies of prediabetes status change are warranted.

Redefining the Role of ADAM17 in Renal Proximal Tubular Cells and Its Implications in an Obese Mouse Model of Pre-Diabetes

Acute and chronic kidney lesions induce an increase in A Disintegrin And Metalloproteinase domain 17 (ADAM17) that cleaves several transmembrane proteins related to inflammatory and fibrotic pathways. Our group has demonstrated that renal ADAM17 is upregulated in diabetic mice and its inhibition decreases renal inflammation and fibrosis. The purpose of the present study was to analyze how Adam17 deletion in proximal tubules affects different renal structures in an obese mice model. Tubular Adam17 knockout male mice and their controls were fed a high-fat diet (HFD) for 22 weeks. Glucose tolerance, urinary albumin-to-creatinine ratio, renal histology, and pro-inflammatory and pro-fibrotic markers were evaluated. Results showed that wild-type mice fed an HFD became obese with glucose intolerance and renal histological alterations mimicking a pre-diabetic condition; consequently, greater glomerular size and mesangial expansion were observed. Adam17 tubular deletion improved glucose tolerance and protected animals against glomerular injury and prevented podocyte loss in HFD mice. In addition, HFD mice showed more glomerular macrophages and collagen accumulation, which was prevented by Adam17 deletion. Galectin-3 expression increased in the proximal tubules and glomeruli of HFD mice and ameliorated with Adam17 deletion. In conclusion, Adam17 in proximal tubules influences glucose tolerance and participates in the kidney injury in an obese pre-diabetic murine model. The role of ADAM17 in the tubule impacts on glomerular inflammation and fibrosis.

Syntaxin 4 Enrichment in β-Cells Prevents Conversion to Autoimmune Diabetes in Non-Obese Diabetic (NOD) Mice

Syntaxin 4 (STX4), a plasma membrane-localized SNARE protein, regulates human islet β-cell insulin secretion and preservation of β-cell mass. We found that human type 1 diabetes (T1D) and NOD mouse islets show reduced β-cell STX4 expression, consistent with decreased STX4 expression, as a potential driver of T1D phenotypes. To test this hypothesis, we generated inducible β-cell-specific STX4-expressing NOD mice (NOD-iβSTX4). Of NOD-iβSTX4 mice, 73% had sustained normoglycemia vs. <20% of control NOD (NOD-Ctrl) mice by 25 weeks of age. At 12 weeks of age, before diabetes conversion, NOD-iβSTX4 mice demonstrated superior whole-body glucose tolerance and β-cell glucose responsiveness than NOD-Ctrl mice. Higher β-cell mass and reduced β-cell apoptosis were also detected in NOD-iβSTX4 pancreata compared with pancreata of NOD-Ctrl mice. Single-cell RNA sequencing revealed that islets from NOD-iβSTX4 had markedly reduced interferon-γ signaling and tumor necrosis factor-α signaling via nuclear factor-κB in islet β-cells, including reduced expression of the chemokine CCL5; CD4⁺ regulatory T cells were also enriched in NOD-iβSTX4 islets. These results provide a deeper mechanistic understanding of STX4 function in β-cell protection and warrant further investigation of STX4 enrichment as a strategy to reverse or prevent T1D in humans or protect β-cell grafts.

Mitochondrial genome-wide analysis of nuclear DNA methylation quantitative trait loci

Mitochondria have a complex communication network with the surrounding cell and can alter nuclear DNA methylation (DNAm). Variation in the mitochondrial DNA (mtDNA) has also been linked to differential DNAm. Genome-wide association studies have identified numerous DNAm quantitative trait loci, but these studies have not examined the mitochondrial genome. Herein, we quantified nuclear DNAm from blood and conducted a mitochondrial genome-wide association study of DNAm, with an additional emphasis on sex- and prediabetes-specific heterogeneity. We used the Young Finns Study (n = 926) with sequenced mtDNA genotypes as a discovery sample and sought replication in the Ludwigshafen Risk and Cardiovascular Health study (n = 2317). We identified numerous significant associations in the discovery phase (P &lt; 10−9), but they were not replicated when accounting for multiple testing. In total, 27 associations were nominally replicated with a P &lt; 0.05. The replication analysis presented no evidence of sex- or prediabetes-specific heterogeneity. The 27 associations were included in a joint meta-analysis of the two cohorts, and 19 DNAm sites associated with mtDNA variants, while four other sites showed haplogroup associations. An expression quantitative trait methylation analysis was performed for the identified DNAm sites, pinpointing two statistically significant associations. This study provides evidence of a mitochondrial genetic control of nuclear DNAm with little evidence found for sex- and prediabetes-specific effects. The lack of a comparable mtDNA data set for replication is a limitation in our study and further studies are needed to validate our results.

MicroRNAs modulation and clinical outcomes at 1 year of follow-up in obese patients with pre-diabetes treated with metformin vs. placebo

BACKGROUNDS

Obese pre-diabetics over express cytokines that influence myocardial function via microRNAs (miRs) expression.

OBJECTIVES

To evaluate inflammatory/oxidative stress, miRs' expression and cardiovascular function in obese pre-diabetics assigned to metformin therapy vs. placebo vs. normo-glycemics at 12 months of follow-up.

MATERIALS AND METHODS

Eighty-three obese patients after abdominoplastic surgery were divided in pre-diabetics (n 55), normo-glycemics (n 28), and assigned to hypocaloric diet. Pre-diabetics were assigned to metformin (n 23) or to placebo (n 22) plus hypocaloric diet.

