UNLABELLED: Finding ways to increase β-cell mass is a key goal of diabetes research. During elevated insulin demand, β-cells turn on endoplasmic reticulum (ER) stress response pathways, and some β-cells enter the cell cy...UNLABELLED: Finding ways to increase β-cell mass is a key goal of diabetes research. During elevated insulin demand, β-cells turn on endoplasmic reticulum (ER) stress response pathways, and some β-cells enter the cell cycle. ER stress response protein activating transcription factor 6 (ATF6α) induces β-cell proliferation, but only in high glucose. The mechanism by which ATF6α increases proliferation, and the reasons for glucose dependence, remain unknown. Here we show that ATF6α activation in mouse and human islet cells increases expression of E2F1, a key cell cycle driver. E2F1 was required for ATF6α-induced proliferation in high glucose. However, E2F1 remained inactive in normal glucose, possibly because retinoblastoma (Rb), a direct E2F1 inhibitor, was in its dephosphorylated, active state. Indeed, inducing Rb phosphorylation by overexpressing cyclin-dependent kinase 4 (CDK4) allowed ATF6α to increase E2F1 activity and β-cell proliferation in normal glucose. E2F1 expression increased in an ATF6α-dependent manner during generalized ER stress by thapsigargin treatment. Importantly, in human β-cells, ATF6α failed to synergize with high glucose to induce proliferation, but the synergy was rescued by adding back CDK6. Taken together, this study establishes a new dual-input β-cell proliferation regulatory mechanism integrating ER load with current glycemic conditions via CDK4/6, in which Rb phosphorylation serves as a glucose sensor that permits ATF6α-driven proliferation. ARTICLE HIGHLIGHTS: Endoplasmic reticulum stress response mediator activating transcription factor 6 (ATF6α) increases pancreatic β-cell proliferation in a glucose-dependent manner, but the mechanism remains unknown. ATF6α activation upregulated mRNA and protein expression of E2F1, a key G1/S phase transition regulator; however, E2F1 activity only increased in high glucose. Glucose dependence of E2F1 activity was mediated by cyclin-dependent kinase 4/6 phosphorylation of retinoblastoma (Rb) protein, derepressing E2F1 in high glucose. Generalized endoplasmic reticulum stressor thapsigargin increased E2F1 abundance in an ATF6-dependent manner. ATF6α increased E2F1 expression in human β-cells and increased human β-cell proliferation when cyclin-dependent kinase 6 (CDK6) was coexpressed.
UNLABELLED: Vascular dysfunction is considered a consequence of diabetes. However, in pancreatic islets, some hemodynamic changes occur before the onset of symptoms. The underlying mechanisms driving islet vascular abnor...UNLABELLED: Vascular dysfunction is considered a consequence of diabetes. However, in pancreatic islets, some hemodynamic changes occur before the onset of symptoms. The underlying mechanisms driving islet vascular abnormalities have not been fully characterized, but islet pericyte dysfunction seems to be an early event in the pathogenesis of type 1 diabetes in humans. It remains to be investigated, however, how abnormal pericyte physiology affects their ability to regulate islet blood flow and vascular permeability. To address this issue, we treated mice with multiple subdiabetogenic doses of the β-cell toxin streptozotocin (STZ; 50 mg/kg) and recorded islet vascular responses when animals developed glucose intolerance but were still not diabetic (average fed glycemia <200 mg/dL). At this stage, pericyte coverage of islet capillaries was abnormal, with capillaries either lacking pericytes or being covered by dysfunctional mural cells, which compromised islet vasomotor responses recorded ex vivo in living pancreas slices. These functional defects interfered with proper regulation of blood flow and compromised islet vascular integrity, because large fluorescent dextrans (500 kDa) could leak from peripheral islet vessels in the exteriorized pancreas of STZ-treated mice. Our study supports that the loss of functional pericyte coverage of islet capillaries is part of a pathogenic process occurring in islets before diabetes onset, associated with a loss of functional β-cell mass and inflammation. ARTICLE HIGHLIGHTS: Pericyte dysfunction is an early event in type 1 diabetes in humans, but how it affects islet microvascular homeostasis in vivo is unknown. We sought to determine whether vascular integrity and blood flow regulation in islets were impaired in a model of partial β-cell loss and inflammation. Islet capillaries lost functional pericyte coverage shortly after low-dose streptozotocin, compromising vascular stability and local control of blood flow. Strategies that preserve vascular niches in islets could be of important therapeutic potential.
