bluuebunny/crossref_metadata_2025 huggingface dataset:
1577-P: CIDEB Knockdown Promotes Increased Hepatic Mitochondrial Fat Oxidation and Reverses Hepatic Steatosis and Hepatic Insulin Resistance by the PKCε-Insulin Receptor Kinase Pathway
Authors: ZHENG JIE , NASIRI ALI , GASPAR RAFAEL C. , HUBBARD BRANDON T. , SAKUMA IKKI , MA XIAOXIAN , MURRAY SUE , PERELIS MARK , BARNES WILLIAM , SAMUEL VARMAN , PETERSEN KITT , SHULMAN GERALD I.
Published: June 2024

Metabolic-dysfunction associated hepatic steatotic liver disease (MASLD) plays a major role in the pathogenesis of type 2 diabetes and can lead to end stage liver disease but there are currently no FDA approved treatments. CIDEB deficiency has been shown to be associated with reduced incidence of MASLD in humans however the mechanism by which it does so remains unknown. We found that knocking down hepatic expression of CIDEB using an antisense oligonucleotide decreased hepatic triglyceride accumulation by ~150% (p = 0.0001) in high fat fed (HFD) mice. This reduction in hepatic fat content could be mostly attributed to a ∼30% increase rates of hepatic mitochondrial fat oxidation as assessed by a novel [13C5]glutamine tracer infusion technique (Q-Flux). In order to assess the impact of reduced hepatic steatosis on hepatic and whole-body insulin sensitivity we performed hyperinsulinemic-euglycemic clamp studies. CIDEB knockdown ameliorated HFD-induced insulin resistance in mice, reflected by ∼2-fold (p = 0.001) increase in the glucose infusion rate required to maintain euglycemia. These improvements in hepatic insulin sensitivity were associated with decreased plasma membrane (PM)/cytosol PKCε translocation and increased insulin-stimulated phosphorylation of IRKY1158, IRKY1162, AktS473 and AktT308 (all p < 0.05).

Conclusion: These results demonstrate that CIDEB knockdown increases mitochondrial fat oxidation and ameliorates HFD-induced hepatic steatosis and hepatic insulin resistance through the PKCε-insulin receptor kinase pathway and suggest that CIDEB knockdown may represent a novel therapeutic approach to treat MASLD.

Disclosure

J. Zheng: None. A. Nasiri: None. R.C. Gaspar: None. B.T. Hubbard: None. I. Sakuma: None. X. Ma: None. S. Murray: Employee; Ionis Pharmaceuticals. M. Perelis: Employee; Ionis Pharmaceuticals. W. Barnes: Employee; Ionis Pharmaceuticals. V. Samuel: None. K. Petersen: None. G.I. Shulman: None.
1583-P: Measuring Mitochondrial Metabolism In Vivo with [1,2-13C2]-L-Glutamine Mass Isotopomers
Authors: SIEBEL STEPHAN , CARDONE REBECCA L. , MASON GRAEME F. , KIBBEY RICHARD
Published: June 2024

Background:Accuracy of tracer-based measurements of in vivo metabolic rates rely on assumptions, i.e., tracer non-interference with metabolism

Aim: [1,2-13C2]-L-glutamine was evaluated to trace hepatic (H) & renal (K) metabolism in rats fed control vs. highfat-highsucrose diets (HFHSD) with validation by independent models and compared to lactate, propionate, and acetate tracing

Methods: Sprague-Dawley rats underwent primed, continuous infusions of [1,2-13C2]-L-glutamine vis-à-vis lactate, propionate, acetate infusions.Plasma/freeze-clamped tissues were obtained at 7 timepoints. Isotopomers were interpreted by steady-state and kinetic Mass Isotopomer Multi-Ordinate Spectral Analysis (MIMOSA)

Results:[1,2-13C2]-L-glutamine equilibrated without significant impact on intermediary/glucose metabolism. Transaminase exchange (v x) was >> citrate synthase (v CS). v PEPCK/v CS was 1.5 in (H) and 1.9 in (K). Pyruvate contributed 76% of anaplerosis in (H) and 90% in (K) with the remainder from propionate (v PCC) (H) and glutamate (vGDH) (H, K)). Citrate lyase (v ACLY/v CS) was significant only in (H) (18%) increasing on HFHSD. Plasma insulin ([i]), glucose ([g]), and/or glucose turnover (Ra) were increased by acetate ([i]=1.5x, p=0.015; [g]=129mg/dl, p=0.021), lactate ([i]=2.03x, p=0.0001; [g]=156mg/dl, p=0.0001, Ra=7.2mg/kg/min, p=0.006), and propionate ([i]=1.7x, p=0.0013; [g]=165mg/dl, p=0.0001, Ra=7.8mg/kg/min, p=0.0017). Lactate, acetate, and propionate increased cataplerosis > HFHSD

Conclusion: [1,2-13C2]-L-glutamine MIMOSA provided unaltered, direct measurements of mitochondrial metabolism validated by independent kinetic and steady-state models and demonstrated comparable v PEPCK and v CS, fast transaminase, substantial v ACLY, v PCC, and minimal v GDH. Metabolic changes induced by HFHSD were less than those caused by lactate, propionate, acetate.

Disclosure

S. Siebel: None. R.L. Cardone: None. G.F. Mason: Consultant; Merck & Co., Inc. R. Kibbey: None.

Funding

National Institutes of Health (5R01DK108283-04)
1589-P: Serum Triglyceride Better Indicator Compared with FiB4 Score for Diagnosis of Liver Fibrosis Assessed via Liver Fibroscan in Indian Patients with Type 2 Diabetes Mellitus Receiving SGLT2i Therapy
Authors: GUPTA VISHAL
Published: June 2024

Aim: Identify biomarker that predicts risk of liver fibrosis (LF). Analyse role of FiB4 score in detecting LF.

