Identification of novel biomarkers to monitor β-cell function and enable early detection of type 2 diabetes risk

Correlation of Serum Endocan Level With Apoptosis Indicators and Severity of Atherosclerotic Lesions of Coronary Arteries in Patients With Coronary Heart Disease

Aim    To study the relationship of blood serum concentration of endocan with indexes of apoptosis and clinical and instrumental characteristics of patients with ischemic heart disease (IHD).Material and methods    The study included 176 subjects (105 men and 71 women). 150 of them were diagnosed with IHD and 26 were healthy volunteers. Anthropometric measurements, coronary angiography, echocardiography, duplex ultrasound scanning of extracranial parts of the brachiocephalic arteries were performed for all patients. Concentrations of endocan (ng / ml), glucose (mmol / l), and apoptotic markers Bcl-2 (ng / ml), Bax (ng / ml), Bcl-2 / Bax, TRAIL (pg / ml), and p53 (ng / ml) were measured in blood serum. Patients were divided into groups based on their SYNTAX scores: group 1 with moderate atherosclerotic lesions of the coronary arteries (CA) (score < 22, 78 patients); group 2 with severe CA atherosclerosis (score 23-32, 37 patients); and group 3 with extremely severe CA lesions (score >33, 35 patients). The control group consisted of healthy volunteers (26 subjects). All groups were age- and sex-matched. Differences were considered statistically significant at p<0.05.Results    A correlation was found between endocan concentration and IHD severity (r=0.32, p<0.001). In group 1, the median endocan concentration was 14.57 ng / ml [8.21; 23.66], in group 2, 19.34 ng / ml [8.425; 26.645], in group 3, 32.13 ng / ml [18.2; 39.12], and in the control group, 6.92 ng / ml [4.62; 9.18]. Correlations of varying strength and significance were observed between the endocan concentration and a number of clinical and instrumental characteristics. Endocan concentrations significantly differed in groups of patients with multifocal atherosclerosis (p<0.01), angina pectoris (p<0.01), a history of myocardial infarction (p<0.001), and obesity (p<0.05) from patients without these signs. Also, a correlation was found between serum endocan concentration and apoptotic markers: TRAIL (r= -0.448, p<0.001); BCL-2 (r= -0.552, p<0.001), Bax (r= -0.519, p<0.001), Bcl-2 / Bax (r= -0.576, p<0.001) and p53 (r= -0.520, p <0.001).Conclusion    The study demonstrated a potential role of endocan as a promising biomarker for risk stratification, prognosis and therapeutic monitoring of IHD patients.

Associations of plasma proteomics with type 2 diabetes and related traits: results from the longitudinal KORA S4/F4/FF4 Study

AIMS/HYPOTHESIS

This study aimed to elucidate the aetiological role of plasma proteins in glucose metabolism and type 2 diabetes development.

METHODS

We measured 233 proteins at baseline in 1653 participants from the Cooperative Health Research in the Region of Augsburg (KORA) S4 cohort study (median follow-up time: 13.5 years). We used logistic regression in the cross-sectional analysis (n=1300), and Cox regression accounting for interval-censored data in the longitudinal analysis (n=1143). We further applied two-level growth models to investigate associations with repeatedly measured traits (fasting glucose, 2 h glucose, fasting insulin, HOMA-B, HOMA-IR, HbA1c), and two-sample Mendelian randomisation analysis to investigate causal associations. Moreover, we built prediction models using priority-Lasso on top of Framingham-Offspring Risk Score components and evaluated the prediction accuracy through AUC.

RESULTS

We identified 14, 24 and four proteins associated with prevalent prediabetes (i.e. impaired glucose tolerance and/or impaired fasting glucose), prevalent newly diagnosed type 2 diabetes and incident type 2 diabetes, respectively (28 overlapping proteins). Of these, IL-17D, IL-18 receptor 1, carbonic anhydrase-5A, IL-1 receptor type 2 (IL-1RT2) and matrix extracellular phosphoglycoprotein were novel candidates. IGF binding protein 2 (IGFBP2), lipoprotein lipase (LPL) and paraoxonase 3 (PON3) were inversely associated while fibroblast growth factor 21 was positively associated with incident type 2 diabetes. LPL was longitudinally linked with change in glucose-related traits, while IGFBP2 and PON3 were linked with changes in both insulin- and glucose-related traits. Mendelian randomisation analysis suggested causal effects of LPL on type 2 diabetes and fasting insulin. The simultaneous addition of 12 priority-Lasso-selected biomarkers (IGFBP2, IL-18, IL-17D, complement component C1q receptor, V-set and immunoglobulin domain-containing protein 2, IL-1RT2, LPL, CUB domain-containing protein 1, vascular endothelial growth factor D, PON3, C-C motif chemokine 4 and tartrate-resistant acid phosphatase type 5) significantly improved the predictive performance (ΔAUC 0.0219; 95% CI 0.0052, 0.0624).

CONCLUSIONS/INTERPRETATION

We identified new candidates involved in the development of derangements in glucose metabolism and type 2 diabetes and confirmed previously reported proteins. Our findings underscore the importance of proteins in the pathogenesis of type 2 diabetes and the identified putative proteins can function as potential pharmacological targets for diabetes treatment and prevention.

Is maternal serum endocan level a novel marker in gestational diabetes mellitus?

AIM

To determine whether there was a significant difference between serum endocan levels of pregnant women with and without gestational diabetes mellitus (GDM).

METHODS

A total of 90 pregnant women, 45 with gestational diabetes and 45 healthy pregnant women, between 24 and 28 gestational weeks, were included in this prospective case-control study. The pregnant women were screened for gestational diabetes using a two-step protocol. Serum endocan levels were measured using a commercially available enzyme-linked immunosorbent assay (ELISA) kit. A p-value of <0.05 was considered statistically significant.

RESULTS

Serum endocan level was significantly higher in the GDM group than in healthy controls (168.46 ± 160.6 vs. 105.66 ± 26.52 pg/mL, respectively; p < 0.001). Serum endocan concentrations were positively correlated with the results of 50 g oral glucose challenge test (GCT) (p < 0.001). Receiver operating characteristic curve analysis showed that endocan with a cut-off point of 133.9 ng/dL indicated women with GDM with a sensitivity of 55.6% and specificity of 88.9% (area under the curve [AUC]: 0.737, 95% CI: 0.634-0.824). The overall differential performance of endocan according to the GDM groups was determined as 73.7% (p < 0.001). Maternal serum endocan level was positively correlated with fasting glucose, postprandial glucose, and glycated hemoglobin (HbA1c) (p < 0.001).

CONCLUSIONS

Elevated endocan levels in gestational diabetes were correlated with fasting glucose, postprandial glucose, HbA1c, and oral glucose tolerance test (OGTT) results. Despite the low sensitivity of 55.6% and the high specificity of 88.9%, we found a high differential performance rate indicating that serum endocan levels were important for the pathophysiology of GDM and should be investigated for the possibility of being a novel marker in larger populations.

