bluuebunny/crossref_metadata_2025 huggingface dataset:
292-OR: Changes in Glycemia during Exercise Differ for Aerobic, Interval, and Resistance Workouts with No Impact of Insulin Delivery Modality for Adults with Type 1 Diabetes (T1D)
Authors: RIDDELL MICHAEL , PATTON SUSANA R. , MARTIN CORBY K. , LI ZOEY , JACOBS PETER G. , GILLINGHAM MELANIE B. , GAL ROBIN L. , DOYLE FRANCIS J. , CLEMENTS MARK A. , CALHOUN PETER , CASTLE JESSICA R. , BECK ROY , RICKELS MICHAEL R.
Published: May 2022

Glycemic responses differ by exercise classification (i.e. aerobic, interval, resistance) in individuals with T1D, but the impact of insulin delivery modality (multiple daily injections [MDI], pump, closed loop) on these differences is unclear. Data from the Type 1 Diabetes Exercise Initiative study allowed us to compare glycemic responses by insulin delivery method. Adults (N=497) with T1D ([mean ± SD] age= 37 ± 14 years; HbA1C= 6.6 ± 0.8%) were assigned to complete six at-home sessions of aerobic, interval, or resistance exercise over 4 weeks, using study-developed instructional videos approximately 30 minutes in duration. Mean [95% CI] change in glucose during the assigned exercise was -[95% CI -22, -16], -15 [-18, -12], and -9 [-12, -7] mg/dL for aerobic, interval, and resistance exercise, respectively (P<0.001) , after adjusting for baseline glucose, insulin delivery modality, age, and sex. This pattern was similar irrespective of insulin delivery modality (Figure) .

In summary, regardless of insulin delivery modality, adults with T1D experienced the largest glucose drop for aerobic exercise followed by interval exercise and resistance exercise.

Disclosure

M.Riddell: Advisory Panel; Zealand Pharma A/S, Zucara Therapeutics, Consultant; Eli Lilly and Company, Jaeb Center for Health Research, Speaker's Bureau; Dexcom, Inc., Eli Lilly and Company, Novo Nordisk. P.Calhoun: None. J.R.Castle: Advisory Panel; Insulet Corporation, Novo Nordisk, Zealand Pharma A/S, Stock/Shareholder; Pacific Diabetes Technologies. R.Beck: Consultant; Diasome, Eli Lilly and Company, Insulet Corporation, Novo Nordisk, Research Support; Ascensia Diabetes Care, Beta Bionics, Inc., Bigfoot Biomedical, Inc., Dexcom, Inc., Eli Lilly and Company, Medtronic, Novo Nordisk, Roche Diabetes Care, Tandem Diabetes Care, Inc. M.R.Rickels: Advisory Panel; Sernova, Corp., Vertex Pharmaceuticals Incorporated, Zealand Pharma A/S, Consultant; L-Nutra Inc. S.R.Patton: None. C.K.Martin: Advisory Panel; Wondr Health, Board Member; EHE Health, Other Relationship; ABGIL, ABGIL, Academy of Nutrition and Dietetics. Z.Li: None. P.G.Jacobs: Other Relationship; Pacific Diabetes Technologies, Research Support; Dexcom, Inc. M.B.Gillingham: None. R.L.Gal: None. F.J.Doyle: Other Relationship; Dexcom, Inc., Insulet Corporation, Roche Diabetes Care, Stock/Shareholder; Mode AGC. M.A.Clements: Consultant; Glooko, Inc., Research Support; Abbott Diabetes, Dexcom, Inc.
293-OR: Effects on Metabolic Control and Body Composition of Insulin Therapy Optimization in Patients with Cystic Fibrosis–Related Diabetes
Authors: GRANCINI VALERIA , PORCARO LAURA L. , GAGLIO ALESSIA , RESI VERONICA , ORSI EMANUELA
Published: May 2022

Cystic fibrosis related diabetes (CFRD) occurs in 19% of adolescents and 40-50% of adults with CF. The partial to complete insulin deficiency leads not only to hyperglycaemia, but also to loss of muscle mass and induction of a catabolic state. Therefore, insulin is the only recommended therapy for CFRD. Continuous subcutaneous insulin infusion (CSII) has been associated to improved glycaemic control in CFRD in small studies, if compared to multiple daily injections (MDI) , mostly due to better coverage of dietary requirements of these patients (high calories, not carbohydrate restrictions, several snacks) . The aim of this study is to evaluate the effects of insulin therapy optimization combined to a structured educational program (training to Sensor Augmented Pump -SAP- therapy and carbohydrates counting) on metabolic control and body composition in patients with CFRD requiring insulin therapy. 22 patients agreed to participate in the program and, at the end of it, switched to SAP therapy. 29 patients continued the outpatient checks without joining the program. Patients of both groups were re-evaluated 2 years after baseline. Patients in the educational program group demonstrated a substantial improvement in glycometabolic control (HbA1c 7.4±1.4 vs. 6.5±0.6%; average blood glucose 8.5±1.6 vs. 7.4±1.1 mmol/L; Glucose management indicator - GMI 7.2±0.9 vs. 6.5±0.5%; time in range - TIR 64.2±18.0 vs. 80.38±10.1%; time above range - TAR 31.0±18.8 vs. 16.2±9.1%; time below range - TBR 4.76±3.5 vs. 3.0±2.0%, P<0.05) and in body composition, assessed with bioimpedance (fat free mass - FFM 78.9±8.6 vs. 85.1±7.0%, total body water - TBW 57.9±6.3 vs. 63.2±6.7 L, P<0.05) . The same parameters didn’t differ from basal to final evaluation in the control group.