Methods: Between Oct’ 22 & Mar’ 23, 66 T2DM patients (waist cmf > 80 cms (F) > 90 cms (M) receiving dapagliflozin irrespective of A1c & who underwent liver fibroscan (Lfib) were retrospectively analysed & studied. LF was performed by Lfib using ARFI. Metavir LF staging classified pt’s: F0 (N); F1 (N - mild); F2 (Mild - mod); F3 (mod - severe); F4 (cirrhosis). Wt-Kg, systolic/diastolic BP (mmHg), Lipid profile mg/dl (TC, LDL-C, TG, HDL), Hs-crp mg/L, LFT, NT-ProBNP pg/ml, eGFR (Cyst-C) & UACR mg/gm were recorded 2-3 mthly & data presented over 1 yr. Exclusion: Preg, <3 mths illness/hospitalisation, alcoholism, hep B, C & autoimmune hepatitis (if LFT was raised). Statistics: ANOVA - compared parameters within stages of LF. One-Way ANOVA, followed by post-hoc Tukey test compared mean TG levels within LF stages. Pearson Chi-square test (comparison of two non-parametric variables) & Spearman rho’s (correlation between Fib4 & LF stages) was used with P-value <0.05 considered statistically significant (S).

Results: Baseline (B) characters: Males 86.4%, avg (age 56.88+8.82, Wt 83.72+11.96, A1c 7.77+1.54, TG 164.16+90.82, hs-CRP 2.57+2.83, GGT 49+51.96 SGPT 40.44+25.89, NT-ProBNP 46.65+45.71, UACR 33.43+99.55 & eGFRCys-C 84.98+20.55. (B) - 1 yr: S reduction in Wt, DBP, A1c, TC, LDL, TG, hs-CRP, SGPT. (B) TG was S different between stages of LF {140.88+71.98 (F0), 143.92+54.32 (F1), 344.33+76.22(F2), 178+51.34 (F3), 259.83+153.64 (F4) p-0.001}. TG >128 (p-0.041) was found S for detecting LF (F2-F4, sensitivity 73.53% & specificity 53.13%). SGPT & GGT (>50) was associated with LF severity (F2-F4), likelihood ratio -4.477 (p-0.031). No correlation was found between FiB4 & stages of LF.

Conclusion: Serum TG is a better predictor compared to FiB4 score in detecting LF in Indian patients with T2DM.

Disclosure

V. Gupta: None.
1591-P: Circulating Levels of ELABELA Is Inversely Associated with Hepatic Fibrosis of Nonalcoholic Fatty Liver Disease in Patients with Type 2 Diabetes Mellitus
Authors: SHI MIN , CAO HUIMIN , LIU YUTING , GU WENSHA , ZHANG HONG
Published: June 2024

Background: Non-alcoholic steatohepatitis is closely associated with the progression of diabetic kidney disease (DKD) in type 2 diabetes mellitus (T2DM). We aimed to investigate whether plasma ELABELA, recently identified as a latent biomarker for DKD, is related to the severity of NAFLD.

Methods: A total of 362 patients with T2DM were enrolled in this study. Noninvasive clinical markers of hepatic fibrosis including fibrosis-4 (FIB-4) index, NAFLD fibrosis score (NFS) and aspartate aminotransferase-to-platelet ratio index (APRI) were determined. The levels of plasma ELABELA, UACR, creatinine and glucometabolic parameters were measured. The relationships between plasma ELABELA and the clinical markers were statistically evaluated.

Results: Based on the median value of the plasma ELABELA, subjects were divided into low and high ELABELA groups. The low ELABELA group showed a significantly longer duration of diabetes, worsened nephropathic indices, and a more enhanced hepatic fibrosis index. A lower ELABELA was associated with a greater odds ratio for the risk of higher hepatic fibrosis stage (OR, 0.98; 95% CI, 0.966 to 0.994). Multiple regression analysis including confounding factors showed that ELABELA independently contributed to decreases in FIB-4 index (P=0.044), NFS (P=0.012). In addition, logistic regression analysis for the prevalence of advanced hepatic fibrosis defined by the cutoff points of the clinical scores showed that ELABELA was the sole and common negative factor for prevalence of advanced hepatic fibrosis (FIB-4 index: P=0.016, NFS: P=0.005).

Conclusion: The decline of plasma ELABELA was independently associated with a higher degree of hepatic fibrosis in patients with T2DM. Considering the common metabolic milieu of renal and hepatic fibrosis in T2DM, the potential use of plasma ELABELA as an effective biomarker reflecting hepatic fibrosis in T2DM needs to be validated in the future.

Disclosure

M. Shi: None. H. Cao: None. Y. Liu: None. W. Gu: None. H. Zhang: None.

Funding

Jiangsu Province Science and Technology Plan Special Funds (BE2023745); Jiangsu Health Commission Medical Scientific Research Project (H2023137)
1618-P: Progression to Glucose Intolerance Is Characterized by Glucagon Secretion Inappropriate for Circulating Glucose
Authors: MOHAN SNEHA , CHRISTIE HANNAH E. , LAURENTI MARCELLO C. , EGAN AOIFE M. , VELLA ADRIAN , DALLA MAN CHIARA
Published: June 2024