The Role of Endocan in Cardiometabolic Disorders

Discovered two decades ago, endocan still represents an intriguing biomarker related to inflammation. Endocan is a soluble dermatan sulphate proteoglycan secreted by endothelial cells. Its expression is observed in tissues related to the enhanced proliferation, especially hepatocytes, lungs, kidneys, etc. Endocan has been investigated in many cardiometabolic disorders that are tightly connected with inflammation, such as type 2 diabetes mellitus, hypertension, atherosclerotic cardiovascular disease, kidney disease, obesity, polycystic ovary syndrome, metabolic syndrome, non-alcoholic fatty liver disease, etc. In this narrative, comprehensive review of the currently available literature, special attention will be paid to the role of endocan in the broad spectrum of cardiometabolic disorders. Since endocan has emerged as a novel endothelial dysfunction marker, the discovery of potential therapeutic strategies for patients with certain cardiometabolic risk factors would be of great importance to delay or even prevent the onset and progression of related complications, mainly cardiovascular.

Human pancreatic islet microRNAs implicated in diabetes and related traits by large-scale genetic analysis

Genetic studies have identified ≥240 loci associated with the risk of type 2 diabetes (T2D), yet most of these loci lie in non-coding regions, masking the underlying molecular mechanisms. Recent studies investigating mRNA expression in human pancreatic islets have yielded important insights into the molecular drivers of normal islet function and T2D pathophysiology. However, similar studies investigating microRNA (miRNA) expression remain limited. Here, we present data from 63 individuals, the largest sequencing-based analysis of miRNA expression in human islets to date. We characterized the genetic regulation of miRNA expression by decomposing the expression of highly heritable miRNAs into cis- and trans-acting genetic components and mapping cis-acting loci associated with miRNA expression [miRNA-expression quantitative trait loci (eQTLs)]. We found i) 84 heritable miRNAs, primarily regulated by trans-acting genetic effects, and ii) 5 miRNA-eQTLs. We also used several different strategies to identify T2D-associated miRNAs. First, we colocalized miRNA-eQTLs with genetic loci associated with T2D and multiple glycemic traits, identifying one miRNA, miR-1908, that shares genetic signals for blood glucose and glycated hemoglobin (HbA1c). Next, we intersected miRNA seed regions and predicted target sites with credible set SNPs associated with T2D and glycemic traits and found 32 miRNAs that may have altered binding and function due to disrupted seed regions. Finally, we performed differential expression analysis and identified 14 miRNAs associated with T2D status-including miR-187-3p, miR-21-5p, miR-668, and miR-199b-5p-and 4 miRNAs associated with a polygenic score for HbA1c levels-miR-216a, miR-25, miR-30a-3p, and miR-30a-5p.

Targeted proteomics identifies potential biomarkers of dysglycaemia, beta cell function and insulin sensitivity in Black African men and women

AIMS/HYPOTHESIS

Using a targeted proteomics approach, we aimed to identify and validate circulating proteins associated with impaired glucose metabolism (IGM) and type 2 diabetes in a Black South African cohort. In addition, we assessed sex-specific associations between the validated proteins and pathophysiological pathways of type 2 diabetes.

METHODS

This cross-sectional study included Black South African men (n=380) and women (n=375) who were part of the Middle-Aged Soweto Cohort (MASC). Dual-energy x-ray absorptiometry was used to determine fat mass and visceral adipose tissue, and fasting venous blood samples were collected for analysis of glucose, insulin and C-peptide and for targeted proteomics, measuring a total of 184 pre-selected protein biomarkers. An OGTT was performed on participants without diabetes, and peripheral insulin sensitivity (Matsuda index), HOMA-IR, basal insulin clearance, insulin secretion (C-peptide index) and beta cell function (disposition index) were estimated. Participants were classified as having normal glucose tolerance (NGT; n=546), IGM (n=116) or type 2 diabetes (n=93). Proteins associated with dysglycaemia (IGM or type 2 diabetes) in the MASC were validated in the Swedish EpiHealth cohort (NGT, n=1706; impaired fasting glucose, n=550; type 2 diabetes, n=210).

RESULTS

We identified 73 proteins associated with dysglycaemia in the MASC, of which 34 were validated in the EpiHealth cohort. Among these validated proteins, 11 were associated with various measures of insulin dynamics, with the largest number of proteins being associated with HOMA-IR. In sex-specific analyses, IGF-binding protein 2 (IGFBP2) was associated with lower HOMA-IR in women (coefficient -0.35; 95% CI -0.44, -0.25) and men (coefficient -0.09; 95% CI -0.15, -0.03). Metalloproteinase inhibitor 4 (TIMP4) was associated with higher insulin secretion (coefficient 0.05; 95% CI 0.001, 0.11; p for interaction=0.025) and beta cell function (coefficient 0.06; 95% CI 0.02, 0.09; p for interaction=0.013) in women only. In contrast, a stronger positive association between IGFBP2 and insulin sensitivity determined using an OGTT (coefficient 0.38; 95% CI 0.27, 0.49) was observed in men (p for interaction=0.004). A posteriori analysis showed that the associations between TIMP4 and insulin dynamics were not mediated by adiposity. In contrast, most of the associations between IGFBP2 and insulin dynamics, except for insulin secretion, were mediated by either fat mass index or visceral adipose tissue in men and women. Fat mass index was the strongest mediator between IGFBP2 and insulin sensitivity (total effect mediated 40.7%; 95% CI 37.0, 43.6) and IGFBP2 and HOMA-IR (total effect mediated 39.1%; 95% CI 31.1, 43.5) in men.

CONCLUSIONS/INTERPRETATION

We validated 34 proteins that were associated with type 2 diabetes, of which 11 were associated with measures of type 2 diabetes pathophysiology such as peripheral insulin sensitivity and beta cell function. This study highlights biomarkers that are similar between cohorts of different ancestry, with different lifestyles and sociodemographic profiles. The African-specific biomarkers identified require validation in African cohorts to identify risk markers and increase our understanding of the pathophysiology of type 2 diabetes in African populations.

Therapeutic Potential of miRNAs for Type 2 Diabetes Mellitus: An Overview

MicroRNA(miRNA)s have been identified as an emerging class for therapeutic interventions mainly due to their extracellularly stable presence in humans and animals and their potential for horizontal transmission and action. However, treating Type 2 diabetes mellitus using this technology has yet been in a nascent state. MiRNAs play a significant role in the pathogenesis of Type 2 diabetes mellitus establishing the potential for utilizing miRNA-based therapeutic interventions to treat the disease. Recently, the administration of miRNA mimics or antimiRs in-vivo has resulted in positive modulation of glucose and lipid metabolism. Further, several cell culture-based interventions have suggested beta cell regeneration potential in miRNAs. Nevertheless, few such miRNA-based therapeutic approaches have reached the clinical phase. Therefore, future research contributions would identify the possibility of miRNA therapeutics for tackling T2DM. This article briefly reported recent developments on miRNA-based therapeutics for treating Type 2 Diabetes mellitus, associated implications, gaps, and recommendations for future studies.