RESULTS

Obese pre-diabetics in metformin vs. placebo, and obese pre-diabetics with placebo vs. normoglycemics, had significant differences about IMT, MPI, and LVM (p < 0.05). Obese pre-diabetics in metformin vs. placebo showed significant reduction in serum miR-195 and miR-27 (p < 0.05). Obese pre-diabetics in metformin vs. normoglycemics showed higher expression of serum miR-195 and miR-27 (p < 0.05). Finally, we found inverse relation between IMT and insulin, HOMA-IR, miR-195, miR-27; between LVEF and Insulin, HOMA-IR, miR-195 and miR-27. We found inverse correlation between LVM and sirtuin-1, Insulin, HOMA-IR, miR-195 and miR-27, and direct correlation with interleukin-6. MPI inversely linked to miR-195 and miR-27.

CONCLUSIONS

In obese pre-diabetics', metformin significantly reduces inflammation/oxidative stress, and miR-195 and miR-27, with reduction in LVM, IMT.

Insulin immunotherapy for pretype 1 diabetes

PURPOSE OF REVIEW

Loss of tolerance to insulin likely contributes to the immunopathogenesis of type 1 diabetes (T1D). Several large clinical trials and smaller mechanistic studies have failed to demonstrate the efficacy of insulin antigen therapy. The growing awareness of the heterogeneity of T1D likely affects the response to various immune therapies including insulin. Identification of biomarkers of clinical response will provide further insight into mechanisms leading to the disease and classify responders in the quest for personalized therapy.

RECENT FINDINGS

Several biomarkers have identified subpopulations in posthoc analyses that showed benefit from oral insulin even though the placebo-controlled study was as a whole unsuccessful. High insulin autoantibody titer, low first phase insulin response, and high Diabetes Prevention Trial-Type 1 Risk Score identify at-risk relatives more likely to benefit from oral insulin. Future incorporation of human leukocyte antigen and the variable number of tandem repeats polymorphism located in the insulin gene promoter (INS VNTR) is of interest for both primary and secondary prevention studies.

SUMMARY

Although primary and secondary prevention trials using oral insulin are ongoing, those completed have been largely unsuccessful. However, we believe that oral insulin should be considered in future trials as part of combination therapies as prerandomization biomarker testing is refined.

Serum microRNA-33 levels in pre-diabetic and diabetic patients

Diabetes mellitus (DM) is a metabolic disease characterized by hyperglycemia and abnormal insulin secretion. MicroRNAs are small, non-coding RNAs that are able to affect cell biological functions and act as biomarkers for some diseases such as DM. In current study, we measured serum miR-33 in three groups (n = 15) as follows; non-diabetic control, pre-diabetic, and DM patients. Real-time PCR method was used to quantify miR-33 expression. miR-33 expression was significantly increased in pre-diabetic subjects compared to other two groups (p < 0.001). FBS (p < 0.001), insulin (p < 0.001), HOMA-IR (p < 0.001), and TG (p = 0.026) were higher in diabetic subjects than the other two groups. In people that had high physical activity, the number of diabetic subjects were zero and most of them were in pre-diabetic group (p = 0.019). Serum miR-33 level significantly and positively correlated with pre-diabetic state (B = 2.67, p = 0.000), Sex (B = 1.03, p = 0.025), and FBS (B = 0.04, p = 0.036) and also miR-33 was significantly and negatively correlated with HOMA-IR (B = - 1.58, p = 0.04). These findings support the possible role of miR-33 to monitor pre-diabetes onset and progression. It needs to be evaluated in future studies with high number of participants to clarify its mechanism and diagnostic viability.

The Mechanisms of the Development of Atherosclerosis in Prediabetes

Lifestyle changes, such as overeating and underexercising, can increase the risk of prediabetes. Diabetes is one of the leading causes of atherosclerosis, and recently it became clear that the pathophysiology of atherosclerosis progresses even before the onset of diabetic symptoms. In addition to changes in platelets and leukocytes in the hyperglycemic state and damage to vascular endothelial cells, extracellular vesicles and microRNAs were found to be involved in the progression of prediabetes atherosclerosis. This review discusses the cellular and molecular mechanisms of these processes, with an intention to enable a comprehensive understanding of the pathophysiology of prediabetes and atherosclerosis.

Low-Frequency Genetic Variant in the Hepatic Glucokinase Gene Is Associated With Type 2 Diabetes and Insulin Resistance in Chinese Population

Glucokinase (GCK) regulates insulin secretion and hepatic glucose metabolism, and its inactivating variants could cause diabetes. We aimed to evaluate the association of a low-frequency variant of GCK (rs13306393) with type 2 diabetes (T2D), prediabetes, or both (impaired glucose regulation [IGR]) in a Chinese population. An association study was first conducted in a random cluster sampling population (sample 1: 537 T2D, 768 prediabetes, and 1,912 control), and then another independent population (sample 2: 3,896 T2D, 2,301 prediabetes, and 868 control) was used to confirm the findings in sample 1. The A allele of rs13306393 was associated with T2D (odds ratio 3.08 [95% CI 1.77-5.36], P = 0.00007) in sample 1; rs13306393 was also associated with prediabetes (1.67 [1.05-2.65], P = 0.03) in sample 2. In a pooled analysis of the two samples, the A allele increased the risk of T2D (1.57 [1.15-2.15], P = 0.005), prediabetes (1.83 [1.33-2.54], P = 0.0003) or IGR (1.68 [1.26-2.25], P = 0.0004), insulin resistance estimated by HOMA (β = 0.043, P = 0.001), HbA_1c (β = 0.029, P = 0.029), and urinary albumin excretion (β = 0.033, P = 0.025), irrespective of age, sex, and BMI. Thus, the Chinese-specific low-frequency variant increased the risk of T2D through reducing insulin sensitivity rather than islet β-cell function, which should be considered in the clinical use of GCK activators in the future.