As part of a series of studies to understand the pathogenesis of prediabetes, we studied 96 nondiabetic individuals (54 ± 1.2 years; BMI 28.4 ± 0.4 Kg/M2) on 2 occasions, 3 years apart using an oral 75g glucose challenge. Weight and body composition were measured prior to each study. Fasting and 120-minute glucose were used to classify subjects’ glucose tolerance at baseline, and at the 3-year visit. Indices for insulin secretion and action were estimated using the oral minimal model. Glucagon secretion rate (GSR) was estimated by deconvolution from peripheral glucagon concentrations. Overall, 32 subjects progressed from normal to Impaired Glucose Tolerance (IGT) or from IGT to type 2 diabetes. Anthropometric variables were similar between progressors and those with stable glucose tolerance at baseline (BMI 28.1 ± 0.7 vs. 28.7 ± 0.6 Kg/M2, p = 0.50), and at 3 years (29.1 ± 0.8 vs. 29.3 ± 0.6 Kg/M2, p = 0.81). No significant differences in baseline fasting and nadir GSR or in Disposition Index (DI - 659 ± 98 vs. 885 ± 86 10-4 dl/kg/min per μU/ml, p = 0.11) were noted. Although, peak glucose concentrations differed significantly at baseline (11.4 ± 0.3 vs. 10.3 ± 0.2 mmol/l, p < 0.01), integrated concentrations did not (462 ± 47 vs. 402 ± 26 mmol/l per 6hr, p = 0.23). At 3-year follow-up, DI declined in the progressors (659 ± 98 vs. 451 ± 65 10-4 dl/kg/min per μU/ml, baseline vs. 3-years p = 0.04). This did not occur in the stable group (885 ± 86 vs. 893 ± 142 10-4 dl/kg/min per μU/ml, p = 0.94). α-cell suppression by glucose (fall in GSR (pmol/min)/glucose rise (mmol/l)) did not differ at baseline (1.3 ± 0.2 vs. 1.5 ± 0.1 nmol/min/L, p = 0.37) but was impaired at 3 years (1.0 ± 0.2 vs. 1.4 ± 0.1 nmol/min/L, p < 0.01) in those who progressed. Analysis of the entire cohort showed that our index of glucagon suppression was inversely correlated to increase in glycemic excursion (R2=0.14, p < 0.01). These data show that α-cell dysfunction accompanies a decline in β-cell function as IGT or overt type 2 diabetes develops.

Disclosure

S. Mohan: None. H.E. Christie: None. M.C. Laurenti: Employee; Angelini Pharma. A.M. Egan: None. A. Vella: Research Support; Novo Nordisk. Consultant; Hanmi Pharm. Co., Ltd., Crinetics Pharmaceuticals, Inc. Advisory Panel; Rezolute, Inc. C. Dalla Man: None.

Funding

National Institutes of Health (DK116723)
1624-P: Is the Contribution of Postoperative Adult Growth Hormone Deficiency to Fatty Liver Greater Than the Contribution of Type 2 Diabetes?
Authors: TSUJIMOTO YUKI , YAMASHIRO KENJI , NISHIMURA RIMEI
Published: June 2024

Background: In recent years, adult growth hormone deficiency (AGHD) has been recognized as one of the risk factors for fatty liver. AGHD is often induced by surgery for pituitary tumors. However, there is no report comparing the contribution of AGHD and type 2 diabetes(T2D) to fatty liver in patients with both conditions following pituitary tumor surgery, so far. Therefore, this study examined the associations of AGHD and T2D with a surrogate marker of fatty liver, "ALT at 3 months post-surgery" in patients undergoing pituitary tumor surgery, using two-way analysis of variance.

Methods: The study included 69 patients who underwent surgery for pituitary tumors and underwent AGHD examination through growth hormone stimulation tests. The dependent variable was ALT at 3 months post-surgery, and independent variables were the presence of T2D (T2D group n=8, non-T2D group n=61) and the presence of AGHD (AGHD group n=23, non-AGHD group n=46).

Results and Conclusion: Both the presence of T2D and AGHD showed significant main effects (p<0.001, p=0.015, respectively), and their interaction demonstrated a significant synergistic effect (p=0.048) as well. It was demonstrated that having T2D and having AGHD both contribute to elevated ALT. However, the contribution rates to ALT were 22.0% for T2D, 5.4% for AGHD, and 3.1% for interaction. Having T2D was identified as the main contributed factor for elevated ALT. Although AGHD is recognized as a risk factor for fatty liver after pituitary tumor surgery, this study revealed that it becomes an extremely strong risk when combined with T2D.

Disclosure

Y. Tsujimoto: None. K. Yamashiro: Other Relationship; Teijin Pharma Limited, Ono Pharmaceutical Co., Ltd. R. Nishimura: Speaker's Bureau; Abbott. Advisory Panel; Abbott Japan Co., Ltd. Speaker's Bureau; Boehringer-Ingelheim, Mitsubishi Tanabe Pharma Corporation, Kowa Company, Ltd., Medtronic, Sanofi, Taiho Pharmaceutical Co. Ltd., Sumitomo Dainippon Pharma Co., Ltd., Teijin Pharma Limited, Eli Lilly and Company, Novo Nordisk A/S. Consultant; Terumo Corporation.
1635-P: Survodutide Weight Loss Is Associated with Changes in Food Preference and Improvement of Dyslipidemia in the Free Choice Diet–Induced Obese Hamster Model
Authors: BRIAND FRANCOIS , AUGUSTIN ROBERT , WESCHE FRANK , DELIC DENIS , KLEIN THOMAS
Published: June 2024

Introduction & Objective: Survodutide, a glucagon/GLP-1 receptor dual agonist, has recently shown significant weight loss in a Phase II trial. To test whether this weight loss is associated with changes in food preference and improvement in dyslipidemia, we evaluated survodutide in the free choice diet-induced obese and dyslipidemic hamster model, with human-like lipoprotein metabolism.