In conclusion, a structured program resulting in therapy optimization leads to a significative improvement in glycometabolic control and, consequently, in body composition, due to insulin’s anabolic effect

Disclosure

V.Grancini: None. L.L.Porcaro: None. A.Gaglio: None. V.Resi: None. E.Orsi: None.
3-OR: Hepatocyte Gdf15 Is Sufficient for Increased Plasma GDF15 Levels and Body Weight Constraint during High-Fat–Diet Feeding and Restores Insulin Sensitivity in a Liver-Specific Manner
Authors: XIE BINGXIAN , MURALI ANJANA , VANDEVENDER AMBER , GIL SILVA AGUSTIN A. , BELLO FIONA , SIPULA IAN J. , DEDOUSIS NIKOLAOS , ALDER JONATHAN , JURCZAK MICHAEL J.
Published: May 2022

Growth and differentiation factor 15 (GDF15) is a stress-induced secreted protein whose plasma levels are increased in obese patients. Recombinant GDF15 reduces body weight (BW) and improves glycemia in obese models, which is largely attributed to central action of GDF15 to suppress feeding. Despite this, the tissue specific sites of GDF15 production during obesity are unknown and the potential for local action is understudied. To determine the hepatocyte specific contribution of Gdf15 to changes in circulating GDF15 and effects on obesity, we utilized a Gdf15 KO-first mouse strain where endogenous expression of Gdf15 can be restored in a tissue specific fashion via Flp recombinase (FLP) . Gdf15 KO-first mice received AAV8-TBG-Gfp (KO+GFP) or AAV8-TBG-Flp (liver specific Gdf15 expression; KO+FLP) and were fed HFD for 12 weeks, alongside age-matched C57BL6 mice (WT) . Plasma GDF15 levels were undetectable in KO+GFP and similar between KO+FLP and WT HFD. BW was reduced in KO+FLP compared with KO+GFP and was not different from HFD WT. Interestingly, differences in BW were due to greater changes in lean (LM) compared with fat mass (FM) . Feeding was reduced in KO+FLP when expressed per mouse but not when expressed per g BW or LM, nor when the relationship between BW/LM and feeding were assessed by ANCOVA. Plasma insulin levels were increased in KO+GFP compared with WT HFD and markedly lower in KO+FLP compared with KO+GFP and WT HFD. Hyperinsulinemic euglycemic clamps demonstrated improved insulin sensitivity in KO+FLP due solely to changes in liver insulin action. These data suggest that feeding alone did not account for the changes in BW or insulin resistance, which would favor loss of FM and a generalized improvement in whole-body insulin sensitivity. They also demonstrate that hepatocyte Gdf15 is sufficient for obesity-associated increases in circulating GDF15 and suggest the potential for local effects of GDF15.

Disclosure

B.Xie: None. A.Murali: None. A.Vandevender: None. A.A.Gil silva: None. F.Bello: None. I.J.Sipula: None. N.Dedousis: None. J.Alder: None. M.J.Jurczak: None.

Funding

Pittsburgh Foundation (MR2020 109502)
300-OR: A Modular Massively Parallel Reporter Assay Uncovers Context-Specific Activity of Diabetes-Associated Regulatory Elements
Authors: TOVAR ADELAIDE
Published: May 2022

Recent genome-wide association studies (GWAS) have identified hundreds of signals associated with type 2 diabetes (T2D) , most (∼90%) of which are found in noncoding regions of the genome enriched in tissue-specific regulatory regions. However, most GWAS signals span hundreds of tightly linked variants, and predicting each of their functional effects is difficult. Consequently, progress to translate associations to mechanisms has proceeded slowly. Here, we have designed a massively parallel reporter assay (MPRA) to systematically screen enhancer activity across a panel of genomic fragments, including (1) islet-specific TSSs defined by cap analysis of gene expression (CAGE) and (2) allelic pairs for over 10k T2D- and metabolic trait-associated variants. We cloned this library up- or downstream of a reporter gene driven by a synthetic housekeeping promoter (SCP1) or the human insulin (INS) promoter, together enabling enhancer activity measurements across different promoter and enhancer contexts. We examined expression bias within our library (FDR < 0.05) and found that 43% of CAGE-defined oligos were marked by positional bias (n = 565/1,305) , skewed towards higher expression in the upstream position (n = 539/565) . In contrast, two unique subsets of GWAS oligos displayed either positional (n = 702/11,656) or promoter (n = 698/11,656) bias. Oligos with positional bias were evenly split between the two cloning positions, while most promoter-biased oligos were more highly expressed when paired with the INS promoter (n = 512/698) . To identify sequence features associated with promoter bias, we performed Lasso regression using a set of 562 genomic annotations. This analysis revealed that presence of HNF1 motifs was associated with higher enhancer activity in the context of the INS promoter. Together, these results indicate that reporter construct design clearly influences assayed regulatory activity, particularly with use of tissue-relevant promoters.

Disclosure

A.Tovar: None.

Funding

National Institutes of Health (R01DK117960, T32DK101357)
301-OR: Modeling the Type 2 Diabetes–Associated ABCC8 Arg1420 His Mutation using iPSC–Derived Pancreatic Islet-Like Cells
Authors: NAIR ANUP K. , TRAURIG MICHAEL , SUTHERLAND JEFF , NELSON ROBERT G. , BOGARDUS CLIFTON , BAIER LESLIE
Published: May 2022

Genetic studies in American Indians from Arizona previously identified a population specific Arg1420 His mutation in ABCC8 which causes hyperinsulinemic hypoglycemia in infancy. The His allele is carried by 3% of this population and associates with increased birthweight, suggesting increased insulin secretion in-utero, and doubles the risk of type 2 diabetes, a disease characterized by reduced insulin secretion. To model the contrary effects of this mutation, we used gene-edited induced pluripotent stem cell (iPSC) derived pancreatic islet-like cells. An iPS cell line created from an American Indian heterozygous for the mutation was gene-edited using CRISPR-CAS9 to generate iPSCs homozygous for the risk (His) and the non-risk (Arg) allele. Multiple iPSC lines for each genotype were differentiated towards pancreatic islet-like cells using a seven-stage differentiation protocol and the effect of the mutation on islet function were assessed. Higher insulin secretion was observed from the His-allele carrying islet-like cells when stimulated with low glucose (2mM) after 1 and 2 weeks of maturation, consistent with a clinical phenotype of hyperinsulinemia in His-allele carriers. Stimulation with 20mM glucose resulted in increased insulin secretion after 2 weeks of maturation only in the Arg-allele (non-risk) carrying islets while no increase was seen in the His-allele carrying islets, consistent with its role in T2D risk. Treatment with diazoxide significantly reduced insulin secretion with no difference between the genotypes. Single cell RNA sequencing of islet-like cells cultured for an extended time (4 weeks) identified many differentially expressed genes in cells with the mutant vs. reference allele that could potentially reveal the mechanism of the increased future T2D risk including G6PC2, a known negative regulator of glucose-stimulated insulin secretion, in beta-like cells and CRH, which has been linked to increased T2D risk, in alpha-like cells.