Pancreatic Islets as a Target of Adipokines

Rising rates of obesity are intricately tied to the type 2 diabetes epidemic. The adipose tissues can play a central role in protection against or triggering metabolic diseases through the secretion of adipokines. Many adipokines may improve peripheral insulin sensitivity through a variety of mechanisms, thereby indirectly reducing the strain on beta cells and thus improving their viability and functionality. Such effects will not be the focus of this article. Rather, we will focus on adipocyte-secreted molecules that have a direct effect on pancreatic islets. By their nature, adipokines represent potential druggable targets that can reach the islets and improve beta-cell function or preserve beta cells in the face of metabolic stress. © 2022 American Physiological Society. Compr Physiol 12:1-27, 2022.

Islet Gene View-a tool to facilitate islet research

Characterization of gene expression in pancreatic islets and its alteration in type 2 diabetes (T2D) are vital in understanding islet function and T2D pathogenesis. We leveraged RNA sequencing and genome-wide genotyping in islets from 188 donors to create the Islet Gene View (IGW) platform to make this information easily accessible to the scientific community. Expression data were related to islet phenotypes, diabetes status, other islet-expressed genes, islet hormone-encoding genes and for expression in insulin target tissues. The IGW web application produces output graphs for a particular gene of interest. In IGW, 284 differentially expressed genes (DEGs) were identified in T2D donor islets compared with controls. Forty percent of DEGs showed cell-type enrichment and a large proportion significantly co-expressed with islet hormone-encoding genes; glucagon (<i>GCG</i>, 56%), amylin (<i>IAPP</i>, 52%), insulin (<i>INS</i>, 44%), and somatostatin (<i>SST</i>, 24%). Inhibition of two DEGs, <i>UNC5D</i> and <i>SERPINE2</i>, impaired glucose-stimulated insulin secretion and impacted cell survival in a human β-cell model. The exploratory use of IGW could help designing more comprehensive functional follow-up studies and serve to identify therapeutic targets in T2D.

Can the Serum Endocan Level Be Used as a Biomarker to Predict Subclinical Atherosclerosis in Patients with Prediabetes?

BACKGROUND

Patients with prediabetes have an increased risk of atherosclerotic cardiovascular disease; therefore, early detection is important.

OBJECTIVE

The present study aimed to reveal the usability of serum endocan levels as a biomarker in the diagnosis of subclinical atherosclerosis in patients with prediabetes, based on CIMT measurements.

METHODS

Participants were classified according to the presence (n=42) or absence (n=42) of prediabetes. Serum endocan, fasting blood sugar, fasting insulin, and glycated hemoglobin (HbA1c) values of patients were examined, and CIMT was measured. The level of significance for statistical analysis was 0.05.

RESULTS

While serum endocan levels were found to be lower in patients with prediabetes, when compared to the control group (p=0.042), CIMT values were found to be higher (p=0.046). When evaluated by multivariate regression analysis, the serum endocan level was found to be associated with CIMT, regardless of other parameters (p=0.007). A negative correlation was found between plasma fasting insulin and endocan levels (r=-0.320, p=0.001).

CONCLUSIONS

Carotid intima media thickness was found to be high and the serum endocan level was low in patients with prediabetes. Decreased serum endocan levels in patients with prediabetes may be a contributing factor to atherosclerosis formation mechanisms.

Severe iatrogenic hypoglycaemia modulates the fibroblast growth factor protein response

INTRODUCTION

There is evidence that fibroblast growth factor (FGF) levels may be implicated in hypoglycaemia, with FGF19 being a potential contributor to insulin-independent pathways driving postprandial hypoglycaemia following bariatric surgery and basic FGF (FGF2) being elevated following mild hypoglycaemia occurring after the glucose tolerance test. However, their response following severe iatrogenic hypoglycaemia is unknown and therefore this pilot exploratory study was undertaken.

METHODS

A case-control study of aged-matched type 2 diabetes (T2D; n = 23) and control (n = 23) subjects who underwent a hyperinsulinaemic clamp, initially to euglycaemia in T2D (5 mmol/L; 90 mg/dl), and then to hypoglycaemia (<2 mmol/L; <36 mg/dl) with subsequent follow-up time course to 24 h. FGF and FGF receptor proteins were determined by Slow Off-rate Modified Aptamer (SOMA)-scan plasma protein measurement.

RESULTS

At baseline, FGF12 (p = .006) was higher and FGF20 (p = .004) was lower in T2D versus controls. At hypoglycaemia, FGF7 was lower in T2D. Post-hypoglycaemic levels of FGF18, FGF19, FGF20 and FGF23 were lower while FGF12 and FGF16 were higher in T2D versus control at different time points. No differences between T2D and controls were seen for FGF1, FGF2, FGF4, FGF6, FGF8, FGF9, FGF10, FGF21 or any of the FGF receptors. At 24 h post-hypoglycaemia, FGF20 (p = .01) differed between controls and T2D, while the levels for the other proteins measured returned to baseline. None of the FGF proteins altered from baseline to euglycaemia when clamped in T2D subjects. FGF23 negatively correlated with fasting blood glucose, but no FGFs correlated with body mass index in T2D.

CONCLUSION

Severe transient hypoglycaemia modulated FGF7, 16, 19, 20 and 23 (known to be associated with diabetes), together with FGF18 and 12, not previously reported to be associated with diabetes but that may be important in the pathophysiology of hypoglycaemia; FGF20 remained low at 24 h. Taken together, these data suggest that recurrent hypoglycaemia may contribute to the development of complications through changes in FGF proteins.

Novel insights into the relationship between α-1 anti-trypsin with the pathological development of cardio-metabolic disorders

According to the previous studies, chronic low-grade systemic inflammatory response has been shown to be significantly associated with the pathological development of cardio-metabolic disorder diseases, including atherosclerosis, type 2 diabetes mellitus, and non-alcoholic fatty liver disease (NAFLD). On the other hand, auto-immunity process could also facilitate the pathogenesis of type 1 diabetes mellitus importantly. Concerning on this notion, the anti-inflammatory therapeutic strategy is demonstrated to embrace an essential function in those cardio-metabolic disorders in clinical practice. The α-1 anti-trypsin, also named Serpin-A1 and as an acute phase endogenous protein, has been verified to have several modulatory effects such as anti-inflammatory response, anti-apoptosis, and immunomodulatory functions. In addition, it is also used for therapeutic strategy of a rare genetic disease caused by the deficiency of α-1 anti-trypsin. Recent emerging evidence has indicated that the serum concentrations of α-1 anti-trypsin levels and its biological activity are significantly changed in those inflammatory and immune related cardio-metabolic disorder diseases. Nevertheless, the underlying mechanism is still not elucidated. In the current review, the basic experiments and clinical trials which provided the evidence revealing the potential therapeutic function of the α-1 anti-trypsin in cardio-metabolic disorder diseases were well-summarized. Furthermore, the results which indicated that the α-1 anti-trypsin presented the possibility as a novel serum biomarker in humans to predict those cardio-metabolic disorder diseases were also elucidated.