Incidence of diabetes mellitus and associated risk factors in the adult population of the Basque country, Spain

The aim of this study was to estimate the incidence of diabetes mellitus in the Basque Country and the risk factors involved in the disease by reassessing an adult population after 7 years of follow-up. In the previous prevalence study, 847 people older than 18 years were randomly selected from all over the Basque Country and were invited to answer a medical questionnaire, followed by a physical examination and an oral glucose tolerance test. In the reassessment, the same variables were collected and the resulting cohort comprised 517 individuals of whom 43 had diabetes at baseline. The cumulative incidence of diabetes was 4.64% in 7 years and the raw incidence rate was 6.56 cases/1000 person-years (95%CI: 4.11-9.93). Among the incident cases, 59% were undiagnosed. The most strongly associated markers by univariate analyses were age > 60 years, dyslipidaemia, prediabetes and insulin resistance. We also found association with hypertension, obesity, family history of diabetes and low education level. Multivariate analysis adjusted for age and sex showed that a set of risk factors assessed together (dyslipidaemia, waist-to-hip-ratio and family history of diabetes) had great predictive value (AUC-ROC = 0.899, 95%CI: 0.846-0.953, p = 0.942), which suggests the need for early intervention before the onset of prediabetes.

Identification of Key LncRNAs and Pathways in Prediabetes and Type 2 Diabetes Mellitus for Hypertriglyceridemia Patients Based on Weighted Gene Co-Expression Network Analysis

AIMS

Prevalence of prediabetes and type 2 diabetes mellitus(T2DM) are increasing worldwide. Key lncRNAs were detected to provide a reference for searching potential biomarkers of prediabetes and T2DM in hypertriglyceridemia patients.

METHODS

The study included 18 hypertriglyceridemia patients: 6 newly diagnosed type 2 diabetes patients, 6 samples with prediabetes and 6 samples with normal blood glucose. Weighted gene co-expression network analysis (WGCNA) was conducted to construct co-expression network and obtain modules related to blood glucose, thus detecting key lncRNAs.

RESULTS

The green, yellow and yellow module was significantly related to blood glucose in T2DM versus normal controls, T2DM versus prediabetes, prediabetes versus normal controls, respectively. ENST00000503273, ENST00000462720, ENST00000480633 and ENST00000485392 were detected as key lncRNAs for the above three groups, respectively.

CONCLUSIONS

For hypertriglyceridemia patients with different blood glucose levels, ENST00000503273, ENST00000462720 and ENST00000480633 could be potential biomarkers of T2DM.

Genome-Wide Association Analysis of Pancreatic Beta-Cell Glucose Sensitivity

CONTEXT

Pancreatic beta-cell glucose sensitivity is the slope of the plasma glucose-insulin secretion relationship and is a key predictor of deteriorating glucose tolerance and development of type 2 diabetes. However, there are no large-scale studies looking at the genetic determinants of beta-cell glucose sensitivity.

OBJECTIVE

To understand the genetic determinants of pancreatic beta-cell glucose sensitivity using genome-wide meta-analysis and candidate gene studies.

DESIGN

We performed a genome-wide meta-analysis for beta-cell glucose sensitivity in subjects with type 2 diabetes and nondiabetic subjects from 6 independent cohorts (n = 5706). Beta-cell glucose sensitivity was calculated from mixed meal and oral glucose tolerance tests, and its associations between known glycemia-related single nucleotide polymorphisms (SNPs) and genome-wide association study (GWAS) SNPs were estimated using linear regression models.

RESULTS

Beta-cell glucose sensitivity was moderately heritable (h2 ranged from 34% to 55%) using SNP and family-based analyses. GWAS meta-analysis identified multiple correlated SNPs in the CDKAL1 gene and GIPR-QPCTL gene loci that reached genome-wide significance, with SNP rs2238691 in GIPR-QPCTL (P value = 2.64 × 10-9) and rs9368219 in the CDKAL1 (P value = 3.15 × 10-9) showing the strongest association with beta-cell glucose sensitivity. These loci surpassed genome-wide significance when the GWAS meta-analysis was repeated after exclusion of the diabetic subjects. After correction for multiple testing, glycemia-associated SNPs in or near the HHEX and IGF2B2 loci were also associated with beta-cell glucose sensitivity.

CONCLUSION

We show that, variation at the GIPR-QPCTL and CDKAL1 loci are key determinants of pancreatic beta-cell glucose sensitivity.

hsa_circ_0111707 Is Associated With Risk of Stress-Related Type 2 Diabetes via Sponging miR-144-3p

INTRODUCTION

Chronic stress plays an important role in the development of type 2 diabetes (T2D). Circular RNAs (circRNAs) play significant roles in regulating the pathogenesis of diseases by regulating gene expression. The aim of the present study was to identify the association between hsa_circ_0111707 and stress-related T2D.

METHODS

The present study was performed based on a three-part design. The association between hsa_circ_0111707 in peripheral blood mononuclear cells (PBMCs) and T2D and stress-related variables were assessed in a cross-sectional study. The causal relationship of hsa_circ_0111707 on T2D was further investigated in a nested case-control study. miR-144-3p as the miRNA target of hsa_circ_0111707 was verified by dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay.