UNLABELLED: Hyperglycemia (HG) is a well-established risk factor for secondary osteoporosis, primarily due to suppressed osteoblast activity. While gut microbiota (GM) dysbiosis has been implicated in various diseases, i...UNLABELLED: Hyperglycemia (HG) is a well-established risk factor for secondary osteoporosis, primarily due to suppressed osteoblast activity. While gut microbiota (GM) dysbiosis has been implicated in various diseases, its role in HG-induced osteoporosis remains poorly understood. Here, we demonstrate that HG mice develop low-turnover osteoporosis accompanied by reduced GM diversity. Fecal microbiota transplantation (FMT) from HG mice (GMHG-FMT) induced osteoporosis in recipient mice, independent of blood glucose levels. A depletion of Bifidobacterium pseudolongum was associated with bone loss, whereas supplementation with either microbiota of normoglycemic mice or B. pseudolongum alleviated osteoporosis in HG mice. Both HG and GMHG-FMT recipient mice exhibited elevated serum interleukin-17A (IL-17A) levels, and anti-IL-17A antibody treatment mitigated osteoporosis in the GMHG-FMT model. Furthermore, decanoic acid levels were elevated in the feces of HG mice and the serum of GMHG-FMT recipients. Decanoic acid promoted the differentiation of naive CD4+ T cells into T helper17 cells, leading to increased IL-17A production. These findings reveal a microbiome dysbiosis-driven decanoic acid/IL-17A axis in HG-induced osteoporosis and highlight the therapeutic potential of microbiome-associated targets. ARTICLE HIGHLIGHTS: This study investigated the role of gut microbiota dysbiosis in hyperglycemia-induced osteoporosis, a condition with unclear mechanisms. We explored whether gut microbiota dysbiosis drives bone loss in hyperglycemia and identified key microbial and molecular pathways. Hyperglycemic mice showed disturbed gut microbiota symbiosis, decreased Bifidobacterium pseudolongum, and elevated decanoic acid, which promoted T helper 17 differentiation and interleukin-17A (IL-17A) production, leading to osteoporosis. Fecal microbiota transplantation from control mice, B. pseudolongum supplementation, and IL-17A blockade alleviated bone loss, highlighting both B. pseudolongum supplementation and IL-17A inhibition as potential therapeutic strategies for hyperglycemia-induced osteoporosis.
UNLABELLED: Maternal obesity is a known risk factor for metabolic dysfunction in offspring; however, its effect on metabolism during pregnancy in female offspring remains unclear. This study investigated how maternal obe...UNLABELLED: Maternal obesity is a known risk factor for metabolic dysfunction in offspring; however, its effect on metabolism during pregnancy in female offspring remains unclear. This study investigated how maternal obesity, induced by high-fat (HF) feeding in C57BL/6J mice, affects the metabolic adaptation to pregnancy in female offspring. Dams were fed an HF diet (60% fat) or chow for 3 months before and during pregnancy. Offspring of HF diet-fed dams (OF-HFD) exhibited reduced fetal growth, followed by rapid postnatal catch-up and increased adult adiposity, compared with offspring of chow-fed dams (OF-CD), despite having similar baseline glucose and insulin levels. During pregnancy, OF-HFD exhibited diminished increases in maternal body fat, blood triglycerides, and insulin concentrations, accompanied by glucose intolerance. In cultured islets, glucose-stimulated insulin secretion was markedly reduced in pregnant OF-HFD, despite unchanged β-cell mass or proliferation. Hepatic triglyceride secretion was decreased, whereas liver insulin signaling was enhanced, suggesting alterations in lipid and glucose metabolism. Feeding OF-HFD an HF diet before and during pregnancy further impaired fetal growth. These findings indicate that maternal obesity impairs the metabolic adaptation to pregnancy in female offspring, characterized by insulin insufficiency and disrupted lipid homeostasis. This may initiate a transgenerational cycle of metabolic dysfunction, potentially increasing the risk of gestational diabetes in subsequent generations. Our findings underscore the need for more research to explore these mechanisms in humans and develop strategies to reduce the long-term effects of maternal obesity. ARTICLE HIGHLIGHTS: Maternal high-fat (HF) diet induces adiposity in first-generation (F1) female offspring, impairing metabolic adaptations during pregnancy. F1 offspring from HF diet-fed dams show diminished fat gain and reduced serum triglycerides, disrupting nutrient availability for fetal growth. Impaired insulin production in F1 pregnancy leads to glucose intolerance, driven by reduced insulin secretion despite normal β-cell mass. Unlike male offspring, F1 females exhibit resistance to fat expansion under HF diet challenge, suggesting sex-specific programming. These findings underscore a transgenerational cycle of metabolic dysfunction, highlighting the need for interventions against maternal obesity.