Progression of Type 1 Diabetes: Circulating MicroRNA Expression Profiles Changes from Preclinical to Overt Disease

Objectives

To evaluate the potential biological involvement of miRNA expression in the immune response and beta cell function in T1D.

Methods

We screened 377 serum miRNAs of 110 subjects divided into four groups: healthy individuals (control group) and patients at different stages of T1D progression, from the initial immunological manifestation presenting islet autoantibodies (AbP group) until partial and strong beta cell damage in the recent (recent T1D group) and long-term T1D, with 2 to 5 years of disease (T1D 2-5y group).

Results

The results revealed 69 differentially expressed miRNAs (DEMs) in relation to controls. Several miRNAs were correlated with islet autoantibodies (IA2A, GADA, and Znt8A), age, and C-peptide levels, mainly from AbP, and recent T1D groups pointing these miRNAs as relevant to T1D pathogenesis and progression. Several miRNAs were related to metabolic derangements, inflammatory pathways, and several other autoimmune diseases. Pathway analysis of putative DEM targets revealed an enrichment in pathways related to metabolic syndrome, inflammatory response, apoptosis and insulin signaling pathways, metabolic derangements, and decreased immunomodulation. One of the miRNAs' gene targets was DYRK2 (dual-specificity tyrosine-phosphorylation-regulated kinase 2), which is an autoantigen targeted by an antibody in T1D. ROC curve analysis showed hsa-miR-16 and hsa-miR-200a-3p with AUCs greater than for glucose levels, with discriminating power for T1D prediction greater than glucose levels. Conclusions/Interpretation. Our data suggests a potential influence of DEMs on disease progression from the initial autoimmune lesion up to severe beta cell dysfunction and the role of miRNAs hsa-miR-16 and hsa-miR-200a-3p as biomarkers of T1D progression.

Alpha-1 antitrypsin: A novel biomarker and potential therapeutic approach for metabolic diseases

It is well recognized that chronic low-grade systemic inflammation and autoimmunity contribute to the pathogenesis of metabolic syndrome, its associated diseases (e.g. type 2 diabetes, non-alcoholic fatty liver disease) and type 1 diabetes, respectively. Consequently, anti-inflammatory agents might play a role in managing these immune associated metabolic diseases. Alpha-1 antitrypsin (AAT), an endogenous acute phase protein being used for treatment of AAT deficiency (a rare genetic disease), has multiple functions including anti-inflammatory, immunomodulatory, anti-apoptosis and cytoprotective effects. In this review, we summarized basic and clinical studies that reported potential therapeutic role of AAT in metabolic syndrome associated diseases and type 1 diabetes. Studies that demonstrated AAT had the possibility to be used as a novel biomarker to predict these immune associated metabolic diseases were also included.

Alpha-1 antitrypsin in autoimmune diseases: Roles and therapeutic prospects

Alpha-1 antitrypsin (A1AT) is a protease inhibitor in the serum. Its primary function is to inhibit the activity of a series of proteases, including proteinase 3, neutrophil elastase, metalloproteases, and cysteine-aspartate proteases. In addition, A1AT also has anti-inflammatory, anti-apoptotic, anti-oxidative stress, anti-viral, and anti-bacterial activities and plays essential roles in the regulation of tissue repair and lymphocyte differentiation and activation. The overactivation of the immune system characterizes the pathogenesis of autoimmune diseases. A1AT treatment shows beneficial effects on patients and animal models with autoimmune diseases such as rheumatoid arthritis and systemic lupus erythematosus. This review summarizes the functions and therapeutic prospects of A1AT in autoimmune diseases.

Diagnostic and Prognostic Protein Biomarkers of β-Cell Function in Type 2 Diabetes and Their Modulation with Glucose Normalization

Development of type-2 diabetes(T2D) is preceded by β-cell dysfunction and loss. However, accurate measurement of β-cell function remains elusive. Biomarkers have been reported to predict β-cell functional decline but require validation. Therefore, we determined whether reported protein biomarkers could distinguish patients with T2D (onset < 10-years) from controls. A prospective, parallel study in T2D (n = 23) and controls (n = 23) was undertaken. In T2D subjects, insulin-induced blood glucose normalization from baseline 7.6 ± 0.4 mmol/L (136.8 ± 7.2 mg/dL) to 4.5 ± 0.07 mmol/L (81 ± 1.2 mg/dL) was maintained for 1-h. Controls were maintained at 4.9 ± 0.1 mmol/L (88.2 ± 1.8 mg/dL). Slow Off-rate Modified Aptamer (SOMA) -scan plasma protein measurement determined a 43-protein panel reported as diagnostic and/or prognostic for T2D. At baseline, 9 proteins were altered in T2D. Three of 13 prognostic/diagnostic proteins were lower in T2D: Adiponectin (p < 0.0001), Endocan (p < 0.05) and Mast/stem cell growth factor receptor-Kit (KIT) (p < 0.01). Two of 14 prognostic proteins [Cathepsin-D (p < 0.05) and Cadherin-E (p < 0.005)], and four of 16 diagnostic proteins [Kallikrein-4 (p = 0.001), Aminoacylase-1 (p = 0.001), Insulin-like growth factor-binding protein-4 (IGFBP4) (p < 0.05) and Reticulon-4 receptor (RTN4R) (p < 0.001)] were higher in T2D. Protein levels were unchanged following glucose normalization in T2D. Our results suggest that a focused biomarker panel may be useful for assessing β-cell dysfunction and may complement clinical decision-making on insulin therapy. Unchanged post-glucose normalization levels indicate these are not acute-phase proteins or affected by glucose variability.

Expression of Circulating MicroRNAs and Myokines and Interactions with Serum Osteopontin in Type 2 Diabetic Patients with Moderate and Poor Glycemic Control: A Biochemical and Molecular Study

BACKGROUND

Cellular miRNAs are expressed in tissue fluids with sufficient amounts and were identified as potential molecular targets for studying the physiological mechanisms and correlations with many human diseases particularly diabetes. However, molecular-based changes among older adults with diabetes mellitus (DM) are rarely fully elucidated.