Methods: Obesity and dyslipidemia were induced with a 20-week free choice diet, with a choice between control chow or high fat/cholesterol diet, and normal or 10% fructose water. Obese hamsters were kept on this free choice diet and treated subcutaneously, once daily for 2 weeks with vehicle or survodutide 20 nmol/kg.

Results: Survodutide treatment for 2 weeks led to a 19% body weight reduction (p<0.0001 vs vehicle). Compared to vehicle, both normal water and chow diet intake were significantly lower during week 1 of survodutide treatment, then returned to baseline values. In contrast, both 10% fructose water and high fat/cholesterol diet intake were rapidly reduced during the whole treatment period (p<0.0001). Survodutide significantly reduced fasting glycemia and hyperinsulinemia, leading to a 75% reduction in HOMA-IR index (p<0.0001). Survodutide reduced plasma free fatty acids (-49%) and triglycerides (-75%; both p<0.001 vs vehicle). Survodutide reduced plasma total cholesterol levels (-41%, p<0.001), resulting in cholesterol lowering in all lipoprotein fractions, including LDL-cholesterol (-31%, p<0.0001 vs vehicle). These effects were further confirmed with fast protein liquid chromatography lipoprotein profiles.

Conclusion: Survodutide induces weight loss in the free choice diet-induced obese hamster model through beneficial changes in food preference, leading to improvement in HOMA-IR and dyslipidemia. These data highlight the potential benefits of survodutide for the treatment of obesity and related comorbidities.

Disclosure

F. Briand: Employee; PHYSIOGENEX. Stock/Shareholder; PHYSIOGENEX. R. Augustin: Employee; Boehringer-Ingelheim. F. Wesche: Employee; Boehringer-Ingelheim. D. Delic: None. T. Klein: Employee; Boehringer-Ingelheim.

Funding

Boehringer Ingelheim
1650-P: Chronic Air Pollution Induces Brown Adipose Dysfunction and Insulin Resistance through Epigenetic Modification of Key Metabolic Circadian and Redox Targets
Authors: RENGASAMY PALANIVEL , DAZARD JEAN-EUDES , PARK BONGSOO , VERGARA-MARTEL ARMANDO , EDWARDS-GLENN JONNELLE , NANDIKOLMATH SURBHI , MOORTHY SKANDA T. , AL-KINDI SADEER G. , BROOK ROBERT D. , RAJAGOPALAN SANJAY
Published: June 2024

Background: Prior studies have demonstrated a strong link between air pollution and type 2 diabetes including brown adipose tissue (BAT) dysfunction, common proximate regulators are poorly characterized. We hypothesized that exposure to ambient fine particulate matter (<2.5μm; PM2.5) modulates insulin resistance through its impact on epigenetic regulators of BAT function.

Methods: Male C57BL/6 mice at the age of 4 weeks were fed a chow diet and exposed to concentrated PM2.5 or filtered air (n = 12 per group) for 24 weeks (6hr/day and 5 days in a week) using a VACES system, that allows chronic exposure to real world air pollution. Glucose and insulin tolerance tests, indirect calorimetry using metabolic cages and PET/CT using 18-FDG uptake were performed between 12-20 weeks following air pollution exposure. BAT was isolated for DNA methylation (DMRs), chromatin accessibility (DARs), and Differentially Expressed Genes (DEGs) analysis using bisulfite, ATAC and RNA-sequencing respectively.

Results: BAT thermogenic activity was reduced by decreased FDG uptake (40%) with significant reduction in peak VO2 and VCO2 and RER at night time by PM2.5. Genome wide differential methylation indicates evidence for hypomethylation and hypermethylation, with widespread chromatin remodeling involving intronic and enhancer elements corresponding to multiple transcription factor binding sites including genes involved in thermogenesis, redox and circadian function. Integrated DAR-DEG-DMR analysis pointed to two targets, a histone deacetylase-9 (HDAC9) and KDM2B, a lysine demethylase. ChIP-qPCR of HDAC9 and KDM2B revealed binding and regulation of RORα, GST1α and PRDM16 with HDAC9 and UCP1 and NRF2 with KDM2B, respectively.

Conclusion: Chronic air pollution exposure affects BAT function and induces insulin resistance through epigenetic regulation of key targets involved in redox function, thermogenesis and circadian function.

Disclosure

P. Rengasamy: None. J. Dazard: None. B. Park: None. A. Vergara-Martel: None. J. Edwards-Glenn: None. S. Nandikolmath: None. S.T. Moorthy: None. S.G. Al-Kindi: None. R.D. Brook: Advisory Panel; Alnylam Pharmaceuticals, Inc. S. Rajagopalan: Consultant; Novo Nordisk, Bayer Inc.
1653-P: Female Mice Are Protected from Deleterious Metabolic Programming Effects of a High-Fat Diet Fed during Pregnancy and Lactation
Authors: KRUSE MICHAEL , SEKI YOSHINORI , QUAN DU XIU , CHARRON MAUREEN J.
Published: June 2024