RESULTS

The relative expression of hsa_circ_0111707 was significantly lower in the T2D and impaired fasting glucose (IFG) cases in comparison with controls. The hsa_circ_0111707 expression was significantly negatively correlated with miR-144-3p expression and plasma cortisol concentration and positively correlated with NR3C1 expression. In addition, hsa_circ_0111707 expression was negatively correlated with scores of "demands at work" and "insecurity at work" of Copenhagen Psychosocial Questionnaire (COPSOQ). Decreased hsa_circ_0111707 expression was associated with increased risk of T2D development. Functional analysis demonstrated that hsa_circ_0111707 functions as a sponge for miR-144-3p.

CONCLUSION

hsa_circ_0111707 is associated with risk of T2D development via sponging miR-144-3p. hsa_circ_0111707 in PBMCs can be considered a potential biomarker of stress-related T2D.

Integrative transcriptomic analysis of pancreatic islets from patients with prediabetes/type 2 diabetes

AIM

To identify new transcriptomic alterations in pancreatic islets associated with metabolic dysfunctions in people with prediabetes (PD)/type 2 diabetes (T2D).

MATERIALS AND METHODS

We collected information from public data repositories T2D related microarray datasets from pancreatic islets. We identified Differential Expressed Genes (DEGs) in non-diabetic (ND) vs people with T2D in each study. To identify relevant DEGs in T2D, we selected those that varied consistently in the different studies for further meta-analysis and functional enrichment analysis. DEGs were also evaluated at the PD stage.

RESULTS

A total of seven microarray datasets were collected and analysed to find the DEGs in each study and meta-analysis was performed with 245 ND and 96 T2D cases. We identified 55 transcriptional alterations potentially associated with specific metabolic dysfunctions in T2D. Meta-analysis showed that 87% of transcripts identified as DEGs (48 out of 55) were confirmed as having statistically significant up- or down-modulation in T2D compared to ND. Notably, nine of these DEGs have not been previously reported as dysregulated in pancreatic islets from people with T2D. Consistently, the most significantly enriched pathways were related to the metabolism and/or development/maintenance of β-cells. Eighteen of the 48 selected DEGs (38%) showed an altered expression in islets from people with PD.

CONCLUSIONS

These results provide new evidence to interpret the pathogenesis of T2D and the transition from PD to T2D. Further studies are necessary to validate its potential use for the development/implementation of efficient new strategies for the prevention, diagnosis/prognosis and treatment of T2D.

Plasma and Urinary (Poly)phenolic Profiles after 4-Week Red Raspberry (Rubus idaeus L.) Intake with or without Fructo-Oligosaccharide Supplementation

Red raspberries (RRB) are high in anthocyanin- and ellagitannin- type (poly)phenols. This study aimed to investigate the effect of 4-week RRB supplementation on (poly)phenolic metabolism in adults with prediabetes and insulin-resistance (PreDM-IR); and whether adding fructo-oligosaccharides (FOS), prebiotics, would augment the microbial metabolites of RRB (poly)phenols. In a randomized crossover clinical trial, subjects (n = 35: PreDM-IR, n = 25; healthy Reference group, n = 10) consumed 1 cup RRB (fresh weight equivalence) per day and RRB with 8 g FOS per day each for 4 weeks in random order separated by 4-week washout. Plasma and urinary (poly)phenolic metabolites were characterized after (0–24 h) consuming a RRB-based test drink (2 cups RRB) at baseline/week 0 and again after 4-week supplementations. A total of 123 (poly)phenolic metabolites were quantified. After 4-week RRB supplementation, several metabolite groups were significantly increased (p < 0.05), including urolithins, phenyl-γ-valerolactones, and phenolic acids. Supplementing FOS with RRB for 4 weeks enhanced benzoic acid derivatives compared to the baseline (p < 0.05). Specific effects of supplementation by metabolic status indicated 4-week RRB supplementation significantly increased microbial metabolites that were lower in PreDM-IR group. Our results suggest alterations in the capacity of PreDM-IR group to metabolize and render bioavailable raspberry-derived (poly)phenols when consumed regularly.

An investigation of causal relationships between prediabetes and vascular complications

Prediabetes is a state of glycaemic dysregulation below the diagnostic threshold of type 2 diabetes (T2D). Globally, ~352 million people have prediabetes, of which 35-50% develop full-blown diabetes within five years. T2D and its complications are costly to treat, causing considerable morbidity and early mortality. Whether prediabetes is causally related to diabetes complications is unclear. Here we report a causal inference analysis investigating the effects of prediabetes in coronary artery disease, stroke and chronic kidney disease, complemented by a systematic review of relevant observational studies. Although the observational studies suggest that prediabetes is broadly associated with diabetes complications, the causal inference analysis revealed that prediabetes is only causally related with coronary artery disease, with no evidence of causal effects on other diabetes complications. In conclusion, prediabetes likely causes coronary artery disease and its prevention is likely to be most effective if initiated prior to the onset of diabetes.

Circulating plasma proteins and new-onset diabetes in a population-based study: proteomic and genomic insights from the STANISLAS cohort

OBJECTIVE

Determining the factors associated with new-onset pre-diabetes and type 2 diabetes mellitus (T2D) is important for improving the current prevention strategies and for a better understanding of the disease.

DESIGN

To study the factors (clinical, circulating protein and genetic) associated with new onset pre-diabetes and T2D in an initially healthy (without diabetes) populational familial cohort with a long follow-up (STANISLAS cohort).