AIM

This study is aimed at identifying circulating miRNAs, which hold the potential to serve as biomarkers for the immune-inflammatory changes in older T2D patients with moderate and poor glycemic control status. In addition, the association of both myokines and osteopontin (OPN) levels with circulating miRNAs was identified.

METHODS

A total of 80 subjects aged 20-80 years were invited during the period of October 2017-May 2018 to participate in this descriptive cross-sectional study. All subjects were diagnosed with T2D for more than 5 years. Subjects were grouped based on glycemic control (HbA1c values) into two groups: moderate glycemic control (>7-8% HbA1c, no = 30) and poor glycemic control (>8% HbA1c, no = 50), respectively. Diabetic control parameters, fasting blood sugar (FS), HbA1c, fasting insulin (IF), insulin resistance (IR), HOMA-IR, inflammatory cytokines (IL-6, IL-8, IL-18, IL-23, TNF-α, and CRP), osteopontin, and myokines (adropin and irisin) were estimated by colorimetric and immune ELISA assays, respectively. In addition, real-time RT-PCR analysis was performed to evaluate the expression of circulating miRNAs, miR-146a and miR-144, in the serum of all diabetic subjects.

RESULTS

In this study, T2D patients with poor glycemic control showed a significant increase in the serum levels of IL-6, IL-8, IL-18, IL-23, TNF-α, CRP, and OPN and a reduction in the levels of myokines, adropin and irisin, compared to patients with moderate glycemic control. The results obtained are significantly correlated with the severity of diabetes measured by HbA1c, FS, IF, and HOMA-IR. In addition, baseline expression of miR-146a is significantly reduced and miR-144 is significantly increased in T2D patients with poor glycemic control compared to those with moderate glycemic control. In all diabetic groups, the expression of miR-146a and miR-144 is significantly correlated with diabetic controls, inflammatory cytokines, myokines, and serum levels of OPN. Respective of gender, women with T2D showed more significant change in the expressed miRNAs, inflammatory cytokines, OPN, and serum myokine markers compared to men. ROC analysis identified AUC cutoff values of miR-146a, miR-144, adropin, irisin, and OPN expression levels with considerable specificity and sensitivity which recommends the potential use of adropin, irisin, and OPN as diagnostic biomarkers for diabetes with varying glycemic control status.

CONCLUSION

In this study, molecular expression of certain microRNA species, such as miR-146a and miR-144, was identified and significantly associated with parameters of disease severity, HbA1c, inflammatory cytokines, myokines, and serum osteopontin in T2D patients with moderate and poor glycemic control. The AUC cutoff values of circulating miRNAs, miR-146a and miR-144; myokines, adropin and irisin; and serum OPN were significantly identified by ROC analysis which additionally recommends the potential use of these biomarkers, miR-146a, miR-144, adropin, irisin, and OPN, as diagnostic biomarkers with considerable specificity and sensitivity for diabetes in patients with varying glycemic control status.

Distinct Molecular Signatures of Clinical Clusters in People With Type 2 Diabetes: An IMI-RHAPSODY Study

Type 2 diabetes is a multifactorial disease with multiple underlying aetiologies. To address this heterogeneity, investigators of a previous study clustered people with diabetes according to five diabetes subtypes. The aim of the current study is to investigate the etiology of these clusters by comparing their molecular signatures. In three independent cohorts, in total 15,940 individuals were clustered based on five clinical characteristics. In a subset, genetic (N = 12,828), metabolomic (N = 2,945), lipidomic (N = 2,593), and proteomic (N = 1,170) data were obtained in plasma. For each data type, each cluster was compared with the other four clusters as the reference. The insulin-resistant cluster showed the most distinct molecular signature, with higher branched-chain amino acid, diacylglycerol, and triacylglycerol levels and aberrant protein levels in plasma were enriched for proteins in the intracellular PI3K/Akt pathway. The obese cluster showed higher levels of cytokines. The mild diabetes cluster with high HDL showed the most beneficial molecular profile with effects opposite of those seen in the insulin-resistant cluster. This study shows that clustering people with type 2 diabetes can identify underlying molecular mechanisms related to pancreatic islets, liver, and adipose tissue metabolism. This provides novel biological insights into the diverse aetiological processes that would not be evident when type 2 diabetes is viewed as a homogeneous disease.

Molecular Aspects of Lifestyle and Environmental Effects in Patients With Diabetes: JACC Focus Seminar

Diabetes is characterized as an integrated condition of dysregulated metabolism across multiple tissues, with well-established consequences on the cardiovascular system. Recent advances in precision phenotyping in biofluids and tissues in large human observational and interventional studies have afforded a unique opportunity to translate seminal findings in models and cellular systems to patients at risk for diabetes and its complications. Specifically, techniques to assay metabolites, proteins, and transcripts, alongside more recent assessment of the gut microbiome, underscore the complexity of diabetes in patients, suggesting avenues for precision phenotyping of risk, response to intervention, and potentially novel therapies. In addition, the influence of external factors and inputs (eg, activity, diet, medical therapies) on each domain of molecular characterization has gained prominence toward better understanding their role in prevention. Here, the authors provide a broad overview of the role of several of these molecular domains in human translational investigation in diabetes.

Comparison of Serum Pharmacodynamic Biomarkers in Prednisone-Versus Deflazacort-Treated Duchenne Muscular Dystrophy Boys

Prednisone (Pred) and Deflazacort (Dfz) are commonly used glucocorticoids (GCs) for Duchenne muscular dystrophy (DMD) treatment and management. While GCs are known to delay the loss of ambulation and motor abilities, chronic use can result in onerous side effects, e.g., weight gain, growth stunting, loss of bone density, etc. Here, we use the CINRG Duchenne natural history study to gain insight into comparative safety of Pred versus Dfz treatment through GC-responsive pharmacodynamic (PD) biomarkers. Longitudinal trajectories of SOMAscan® protein data obtained on serum of DMD boys aged 4 to 10 (Pred: n = 7; Dfz: n = 8) were analyzed after accounting for age and time on treatment. Out of the pre-specified biomarkers, seventeen candidate proteins were differentially altered between the two drugs (p < 0.05). These include IGFBP-2 and AGER associated with diabetes complications, and MMP-3 associated with extracellular remodeling. As a follow-up, IGFBP-2, MMP-3, and IGF-I were quantified with an ELISA using a larger sample size of DMD biosamples (Dfz: n = 17, Pred: n = 12; up to 76 sera samples) over a longer treatment duration. MMP-3 and IGFBP-2 validated the SOMAscan® signal, however, IGF-I did not. This study identified GC-responsive biomarkers, some associated with safety, that highlight differential PD response between Dfz and Pred.

Integrating Genetics and the Plasma Proteome to Predict the Risk of Type 2 Diabetes

PURPOSE OF THE REVIEW

Proteins are the central layer of information transfer from genome to phenome and represent the largest class of drug targets. We review recent advances in high-throughput technologies that provide comprehensive, scalable profiling of the plasma proteome with the potential to improve prediction and mechanistic understanding of type 2 diabetes (T2D).