Obesity induced by a high fat (HF) diet during pregnancy (P) and lactation (L) shows a sexual dimorphic response in offspring. Studies reported a metabolic benefit for female compared to male offspring. The mechanisms that determine sexual dimorphic responses are still poorly understood. This study investigates the metabolic phenotype, adipose tissue distribution and hepatic lipid metabolism in female offspring exposed to a HF diet during P/L and early adulthood. CD1 female offspring mice were exposed to either a control (C) or a HF diet during P/L and fed a regular chow after weaning for 23 wks and then re-exposed to either the C or HF diet for 19 wks. This resulted into mice exposed to the C diet during P/L and re-exposed to either the C (C-C) or HF (C-H) diet, and mice exposed to the HF diet during P/L and re-exposed to either the C (H-C) or HF (H-H) diet (n=3-5). Body weight (BW), body composition, food intake (FI), fasted blood glucose and insulin levels, intra peritoneal glucose (ipGTT) and insulin (ipITT) tolerance were measured. Mice were sacrificed at 45 wks and qRT-PCR of stearoyl-CoA-desaturase 1 (SCD-1) as a marker of lipogenesis and of caveolin-1 (CAV1) as a protective marker of hepatic steatosis was performed in liver. BW, adiposity and ipGTT and ipITT were not different between C-H and H-H. However adiposity was increased 3.0-fold in C-H compared to C-C and 2.0-fold in H-H compared to H-C, respectively (both p<0.05). FI and fasted glucose and insulin were not different between groups. Gene expression of SCD-1 was downregulated by 69% in C-H compared to C-C and by 81% in H-H compared to H-C, respectively, (both p<0.05) in liver. In contrast, hepatic CAV1 gene expression was increased 1.93-fold in H-H compared to H-C (p<0.05). These data show that female mice are protect from the deleterious programming effects of a HF diet. Moreover, mice exposed to a HF diet during P/L exhibit protective mechanisms to prevent hepatic steatosis when re-exposed to HF diet in early adulthood.

Disclosure

M. Kruse: None. Y. Seki: None. X. Du: None. M.J. Charron: None.
166-OR: The Alpha–Catenin–Cholesterol Biosynthesis Axis Regulates Tight Junction Formation in Pancreatic Islets
Authors: TIXI WILMA , YEUNG WILSON , CHIU AMY , DHAWAN SANGEETA , SHIH BEN
Published: June 2024

Introduction & Objective: The functionality of pancreatic islets relies on the structural integrity of cellular junctions, such as tight junctions (TJs). At the heart of this junctional integrity is the cell adhesion protein Alpha-Catenin (Ctnna1). Alterations in Ctnna1 result in impaired islet clustering and functionality. We observed that islet cells with targeted Ctnna1 ablation (Ctnna1-KO) showed weakened TJs and diminished cholesterol biosynthesis. Recognizing the vital relationship between TJs and cholesterol-rich domains for cellular integrity, we explored Ctnna1's role in modulating TJ formation through the cholesterol biosynthesis pathway. We aim to deepen our understanding of cellular cohesion mechanisms and identify potential therapeutic strategies to enhance pancreatic islet functionality.

Methods: We crossbred mice with Ngn3-promoter-driven Cre recombinase and Ctnna1flox/flox. We analyzed pancreata across various developmental stages and conducted rescue experiments comparing TJ formation in control and Ctnna1-KO mice. This included treating isolated 8-week-old mouse islets with cholesterol or its intermediate precursors isoprenoids in vitro and feeding 8-week-old mice a high-fat diet for eight weeks in vivo. Complementary experiments with human islets treated with statin provided further human context.

Results: Our findings indicate a significant compromise in the structural integrity of TJs in the absence of alpha-Catenin. However, cholesterol supplementation partially restored this integrity, suggesting a potential pathway for therapeutic intervention.

Conclusions: Our study highlights the pivotal role of alpha-Catenin-dependent cholesterol biosynthesis in maintaining the structural and functional integrity of tight junctions within pancreatic islets. Manipulating this pathway could offer new avenues for therapeutic interventions to preserve or enhance islet function, potentially impacting diabetes treatment.

Disclosure

W. Tixi: None. W. Yeung: None. A. Chiu: None. S. Dhawan: None. B. Shih: None.

Funding

The California Institute for Regenerative Medicine (CIRM) TG EDUC4-12772; National Institutes of Health/National Institute of Diabetes and Digestive and Kidney Diseases (NIH/NIDDK) (1RO1DK120523)
1662-P: Petrelintide (ZP8396) Significantly Reduces Fat Mass while Preserving Lean Mass in DIO Rats
Authors: VESTERGAARD BILL , BAADER-PAGLER TAMARA , GRIFFIN JON
Published: June 2024

The obesity pandemic is a major health crisis and current treatments are primarily focused on weight loss. However, health benefits from weight loss can be compromised by the weight-loss-associated loss of lean body mass. Here we investigate the effect of petrelintide, a novel once-weekly amylin analog on weight loss with comparison of changes of fat mass and lean mass in DIO (diet-induced obese) rats.

DIO rats were treated with either vehicle (every second day), liraglutide (5 nmol/kg twice daily) or petrelintide (2 nmol/kg every second day or 10 nmol/kg every fourth day) for a 30-day treatment period. Body weight was measured daily, and body composition was measured by use of EchoMRI at baseline and at day 29 of treatment.

Treatment with liraglutide and petrelintide resulted in significantly lower relative body weight compared to vehicle (3.3 % ± 0.7 vehicle, -0.1 % ± 1.1 liraglutide, -4.1 % ± 0.6 petrelintide 2 nmol/kg, -7.8 % ± 0.7 petrelintide 10 nmol/kg; relative to initial body weights ± SEM). Treatment with petrelintide resulted in significant reduction of fat mass in comparison to vehicle, which liraglutide did not (2.0% ± 0.5 liraglutide, -0.3 % ± 0.5 petrelintide 2 nmol/kg, -1.6 % ± 0.5 petrelintide 10 nmol/kg, 3.2 % ± 0.4 vehicle; mean change in fat mass as % of body weight ± SEM).