METHODS

A total of 1506 participants attended both the visit 1 and visit 4, separated by ≈20 years. Over 400 proteins, GWAS and genetic associations were studied using models adjusted for potential confounders. Both prospective (V1 to V4) and cross-sectional (V4) analyses were performed.

RESULTS

People who developed pre-diabetes (n = 555) and/or T2D (n = 73) were older, had higher BMI, blood pressure, glucose, LDL cholesterol, and lower eGFR. After multivariable selection, PAPP-A (pappalysin-1) was the only circulating protein associated with the onset of both pre-diabetes and T2D with associations persisting at visit 4 (i.e. ≈20 years later). FGF-21 (fibroblast growth factor 21) was a strong prognosticator for incident T2D in the longitudinal analysis, but not in the cross-sectional analysis. The heritability of the circulating PAPP-A was estimated at 44%. In GWAS analysis, the SNP rs634737 was associated with PAPP-A both at V1 and V4. External replication also showed lower levels of PAPP-A in patients with T2D.

CONCLUSIONS

The risk of developing pre-diabetes and T2D increases with age and with features of the metabolic syndrome. Circulating PAPP-A, which has an important genetic component, was associated with both the development and presence of pre-diabetes and T2D.

Early Metabolic Features of Genetic Liability to Type 2 Diabetes: Cohort Study With Repeated Metabolomics Across Early Life

OBJECTIVE

Type 2 diabetes develops for many years before diagnosis. We aimed to reveal early metabolic features characterizing liability to adult disease by examining genetic liability to adult type 2 diabetes in relation to metabolomic traits across early life.

RESEARCH DESIGN AND METHODS

Up to 4,761 offspring from the Avon Longitudinal Study of Parents and Children were studied. Linear models were used to examine effects of a genetic risk score (162 variants) for adult type 2 diabetes on 229 metabolomic traits (lipoprotein subclass-specific cholesterol and triglycerides, amino acids, glycoprotein acetyls, and others) measured at age 8 years, 16 years, 18 years, and 25 years. Two-sample Mendelian randomization (MR) was also conducted using genome-wide association study data on metabolomic traits in an independent sample of 24,925 adults.

RESULTS

At age 8 years, associations were most evident for type 2 diabetes liability (per SD higher) with lower lipids in HDL subtypes (e.g., -0.03 SD [95% CI -0.06, -0.003] for total lipids in very large HDL). At 16 years, associations were stronger with preglycemic traits, including citrate and with glycoprotein acetyls (0.05 SD; 95% CI 0.01, 0.08), and at 18 years, associations were stronger with branched-chain amino acids. At 25 years, associations had strengthened with VLDL lipids and remained consistent with previously altered traits, including HDL lipids. Two-sample MR estimates among adults indicated persistent patterns of effect of disease liability.

CONCLUSIONS

Our results support perturbed HDL lipid metabolism as one of the earliest features of type 2 diabetes liability, alongside higher branched-chain amino acid and inflammatory levels. Several features are apparent in childhood as early as age 8 years, decades before the clinical onset of disease.

A Nutrigenetic Approach to Investigate the Relationship between Metabolic Traits and Vitamin D Status in an Asian Indian Population

Studies in Asian Indians have examined the association of metabolic traits with vitamin D status. However, findings have been quite inconsistent. Hence, we aimed to explore the relationship between metabolic traits and 25-hydroxyvitamin D [25(OH)D] concentrations. We investigate whether this relationship was modified by lifestyle factors using a nutrigenetic approach in 545 Asian Indians randomly selected from the Chennai Urban Rural Epidemiology Study (219 normal glucose tolerant individuals, 151 with pre-diabetes and 175 individuals with type 2 diabetes). A metabolic genetic risk score (GRS) was developed using five common metabolic disease-related genetic variants. There was a significant interaction between metabolic GRS and carbohydrate intake (energy%) on 25(OH)D (Pinteraction = 0.047). Individuals consuming a low carbohydrate diet (≤62%) and those having lesser number of metabolic risk alleles (GRS ≤ 1) had significantly higher levels of 25(OH)D (p = 0.033). Conversely, individuals consuming a high carbohydrate diet despite having lesser number of risk alleles did not show a significant increase in 25(OH)D (p = 0.662). In summary, our findings show that individuals carrying a smaller number of metabolic risk alleles are likely to have higher 25(OH)D levels if they consume a low carbohydrate diet. These data support the current dietary carbohydrate recommendations of 50%-60% energy suggesting that reduced metabolic genetic risk increases 25(OH)D.

Screening and functional studies of long noncoding RNA in subjects with prediabetes

BACKGROUND

In recent years, long noncoding RNAs (LncRNAs) have been found to play an important role in type 2 diabetes mellitus. However, research on the relationship between LncRNAs and prediabetes is still emerging.

OBJECTIVES

The study aim was to screen differently expressed LncRNAs and understand their localization and function in patients with prediabetes.

METHODS

We used microarray analysis to screen LncRNAs in prediabetes participants.To further clarify the localization and function of the expressed mRNAs, we used gene ontology analysis and pathway analysis. Then, internal validations were performed using individual quantitative real-time polymerase chain reaction (qRT-PCR) assays.

RESULTS

We identified 55 differently expressed LncRNAs and 36 mRNAs in prediabetes participants comparing with controls. Gene ontology analysis indicated that the most enriched transcript terms were multicellular organismal process, plasma membrane, and binding. Pathway analysis indicated that the differently expressed mRNAs were involved in processes such as starch and sucrose metabolism, pantothenate and coenzyme A biosynthesis, and nicotinate and nicotinamide metabolism. The qRT-PCR results showed a trend consistent with the microarray results in 30 patients and 30 healthy controls.