Disclosure

A.K.Nair: None. M.Traurig: None. J.Sutherland: Stock/Shareholder; Bristol-Myers Squibb Company, Johnson & Johnson, Pfizer Inc. R.G.Nelson: None. C.Bogardus: None. L.Baier: None.

Funding

NIH Intramural
304-OR: Proteomic Profile and Inflammatory Response of Islet Stressomes Released during Isolation
Authors: SARAVANAN PRATHAB BALAJI , KALIVARATHAN JAGAN , LEVY MARLON F. , KANAK MAZHAR A.
Published: May 2022

Purpose: Islets undergo enormous stress during isolation and peri-transplant periods which causes a significant release of stressomes (exosomes released during stress) . Uncovering the biological role of such vesicles is vital for long-term graft function and survival. Here, we sought to identify the global protein content and significance of stressomes isolated during isolation in autologous islet transplantation (AIT) .

Methods: Post-transplant stress was mimicked in vitro by exposing human islets to hypoxia and cytokines (Cyt+Hyp) . Stressome protein contents were characterized by mass spectrometry and immunoblotting. Similar stressomes were also isolated from the islet infusion bag samples of AIT recipients (N=20) . The stressome protein levels were correlated with 1-year AIT outcomes. Finally, these islet stressomes were treated to another set of purified islets and macrophages to find their uptake and immune response.

Results: The mass spectrometry analysis has revealed the islet stressomes contain DAMP proteins like histones (H2B, H3, and H4) . The canonical ER stress signal plays a crucial role in the biogenesis of islet stressomes induced by (Cyt+Hyp) . Exosomes isolated from the infusion bags showed an elevated histone level in the insulin-dependent (ID) group. Moreover, high levels of DAMP proteins were positively correlated with increased post-transplant recipients insulin requirements (p=0.029) . The fluorescent confocal microscopy analysis has revealed these stressomes were easily uptaken by the macrophages and also conferred an inflammatory phenotype. Instead, the stressome treated islets showed elevated expression of innate immune receptors like TLR2 and AGTR1.

Conclusion: The study has identified the islet stressome global protein content and briefs its prospective to induce islet inflammation and graft loss in AIT.

Disclosure

P.Saravanan: None. J.Kalivarathan: None. M.F.Levy: Research Support; Vertex Pharmaceuticals Incorporated, Speaker's Bureau; AbbVie Inc., Sanofi Genzyme. M.A.Kanak: None.
307-OR: Impaired Differentiation of Trpv1-Positive Adipose Progenitors Activates Compensatory Thermogenic Mechanisms
Authors: CAMARA HENRIQUE , SHAMSI FARNAZ , LYNES MATTHEW , TSENG YU-HUA
Published: May 2022

Brown and beige thermogenic adipocytes are specialized in energy consumption and linked to metabolic health. Canonically, thermogenic adipocytes are thought to be derived from mesenchymal PdgfRα+ adipocyte progenitor cells (APC) . We recently identified a novel population of cold-recruited APCs from the vascular smooth muscle lineage marked by the expression of the ion channel Trpv1 in mouse adipose tissue. To determine the function of the Trpv1+ APC-derived adipocytes, we impaired their adipogenic capacity by deletion of Pparγ in Trpv1-expressing cells in mice (Trpv1-Cre::Pparγ-flox) . Inhibition of de novo adipogenesis from Trpv1+ APCs resulted in modest changes in brown adipose tissue, but it caused a marked reduction in the expression of cold-induced browning genes, including UCP1, in white adipose tissue (WAT) , indicating impaired beige adipogenesis. Interestingly, Trpv1-Cre::Pparγ-flox mice did not show altered weight gain, glucose tolerance, or insulin sensitivity on either regular chow or high-fat diets. This discrepancy led us to search for potential compensatory mechanisms. We observed increased PdgfRα expression in WAT of Trpv1-Cre::Pparγ-flox animals, suggesting that impaired adipogenic capacity of the Trpv1+ APCs may trigger recruitment of the PdgfRα+ APCs. Additionally, while UCP1 expression was noticeably reduced in the beige adipocytes within WAT, the expression of transcripts involved in the UCP1-independent thermogenic pathways, including Ckmt1, Gatm, and Slc6a8, key components of the creatine futile cycle, was increased in the WAT of the Trpv1-Cre::Pparγ-flox mice upon cold exposure. Together, these data highlight a potential distinction between the thermogenic pathways mediated by adipocytes derived from the Trpv1+ versus those derived from the PdgfRα+ APCs. This functional difference of thermogenic adipocytes could be critical in designing strategies to target these cells as a therapeutic approach for metabolic diseases.

Disclosure

H.Camara: None. F.Shamsi: None. M.Lynes: None. Y.Tseng: Consultant; Cellarity.

Funding

National Institutes of Health (R01DK102898)
310-OR: Histone Variant H2A.Z-Mediated Chromatin Organization Regulates Brown Adipocyte Thermogenic Function
Authors: ZHANG YANG , ZHENG RONGBIN , WANG CHIH-HAO , DARCY JUSTIN , CHEN KAIFU , TSENG YU-HUA
Published: May 2022

Obesity accounts for a substantial and growing burden of global disease, leading to high morbidity and mortality in type 2 diabetes, cardiovascular disease, and certain cancers. Brown adipose tissue (BAT) dissipates energy as heat and has been proposed as a therapeutic target to combat obesity. The unique thermogenic capacity of BAT is primarily conferred by uncoupling protein 1 (Ucp1) , which dissipates energy by uncoupling the proton motive force from ATP generation. To identify novel transcriptional regulators of Ucp1, we performed an unbiased CRISPR/Cas9-based chromatin immunoprecipitation assay (enChIP) and identified H2A.Z as a novel trans-acting factor recruited to the promoter and enhancer of Ucp1 by β3-adrenergic receptor (β3-AR) stimulation. H2A.Z is an essential and evolutionary conserved histone variant of the canonical histone H2A. Knockdown of H2A.Z in brown adipocytes led to lower β3-AR-induced Ucp1 level and impeded the expression of other known thermogenic genes (e.g., Cidea, Pgc1a) , leading to impaired cellular thermogenesis. Mechanistically, by profiling the genome-wide distribution of H2A.Z via ChIP-seq, we observed H2A.Z was enriched at promoter and enhancer of Ucp1 upon β3-AR stimulation, which is consistent with the enChIP result. Intriguingly, we found that the average occupancy of H2A.Z in the promoter and enhancer regions of other β3-AR-upregulated genes (e.g., Zfp516, Vdr, Pck1, Gys2) was also higher than that in non-stimulated condition, indicating a global regulatory role of H2A.Z in the thermogenic program in response to β3-AR stimulation. Additionally, in the enhancer regions of β3-AR-induced genes, we also detected an increased level of H2A.Z acetylation, which is a mark of active chromatin and confers an open chromatin conformation. Taken together, these findings reveal the essential role of H2A.Z-mediated chromatin organization in BAT thermogenic function.