UNLABELLED: Type 1 diabetes (T1D) is characterized by autoimmune destruction of insulin-producing β-cells. Recent evidence has implicated hybrid insulin peptides (HIPs) as targets of autoreactive CD4 T cells in human T1D...UNLABELLED: Type 1 diabetes (T1D) is characterized by autoimmune destruction of insulin-producing β-cells. Recent evidence has implicated hybrid insulin peptides (HIPs) as targets of autoreactive CD4 T cells in human T1D patients and as critical autoantigens recognized by diabetogenic T cells in nonobese diabetic (NOD) mice. HIPs form within pancreatic islets through cross-linking reactions between proinsulin fragments and various β-cell peptides. In the NOD mouse model, highly pathogenic CD4 T cells specifically target HIPs generated through transpeptidation mediated by cathepsin D (CatD). These disease-relevant HIPs consistently incorporate a C-peptide fragment terminating in a critical leucine residue that binds to other β-cell peptides. In vitro experiments demonstrated that substituting isoleucine for this leucine residue in human C-peptide inhibited CatD-mediated HIP formation. To investigate the in vivo significance of this finding, we engineered NOD mice carrying a leucine-to-isoleucine mutation in the insulin 2 gene (NOD INS2I/I). Mass spectrometric analysis revealed significantly reduced HIP formation in islets from NOD INS2I/I mice. Significantly decreased activation of HIP-reactive T cells to islets from these mice was also observed. Furthermore, the NOD INS2I/I mice showed significantly delayed diabetes onset, with 43% remaining disease-free at 1 year compared with only 10% of wild-type NOD controls. These findings implicate HIPs as key mediators in T1D pathogenesis and demonstrate that targeted disruption of HIP formation significantly alters disease progression. Inhibiting CatD-mediated transpeptidation represents a promising therapeutic approach for preventing or delaying T1D onset in genetically susceptible individuals. ARTICLE HIGHLIGHTS: Hybrid insulin peptides (HIPs) have been identified as targets of autoreactive T cells in type 1 diabetes, although their causal role in disease pathogenesis has remained unclear. We demonstrated that a single leucine-to-isoleucine substitution in insulin C-peptide significantly disrupts cathepsin D-mediated HIP formation in nonobese diabetic (NOD) mouse islets. NOD mice engineered with this precise modification (NOD INS2I/I) showed significantly reduced HIP content, decreased T-cell reactivity, and significantly delayed diabetes onset (43% disease-free at 1 year vs. 10% in controls). These findings establish a mechanistic link between HIP formation and disease progression, revealing cathepsin D-mediated transpeptidation as a potential therapeutic target for intervention in at-risk individuals.
The control of muscle glucose uptake (MGU) is distributed across delivery, transport, and phosphorylation of glucose. These steps have been defined as control points of MGU in vivo due to the application of isotopic trac...The control of muscle glucose uptake (MGU) is distributed across delivery, transport, and phosphorylation of glucose. These steps have been defined as control points of MGU in vivo due to the application of isotopic tracer techniques to transgenic mouse models. Using these techniques in a classic study published in Diabetes, Fueger et al. demonstrated that overexpression in skeletal muscle of hexokinase II (HKII), the enzyme responsible for intracellular glucose phosphorylation, enhanced MGU in insulin-sensitive but not in insulin-resistant mice. Conversely, HKII overexpression enhanced MGU in insulin-resistant mice in response to exercise. Since exercise reduces barriers of glucose delivery and transport, this suggested that these two processes contribute to the dysregulation of MGU in insulin-resistant states. These fundamental findings have spurred subsequent studies highlighting the contribution of glucose delivery and transport to the regulation of MGU in health and disease.