RECENT FINDINGS

Technological and analytical advancements have enabled identification of novel protein biomarkers and signatures that help to address challenges of existing approaches to predict and screen for T2D. Genetic studies have so far revealed putative causal roles for only few of the proteins that have been linked to T2D, but ongoing large-scale genetic studies of the plasma proteome will help to address this and increase our understanding of aetiological pathways and mechanisms leading to diabetes. Studies of the human plasma proteome have started to elucidate its potential for T2D prediction and biomarker discovery. Future studies integrating genomic and proteomic data will provide opportunities to prioritise drug targets and identify pathways linking genetic predisposition to T2D development.

Plasma microRNAs biomarkers in mild cognitive impairment among patients with type 2 diabetes mellitus

Objectives

To assess the potential value of some miRNAs as diagnostic biomarkers for mild cognitive impairment (MCI) among patients with type2 diabetes mellitus (T2DM) and to identify other risk factors for MCI among them.

Methods

This study enrolled 163 adults with T2DM using face to face interview. Cognitive function with its domains was assessed using Adenbrooke’s Cognitive Examination III (ACE III). Lipid profile, glycated hemoglobin, and miR-128, miR-132, miR- 874, miR-134, miR-323, and miR-382 expressions, using quantitative real-time PCR, were assessed.

Results

MCI was detected among 59/163 (36.2%) patients with T2DM. Plasma expression of miR-132 was significantly higher in T2DM patients with MCI compared to those without MCI and to normal cognitive healthy individuals (median = 2, 1.1 and 1.2 respectively, P < 0.05. Logistic regression analysis showed that higher miR-132 expression with adjusted odds ratio (AOR): 1.2 (95% CI 1.0–1.3), female gender (AOR:2.1; 95%CI 1.0–4.3), education below postgraduate (secondary and university education with AOR: 9.5 & 19.4 respectively) were the significant predicting factors for MCI among T2DM patients. Using ROC curve, miR-132 was the only assayed miRNA that significantly differentiates T2DM patients with MCI from those with normal cognition with 72.3% sensitivity, 56.2% specificity, and 63.8% accuracy (P < 0.05). Other studied miRNAs showed lower sensitivity and specificity for detecting MCI among studied T2DM participants.

Conclusion

MCI affects nearly one-third of adult patients with T2DM. A significantly over expression of miR-132 was detected among T2DM with MCI compared to those with normal cognition.

Endocan: A novel biomarker for risk stratification, prognosis and therapeutic monitoring in human cardiovascular and renal diseases

The vascular endothelium is localized at the interface between the blood and surrounding tissues, playing a pivotal role in the maintenance of tissue-fluid homeostasis and in the regulation of host defense, inflammation, vascular tone and remodeling, angiogenesis and haemostasis. The dysfunctional endothelium was shown to be implicated in the pathophysiology of several endothelial-dependent disorders, such as arterial hypertension, coronary artery disease, heart failure and chronic kidney disease, in which it is an early predictor of cardiovascular events. Endocan is a soluble dermatan sulphate proteoglycan mainly secreted by the activated endothelium. It is upregulated by several proinflammatory cytokines and proangiogenic factors and may itself contribute to the inflammatory status. In addition of being a surrogate marker of inflammation and endothelial dysfunction, it seems to be involved in the regulation of several proliferative and neovascularization processes. Therefore, its utility as a biomarker in a wide spectrum of diseases has been increasingly explored. Here, we review the current evidence concerning the role of endocan in several human cardiovascular and renal diseases, where it seems to be a promising biomarker for risk stratification, prognosis and therapeutic monitoring.

Adipokines as key players in β cell function and failure

The growing prevalence of obesity and its related metabolic diseases, mainly Type 2 diabetes (T2D), has increased the interest in adipose tissue (AT) and its role as a principal metabolic orchestrator. Two decades of research have now shown that ATs act as an endocrine organ, secreting soluble factors termed adipocytokines or adipokines. These adipokines play crucial roles in whole-body metabolism with different mechanisms of action largely dependent on the tissue or cell type they are acting on. The pancreatic β cell, a key regulator of glucose metabolism due to its ability to produce and secrete insulin, has been identified as a target for several adipokines. This review will focus on how adipokines affect pancreatic β cell function and their impact on pancreatic β cell survival in disease contexts such as diabetes. Initially, the "classic" adipokines will be discussed, followed by novel secreted adipocyte-specific factors that show therapeutic promise in regulating the adipose-pancreatic β cell axis.

Molecular biomarkers in diabetes mellitus (DM)

Background: Diabetes mellitus (DM) is a growing epidemic metabolic syndrome, which affects near 5.6% of the world's population. Almost 12% of health expenditure is dedicated to this disorder. Discovering and developing biomarkers as a practical guideline with high specificity and sensitivity for the diagnosis, prognosis, and clinical management of DM is one of the subjects of great interest among DM researchers due to the long-lasting asymptomatic clinical manifestation of DM. In this study, we described a recently identified molecular biomarker involved in DM. Methods: This review study was done at the Diabetes Research Center affiliated to Shahid Sadoughi University of Medical Sciences. PubMed, Scopus, Google Scholar, and Web of Science were searched using the following keywords: "diabetes mellitus", "biomarker", "microRNA", "diagnostic tool" and "clinical manifestation." Results: A total of 107 studies were finally included in this review. After evaluating numerous articles, including original, metaanalysis, and review studies, we focused on molecular biomarkers involved in DM diagnosis and management. Conclusion: Increasing interest in biomarkers associated with DM goes back to its role in decreasing diabetes-related morbidity and mortality. This review focused on major molecular biomarkers such as proteomic and microRNA (miRNAs) as novel and interesting DM biomarkers that can help achieve timely diagnosis of DM.

Diabetes-induced Proteome Changes Throughout Development

BACKGROUND

Diabetes Mellitus (DM) is a multisystemic disease involving the homeostasis of insulin secretion by the pancreatic islet beta cells (β-cells). It is associated with hypertension, renal disease, and arterial and arteriolar vascular diseases.

DISCUSSION

The classification of diabetes is identified as type 1 (gene linked β-cell destruction in childhood) and type 2 (late onset associated with β-cell overload and insulin resistance in peripheral tissues. Type 1 diabetes is characterized by insulin deficiency, type 2 diabetes by both insulin deficiency and insulin resistance. The former is a genetically programmed loss of insulin secretion whereas the latter constitutes a disruption of the homeostatic relationship between the opposing activity of β- cell insulin and alpha cell (α-cell) glucagon of the Islets of Langerhans. The condition could also occur in pregnancy, as a prenatal occurring event, possibly triggered by the hormonal changes of pregnancy combined with β-cell overload. This review discusses the molecular basis of the biomolecular changes that occur with respect to glucose homeostasis and related diseases in DM. The underlying link between pancreatic, renal, and microvascular diseases in DM is based on oxidative stress and the Unfolded Protein Response (UPR).