Disclosure

Y.Zhang: None. R.Zheng: None. C.Wang: None. J.Darcy: None. K.Chen: None. Y.Tseng: Consultant; Cellarity.

Funding

National Institutes of Health (R01DK102898)
313-OR: A Cytoskeleton-Based Mechanism Regulates Lipid Metabolism and Energy Homeostasis in Brown Adipose Tissue
Authors: AGUILLARD ASHLEY , ARRICASTRES JUNE , TZENG JOYCE , LORENZO DAMARIS
Published: May 2022

Genetic variants in ANK2, encoding ankyrin-B (AnkB) , increase risk of obesity and type 2 diabetes in humans. We previously concluded that AnkB deficiency in white (WAT) and brown (BAT) adipose tissue (AT) of mice (AT-AnkB KO) led to lipotoxicity, WAT hypertrophy, and insulin resistance associated with age and consumption of a high-fat diet. These metabolic deficits were caused by impairments in glucose transporter GLUT4 endocytosis in WAT due to AnkB deficiency. Additionally, we found that AT-AnkB KO mice had decreased energy expenditure and lipid accumulation in BAT prior to the onset of obesity suggesting a potential role of AnkB in BAT. However, the role of AnkB in BAT and its contribution to metabolic homeostasis through BAT has not been elucidated.

We investigated the role of AnkB in mice conditionally lacking AnkB in BAT (BAT-AnkB KO) . Based on histological and transmission electron microscopy analysis, we found that young (4-month-old) BAT-AnkB KO mice have enlarged lipid droplets, lipid accumulation, and decreased mitochondrial content in BAT with no changes in BAT size, body weight, or body composition. Consistent with these findings, primary brown adipocytes from BAT-AnkB KO mice exhibited lipid accumulation suggesting that AnkB may regulate lipid homeostasis in BAT in a cell-autonomous manner. Similar to our previous findings, young BAT-AnkB KO mice also had decreases in oxygen consumption and energy expenditure. These mice also exhibit minimal changes in glucose handling and insulin tolerance at 4-months of age. Proteomic-MS analysis was performed on AnkB associated proteins from BAT which revealed that GLUT4 as well as a number of critical regulators of lipid metabolism form complexes with AnkB in BAT. In combination with this data, we will present our latest findings in gene expression of genes regulating lipid metabolism and mitochondrial function as well as cellular assays in brown adipocytes that may highlight metabolic pathways regulated by AnkB in BAT.

Disclosure

A.Aguillard: None. J.Arricastres: None. J.Tzeng: None. D.Lorenzo: None.

Funding

American Diabetes Association (1-19-JDF-081)
317-OR: The Novel Glucokinase GCK (Q26L) Gene Mutation Site Causes Diabetes
Authors: JI SHUHUI , SHU HUA , FENG WENLI , ZHEN JINYANG , QIAO JINGTING , HUANG YADI , CHEN SHANSHAN , LIU MING
Published: May 2022

Glucokinase (GCK) mainly exists in pancreatic β-cell, hepatocytes and brain, and is the first-rate limiting enzyme in glucose metabolism pathway. The heterozygous inactivation mutation of GCK leads to Maturity-onset diabetes of the young (MODY2) , an autosomal dominant mild fasting hyperglycemia. In the monogenic diabetes registration project initiated by our research group, we found a novel inactivation mutation site of GCK gene, c.77A>T (p.Q26L) . We sought to explore the pathogenic mechanism with a newly constructed mouse model.The proband was first diagnosed with diabetes at 11. Her father was diagnosed with diabetes at 32, and his mother was healthy. Genetic testing showed there was a novel heterozygous missense mutation site c.77A >T in exon 1 of the GCK of the proband, which resulted in the change of the 26th amino acid from glutamine to leucine. The pedigree indicated the mutation of proband was inherited from her father, not her mother. A global knock-in GCK (Q26L) mice (GCKKI/-) model was successfully established. From 3-16 weeks, substantial group differences in fasting blood glucose, other than body weight, was observed in GCKKI/-. At 3-week, impaired glucose tolerance and lower serum insulin level of GCKKI/- mice were detected. There was no difference in insulin sensitivity and content of proinsulin and insulin in the islet of GCKKI/-. In vitro experiment, decreased glucose-stimulated insulin secretion was observed in the GCKKI/-, but no significant changes in KCl stimulated insulin secretion. Furthermore, the results of different glucose concentration stimulated insulin secretion and islet perfusion showed the insulin secretion threshold increased and the insulin secretion ability decreased in the GCKKI/-. In the GCKKI/- liver, there were no changes in the morphology, but glycogen content was reduced. The level of plasma HDL significantly increased, plasma TC and LDL levels decreased, and TG levels did not change.

Disclosure

S.Ji: None. H.Shu: None. W.Feng: None. J.Zhen: None. J.Qiao: None. Y.Huang: None. S.Chen: None. M.Liu: None.

