Hepatic non-parenchymal S100A9-TLR4-mTORC1 axis normalizes diabetic ketogenesis.

Unrestrained ketogenesis leads to life-threatening ketoacidosis whose incidence is high in patients with diabetes. While insulin therapy reduces ketogenesis this approach is sub-optimal. Here, we report an insulin-independent pathway able to normalize diabetic ketogenesis. By generating insulin deficient male mice lacking or re-expressing Toll-Like Receptor 4 (TLR4) only in liver or hepatocytes, we demonstrate that hepatic TLR4 in non-parenchymal cells mediates the ketogenesis-suppressing action of S100A9. Mechanistically, S100A9 acts extracellularly to activate the mechanistic target of rapamycin complex 1 (mTORC1) in a TLR4-dependent manner. Accordingly, hepatic-restricted but not hepatocyte-restricted loss of Tuberous Sclerosis Complex 1 (TSC1, an mTORC1 inhibitor) corrects insulin-deficiency-induced hyperketonemia. Therapeutically, recombinant S100A9 administration restrains ketogenesis and improves hyperglycemia without causing hypoglycemia in diabetic mice. Also, circulating S100A9 in patients with ketoacidosis is only marginally increased hence unveiling a window of opportunity to pharmacologically augment S100A9 for preventing unrestrained ketogenesis. In summary, our findings reveal the hepatic S100A9-TLR4-mTORC1 axis in non-parenchymal cells as a promising therapeutic target for restraining diabetic ketogenesis.

Association Between Lactates, Blood Glucose, and Systemic Oxygen Delivery in Children After Cardiopulmonary Bypass.

Objective: Lactate is often used as a surrogate marker of inappropriate oxygen delivery. It has been shown that hyperlactatemia is associated with worse clinical outcome in children after cardiac surgery. The purpose of this study is to evaluate the association of hyperlactatemia, low systemic oxygen delivery, and hyperglycemia, in children admitted to the pediatric critical care unit after cardiopulmonary bypass. Design: Secondary analysis of an observational cohort study. Setting: Tertiary pediatric critical care unit (PICU). Patients: Ninety-three patients, aged 6 months to 16 years, undergoing cardiac surgery with cardiopulmonary bypass. Interventions: None. Measurements and Main Results: Metabolic tests (blood glucose, lactate, lactate/pyruvate ratio, and ketones) and oxygen extraction (SaO2-SvO2) were performed before anesthesia, at the end of cardiopulmonary bypass, at PICU admission, and at 4 and 12 h after PICU admission. Four hours after PICU admission, 62% of the patients had hyperlactatemia (>2 mmol/L), of whom 55% had normal oxygen extraction (SaO2-SvO2 < 30%). There was no correlation between lactate and oxygen extraction (R = -0.09, p = 0.41) but there was a moderate correlation between lactate and blood glucose (R = 0.55, p < 0.001). Using a logistic regression model, hyperlactatemia at 4 h after PICU admission was independently associated with hyperglycemia (p = 0.007) and lactate/pyruvate ratio (p = 0.007) at the same timepoint, as well as with lactate at PICU admission (p = 0.002), but not with weight (p = 0.45), severity of the cardiac lesion (p = 0.85), duration of bypass (p = 0.16), or oxygen extraction, as evaluated by SaO2-SvO2 (p = 0.54). At 12 h after PICU admission, there was a very week correlation between lactate and blood glucose (R = 0.27, p = 0.007), but none between lactate and oxygen extraction (R = 0.13, p = 0.20). Conclusion: In children after cardiopulmonary bypass, lactates are not correlated with higher oxygen extraction, but are correlated with hyperglycemia, at both 4 and 12 h after PICU admission. Future research is warranted to better define this relationship.

Global Inequality in Type 1 Diabetes: a Comparison of Switzerland and Low-and Middle-Income Countries.

Globally it is estimated that over 1 million children and adolescents have Type 1 diabetes with large variations in incidence between different contexts. Health systems need to provide a variety of elements to ensure appropriate diabetes care, such as service delivery; healthcare workforce; information; medical products and technologies; financing and leadership and governance. Describing these elements between Geneva, Switzerland, a high-income country with high spending on healthcare and a large density of doctors, and low- and middle-income countries this article aims to highlight the global inequality of diabetes care. Type 1 diabetes can serve as a litmus as we move towards the centenary of the discovery of insulin and beyond as there is a need for a global movement to ensure that innovation in the management of diabetes benefits the whole diabetes community and not just a select few.

Systematic Genetic Study of Youth With Diabetes in a Single Country Reveals the Prevalence of Diabetes Subtypes, Novel Candidate Genes, and Response to Precision Therapy.