CONCLUSION

Studying proteome changes in diabetes can deepen our understanding of the biomolecular basis of disease and help us acquire more efficient therapies.

Pediatric Clinical Endpoint and Pharmacodynamic Biomarkers: Limitations and Opportunities

Medical research in children typically lags behind that of adult research in both quantity and quality. The conduct of rigorous clinical trials in children can raise ethical concerns because of children's status as a 'vulnerable' population. Moreover, carrying out studies in pediatrics also requires logistical considerations that rarely occur with adult clinical trials. Due to the relatively smaller number of pediatric studies to support evidence-based medicine, the practice of medicine in children is far more reliant upon expert opinion than in adult medicine. Children are at risk of not receiving the same level of benefits from precision medicine research, which has flourished with new technologies capable of generating large amounts of data quickly at an individual level. Although progress has been made in pediatric pharmacokinetics, which has led to safer and more effective dosing, gaps in knowledge still exists when it comes to characterization of pediatric disease and differences in pharmacodynamic response between children and adults. This review highlights three specific therapeutic areas where biomarker development can enhance precision medicine in children: asthma, type 2 diabetes mellitus, and pain. These 'case studies' are meant to update the reader on biomarkers used currently in the diagnosis and treatment of these conditions, and their shortcomings within a pediatric context. Current research on surrogate endpoints and pharmacodynamic biomarkers in the above therapeutic areas will also be described. These cases highlight the current lack in pediatric specific surrogate endpoints and pharmacodynamic biomarkers, as well as the research presently being conducted to address these deficiencies. We finally briefly highlight other therapeutic areas where further research in pediatric surrogate endpoints and pharmacodynamic biomarkers can be impactful to the care of children.

Obstructive Sleep Apnea Exacerbates Glucose Dysmetabolism and Pancreatic β-Cell Dysfunction in Overweight and Obese Nondiabetic Young Adults

PURPOSE

This study aimed to investigate the effects of obstructive sleep apnea (OSA) on the pancreatic β-cells dysfunction and their implications in the glucose dysmetabolism of overweight and obese nondiabetic young adults.

MATERIALS AND METHODS

The cross-sectional analysis included 422 subjects (261 males/161 females) with the mean age of 27.77 ± 7.51 years and average body mass index (BMI) of 34.84 ± 5.69 kg/m². All subjects underwent polysomnography (PSG), oral glucose tolerance-insulin releasing test (OGTT-IRT) and serum glycosylated hemoglobin A1 (HbA1c) measurement. The glucose metabolism and pancreatic β-cell function in relation to measures of OSA were determined adjustment for important confounders such as age and sex.

RESULTS

OSA subjects accounted for 54.91% in the normal glucose tolerance (NGT) group and 72.11% in the prediabetes (preDM) group (P =0.001). HbA1c was the highest in the preDM subjects with severe OSA. In the NGT subjects, the 1-h glucose level significantly elevated with the OSA severity, and the homeostasis model assessment-β (HOMA-β) was negatively related to nocturnal mean SpO₂ (P <0.05). In the preDM subjects, HOMA-β, early phase insulinogenic index (∆I₃₀/∆G₃₀), total area under the curve of insulin in 180 min (AUC-I₁₈₀), and the oral disposition index (DI_O) were the lowest in the severe OSA group. DI_O was associated with higher oxygen desaturation index (ODI) and lower nocturnal mean SpO₂, and AUC-I₁₈₀ was negatively related to TS90 (P <0.05).

CONCLUSION

Our study indicated higher prevalence of OSA in overweight and obese nondiabetic young adults, especially preDM subjects. The impaired glucose tolerance was observed early after glucose intake in the NGT subjects. OSA induces compensatory increase in the pancreatic β-cell function in the NGT subjects, while pancreatic β-cell dysfunction is present in the preDM subjects with severe OSA.

MicroRNA Signatures as Future Biomarkers for Diagnosis of Diabetes States

Diabetes results from the inability of pancreatic islets to maintain blood glucose concentrations within a normal physiological range. Clinical features are usually not observed until islets begin to fail and irreversible damage has occurred. Diabetes is generally diagnosed based on elevated glucose, which does not distinguish between type 1 and 2 diabetes. Thus, new diagnostic approaches are needed to detect different modes of diabetes before manifestation of disease. During prediabetes (pre-DM), islets undergo stress and release micro (mi) RNAs. Here, we review studies that have measured and tracked miRNAs in the blood for those with recent-onset or longstanding type 1 diabetes, obesity, pre-diabetes, type 2 diabetes, and gestational diabetes. We summarize the findings on miRNA signatures with the potential to stage progression of different modes of diabetes. Advances in identifying selective biomarker signatures may aid in early detection and classification of diabetic conditions and treatments to prevent and reverse diabetes.

Cathepsin D improves the prediction of undetected diabetes in patients with myocardial infarction

Background: Newer therapeutic agents for type 2 diabetes mellitus can improve cardiovascular outcomes, but diabetes remains underdiagnosed in patients with myocardial infarction (MI). We sought to identify proteomic markers of undetected dysglycaemia (impaired fasting glucose, impaired glucose tolerance, or diabetes mellitus) to improve the identification of patients at highest risk for diabetes. Materials and methods: In this prospective cohort, 626 patients without known diabetes underwent oral glucose tolerance testing (OGTT) during admission for MI. Proximity extension assay was used to measure 81 biomarkers. Multivariable logistic regression, adjusting for risk factors, was used to evaluate the association of biomarkers with dysglycaemia. Subsequently, lasso regression was performed in a 2/3 training set to identify proteomic biomarkers with prognostic value for dysglycaemia, when added to risk factors, fasting plasma glucose, and glycated haemoglobin A1c. Determination of discriminatory ability was performed in a 1/3 test set. Results: In total, 401/626 patients (64.1%) met the criteria for dysglycaemia. Using multivariable logistic regression, cathepsin D had the strongest association with dysglycaemia. Lasso regression selected seven markers, including cathepsin D, that improved prediction of dysglycaemia (area under the receiver operator curve [AUC] 0.848 increased to 0.863). In patients with normal fasting plasma glucose, only cathepsin D was selected (AUC 0.699 increased to 0.704). Conclusions: Newly detected dysglycaemia, including manifest diabetes, is common in patients with acute MI. Cathepsin D improved the prediction of dysglycaemia, which may be helpful in the a priori risk determination of diabetes as a motivation for confirmatory OGTT.