Brøns C, Elingaard-Larsen LO, Justesen L
… +12 more, Villumsen SO, Thuesen ACB, Engelhard LM, Gertsen SS, Ried-Larsen M, Prasad RB, Hansen T, Danielsen ER, van Hall G, Sparks LM, López-Andrés N, Vaag A
UNLABELLED: Low birth weight (LBW) is a risk factor for type 2 diabetes (T2D). We hypothesized that 4 weeks of carbohydrate overfeeding (COF) with +25% energy would unmask key T2D perturbations among 22 nonobese LBW men,...UNLABELLED: Low birth weight (LBW) is a risk factor for type 2 diabetes (T2D). We hypothesized that 4 weeks of carbohydrate overfeeding (COF) with +25% energy would unmask key T2D perturbations among 22 nonobese LBW men, including five with screen-detected metabolic dysfunction-associated steatotic liver disease (MASLD), compared with 21 healthy control participants with normal birth weight (NBW). Body weight, lean and fat mass, and hepatic fat content increased to the same extent in both groups during COF, whereas fasting glucose and insulin resistance increased significantly more in LBW compared with NBW participants. The differential COF responses were most pronounced in LBW participants without MASLD, including increased resting energy expenditure. Plasma adiponectin was lower, whereas fibroblast growth factor 21 levels increased more during COF in LBW participants. Subcutaneous adipose tissue (SAT) density was lower in LBW participants and decreased during COF in both groups. Serum alanine, phosphatidylcholines, and triglycerides increased significantly more in LBW participants during COF. Multiomics analysis of SAT RNA sequencing, serum lipidomics, and metabolomics uncovered impaired peroxisome proliferator-activated receptor signaling as well as aberrant collagen and extracellular matrix regulation in LBW participants. The results document differential and MASLD-independent metabolic perturbations in LBW participants during COF. ARTICLE HIGHLIGHTS: Individuals with low birth weight (LBW) are at increased risk of type 2 diabetes. Four weeks of carbohydrate overfeeding (COF) was associated with differential elevations in fasting glucose, lipids, alanine, insulin resistance, and resting energy expenditure in LBW participants versus control participants. Multiomics analyses indicated reduced peroxisome proliferator-activated receptor signaling, as well as differential expression of genes involved in collagen and extracellular matrix metabolism in LBW participants during COF. Interestingly, the COF perturbations in LBW participants became more pronounced when excluding five LBW men with screen-detected metabolic dysfunction-associated steatotic liver disease. The findings support the notion of unhealthy subcutaneous adipose tissue expandability potentially underlying a reduced metabolic buffering capacity in nonobese LBW men.
UNLABELLED: Adipocyte size is linked to insulin resistance and the risk of developing type 2 diabetes. We aimed to generate a surrogate method to estimate adipocyte size by measuring adipose tissue gene expression using...UNLABELLED: Adipocyte size is linked to insulin resistance and the risk of developing type 2 diabetes. We aimed to generate a surrogate method to estimate adipocyte size by measuring adipose tissue gene expression using quantitative real-time PCR (qRT-PCR), which could be used alongside systemic measures of insulin sensitivity to predict type 2 diabetes risk. We examined the relationship of 40,591 genes with abdominal subcutaneous adipocyte size in 132 adults and validated the findings in additional cohorts with available transcriptomic and adipocyte size data. qRT-PCR analysis of gene expression in abdominal adipose tissue biopsies was used to develop a standardized adipocyte size estimate. This estimate was compared alongside systemic and adipose insulin sensitivity measures, including adipocyte lipogenesis, hyperinsulinemic-euglycemic clamp, adipose insulin resistance, and HOMA. Transcriptome-wide analyses found that UCHL1 gene expression strongly correlated with adipocyte size, independent of other genes and additional cofactors, such as insulin resistance (β-coefficient 0.32; P = 0.002). Using qRT-PCR, UCHL1 expression accurately estimated adipocyte size across a wide range of adipocyte volumes with high precision (receiver operating characteristic area under the curve 0.94) and showed strong correlations with all insulin sensitivity measures (adjusted r2 = 0.2-0.6; P < 0.0001). We scaled the measurement of UCHL1 expression to 25-mg adipose biopsies and provided a standard operating procedure for routinely estimating adipocyte size. In summary, we provide a simple, accurate, and accessible surrogate measure to estimate an individual's adipocyte size, which may be useful in clinical insulin resistance studies. ARTICLE HIGHLIGHTS: Adipocyte size is linked to insulin resistance and the risk of developing type 2 diabetes. A surrogate method was generated to estimate adipocyte size by measuring adipose tissue gene expression using quantitative real-time PCR. UCHL1 expression was found to correlate across a wide range of adipocyte cell volumes (38-1,420 pL) and to strongly and independently correlate with measured adipocyte volume when examined alongside measures for insulin resistance. Clinicians can use this method to estimate adipocyte size from an adipose tissue needle biopsy and routine quantitative real-time PCR measurement using the provided equation and methodological framework.