Identifying gene variants causing monogenic diabetes (MD) increases understanding of disease etiology and allows for implementation of precision therapy to improve metabolic control and quality of life. Here, we aimed to assess the prevalence of MD in youth with diabetes in Lithuania, uncover potential diabetes-related gene variants, and prospectively introduce precision treatment. First, we assessed all pediatric and most young-adult patients with diabetes in Lithuania (n = 1,209) for diabetes-related autoimmune antibodies. We then screened all antibody-negative patients (n = 153) using targeted high-throughput sequencing of >300 potential candidate genes. In this group, 40.7% had MD, with the highest percentage (100%) in infants (diagnosis at ages 0-12 months), followed by those diagnosed at ages >1-18 years (40.3%) and >18-25 years (22.2%). The overall prevalence of MD in youth with diabetes in Lithuania was 3.5% (1.9% for GCK diabetes, 0.7% for HNF1A, 0.2% for HNF4A and ABCC8, 0.3% for KCNJ11, and 0.1% for INS). Furthermore, we identified likely pathogenic variants in 11 additional genes. Microvascular complications were present in 26% of those with MD. Prospective treatment change was successful in >50% of eligible candidates, with C-peptide >252 pmol/L emerging as the best prognostic factor.

An Intervention by a Patient-Designed Do-It-Yourself Mobile Device App Reduces HbA1c in Children and Adolescents with Type 1 Diabetes: A Randomized Double-Crossover Study.

BACKGROUND: Prevention of type 1 diabetes mellitus (T1DM)-related complications is dependent on metabolic control. The recommended glycated hemoglobin (HbA1c) values <7.5% (58.5 mmol/mol) are met only by a minority of diabetic children and especially adolescents. The aim of this study was to evaluate the impact of an intervention comprising the use of Webdia, a patient-designed app for smartphones, on metabolic control of T1DM in children. METHODS: Fifty-five patients with T1DM, 10-18 years of age, were included in this single-center, randomized double-crossover study. We tested an intervention consisting of using Webdia for 3 months with monthly feedback and adaptation of the treatment. Main outcome was modification of HbA1c. Secondary outcomes were the prevalence of hypoglycemia and quality of life (QoL). RESULTS: Of the 55 included patients, 33 completed the study, 9 dropped out, and 13 were excluded due to insufficient use of the app. The app was well accepted by the users who completed the study (46.4% rated the program as good and 39.3% as excellent). The intervention led to a reduction of HbA1c by 0.33%, compared to the control group in which HbA1c rose by 0.21% (P = 0.048) in patients with HbA1c values >8.0% (63.9 mmol/mol) at inclusion, without increasing the prevalence of hypoglycemia (8.52 ± 9.45 hypoglycemic events during last 2 weeks of intervention vs. 7.62 ± 6.37 observation, P = 0.680). QoL scores were not modified. CONCLUSIONS: The intervention resulted in a significant decrease in HbA1c, without increasing the prevalence of hypoglycemia in patients with initial HbA1c >8.0% (63.9 mmol/mol).

Accuracy, satisfaction and usability of a flash glucose monitoring system among children and adolescents with type 1 diabetes attending a summer camp.

BACKGROUND: The study aimed to assess accuracy, satisfaction and usability of a flash glucose monitoring system (FGM) in children and adolescents with type 1 diabetes mellitus (T1DM) attending a diabetes summer camp. METHODS: Sixty-six children and adolescents with T1DM aged 6 to 17 years participating in a 7-day medically supervised summer camp were enrolled. Capillary blood glucose (BG) and flash glucose (FG) values were measured simultaneously at breakfast, lunch, and dinner and for any given FG value <72 mg/dL (<4.0 mmol/L) during daytime, <108 mg/dL (<6.0 mmol/L) at nighttime, >270 mg/dL (>15.0 mmol/L) or when patient symptoms were discordant with sensor readings. Sensor-related issues were documented and patients' and healthcare professionals' (HCPs) satisfaction was evaluated. RESULTS: FGM demonstrated satisfactory clinical accuracy compared to reference capillary BG values with 98.8% of values falling within the clinically acceptable zones (A and B) of the consensus error grid. Overall mean absolute relative difference (MARD) was 16.7% ± 16.1%. Specific calculations of mean absolute difference (MAD), mean relative difference (MRD), and mean difference (MD) demonstrated that FGM overestimated BG values across all glycemic ranges. Overall satisfaction with the FGM was high in 91.7% participants and 95.0% HCPs, although confidence in the system was low in 18.0% participants and 40.0% HCPs. CONCLUSIONS: The FGM exhibited satisfactory clinical accuracy. However, based on the present data, we conclude that no decision should be taken on the basis of a single, non-verified, FGM value alone. Our study highlights the need for revised therapeutic education for patients/families and further investigation on the integration of sensor readings in clinical decision-making.