CONCLUSIONS

We found aberrantly expressed LncRNAs and mRNAs in prediabetes subjects, and demonstrated that these LncRNAs are involved in the entire prediabetes biological process.

Metabolic changes during pregnancy in glucose-intolerant NZO mice: A polygenic model with prediabetic metabolism

Gestational diabetes mellitus (GDM) is a complex metabolic disease involving genetic and environmental factors. Recent studies have underlined its heterogeneity, so it is reasonable to divide patients into subpopulations depending on whether an insulin secretion or sensitivity defect is predominant. Since testing for GDM is usually performed in the second trimester, misinterpretation of prediabetes as gestational diabetes may occur. As with type 2 diabetes (T2DM), rodent models are needed for both GDM and prediabetes, but few do exist. Here, we compared the metabolic changes in pregnant normal NMRI mice with those in New Zealand obese (NZO) mice. Male animals of this strain are an established model of T2DM, whereas female mice of this strain are protected from hyperglycemia and β-cell death. We demonstrate that female NZO mice exhibited impaired glucose tolerance, preconceptional hyperinsulinemia, and hyperglucagonemia without any signs of manifest diabetes. The NZO model showed, compared with the NMRI control strain, a reduced proliferative response of the Langerhans islets during pregnancy (3.7 ± 0.4 vs. 7.2 ± 0.8% Ki-67-positive nuclei, p = .004). However, oral glucose tolerance tests revealed improved stimulation of insulin secretion in both strains. But this adaption was not sufficient to prevent impaired glucose tolerance in NZO mice compared with the NMRI control (p = .0002). Interestingly, glucose-stimulated insulin secretion was blunted in isolated primary NZO islets in perifusion experiments. In summary, the NZO mouse reflects important characteristics of human GDM and prediabetes in pregnancy and serves as a model for subpopulations with early alterations in glucose metabolism and primary insulin secretion defect.

Mitochondrial Dysfunction, Insulin Resistance, and Potential Genetic Implications

Insulin resistance (IR) is fundamental to the development of type 2 diabetes (T2D) and is present in most prediabetic (preDM) individuals. Insulin resistance has both heritable and environmental determinants centered on energy storage and metabolism. Recent insights from human genetic studies, coupled with comprehensive in vivo and ex vivo metabolic studies in humans and rodents, have highlighted the critical role of reduced mitochondrial function as a predisposing condition for ectopic lipid deposition and IR. These studies support the hypothesis that reduced mitochondrial function, particularly in insulin-responsive tissues such as skeletal muscle, white adipose tissue, and the liver, is inextricably linked to tissue and whole body IR through the effects on cellular energy balance. Here we discuss these findings as well as address potential mechanisms that serve as the nexus between mitochondrial malfunction and IR.

Predictive effect of GIPR SNP rs10423928 on glucose metabolism liver fat and adiposity in prediabetic and diabetic subjects

The gastric inhibitory polypeptide receptor (GIPR) regulates postprandial metabolism. In this context GIPR SNP rs10423928 seems toplay an important role in modulating glucose metabolism and insulinsensitivity. However, evidence regarding thisparticular SNP is still vague. In this study, we collected baseline data from four different dietaryintervention studies. We genotyped 424 subjects with prediabetes and 73with diabetes for GIPR SNP rs10423928 and examined its impact on glucosemetabolism, insulin sensitivity and body fat accumulation. We extended previous data by showing that carriers of the A allele withprediabetes displayed increased fasting glucose (p = 0.015). Unexpectedly,A allele carriers showed lower glucose levels 2 h (p = 0.021) after anoral glucose challenge compared to T/T homozygous individuals. A allelecarriers also showed significantly higher insulin sensitivity (p < 0.001)(assessed by Cederholm Index), indicating an enhanced ß-cell response. This study points to a potential protective role for rs10423928 inglucose metabolism and insulin sensitivity in subjects with prediabetes.Further studies are necessary to confirm these results.

The risk of progression to type 1 diabetes is highly variable in individuals with multiple autoantibodies following screening

AIMS/HYPOTHESIS

Young children who develop multiple autoantibodies (mAbs) are at very high risk for type 1 diabetes. We assessed whether a population with mAbs detected by screening is also at very high risk, and how risk varies according to age, type of autoantibodies and metabolic status.

METHODS

Type 1 Diabetes TrialNet Pathway to Prevention participants with mAbs (n = 1815; age, 12.35 ± 9.39 years; range, 1-49 years) were analysed. Type 1 diabetes risk was assessed according to age, autoantibody type/number (insulin autoantibodies [IAA], glutamic acid decarboxylase autoantibodies [GADA], insulinoma-associated antigen-2 autoantibodies [IA-2A] or zinc transporter 8 autoantibodies [ZnT8A]) and Index60 (composite measure of fasting C-peptide, 60 min glucose and 60 min C-peptide). Cox regression and cumulative incidence curves were utilised in this cohort study.

RESULTS

Age was inversely related to type 1 diabetes risk in those with mAbs (HR 0.97 [95% CI 0.96, 0.99]). Among participants with 2 autoantibodies, those with GADA had less risk (HR 0.35 [95% CI 0.22, 0.57]) and those with IA-2A had higher risk (HR 2.82 [95% CI 1.76, 4.51]) of type 1 diabetes. Those with IAA and GADA had only a 17% 5 year risk of type 1 diabetes. The risk was significantly lower for those with Index60 <1.0 (HR 0.23 [95% CI 0.19, 0.30]) vs those with Index60 values ≥1.0. Among the 12% (225/1815) ≥12.0 years of age with GADA positivity, IA-2A negativity and Index60 <1.0, the 5 year risk of type 1 diabetes was 8%.