UNLABELLED: Diabetes currently affects ∼37 million adults in the U.S. and 537 million people worldwide, with type 2 diabetes (T2D) accounting for 90%-95% of the diabetes burden. The transition from normal glucose regulat...UNLABELLED: Diabetes currently affects ∼37 million adults in the U.S. and 537 million people worldwide, with type 2 diabetes (T2D) accounting for 90%-95% of the diabetes burden. The transition from normal glucose regulation (NGR) to T2D is via an intermediate stage of prediabetes, characterized by impaired fasting glucose (IFG) and impaired glucose tolerance (IGT). Prediabetes affects ∼98 million adults in the U.S.; worldwide, more than 541 million adults have IGT and 319 million adults have IFG. Prediabetes is associated with increased risks of developing vascular and neuropathic complications, besides the risk of progression to T2D. Discussed herein are the demographic, anthropometric, biobehavioral, biochemical, and molecular factors associated with the transition from NGR to prediabetes. The natural history of prediabetes predicts time-dependent progression to T2D, as sustained recovery from prediabetes is uncommon without intervention. Lifestyle modification and certain medications interrupt the progression to T2D and may restore NGR. The landmark intervention trials are discussed, with an interpretive focus on their limitations and the need for novel approaches for durable reversal of prediabetes. ARTICLE HIGHLIGHTS: Prediabetes, an intermediate stage in the pathogenesis of type 2 diabetes (T2D), affects ∼98 million U.S. adults and >800 million people worldwide. Prediabetes shares common pathophysiological mechanisms with T2D and progresses to T2D at variable rates based on risk factor burden. Less well studied is the initial transition from normoglycemia to prediabetes. Discussed herein are behavioral, clinical, biochemical, and molecular factors associated with development of prediabetes. Current approaches to prediabetes management are discussed, with an interpretive focus on their limitations and the need for novel interventions for durable reversal of prediabetes and avoidance of related complications.
UNLABELLED: Diabetic kidney disease (DKD) progression involves NIMA-related kinase 7 (NEK7)-driven podocyte pyroptosis, with hyperglycemia-induced O-GlcNAcylation as a key posttranslational regulator. This study elucidat...UNLABELLED: Diabetic kidney disease (DKD) progression involves NIMA-related kinase 7 (NEK7)-driven podocyte pyroptosis, with hyperglycemia-induced O-GlcNAcylation as a key posttranslational regulator. This study elucidates how O-GlcNAc modification governs NEK7 stability and its pathological role. We used clinical DKD specimens, high-glucose-stimulated podocytes, and streptozotocin-induced diabetic mice to first examine NEK7, O-GlcNAc, O-GlcNAc transferase (OGT), and glutamine fructose-6-phosphate amidotransferase 1 (GFPT1) expression, confirming the pyroptosis role of NEK7 via siRNA knockdown. Bioinformatic analysis predicted O-GlcNAcylation motifs, validated by T302A mutagenesis and coimmunoprecipitation. Protein stability was assessed using cycloheximide chase and ubiquitination assays. Therapeutic efficacy of the GFPT1 inhibitor (6-diazo-5-oxo-l-norleucine) DON was evaluated in vitro and in vivo through biochemical parameters, histopathology, and pyroptosis markers. Chronic hyperglycemia activated the hexosamine biosynthetic pathway (HBP), elevating pathology-associated O-GlcNAc modifications that promoted NEK7 accumulation via posttranslational stabilization. This was accompanied by upregulated O-GlcNAc, OGT, and GFPT1 in DKD glomeruli and high-glucose podocytes. Crucially, threonine 302 was