Furthermore, treatment with petrelintide resulted in significant preservation of relative lean mass in comparison to vehicle, which liraglutide did not (-3.8 % ± 0.3 vehicle, -2.4 % ± 0.6 liraglutide, -0.8 % ± 0.4 petrelintide 2 nmol/kg, 0.1 % ± 0.4 petrelintide 10 nmol/kg; mean change in lean mass as % of body weight ± SEM).

In conclusion, petrelintide shows preferential fat mass loss and preservation of relative lean mass during weight loss in DIO rats. Based on these findings, petrelintide could hold the potential to reduce the loss of lean body mass associated with weight loss in humans. Petrelintide is currently being explored in a multiple ascending dose (MAD) study to assess the potential for the management of obesity.

Disclosure

B. Vestergaard: Employee; Zealand Pharma A/S, Novo Nordisk A/S. T. Baader-Pagler: Employee; Boehringer-Ingelheim. J. Griffin: Employee; Zealand Pharma A/S.
1670-P: Fast and Robust Assessment of Abdominal Obesity in Individuals with a Range of Cardiometabolic and Liver Tissue Characteristics—A Retrospective Analysis of UK Biobank Data
Authors: NOWAK MAGDALENA , MCGONIGLE JOHN , HILL CHARLES E. , WADDELL TOM H. , DENNIS ANDREA , CARDIEL CASTRO LUIS F. , THOMAIDES-BREARS HELENA B.
Published: June 2024

Current guidelines recommend screening individuals with diabetes for risk of metabolic dysfunction-associated steatotic liver disease (MASLD), and use of magnetic resonance imaging (MRI) in the assessment of MASLD. We compared two methods of MRI-based assessment of visceral and subcutaneous adipose tissue (VAT, SAT) and their relationship to cardiometabolic risk factors and liver tissue characteristics. A subset of 266 participants from the UK Biobank were selected based on type 2 diabetes (T2D) with imaging and controls matched for age, sex, and BMI (50% T2D, median: BMI 29kg/m2, age 56 years, 68% male). Liver MRI scans were analysed using LiverMultiScan.  A single slice at the third lumbar (L3) vertebra was extracted from whole-body Dixon MRI and cross-sectional areas of SAT and VAT were manually segmented. These were paired with SAT and VAT from a volumetric approach (top of T9 to top of femoral head). The results show a very strong correlation between a single-slice L3 assessment and volumetric assessment of body composition (VAT T2D [rho=0.9] and non-T2D [rho: 0.93]; SAT T2D [rho=0.91] and non-T2D [rho=0.94], all p values < 0.0001). Strength of correlations was maintained even with abnormal liver characteristics (MASLD in 55% and steatohepatitis in 9%) and regardless of sex, age or BMI categories (median rho value 0.92, all p values < 0.0001). The single-slice L3 method for quantifying VAT and SAT demonstrates a robust correlation with the fully-sampled volumetric assessment in individuals with a broad range of cardiometabolic characteristics. The short scanning duration (<15 min when combined with LiverMultiScan) offers a practical and efficient option for clinical applications, including monitoring treatment responses in MASLD and obesity clinical trials.

Disclosure

M. Nowak: Employee; Perspectum Ltd. J. McGonigle: Employee; Perspectum Ltd. C.E. Hill: Employee; Perspectum Ltd. T.H. Waddell: Employee; Perspectum Ltd. A. Dennis: Employee; Perspectum Ltd. L.F. Cardiel Castro: Employee; Perspectum Ltd. H.B. Thomaides-Brears: Employee; Perspectum Ltd. Stock/Shareholder; Perspectum Ltd.
1720-P: Single Nucleus Transcriptome Profiling of Human Islet Cells under Metabolic Stress In Vivo
Authors: KANG RANDY , LEE JUNGEUN , VARELA MIGUEL A. , KARAKOSE ESRA , STEWART ANDREW F. , SCOTT DONALD , GARCIA-OCANA ADOLFO , LU GEMING
Published: June 2024

Obesity causes metabolic stress and alterations in the growth and function of islet cells. However, single-cell transcriptome analysis of human islet cells in vivo under the pressure of obesogenic diets and metabolic stress has not been described. Here, we have analyzed the transcriptome profile of human islet grafts transplanted into Rag1-/- immunodeficient mice fed with high fat diet (HFD) using single nucleus RNA sequencing. We have also analyzed activated pathways by gene set enrichment analysis (GSEA) and ligand-receptor interactions by CellChat in the human islet grafts. Diabetic mice were transplanted with 1300 human islets under the kidney capsule. After returning to euglycemia (2 weeks post-transplant), mice were fed with regular diet (RD) or HFD for 4 weeks. A total of 8 human islet grafts (4 pairs of mice, 4 different adult nondiabetic human islet preparations) comprising 45,691 cells were analyzed. HFD-fed mice displayed hyperglycemia, hyperinsulinemia, glucose intolerance and increased human β-cell volume in the islet grafts. Human β-cells showed upregulation of INS, key identity genes (FXYD2, IAPP) and insulin secretion-related genes (SCG3, CHRM3), and downregulation of MAFA and cell integrity-related genes (LRP1B, CDH20, NLGN4Y). Pathway analysis showed enhanced enrichment of the acetylcholine-insulin secretion pathway while decreased enrichment of the endocrine progenitor cell pathway. Ligand-receptor interaction analysis unveiled enhanced communication between α- and β-cells, particularly in molecules involved in inflammation (CD99-CD99), cell adhesion (JAM3-F11R), growth (NRG3-ERBB4) and neuronal communication (NRG1-ERBB4, NCAM1-NCAM1). Our study provides the first single nucleus transcriptome profile of human islet cells in vivo under short-term metabolic stress. It highlights alterations in genes involved in cell integrity, inulin secretion and endocrine progenitor pathways and in ligand-receptor interactions between α- and β-cells.