Funding

National Natural ScienceFoundation of China (81830025,81620108004,81800733,and 81900720) , the Ministry of Science and Technologyof China (2019YFA0802502) , the Tianjin Municipal Science andTechnology Bureau (17ZXMFSY00150)
319-OR: Na+/K+ ATPase Activation Is a Conserved Mechanism for Gi/o Protein-Coupled Receptor Control of Pancreatic ß-Cell Electrical Excitability and Insulin Secretion
Authors: DICKERSON MATTHEW , DADI PRASANNA , ZABORSKA KAROLINA E. , NAKHE ARYA Y. , SCHAUB CHARLES , DOBSON JORDYN , WRIGHT NICOLE M. , LYNCH JOSHUA , SCOTT CLAIRE , JACOBSON DAVID
Published: May 2022

Gi/o protein-coupled receptor (Gi/o-GPCR) inhibition of pancreatic β-cell Ca2+ entry limits islet insulin secretion; however, the mechanism has not been identified. As Gi/o-GPCRs activate G protein-gated inwardly rectifying K+ (GIRK) channels, we examined their contribution to β-cell Gi/o signaling. However, Gi/o-GPCR-induced β-cell GIRK currents were not observed; this was demonstrated with a pharmacological approach and by genetic knockout of the predominant β-cell GIRK channel subunit. Thus, we increased the chemical driving force for K+ movement through GIRK channels by removing extracellular K+. Interestingly, under these conditions Gi/o-GPCR-induced β-cell membrane potential (Vm) hyperpolarization was lost even though K+ channel activation could still hyperpolarize Vm, which indicated that Gi/o-GPCRs do not hyperpolarize β-cell Vm by activating K+ channels. As extracellular K+ is required for Na+/K+ ATPase (NKA) activity, we next tested and found that mouse and human β-cell NKAs were activated by Gi/o-GPCRs. Stimulation of Gi/o-GPCRs initiated cyclical β-cell NKA activity, resulting in islet Ca2+ oscillations. Moreover, paracrine activation of β-cell NKAs by intraislet δ-cell somatostatin (SST) secretion decelerated islet Ca2+ oscillations and diminished insulin secretion, which was mediated by direct activation of β-cell Gi/o-GPCRs. Gi/o signaling induced islet Ca2+ oscillations through Src tyrosine kinase-dependent NKA phosphorylation and activation; an effect that was recapitulated by stimulating insulin receptor tyrosine kinases. Whereas, islet NKA function was completely inhibited by cAMP-dependent PKA activation. Therefore, these findings reveal that NKA-mediated hyperpolarization of β-cell Vm is the primary and conserved mechanism for Gi/o-GPCR control of electrical excitability, Ca2+ handling, and insulin secretion.

Disclosure

M.Dickerson: None. D.Jacobson: None. P.Dadi: None. K.E.Zaborska: None. A.Y.Nakhe: None. C.Schaub: None. J.Dobson: None. N.M.Wright: None. J.Lynch: None. C.Scott: None.

Funding

American Diabetes Association (1-17-IBS-024) ; Vanderbilt Integrated Training in Engineering and Diabetes Grant (T32DK101003) , National Institutes of Health Grants (DK-097392 and DK-115620) , Juvenile Diabetes Research Foundation Grant (2-SRA-2019-701-S-B) , and a Pilot and Feasibility grant through the Vanderbilt Diabetes Research and Training Center Grant (P60-DK-20593) .
320-OR: Maternal Overnutrition Confers Increased Spare Respiratory Capacity and Glucose-Stimulated Insulin Secretion in Nonhuman Primate Offspring Islets
Authors: CARROLL DARIAN T. , ELSAKR JOSEPH M. , RICCIARDI VALERIE F. , DUNN JENNIFER C. , LINDSLEY SARAH R. , DEAN TYLER , KIRIGITI MELISSA , TAKAHASHI DIANA L. , WESOLOWSKI STEPHANIE R. , MCCURDY CARRIE E. , KIEVIT PAUL , AAGAARD KJERSTI M. , FRIEDMAN JACOB E. , GANNON MAUREEN
Published: May 2022

The Developmental Origins of Health and Disease hypothesis states that the intrauterine environment influences postnatal health and adult disease susceptibility. In the United States, over 30% of women of childbearing age are obese, in part due to Western Style Diet (WSD) consumption. Previous data from our group using a Japanese macaque model, revealed that maternal overnutrition increases the β:α cell ratio in the islets of offspring. WSD-exposed offspring islets also exhibit inappropriate hypersecretion of insulin in response to glucose at 1 and 3 years of age. We hypothesize that fetal exposure to WSD induces a compensatory increase in β-cell fuel metabolism resulting in an inappropriate increase in insulin secretion by offspring islets. When we assessed the effect of maternal diet on mitochondrial respiration in offspring islets, we found that spare respiratory capacity is increased in islets of one year old WSD-exposed male offspring, suggesting an increased capacity to adapt to increased metabolic demand. This could be due to increased mitochondrial abundance; however, maternal overnutrition does not appear to increase β cell mitochondrial density when analyzed via transmission electron microscopy (TEM) . Insulin granule density is increased in male offspring islets in TEM micrographs, implying that insulin production is increased in response to intrauterine WSD exposure. Transcripts for CACNA1C (voltage gated calcium channel subunit) , ABCC8 (ATP-sensitive potassium channel subunit) , and VAMP2 (vesicle fusion) are increased in response to maternal WSD exposure in offspring islets. Thus, our data suggest that increases in insulin secretion in offspring exposed to maternal overnutrition result from changes in metabolic and secretion pathways. Importantly, these mechanisms could potentiate hyperinsulinism which may predispose offspring to insulin resistance and beta cell failure in adulthood.

Disclosure

D.T. Carroll: None. V.F. Ricciardi: None. J.C. Dunn: None. S.R. Lindsley: None. T. Dean: None. M. Kirigiti: None. S.R. Wesolowski: None. C.E. McCurdy: None. P. Kievit: Research Support; Novo Nordisk A/S. J.E. Friedman: None. M. Gannon: None.