identified as the primary O-GlcNAcylation site of NEK7. This modification reduced proteasomal degradation, extended NEK7 half-life, and enhanced NLRP3 inflammasome activation and interleukin release. Pharmacological HBP inhibition using DON normalized O-GlcNAcylation, suppressed pyroptosis, and mitigated renal injury. We report the discovery of the glucose/O-GlcNAc/NEK7/NLRP3 axis driving podocyte pyroptosis in DKD, proposing threonine 302 as a potential therapeutic target. These findings establish a novel posttranslational modification mechanism and suggest a dual-target therapeutic strategy for DKD management. ARTICLE HIGHLIGHTS: We identify threonine 302 as the critical O-GlcNAcylation site on NIMA-related kinase 7 (NEK7), which stabilizes NEK7 by inhibiting its proteasomal degradation, thereby enhancing NLRP3 inflammasome activation and podocyte pyroptosis in diabetic kidney disease (DKD). Chronic hyperglycemia activates the hexosamine biosynthetic pathway (HBP), driving pathological O-GlcNAcylation and significant upregulation of NEK7, O-GlcNAc transferase, and glutamine fructose-6-phosphate amidotransferase 1 in glomeruli from patients with DKD and experimental models. This study establishes the discovery of the pathogenic glucose/O-GlcNAc/NEK7/NLRP3 signaling axis, identifying a novel posttranslational mechanism driving podocyte loss in DKD progression. Pharmacological inhibition of the HBP with 6-diazo-5-oxo-l-norleucine normalizes O-GlcNAcylation, suppresses NEK7-driven pyroptosis, and mitigates renal injury, demonstrating the therapeutic potential of targeting threonine 302, NEK7, or the HBP for DKD management.
UNLABELLED: Somatostatin is a powerful inhibitor of insulin secretion and β-cell electrical activity, but the effects are weak in intact islets, possibly because of high intraislet somatostatin levels. We used optogeneti...UNLABELLED: Somatostatin is a powerful inhibitor of insulin secretion and β-cell electrical activity, but the effects are weak in intact islets, possibly because of high intraislet somatostatin levels. We used optogenetics in conjunction with hormone secretion measurements, electrophysiology, and cytoplasmic free Ca2+ concentration ([Ca2+]i) imaging to interrogate the relative roles of paracrine and electrical control of β-cells by δ-cells. We confirm that optoactivation and optoinhibition of δ-cells stimulated and inhibited their electrical activity and somatostatin secretion, respectively. Unexpectedly, neither optoactivation nor optoinhibition of δ-cells had any effect on insulin secretion at 1 or 20 mmol/L glucose. Paradoxically, optoactivation of δ-cells at 6 mmol/L glucose increased insulin secretion by 113%, an effect that correlated with β-cell action potential firing. In [Ca2+]i imaging experiments, optoactivation of δ-cells induced islet-wide β-cell [Ca2+]i transients and synchronized the oscillatory pattern induced by 7 mmol/L glucose. Conversely, optoinhibition of δ-cells and somatostatin secretion reduced rather than increased β-cell electrical activity and [Ca2+]i in the <10% of β-cells situated <20 µm from δ-cells. We propose that δ-cells, in addition to subserving an inhibitory paracrine effect, play a role in the rapid propagation of electrical signals across the islet, possibly contributing to the coordination of β-cell activity. ARTICLE HIGHLIGHTS: Optical activation or δ-cells stimulate somatostatin secretion. δ-Cell depolarization evokes β-cell action potential firing and insulin release. δ-Cell activation results in islet-wide synchronized β-cell cytoplasmic free Ca2+ concentration increases. δ-Cell inhibition aborts cytoplasmic free Ca2+ concentration oscillations in β-cell neighbors.