Disclosure

R. Kang: None. J. Lee: None. M.A. Varela: None. E. Karakose: None. A.F. Stewart: None. D. Scott: None. A. Garcia-Ocana: Consultant; Sun Pharmaceutical Industries Ltd. G. Lu: None.

Funding

NIH/NIDDK (DK126450-01)
1726-P: ALDH3B2 Regulates Beta-Cell Neogenesis from Pancreatic Duct Cells
Authors: LI JIAN , YI PENG
Published: June 2024

Introduction & Objective: Pancreatic beta cell neogenesis is a phenomenon whereby new beta cells are generated from other pancreatic progenitor cells. Although human beta-cell neogenesis has been directly observed, questions remain as to exactly how beta-cell neogenesis is controlled and whether it can be induced with unknown genes.

Methods: A genome-wide CRISPR screen was employed on the REPB-PANC-1 cells with a human lentiviral genome-wide CRISPR knockout library (GeCKO v2). (Reporter construct: Rat insulin promoter 3.1 (RIP)-EGFP-P2A-Blasticidin-S deaminase (BSD). Statistical analyses were performed by unpaired or paired tests as indicated using the Prism 8 software.

Results: We demonstrated that the loss-of-function of a single gene,ALDH3B2, in pancreatic duct cells is sufficient to induce bonafide cell trans-differentiation from human pancreatic duct cells to beta-like cells. The gene expression of ofPDX1, INS, and SLC2A1 were significantly upregulated in the mutant primary pancreatic ductal cells; We demonstrated that the trans-differentiated human pancreatic beta-like cells are responsive to glucose challengein vivo and able to significantly lower blood glucose in diabetic animal models.

Conclusion: Overall, our whole study led to the discovery ofALDH3B2 as a beta-cell neogenesis regulator. Our finding was conducted using human pancreatic duct cell lines or primary human pancreatic duct cells, which provides a good basis for translating into future human diabetes therapeutics.

Disclosure

J. Li: None. P. Yi: None.
1731-P: Screening Human Islets to Identify Small Molecules Enhancing Glucagon Secretion under Hypoglycemia
Authors: BATE THOMAS S.R. , REIHSMANN CONRAD , ARAMANDLA RADHIKA , DAVIS COREY , MEI SHAOJUN , BRADLEY AMBER , BAUER JOSHUA , PARKER STEPHEN , SAUNDERS DIANE C. , POWERS ALVIN C. , BRISSOVA MARCELA
Published: June 2024

In type 1 diabetes (T1D), α cell function is dysregulated with loss of glucagon secretion in response to hypoglycemia that precedes a secretory impairment of major α cell stimulus, epinephrine, produced by adrenal chromaffin cells. Recurrent hypoglycemic episodes, which correlate with progressive β cell loss in T1D, lead to an impairment of sympathoadrenal responses and the risk of a life-threatening hypoglycemia unawareness syndrome. To discover new molecules that activate signaling pathways in human α cells and promote glucagon secretion during hypoglycemia, we used our primary human pseudoislet system for screening of 1027 FDA-approved compounds from ion channel and GPCR compound library (APExBIO). The compound screen was optimized for pseudoislet formation in 96-well format including state-of-the-art liquid-handling platforms for compound addition and analysis of glucagon secretion from a single pseudoislet in the presence of carefully selected internal standards. Using this approach, we identified several ‘hit’ compounds targeting both ion channels and GPCRs that increased glucagon secretion above positive controls including 1.7 mM glucose + 20 mM arginine. Notably, nearly 30 compounds targeting GPCRs including opioid, oxytocin, histamine H1, dopamine, 5-HT, adrenergic, and muscarinic receptors elicited robust glucagon responses across multiple human islet donors (N=3). Additionally, we leveraged our single cell and bulk RNA-seq datasets to evaluate target specificity and facilitate the compound selection process based on target expression changes in T1D α cells. Overall, the primary human pseudoislet system is ideal for the screen because it maintains 3-D islet cell arrangement, islet microenvironment, and allows for generation of α cell-enriched, T1D-like pseudoislets as a model system for further compound validation. This could lead to repurposing of FDA-approved drugs for treatment of hypoglycemia and rapid translation for clinical testing.

Disclosure

T.S.R. Bate: None. C. Reihsmann: None. R. Aramandla: None. C. Davis: None. S. Mei: None. A. Bradley: None. J. Bauer: None. S. Parker: Research Support; Pfizer Inc. D.C. Saunders: None. A.C. Powers: None. M. Brissova: None.
1737-P: Bulk GABA Secretion from Pancreatic Islets Is Not Co-released with Insulin
Authors: STIS AUSTIN E. , MARA FERREIRA SANDRA , LAZIMI CHARLES , PHELPS EDWARD
Published: June 2024

Introduction & Objective: Gamma Aminobutyric Acid (GABA) is a neurotransmitter found in inhibitory neurons but is also synthesized and secreted at high levels in pancreatic islets by beta cells. In neurons, GABA is packaged into synaptic vesicles by the vesicular GABA transporter (VGAT) for regulated secretion. In beta cells, evidence exists for regulated GABA secretion from insulin granules and for tonic GABA release from the cytosol via volume regulated anion channels (VRAC) with an osmotic dependence. Since GABA is a potent paracrine and autocrine signal in the islet, determining the dominant mechanism of release is vital to understand its function in the islet.