Funding

NIH-NIDDK (5T32 DK7563-30, R24DK090964-06, 1R01DK128187)
34-OR: SARS-CoV-2 Infection Is Not Associated with Presence of Islet Autoantibodies in Children: Autoimmunity Screening for Kids (ASK)
Authors: RASMUSSEN CRISTY GENO , JIA XIAOFAN , SHORROSH HANAN , YU LIPING , FROHNERT BRIGITTE I. , SIMMONS KIMBER M. , STECK ANDREA , PYLE LAURA , REWERS MARIAN
Published: May 2022

Viral infections may trigger islet autoimmunity leading to type 1 diabetes (T1D) . We hypothesized SARS-CoV-2 infection is associated with presence of islet autoantibodies (IAb) in children. Between 8/2020 and 12/2021, ASK screened 47general population Colorado children aged 1-17 y for IAb to GAD, insulin, IA-2 and ZnT8 as well as antibodies to SARS-CoV-2 receptor binding domain (CoV-2 RBDAb) - a sensitive and specific marker of infection. Of those, 4172 (89%) have not previously received SARS-CoV-2 vaccine. During the study period, prevalence of CoV-2 RBDAb increased in unvaccinated from 1% to 58% and up to 100% among vaccinated. Among all children, the prevalence increased from 1% to 72% - an estimate of herd immunity (Figure) . Among the unvaccinated, prevalence of multiple or single high-affinity IAb did not differ between children positive vs. negative for CoV-2 RBDAb, respectively 1.23% (16/1297) vs. 1.00% (29/2875) , p=0.52. In multivariate logistic regression, presence of IAb was not associated with presence of CoV-2 RBDAb (OR=1.40, p=0.31) , adjusting for age, sex, race/ethnicity, and family history of T1D. While we found no association between past SARS-CoV-2 infection and islet autoimmunity, a confirmation in a larger population is warranted. Longer follow-up will help assess whether SARS-CoV2 infection accelerates progression from islet autoimmunity to diabetes.

Disclosure

C.Geno rasmussen: None. X.Jia: None. H.Shorrosh: None. L.Yu: None. B.I.Frohnert: Advisory Panel; Provention Bio, Inc. K.M.Simmons: Advisory Panel; Provention Bio, Inc., Consultant; Dexcom, Inc. A.Steck: None. L.Pyle: None. M.Rewers: Consultant; Janssen Research & Development, LLC, Medscape, Provention Bio, Inc., Research Support; Dexcom, Inc., JDRF, Roche Diagnostics USA.

Funding

JDRF 2-SRA-2021-1065-M-N
344-OR: Body Composition Trajectories from Birth to 5 Years and Hepatic Fat in Early Childhood
Authors: COHEN CATHERINE C. , HARRALL KRISTEN K. , GILLEY STEPHANIE P. , PERNG WEI , SAUDER KATHERINE A. , SHANKAR KARTIK , GLUECK DEBORAH H. , DABELEA DANA
Published: May 2022

Adiposity is an established risk factor for pediatric nonalcoholic fatty liver disease (NAFLD) , but little is known about the influence of body composition changes earlier in life on future NAFLD risk. Here, we examined associations of body composition trajectories from birth to early childhood with hepatic fat (HF) in early childhood in the Colorado Healthy Start cohort. Fat-free mass index (FFMI) , fat mass index (FMI) , and percent fat mass (%FM) were assessed at birth and/or ∼5 yrs in 1,235 children by air displacement plethysmography. At ∼5 yrs, HF was assessed by magnetic resonance imaging in a sub-sample of 285 children. We used a two-stage modeling approach: first, FFMI, FMI, and %FM trajectories were estimated using mixed models with random intercepts and slopes; second, associations of participant-specific deviations with HF were assessed by linear regression adjusted for confounders. As shown in Table 1, random intercepts for FFMI, FMI, and %FM at birth were all inversely associated with HF in early childhood; whereas %FM slope (i.e., velocity) from birth to ∼5 years was associated with higher HF. These findings suggest that smaller weight at birth, followed by greater gains in %FM are associated with higher HF in early childhood. This supports an influence of early life body composition patterns on HF susceptibility and the importance of perinatal strategies aiming to promote healthy adiposity in infancy/childhood.

Disclosure

C.C. Cohen: None. S.P. Gilley: None. W. Perng: None. K.A. Sauder: None. K. Shankar: None. D.H. Glueck: None. D. Dabelea: None.
345-OR: Longitudinal Changes in Arterial Stiffness and Heart Rate Variability in Youth-Onset Type 1 vs. Type 2 Diabetes
Authors: SHAH AMY S. , ISOM SCOTT , DAGOSTINO RALPH , DOLAN LAWRENCE M. , DABELEA DANA , IMPERATORE GIUSEPPINA , MOTTL AMY K. , LUSTIGOVA EVA , PIHOKER CATHERINE , MARCOVINA SANTICA M. , URBINA ELAINE M.
Published: May 2022

Limited data exist examining arterial stiffness and heart rate variability (HRV) over time in young adults with youth-onset type 1 (T1D) and type 2 diabetes (T2D) . We compared arterial stiffness and HRV over time and by diabetes type and determined the risk factors associated with worsening arterial stiffness and HRV. Arterial stiffness (pulse wave velocity, augmentation index) and HRV (SDNN and PNN50) were measured twice (∼ 5 years apart) in the SEARCH for Diabetes in Youth Study. Linear regression models assessed risk factors overtime and with arterial stiffness and HRV at follow-up. Of 1159 participants studied, 949 had T1D (mean age 17.1 ± 4.7 years, 60.3% non-Hispanic White, 55% female) and 2had T2D (mean age 22.1 ± 3.5 years, 23.8% non-Hispanic White, 71% female) at initial assessment when diabetes duration was 7.9 years (both groups) . Participants with T2D vs. T1D had greater arterial stiffness and more abnormalities in HRV at initial and follow-up assessments (Figure) .For AIx and PNN50 T2D compared to T1D had a greater change over time (p<0.05) . Risk factors associated with worse arterial stiffness and HRV at follow-up in both T1D and T2D included higher BP, HbA1c, waist circumference, and triglycerides overtime, and longer diabetes duration. Arterial stiffness and HRV worsened over time with greater changes among those with T2D and features of the metabolic syndrome regardless of diabetes type.

Disclosure

A.S. Shah: None. R. Dagostino: Consultant; Aetion, Inc., AstraZeneca, Biogen, Bristol-Myers Squibb Company, Daiichi Sankyo, Merck & Co., Inc. L.M. Dolan: None. D. Dabelea: None. G. Imperatore: None. A.K. Mottl: Advisory Panel; Bayer AG. Board Member; Bayer AG. Research Support; Alexion Pharmaceuticals, Inc., Aurinia, Bayer AG, Boehringer Ingelheim International GmbH, Pfizer Inc. E. Lustigova: None. C. Pihoker: None. S.M. Marcovina: None. E.M. Urbina: Advisory Panel; Astellas Pharma Inc.