UNLABELLED: Accurate prediction of diabetic kidney disease progression is challenging, but mandatory. Urinary Dickkopf-3 (uDKK3), a tubular, epithelial-derived glycoprotein and marker of tubular injury, is a promising bi...UNLABELLED: Accurate prediction of diabetic kidney disease progression is challenging, but mandatory. Urinary Dickkopf-3 (uDKK3), a tubular, epithelial-derived glycoprotein and marker of tubular injury, is a promising biomarker for kidney function decline. We explored the clinical utility of uDKK3 to predict kidney function decline and adverse cardiovascular events in patients with type 2 diabetes mellitus (T2DM) in a primary health care setting. In this cohort study, 3,232 patients with T2DM were analyzed. The primary end point was a composite of a sustained estimated glomerular filtration rate (eGFR) decline ≥40%; a sustained increase in albuminuria of at least 30%, including a transition in albuminuria class; progression to end-stage kidney disease; and death from kidney failure. After adjustment for confounding variables, uDKK3 values >200 pg/mg creatinine were associated with a higher risk of the composite kidney end point during a median follow-up of 4.26 years. Furthermore, uDKK3 improved the prediction of the 1-year eGFR decline on top of albuminuria. Individuals with high uDKK3 levels also had an increased risk for adverse cardiovascular events and all-cause mortality. uDKK3 identifies patients with T2DM at high risk for kidney function decline on top of established biomarkers (albuminuria and eGFR). In primary care, uDKK3 may help to identify high-risk patients who might benefit from intensified treatment and/or referrals to specialists. ARTICLE HIGHLIGHTS: Prediction of kidney function decline is challenging in patients with type 2 diabetes mellitus (T2DM). Urinary Dickkopf-3 (uDKK3), a profibrotic tubular protein, is a promising biomarker for detecting tubular injury and predicting the progression of chronic kidney disease. This study assessed whether uDKK3 measurements improve risk prediction in patients with T2DM treated at the primary care level. Elevated uDKK3 levels were associated with kidney function decline, on top of established biomarkers (estimated glomerular filtration rate and albuminuria). uDKK3 also identified patients at increased risk for cardiovascular events. uDKK3 may help identify high-risk patients in primary care who could benefit from intensified treatment and/or referrals to specialists.
UNLABELLED: An intrinsic hallmark of type 1 diabetes is the correlation between appearance of autoantibodies directed against islet cell autoantigens with subsequent development of the disease. We recently studied effect...UNLABELLED: An intrinsic hallmark of type 1 diabetes is the correlation between appearance of autoantibodies directed against islet cell autoantigens with subsequent development of the disease. We recently studied effects of human monoclonal autoantibodies (mAbs) derived from a patient with prediabetes and demonstrated that a GAD65mAb penetrated and accumulated in β-cells and significantly reduced the insulin secretion rate (ISR). Accordingly, in the current study, we performed more detailed analyses of the effects of this GAD65mAb on rat and human islets. ISR was suppressed by ∼40% after 3 days of exposure. Mechanisms mediating the effects were found to involve inhibition of mitochondrial generation of ATP, which decreased in parallel with that of ISR. As expected, the GAD65mAb inhibited γ-aminobutyric acid secretion. The effects of GAD65mAb were observed in rat and human islets but not in mouse islets, which do not express GAD65. GAD65mAb also reduced insulin secretion in vivo, where decreased insulin levels after intraperitoneal (i.p.) injection of glucose were observed in rats after i.p. injection of GAD65mAb. Thus, it appears that an islet cell autoantibody against GAD65 can directly impact and impair secretory function in islets in vitro and in vivo through a mechanism that involves inhibition of mitochondrial energetics. ARTICLE HIGHLIGHTS: This study was undertaken to further investigate the ability of a monoclonal autoantibody to GAD65 from a patient with pre-type 1 diabetes to be deleterious to islet function. The study was designed to further characterize the effects, understand the mechanism mediating the effects, and demonstrate that the effects were operational in vivo. The effects of the GAD65 monoclonal antibody reduced ATP, γ-aminobutyric acid secretion, and insulin secretion with a similar time course and concentration dependency, which appeared to be mediated by effects on mitochondrial energetics and were similar in vivo in rats as in vitro. These findings raise the possibility that autoantibodies could play a pathogenic role in the development of type 1 diabetes.