CONCLUSIONS/INTERPRETATION

Type 1 diabetes risk varies substantially according to age, autoantibody type and metabolic status in individuals screened for mAbs. An appreciable proportion of older children and adults with mAbs appear to have a low risk of progressing to type 1 diabetes at 5 years. With this knowledge, clinical trials of type 1 diabetes prevention can better target those most likely to progress.

Metabolic and Genetic Determinants of Glucose Shape After Oral Challenge in Obese Youths: A Longitudinal Study

CONTEXT

The time-to-glucose-peak following the oral glucose tolerance test (OGTT) is a highly reproducible marker for diabetes risk. In obese youths, we lack evidence for the mechanisms underlying the effects of the TCF7L2 rs7903146 variant on glucose peak.

METHODS

We analyzed the metabolic phenotype and the genotype for the TCF7L2 rs7903146 in 630 obese youths with normal (NGT) and impaired (IGT) glucose tolerance. Participants underwent a 3-hour, 9-point OGTT to estimate, using the oral minimal model, the disposition index (DI), the static (φstatic) and dynamic (φdynamic) components β-cell responsiveness and insulin sensitivity (SI). In a subgroup (n = 241) longitudinally followed for 2 years, we estimated the effect of time-to-glucose-peak on glucose tolerance change.

RESULTS

Participants were grouped into early (<30 minutes) and late (≥30 minutes) glucose peakers. A delayed glucose peak was featured by a decline in φstatic (P < .001) in the absence of a difference in φdynamic. The prevalence of T-risk allele for TCF7L2 rs7903146 variant significantly increased in the late peak group. A lower DI was correlated with higher glucose concentration at 1 and 2 hours, whereas SI was inversely associated with 1-hour glucose. Glucose peak <30 minutes was protective toward worsening of glucose tolerance overtime (odds ratio 0.35 [0.15-0.82]; P = .015), with no subjects progressing to NGT or persisting IGT, in contrast to the 40% of progressor in those with late glucose peak.

CONCLUSION

The prevalence of T-risk allele for the TCF7L2 rs7903146 prevailed in the late time-to-glucose peak group, which in turn is associated with impaired β-cell responsiveness to glucose (φ), thereby predisposing to prediabetes and diabetes in obese youths.

In silico transcriptional analysis of mRNA and miRNA reveals unique biosignatures that characterizes different types of diabetes

Diabetes (DM) has a significant impact on public health. We performed an in silico study of paired datasets of messenger RNA (mRNA) micro-RNA (miRNA) transcripts to delineate potential biosignatures that could distinguish prediabetes (pre-DM), type-1DM (T1DM) and type-2DM (T2DM). Two publicly available datasets containing expression values of mRNA and miRNA obtained from individuals diagnosed with pre-DM, T1DM or T2DM, and normoglycemic controls (NC), were analyzed using systems biology approaches to define combined signatures to distinguish different clinical groups. The mRNA profile of both pre-DM and T2DM was hallmarked by several differentially expressed genes (DEGs) compared to NC. Nevertheless, T1DM was characterized by an overall low number of DEGs. The miRNA signature profiles were composed of a substantially lower number of differentially expressed targets. Gene enrichment analysis revealed several inflammatory pathways in T2DM and fewer in pre-DM, but with shared findings such as Tuberculosis. The integration of mRNA and miRNA datasets improved the identification and discriminated the group composed by pre-DM and T2DM patients from that constituted by normoglycemic and T1DM individuals. The integrated transcriptomic analysis of mRNA and miRNA expression revealed a unique biosignature able to characterize different types of DM.

Interaction Between Type 2 Diabetes Prevention Strategies and Genetic Determinants of Coronary Artery Disease on Cardiometabolic Risk Factors

Coronary artery disease (CAD) is more frequent among individuals with dysglycemia. Preventive interventions for diabetes can improve cardiometabolic risk factors (CRFs), but it is unclear whether the benefits on CRFs are similar for individuals at different genetic risk for CAD. We built a 201-variant polygenic risk score (PRS) for CAD and tested for interaction with diabetes prevention strategies on 1-year changes in CRFs in 2,658 Diabetes Prevention Program (DPP) participants. We also examined whether separate lifestyle behaviors interact with PRS and affect changes in CRFs in each intervention group. Participants in both the lifestyle and metformin interventions had greater improvement in the majority of recognized CRFs compared with placebo (P < 0.001) irrespective of CAD genetic risk (P interaction > 0.05). We detected nominal significant interactions between PRS and dietary quality and physical activity on 1-year change in BMI, fasting glucose, triglycerides, and HDL cholesterol in individuals randomized to metformin or placebo, but none of them achieved the multiple-testing correction for significance. This study confirms that diabetes preventive interventions improve CRFs regardless of CAD genetic risk and delivers hypothesis-generating data on the varying benefit of increasing physical activity and improving diet on intermediate cardiovascular risk factors depending on individual CAD genetic risk profile.