Funding

NIH and CDC
358-OR: The Effect of Glucagon-Like Peptide-1 Receptor Blockade on Glucagon-Induced Stimulation of Insulin Secretion
Authors: FARAHANI RAHELE A. , EGAN AOIFE M. , WELCH ANDREW A. , LAURENTI MARCELLO C. , COBELLI CLAUDIO , DALLA MAN CHIARA , VELLA ADRIAN
Published: May 2022

Data from transgenic rodent models suggest that glucagon acts as an insulin secretagogue by signalling through the Glucagon-Like Peptide-1 Receptor (GLP1R) present on β-cells. This occurs at high concentrations as are present within the islet. However, its net contribution to physiologic insulin secretion is unknown. To address this question, we studied 12 non-diabetic, weight-stable individuals (26±1 years,25±1 kg/m2) on 2 occasions. During a hyperglycemic clamp (∼8.9mmol/l) where glucose was labeled with [3-3H] glucose, glucagon was infused at 0.4ng/kg/min, for 1 hour, increasing by 0.2ng/kg/min every hour for a total of 5 hours. Subjects were studied on two occasions in random order. On one occasion Exendin-9,39 (300pmol/kg/min) was infused to block the GLP1R, while on the control day saline was infused. The insulin secretion rate (ISR) was calculated by nonparametric deconvolution from plasma concentrations of C-peptide. Endogenous glucose production (EGP) and glucose disappearance (Rd) were measured using the tracer-dilution technique. Glucagon concentrations rose from baseline (6.6±2.1 vs. 5.4±1.5 pmol/l, saline vs. exendin-9,39 respectively, p=0.22) to values that, by design, did not differ between study days (17.8±1.8 vs. 17.1±1.1 pmol/l, p>0.1) . This was accompanied by a rise in C-peptide from fasting concentrations. Integrated C-peptide concentrations were slightly, but significantly, decreased during exendin-9,39 infusion (721±65 vs. 648±55 nmol per 5hr, p=0.02) . In addition, integrated insulin secretion rate was lower during exendin-9,39 infusion (213±26 vs. 191±22 nmol per 5 hr, saline vs. exendin-9,39 respectively, p = 0.03) . Both EGP and Rd did not differ significantly on either experimental day. These data show that in non-diabetic humans, during hyperglycemia as seen in the postprandial period, glucagon partially stimulates the β-cell through GLP1R. It remains to be ascertained if this also applies to individuals with type 2 diabetes.

Disclosure

R.A. Farahani: None. A.A. Welch: None. M.C. Laurenti: None. C. Cobelli: None. C. Dalla Man: Research Support; Becton, Dickinson and Company, Sanofi-Aventis Deutschland GmbH. A. Vella: Advisory Panel; Crinetics Pharmaceuticals, Inc., Rezolute, Inc., vTv Therapeutics, Zealand Pharma A/S. Other Relationship; Novo Nordisk.

Funding

National Institutes of Health (DK126206)
359-OR: Imaging Pancreatic Blood Flow during Stimulation of Insulin Secretion in Humans
Authors: SIMONSON DONALD C. , TASO MANUEL , MCGRATH COLLEEN , WALDMAN STEPHANIE A. , PAPADOPOULOU FOTINI , ALSOP DAVID C.
Published: May 2022

Non-invasive imaging of endocrine pancreatic function could provide valuable insights into the magnitude and temporal pattern of β-cell dysfunction in diabetes. Islets comprise 1-2% of pancreatic mass, but receive about 10-20% of pancreatic blood flow, which increases further during stimulation of insulin secretion. We examined the relationship between pancreatic blood flow (PBF) and insulin secretory dynamics in 12 healthy volunteers (6M / 6F, age = 29 ± 5 yrs, BMI = 24.0 ± 2.7 kg/m², HbA1c = 5.1 ± 0.3 %, FPG = 88 ± mg/dl, fasting insulin = 3.7 ± 2.3 μU/ml) . PBF was measured by pseudo-continuous arterial spin labeling (ASL) MRI, with the labeling plane positioned 5-6 cm superior to the imaging slice to label blood in the descending aorta. Fasting subjects were placed in a 3T scanner, and PBF was measured during 1) a 15 min basal period, 2) a +100 mg/dl hyperglycemic clamp for 40 min, followed by 3) a 5 gm bolus of arginine to assess maximal acute insulin response (AIRmax) . First phase (0-min) insulin response to hyperglycemia was 181 ± 96 μU/ml · min, and AIRmax after arginine + hyperglycemia (40-50 min) was 1097 ± 629 μU/ml · min. Basal PBF (188 ± 53 ml/100 gm/min) increased during first phase insulin release, peaking at 212 ± 66 at 12 min, subsequently returned to basal levels (176 ± 59) from 10-40 min during sustained hyperglycemia,and peaked again at 2± 62 at 2 min after arginine. Although there were no significant correlations between glucose, insulin or c-peptide levels and PBF, time-series Granger causality analysis demonstrated that the time-derivative of c-peptide and insulin concentrations, reflectingacute changes in insulin secretion, preceded the increase in PBF (p=0.03 for d[c-peptide]/dt, and p = 0.for d[insulin]/dt) . Conclusions: 1) Changes in PBF during stimulation of insulin secretion in humans can be imaged non-invasively by ASL, 2) Insulin secretion precedes changes in PBF, and 3) The rate of change in insulin and c-peptide release predicts subsequent modulation of PBF.