Combined Pancreatic Islet-Lung-Liver Transplantation in a Pediatric Patient with Cystic Fibrosis-Related Diabetes.

BACKGROUND: Cystic fibrosis-related diabetes (CFRD) is the most frequent extrapulmonary complication of cystic fibrosis (CF). METHODS: We report the first combined pancreatic islet-lung-liver transplantation in a 14-year-old adolescent. CFTR was analyzed by Sanger sequencing. Further genes were analyzed by high-throughput sequencing. RESULTS: The patient was diagnosed with CF at the age of 14 months. Nine years later, after diagnosis of CFRD, the patient's BMI and lung function began to decline. Bilateral lung transplantation with simultaneous liver transplantation was performed at the age of 14.5 years. The first islet transplantation (IT) was carried out 10 days later. Six months later, C-peptide secretion after arginine stimulation showed peak values of 371 pmol/L (vs. 569 pmol/L before IT) and insulin doses had slightly increased (1.40 vs. 1.11 units/kg/day before IT). A second IT was performed at the age of 15 years, a third at 16 years. Two years after the first IT, arginine-stimulated C-peptide secretion increased to 2,956 pmol/L and insulin doses could be reduced to 0.82 units/kg/day. HbA1c decreased from 7.3% (57.4 mmol/mol) to 5.9% (41.0 mmol/mol). CONCLUSION: IT following lung and liver transplantation, with injection of islets into a transplanted organ, is feasible. It improves C-peptide secretion, decreases insulin needs, and lowers HbA1c.

Activation of Nicotinic Acetylcholine Receptors Decreases Apoptosis in Human and Female Murine Pancreatic Islets.

Type 1 diabetes (T1DM) results from destruction of most insulin-secreting pancreatic ß-cells. The persistence of ß-cells decades after the onset of the disease indicates that the resistance of individual cells to the autoimmune insult is heterogeneous and might depend on the metabolic status of a cell at a given moment. The aim of this study is to investigate whether activation of nicotinic acetylcholine receptors (nACh-Rs) could increase ß-cell resistance against the adverse environment prevailing at the onset of T1DM. Here, we show that nACh-R activation by nicotine and choline, 2 agonists of the receptor, decreases murine and human ß-cell apoptosis induced by proinflammatory cytokines known to be present in the islet environment at the onset of T1DM. The protective mechanism activated by nicotine and choline involves attenuation of mitochondrial outer membrane permeabilization via modulation of endoplasmic reticulum stress, of the activity of B-cell lymphoma 2 family proteins and cytoplasmic calcium levels. Local inflammation and endoplasmic reticulum stress being key determinants of ß-cell death in T1DM, we conclude that pharmacological activation of nACh-R could represent a valuable therapeutic option in the modulation of ß-cell death in T1DM.

Ketosis After Cardiopulmonary Bypass in Children Is Associated With an Inadequate Balance Between Oxygen Transport and Consumption.

OBJECTIVES: Hyperglycemia after cardiac surgery and cardiopulmonary bypass in children has been associated with worse outcome; however, causality has never been proven. Furthermore, the benefit of tight glycemic control is inconsistent. The purpose of this study was to describe the metabolic constellation of children before, during, and after cardiopulmonary bypass, in order to identify a subset of patients that might benefit from insulin treatment. DESIGN: Prospective observational study, in which insulin treatment was initiated when postoperative blood glucose levels were more than 12 mmol/L (216 mg/dL). SETTING: Tertiary PICU. PATIENTS: Ninety-six patients 6 months to 16 years old undergoing cardiac surgery with cardiopulmonary bypass. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Metabolic tests were performed before anesthesia, at the end of cardiopulmonary bypass, at PICU admission, and 4 and 12 hours after PICU admission, as well as 4 hours after initiation of insulin treatment. Ketosis was present in 17.9% patients at the end of cardiopulmonary bypass and in 31.2% at PICU admission. Young age was an independent risk factor for this condition. Ketosis at PICU admission was an independent risk factor for an increased difference between arterial and venous oxygen saturation. Four hours after admission (p = 0.05). Insulin corrected ketosis within 4 hours. CONCLUSIONS: In this study, we found a high prevalence of ketosis at PICU admission, especially in young children. This was independently associated with an imbalance between oxygen transport and consumption and was corrected by insulin. These results set the basis for future randomized controlled trials, to test whether this subgroup of patients might benefit from increased glucose intake and insulin during surgery to avoid ketosis, as improving oxygen transport and consumption might improve patient outcome.