Gene Expression Analysis of the Pre-Diabetic Pancreas to Identify Pathogenic Mechanisms and Biomarkers of Type 1 Diabetes

Type 1 Diabetes (T1D) occurs as a result of the autoimmune destruction of pancreatic β-cells by self-reactive T cells. The etiology of this disease is complex and difficult to study due to a lack of disease-relevant tissues from pre-diabetic individuals. In this study, we performed gene expression analysis on human pancreas tissues obtained from the Network of Pancreatic Organ Donors with Diabetes (nPOD), and showed that 155 genes were differentially expressed by ≥2-fold in the pancreata of autoantibody-positive (AA+) at-risk individuals compared to healthy controls. Only 48 of these genes remained changed by ≥2-fold in the pancreata of established T1D patients. Pathway analysis of these genes showed a significant association with various immune pathways. We were able to validate the differential expression of eight disease-relevant genes by QPCR analysis: A significant upregulation of CADM2, and downregulation of TRPM5, CRH, PDK4, ANGPL4, CLEC4D, RSG16, and FCGR2B was confirmed in the pancreata of AA+ individuals versus controls. Studies have already implicated FCGR2B in the pathogenesis of disease in non-obese diabetic (NOD) mice. Here we showed that CADM2, TRPM5, PDK4, and ANGPL4 were similarly changed in the pancreata of pre-diabetic 12-week-old NOD mice compared to NOD.B10 controls, suggesting a possible role for these genes in the pathogenesis of both T1D and NOD disease. The loss of the leukocyte-specific gene, FCGR2B, in the pancreata of AA+ individuals, is particularly interesting, as it may serve as a potential whole blood biomarker of disease progression. To test this, we quantified FCGR2B expression in peripheral blood samples of T1D patients, and AA+ and AA- first-degree relatives of T1D patients enrolled in the TrialNet Pathway to Prevention study. We showed that FCGR2B was significantly reduced in the peripheral blood of AA+ individuals compared to AA- controls. Together, these findings demonstrate that gene expression analysis of pancreatic tissue and peripheral blood samples can be used to identify disease-relevant genes and pathways and potential biomarkers of disease progression in T1D.

Metallothionein 1 negatively regulates glucose-stimulated insulin secretion and is differentially expressed in conditions of beta cell compensation and failure in mice and humans

AIMS/HYPOTHESIS

The mechanisms responsible for beta cell compensation in obesity and for beta cell failure in type 2 diabetes are poorly defined. The mRNA levels of several metallothionein (MT) genes are upregulated in islets from individuals with type 2 diabetes, but their role in beta cells is not clear. Here we examined: (1) the temporal changes of islet Mt1 and Mt2 gene expression in mouse models of beta cell compensation and failure; and (2) the role of Mt1 and Mt2 in beta cell function and glucose homeostasis in mice.

METHODS

Mt1 and Mt2 expression was assessed in islets from: (1) control lean (chow diet-fed) and diet-induced obese (high-fat diet-fed for 6 weeks) mice; (2) mouse models of diabetes (db/db mice) at 6 weeks old (prediabetes) and 16 weeks old (after diabetes onset) and age-matched db/+ (control) mice; and (3) obese non-diabetic ob/ob mice (16-week-old) and age-matched ob/+ (control) mice. MT1E, MT1X and MT2A expression was assessed in islets from humans with and without type 2 diabetes. Mt1-Mt2 double-knockout (KO) mice, transgenic mice overexpressing Mt1 under the control of its natural promoter (Tg-Mt1) and corresponding control mice were also studied. In MIN6 cells, MT1 and MT2 were inhibited by small interfering RNAs. mRNA levels were assessed by real-time RT-PCR, plasma insulin and islet MT levels by ELISA, glucose tolerance by i.p. glucose tolerance tests and overnight fasting-1 h refeeding tests, insulin tolerance by i.p. insulin tolerance tests, insulin secretion by RIA, cytosolic free Ca²⁺ concentration with Fura-2 leakage resistant (Fura-2 LR), cytosolic free Zn²⁺ concentration with Fluozin-3, and NAD(P)H by autofluorescence.

RESULTS

Mt1 and Mt2 mRNA levels were reduced in islets of murine models of beta cell compensation, whereas they were increased in diabetic db/db mice. In humans, MT1X mRNA levels were significantly upregulated in islets from individuals with type 2 diabetes in comparison with non-diabetic donors, while MT1E and MT2A mRNA levels were unchanged. Ex vivo, islet Mt1 and Mt2 mRNA and MT1 and MT2 protein levels were downregulated after culture with glucose at 10-30 mmol/l vs 2-5 mmol/l, in association with increased insulin secretion. In human islets, mRNA levels of MT1E, MT1X and MT2A were downregulated by stimulation with physiological and supraphysiological levels of glucose. In comparison with wild-type (WT) mice, Mt1-Mt2 double-KO mice displayed improved glucose tolerance in association with increased insulin levels and enhanced insulin release from isolated islets. In contrast, isolated islets from Tg-Mt1 mice displayed impaired glucose-stimulated insulin secretion (GSIS). In both Mt1-Mt2 double-KO and Tg-Mt1 models, the changes in GSIS occurred despite similar islet insulin content, rises in cytosolic free Ca²⁺ concentration and NAD(P)H levels, or intracellular Zn²⁺ concentration vs WT mice. In MIN6 cells, knockdown of MT1 but not MT2 potentiated GSIS, suggesting that Mt1 rather than Mt2 affects beta cell function.

CONCLUSIONS/INTERPRETATION

These findings implicate Mt1 as a negative regulator of insulin secretion. The downregulation of Mt1 is associated with beta cell compensation in obesity, whereas increased Mt1 accompanies beta cell failure and type 2 diabetes.