Disclosure

D.C.Simonson: Stock/Shareholder; GI Windows, Phase V Technologies, Inc. M.Taso: Research Support; GE Healthcare Systems. C.Mcgrath: None. S.A.Waldman: None. F.Papadopoulou: None. D.C.Alsop: Other Relationship; GE Healthcare Systems, Hitachi, Ltd., Philips Healthcare, Siemens, UIH America, Research Support; GE Healthcare Systems.
360-OR: Hyperglucagonemia Reduces De Novo Lipogenesis and Increases Gluconeogenesis in Healthy Subjects
Authors: CHEN XI , CARLI FABRIZIA , PEZZICA SAMANTHA , MOCCIARO GABRIELE , CIOCIARO DEMETRIO , GASTALDELLI AMALIA , DEFRONZO RALPH A. , TRIPATHY DEVJIT
Published: May 2022

Although the effect of glucagon on glucose metabolism has been well characterized, its effect on lipid metabolism, particularly lipolysis and de novo lipogenesis, in humans in vivo has been poorly studied with controversial results. We examined the effect of short-term hyperglucagonemia on de novo lipogenesis (DNL) and endogenous glucose production (EGP) in 8 healthy normal glucose tolerant subjects (5M/3F, age=35±5, BMI= 24±1) who received a 12-hour (6PM to 6AM) glucagon infusion (6ng/kg/min) infusion with measurement of EGP (3-3H-glucose) on the following morning 6-AM. Subjects received deuterated water (D2O, 5g/kg fat free mass) at PM on the night prior to study. 8 weeks later subjects returned for a repeat study with 12-hour infusion of normal saline. DNL was quantified by measuring the incorporation of deuterated water into circulating triglycerides. Gluconeogenic rate was measured as (EGP) x (plasma C5/C2 glucose ratio) (EGP) x (plasma C5/C2 glucose ratio) . Plasma esterified and non-esterified FFA levels were measured with gas chromatography mass spectrometry (GC-MS) . Plasma glucagon increased from 57±3 to 219±21 pg/ml within one hour and remained elevated throughout the study. DNL was significantly decreased (1.64 ± 0.58% vs. 3.± 0.98%, p<0.05) after glucagon versus saline infusion. Both plasma palmitate (0.73 ± 0.vs. 0.67 ± 0.mmol/L) and total FFA (1.35 ± 0.vs. 1.21 ±0.mmol/L) concentrations were elevated after glucagon infusion (p<0.05) . EGP increased following glucagon infusion (2.13 ± 0.14 vs. 1.97± 0.11mg/kg/min, p =0.006) . The increase in EGP was primarily due to increased gluconeogenesis (1.48 ± 0.14 vs. 1.27 ± 0.11, p=0.02) , while the rate of glycogenolysis did not change (0.65± 0.14 vs. 0.70± 0.11, p=ns) . Conclusion: Short-term (12-hour) physiologic hyperglucagonemia in healthy subjects reduces hepatic de novo lipogenesis, stimulates adipose tissue lipolysis, and increases hepatic glucose production by increasing gluconeogenesis.

Disclosure

X.Chen: None. F.Carli: None. S.Pezzica: None. G.Mocciaro: None. D.Ciociaro: None. A.Gastaldelli: Advisory Panel; Boehringer Ingelheim International GmbH, Novo Nordisk Global Business Services, Consultant; Boehringer Ingelheim International GmbH, Inventiva Pharma, Other Relationship; Eli Lilly and Company, Gilead Sciences, Inc., Pfizer Inc., Speaker's Bureau; Novo Nordisk. R.A.Defronzo: Advisory Panel; AstraZeneca, Boehringer Ingelheim International GmbH, Intarcia Therapeutics, Inc., Novo Nordisk, Research Support; AstraZeneca, Boehringer Ingelheim International GmbH, Merck & Co., Inc., Speaker's Bureau; AstraZeneca. D.Tripathy: None.

Funding

EFSD Albert Renold Travel Fellowship; FAVHR
366-OR: 14-3-3-ζ Contributes to Effect of ß-Cell GLP1 Receptor Signaling to Alter a-Cell Proglucagon Processing
Authors: HOLTER MARLENA , PHUONG DARYL , LEE ISAAC S.H. , SAIKIA MRIDUSMITA , WEIKERT LISA A. , ANDERSON ELIZABETH T. , FU QIN , ZHANG SHENG , SLOOP KYLE , CUMMINGS BETHANY
Published: May 2022

Glucagon like peptide 1 (GLP1) , a classically gut derived hormone, potentiates insulin secretion. New evidence suggests that α cells can produce GLP1 under certain conditions, which may offer a novel therapeutic modality for treating diabetes; however, the mechanisms regulating α cell GLP1 production are unknown. We previously found that enhanced β cell GLP1 receptor (GLP1R) signaling activates α cell GLP1 by activating prohormone convertase 1/3 (Pcsk1) expression. We tested the hypothesis that enhanced β cell GLP1R signaling activates α cell GLP1 production through paracrine factors. We studied the impact of conditioned media (CM) generated from β cell GLP1R WT and KO islets of saline (CTRL) and liraglutide (LIRA) treated mice on α cell gene expression and function. CM from LIRA treated islets increased α cell Pcsk1 expression and active GLP-1 secretion only if β cells expressed the GLP1R (Pcsk1 expression (AU) : CTRL WT=1.0±0.1, LIRA WT=2.0±0.3, CTRL KO=1.1±0.2, LIRA KO=1.1±0.2, P<0.01; active GLP-1 (pg/mL) : CTRL WT=124±44, LIRA WT=682±247, CTRL KO=173±101, LIRA KO=116±30, P<0.05) . Subsequent identification of the proteome secreted by mouse and human islets in response to LIRA and CTRL revealed 14-3-3-ζ as a lead candidate in the regulation of α cell Pcsk1 expression. To assess the role of 14-3-3-ζ, islets from LIRA treated mice were treated with and without 14-3-3-ζ, and islets from CTRL treated mice were treated with and without the 14-3-3 inhibitor, R18. Addition of 14-3-3-ζ ablated the effect of CM from LIRA treated islets to increase α cell Pcsk1 expression, while inhibition of 14-3-3 with R18 in CTRL islets resulted in CM that mimicked the effect of CM from LIRA treated islets to stimulate α cell Pcsk1 expression (Pcsk1 expression: CTRL=1.1±0.2, R18=2.0±0.2, LIRA=2.4±0.3, LIRA+14-3-3-ζ=1.3±0.1, P<0.05) . These data refine our understanding of α cell GLP1 regulation and identify 14-3-3-ζ as a potential target with which to enhance α cell GLP1 production for diabetes treatment.

Disclosure

M.Holter: None. B.Cummings: None. D.Phuong: None. I.S.H.Lee: None. M.Saikia: None. L.A.Weikert: Stock/Shareholder; Merck & Co., Inc., Oramed Pharmaceuticals. E.T.Anderson: None. Q.Fu: None. S.Zhang: None. K.Sloop: Employee; Eli Lilly and Company.

Funding

NIH/NIDDK (F30 DK126538) Department of Defense (W81XWH-18-1-0206) The Hartwell Foundation NIH/NIDDK (R56DK124853)