Diabetic Striatopathy in Childhood: A Case Report.

Diabetic striatopathy is a well-known complication of diabetes in adults. To our knowledge, only 2 cases have been reported in children. We here report the case of a teenager in whom diabetic striatopathy was revealed by the subacute appearance of hemichorea-hemiballism in the context of weight loss, polyuria, and polydipsia. Glycemia control allowed rapid clinical recovery despite established striatal lesions documented on MRI. We also discuss current hypotheses about pathophysiological processes underlying this entity.

Gene Variants Associated with Transient Neonatal Diabetes Mellitus in the Very Low Birth Weight Infant.

BACKGROUND: Transient and permanent neonatal diabetes mellitus (NDM), usually defined as diabetes diagnosed within the first 6 months of life, are rare conditions occurring in 1:90,000-260,000 live births. The origin of NDM is rarely related to type 1 diabetes, but rather to single gene defects. METHODS: Genetic analysis was performed using targeted parallel sequencing including 323 diabetes genes. Data were filtered by a locally developed program. RESULTS: A very low birth weight neonate born at 28 weeks postmenstrual age developed diabetes 13 days after birth. The patient was treated with continuous subcutaneous insulin infusion. After 1 month, insulin treatment could be stopped. At 18 months of age, the child was normoglycemic and developing normally. Genetic analysis revealed a novel variant (p.Pro190Leu) in HNF4A, which is located in the ligand binding domain of the transcription factor, and the p.Glu23Lys variant in KCNJ11, which is associated with type 2 diabetes. CONCLUSION: Here, we describe a novel HNF4A variant associated with transient NDM in a premature infant. We hypothesize that the neonatal phenotype previously described in carriers of HNF4A mutations was modified by the additional variant in KCNJ11 and prematurity.

Early metabolic defects in dexamethasone-exposed and undernourished intrauterine growth restricted rats.

Poor fetal growth, also known as intrauterine growth restriction (IUGR), is a worldwide health concern. IUGR is commonly associated with both an increased risk in perinatal mortality and a higher prevalence of developing chronic metabolic diseases later in life. Obesity, type 2 diabetes or metabolic syndrome could result from noxious "metabolic programming." In order to better understand early alterations involved in metabolic programming, we modeled IUGR rat pups through either prenatal exposure to synthetic glucocorticoid (dams infused with dexamethasone 100 µg/kg/day, DEX) or prenatal undernutrition (dams feeding restricted to 30% of ad libitum intake, UN). Physiological (glucose and insulin tolerance), morphometric (automated tissue image analysis) and transcriptomic (quantitative PCR) approaches were combined during early life of these IUGR pups with a special focus on their endocrine pancreas and adipose tissue development. In the absence of catch-up growth before weaning, DEX and UN IUGR pups both presented basal hyperglycaemia, decreased glucose tolerance, and pancreatic islet atrophy. Other early metabolic defects were model-specific: DEX pups presented decreased insulin sensitivity whereas UN pups exhibited lowered glucose-induced insulin secretion and more marked alterations in gene expression of pancreatic islet and adipose tissue development regulators. In conclusion, these results show that before any catch-up growth, IUGR rats present early physiologic, morphologic and transcriptomic defects, which can be considered as initial mechanistic basis of metabolic programming.

A novel SRY mutation leads to asymmetric SOX9 activation and is responsible for mixed 46,XY gonadal dysgenesis.

BACKGROUND: SRY, located on the Y chromosome, is one of the key genes involved in human sex determination. SRY mutations are responsible for 10-15% of all cases of 46,XY gonadal dysgenesis (GD) but are rarely implicated in the pathogenesis of mixed GD. METHODS: SRY was analyzed by sequence analysis of DNA extracted from blood leukocytes. SRY activity was evaluated by SOX9 immunostaining, one of the targets of SRY. RESULTS: We report a case of mixed GD due to a novel SRY point mutation in a patient with a 46,XY karyotype, without mosaicism or submicroscopic genomic imbalances. Hormonal studies showed low anti-müllerian hormone and histological examination of the gonads showed a streak gonad on the right side and a left dysgenetic testis, thus permitting the diagnosis of mixed GD. Immunostaining for SOX9, a target of SRY, was positive in nuclei of Sertoli and epididymal cells in the left gonad and negative on the right, thus indicating asymmetric activation of SRY. CONCLUSION: Mixed GD can result from SRY mutations without mosaicism, neither in peripheral blood, nor within the gonads. The asymmetric effect of the point mutation implies the presence of local factors modulating SRY expression or action.