Noggin levels in nonalcoholic fatty liver disease: the effect of vitamin E treatment

AIM

The evaluation of (a) noggin levels in patients with simple steatosis (SS) vs. nonalcoholic steatohepatitis (NASH) vs. controls, and (b) the effect of combined spironolactone plus vitamin E vs. vitamin E monotherapy on noggin levels in biopsy-proven patients with nonalcoholic fatty liver disease (NAFLD).

METHODS

In the case-control study, 15 patients with SS, 16 with NASH, and 24 controls were included. In the randomized controlled trial, NAFLD patients were assigned to vitamin E (400 IU/d) or spironolactone (25 mg/d) plus vitamin E for 52 weeks.

RESULTS

Noggin levels were lower in SS (5.8 ± 1.5 pmol/l) and NASH (8.7 ± 2.4 pmol/l) patients than in controls (13.7 ± 2.7 pmol/l; p for trend = 0.040), but were similar in SS and NASH patients. After adjustment for potential cofounders, log(noggin) remained different between groups. Log(noggin) levels similarly increased post-treatment in both groups: log(noggin) was not different between groups (p = 0.20), but increased within groups over time (p < 0.001), without a significant group × time interaction (p = 0.62). Log(noggin) significantly increased at month 2 post-treatment (p = 0.008 vs. baseline) and remained stable thereafter.

CONCLUSIONS

Lower noggin levels were observed in NAFLD patients than in controls. Noggin levels increased similarly by either combined low-dose spironolactone plus vitamin E or vitamin E monotherapy.

TRIAL REGISTRATION

NCT01147523.

Aptamer-based search for correlates of plasma and serum water T2: implications for early metabolic dysregulation and metabolic syndrome

Background

Metabolic syndrome is a cluster of abnormalities that increases the risk for type 2 diabetes and atherosclerosis. Plasma and serum water T₂ from benchtop nuclear magnetic resonance relaxometry are early, global and practical biomarkers for metabolic syndrome and its underlying abnormalities. In a prior study, water T₂ was analyzed against ~ 130 strategically selected proteins and metabolites to identify associations with insulin resistance, inflammation and dyslipidemia. In the current study, the analysis was broadened ten-fold using a modified aptamer (SOMAmer) library, enabling an unbiased search for new proteins correlated with water T₂ and thus, metabolic health.

Methods

Water T₂ measurements were recorded using fasting plasma and serum from non-diabetic human subjects. In parallel, plasma samples were analyzed using a SOMAscan assay that employed modified DNA aptamers to determine the relative concentrations of 1310 proteins. A multi-step statistical analysis was performed to identify the biomarkers most predictive of water T₂. The steps included Spearman rank correlation, followed by principal components analysis with variable clustering, random forests for biomarker selection, and regression trees for biomarker ranking.

Results

The multi-step analysis unveiled five new proteins most predictive of water T₂: hepatocyte growth factor, receptor tyrosine kinase FLT3, bone sialoprotein 2, glucokinase regulatory protein and endothelial cell-specific molecule 1. Three of the five strongest predictors of water T₂ have been previously implicated in cardiometabolic diseases. Hepatocyte growth factor has been associated with incident type 2 diabetes, and endothelial cell specific molecule 1, with atherosclerosis in subjects with diabetes. Glucokinase regulatory protein plays a critical role in hepatic glucose uptake and metabolism and is a drug target for type 2 diabetes. By contrast, receptor tyrosine kinase FLT3 and bone sialoprotein 2 have not been previously associated with metabolic conditions. In addition to the five most predictive biomarkers, the analysis unveiled other strong correlates of water T₂ that would not have been identified in a hypothesis-driven biomarker search.

Conclusions

The identification of new proteins associated with water T₂ demonstrates the value of this approach to biomarker discovery. It provides new insights into the metabolic significance of water T₂ and the pathophysiology of metabolic syndrome.

Electronic supplementary material

The online version of this article (10.1186/s40364-018-0143-x) contains supplementary material, which is available to authorized users.

A proteomic signature that reflects pancreatic beta-cell function

AIM

Proteomics has the potential to enhance early identification of beta-cell dysfunction, in conjunction with monitoring the various stages of type 2 diabetes onset. The most routine method of assessing pancreatic beta-cell function is an oral glucose tolerance test, however this method is time consuming and carries a participant burden. The objectives of this research were to identify protein signatures and pathways related to pancreatic beta-cell function in fasting blood samples.

METHODS

Beta-cell function measures were calculated for MECHE study participants who completed an oral glucose tolerance test and had proteomic data (n = 100). Information on 1,129 protein levels was obtained using the SOMAscan assay. Receiver operating characteristic curves were used to assess discriminatory ability of proteins of interest. Subsequent in vitro experiments were performed using the BRIN-BD11 pancreatic beta-cell line. Replication of findings were achieved in a second human cohort where possible.

RESULTS

Twenty-two proteins measured by aptamer technology were significantly associated with beta-cell function/HOMA-IR while 17 proteins were significantly associated with the disposition index (p ≤ 0.01). Receiver operator characteristic curves determined the protein panels to have excellent discrimination between low and high beta-cell function. Linear regression analysis determined that beta-endorphin and IL-17F have strong associations with beta-cell function/HOMA-IR, β = 0.039 (p = 0.005) and β = -0.027 (p = 0.013) respectively. Calcineurin and CRTAM were strongly associated with the disposition index (β = 0.005 and β = 0.005 respectively, p = 0.012). In vitro experiments confirmed that IL-17F modulated insulin secretion in the BRIN-BD11 cell line, with the lower concentration of 10 ng/mL significantly increasing glucose stimulated insulin secretion (p = 0.043).

CONCLUSIONS

Early detection of compromised beta-cell function could allow for implementation of nutritional and lifestyle interventions before progression to type 2 diabetes.

Prioritising Risk Factors for Type 2 Diabetes: Causal Inference through Genetic Approaches

PURPOSE OF THE REVIEW

Causality has been demonstrated for few of the many putative risk factors for type 2 diabetes (T2D) emerging from observational epidemiology. Genetic approaches are increasingly being used to infer causality, and in this review, we discuss how genetic discoveries have shaped our understanding of the causal role of factors associated with T2D.

RECENT FINDINGS

Genetic discoveries have led to the identification of novel potential aetiological factors of T2D, including the protective role of peripheral fat storage capacity and specific metabolic pathways, such as the branched-chain amino acid breakdown. Consideration of specific genetic mechanisms contributing to overall lipid levels has suggested that distinct physiological processes influencing lipid levels may influence diabetes risk differentially. Genetic approaches have also been used to investigate the role of T2D and related metabolic traits as causal risk factors for other disease outcomes, such as cancer, but comprehensive studies are lacking. Genome-wide association studies of T2D and metabolic traits coupled with high-throughput molecular phenotyping and in-depth characterisation and follow-up of individual loci have provided better understanding of aetiological factors contributing to T2D.