Connexin-dependent signaling in neuro-hormonal systems.

The advent of multicellular organisms was accompanied by the development of short- and long-range chemical signalling systems, including those provided by the nervous and endocrine systems. In turn, the cells of these two systems have developed mechanisms for interacting with both adjacent and distant cells. With evolution, such mechanisms have diversified to become integrated in a complex regulatory network, whereby individual endocrine and neuro-endocrine cells sense the state of activity of their neighbors and, accordingly, regulate their own level of functioning. A consistent feature of this network is the expression of connexin-made channels between the (neuro)hormone-producing cells of all endocrine glands and secretory regions of the central nervous system so far investigated in vertebrates. This review summarizes the distribution of connexins in the mammalian (neuro)endocrine systems, and what we know about the participation of these proteins on hormone secretion, the life of the producing cells, and the action of (neuro)hormones on specific targets. The data gathered since the last reviews on the topic are summarized, with particular emphasis on the roles of Cx36 in the function of the insulin-producing beta cells of the endocrine pancreas, and of Cx40 in that of the renin-producing juxta-glomerular epithelioid cells of the kidney cortex. This article is part of a Special Issue entitled: The Communicating junctions, composition, structure and characteristics.

Connexins protect mouse pancreatic ß cells against apoptosis.

Type 1 diabetes develops when most insulin-producing ß cells of the pancreas are killed by an autoimmune attack. The in vivo conditions modulating the sensitivity and resistance of ß cells to this attack remain largely obscure. Here, we show that connexin 36 (Cx36), a trans-membrane protein that forms gap junctions between ß cells in the pancreatic islets, protects mouse ß cells against both cytotoxic drugs and cytokines that prevail in the islet environment at the onset of type 1 diabetes. We documented that this protection was at least partially dependent on intercellular communication, which Cx36 and other types of connexin channels establish within pancreatic islets. We further found that proinflammatory cytokines decreased expression of Cx36 and that experimental reduction or augmentation of Cx36 levels increased or decreased ß cell apoptosis, respectively. Thus, we conclude that Cx36 is central to ß cell protection from toxic insults.

Connexin implication in the control of the murine beta-cell mass.

Diabetes develops when the insulin needs of peripheral cells exceed the availability or action of the hormone. This situation results from the death of most beta-cells in type 1 diabetes, and from an inability of the beta-cell mass to adapt to increasing insulin needs in type 2 and gestational diabetes. We analyzed several lines of transgenic mice and showed that connexins (Cxs), the transmembrane proteins that form gap junctions, are implicated in the modulation of the beta-cell mass. Specifically, we found that the native Cx36 does not alter islet size or insulin content, whereas the Cx43 isoform increases both parameters, and Cx32 has a similar effect only when combined with GH. These findings open interesting perspectives for the in vitro and in vivo regulation of the beta-cell mass.

Connexin36 and pancreatic beta-cell functions.

Most cell types are functionally coupled by connexin (Cx) channels, i.e. exchange cytoplasmic ions and small metabolites through gap junction domains of their membrane. This form of direct cell-to-cell communication occurs in all existing animals, whatever their position in the phylogenetic scale, and up to humans. Pancreatic beta-cells are no exception, and normally cross-talk with their neighbors via channels made of Cx36. These exchanges importantly contribute to coordinate and synchronize the function of individual cells within pancreatic islets, particularly in the context of glucose-induced insulin secretion. Compelling evidence now indicates that Cx36-mediated coupling, and/or the Cx36 protein per se, play significant regulatory roles in various beta-cell functions, ranging from the biosynthesis, storage and release of insulin. Recent preliminary data further suggest that the protein may also be implicated in the balance of beta-cell growth versus necrosis and apoptosis, and in the regulated expression of specific genes. Here, we review this evidence, discuss the possible involvement of Cx36 in the pathophysiology of diabetes, and evaluate the relevance of this connexin in the therapeutic approaches to the disease.

Involvement of gap junctional communication in secretion.

Glands were the first type of tissues in which the permissive role of gap junctions in the cell-to-cell transfer of membrane-impermeant molecules was shown. During the 40 years that have followed this seminal finding, gap junctions have been documented in all types of multicellular secretory systems, whether of the exocrine, endocrine or pheromonal nature. Also, compelling evidence now indicates that gap junction-mediated coupling, and/or the connexin proteins per se, play significant regulatory roles in various aspects of gland functions, ranging from the biosynthesis, storage and release of a variety of secretory products, to the control of the growth and differentiation of secretory cells, and to the regulation of gland morphogenesis. This review summarizes this evidence in the light of recent reports.