Methods: To interrogate GABA and insulin co-secretion, isolated BL/6 mouse islets were stimulated with glucose, treated with and without diazoxide and forskolin, and analyzed for supernatant insulin and GABA by ELISA and HPLC. The relationship between GABA secretion and VGAT in beta cells was investigated via immunostaining, single-cell RNA-seq dataset (HPAP), Vgat-ires-Cre x Ai14 tdTomato reporter mice, and VGAT-GFP adenoviral beta cell transduction.

Results: Diazoxide blocked while forskolin enhanced glucose-stimulated insulin release, but neither drug affected GABA secretion, indicating bulk GABA secretion is not correlated with insulin at the whole islet level. VGAT reporter mice showed many tdTomato+ neurons in the CNS but no tdTomato expression in islets. Immunostaining of islets for VGAT and analysis of the HPAP dataset showed VGAT was undetectable in beta cells. VGAT-GFP overexpression in human beta cells failed to localize VGAT to vesicles, although mouse hippocampal neurons with the same construct showed co-localization with synaptic boutons.

Conclusion: Low expression and/or poor vesicular localization of VGAT indicates regulated secretion of GABA from insulin granules appears unlikely to be the dominant release mechanism from whole islets, suggesting tonic release of GABA plays a more significant role in islet physiology.

Disclosure

A.E. Stis: None. S. Ferreira: None. C. Lazimi: None. E. Phelps: Research Support; Immunocore, Ltd, MESO SCALE DIAGNOSTICS, LLC.

Funding

National Institutes of Health (R01DK124267)
1738-P: Stress-Independent Continuous Activation of ATF6α in Pancreatic ß-Cells In Vivo Causes Diabetes
Authors: RAPPA ANDREW , SHARMA ROHIT B. , ALONSO LAURA C.
Published: June 2024

Introduction & Objective: β-cell dysfunction is a required step in the progression to T2D. ATF6α is a key component of the Unfolded Protein Response (UPR) during Endoplasmic Reticulum (ER) stress. While ATF6α increases β-cell proliferation in certain conditions, pathological UPR activation harms β-cells. Whether excess ATF6α activation impairs in vivo β-cell function is not known.

Methods: Using destabilized-domain technology, our lab generated knock-in mice expressing the N-terminal fragment of human ATF6α fused to a ligand-dependent Dihydrofolatereductase (DHFR-ATF6α). These mice allow cell-type-specific (via Cre recombinase) temporal activation (via Trimethoprim (TMP)) of ATF6α in β-cells in live mice.

Results: Intraperitoneal (acute) or dietary (chronic) TMP exposure increased mRNA abundance of ATF6α target genes Pdia4, Grp78, Chop, Hyou1, Herpud1, Sel1l, but not sXBP1 target genes Erdj4, Sec24d, Ssr3 in islets from DHFR-ATF6α mice compared to Cre controls. After 7- and 14-days of dietary TMP exposure, both male and female DHFR-ATF6α mice had markedly impaired glucose tolerance, which was associated with normal insulin sensitivity and β-cell mass suggesting glucose intolerance was due to a defect in either insulin production or secretion. In vivo glucose-stimulated insulin secretion was reduced at 7-days while islet insulin content was reduced at 14-days but not 7-days. Ins1 and Ins2 mRNA were unchanged at either time point. Consistent with reduced insulin content, fewer mature insulin granules were observed at 14-days by TEM, along with marked morphological changes in β-cell ultrastructure. Preliminary confocal analysis suggested expansion of ER-marker KDEL in β-cells after ATF6α activation.

Conclusion: Continuous activation of ATF6α in β-cells in live mice causes β-cell dysfunction, with impaired insulin production and insulin secretion, and morphological abnormalities. Dysregulated ATF6α activation may participate in T2D pathogenesis.

Disclosure

A. Rappa: None. R.B. Sharma: None. L.C. Alonso: None.

Funding

National Institutes of Health (R01DK135304, R01DK124906, and R01DK114686)
1739-P: Genetic Deletion of Mitochondrial PEP Carboxykinase (PCK2) in Pancreatic α-Cells Increases Amino Acid-Stimulated Ca2+ Influx
Authors: JIN ERLI , FOSTER HANNAH R. , POTAPENKO EVGENIY , KNUTH EMILY R. , MERRINS MATTHEW J.
Published: June 2024

Amino acids potently stimulate glucagon secretion, but their mechanisms of action remain largely unknown. To assess the effects of individual amino acids on α-cell Ca2+, we used GcgCreERT:GCaMP6s Ca2+ reporter. We focused on alanine, arginine, glutamine, and leucine, which have the potential to affect Ca2+ and glucagon release via their transport or metabolism. Under hypoglycemic conditions, when β-cells are inactive, alanine and arginine provoked a sustained increase in α-cell Ca2+, while the mitochondria fuels glutamine and leucine lowered Ca2+ after alanine and arginine are applied. However, when applying these four amino acids simultaneously, Ca2+ influx is increased above that stimulated by arginine and alanine alone, suggesting the effect of mitochondria fuels on Ca2+ is membrane-potential dependent. Phosphoenolpyruvate (PEP) cycle can be fueled by mitochondria fuels and potentially affects KATP channels via the ATP-generating enzyme pyruvate kinase (PK). To test this hypothesis, we used CRISPR to generate mice lacking the mitochondrial PEP-generating enzyme PCK2 in α-cells (GcgCreERT:Pck2f/f:GCaMP6s). PEP cycle ablation increased Ca2+ influx stimulated by alanine and arginine, much more strongly when leucine and glutamine were provided as mitochondria fuels. Pharmacological activation of PK reduces amino acid-stimulated Ca2+ influx. Taken together, the effect of mitochondria fuels on α-cell Ca2+ is most likely membrane potential dependent, and α-cell PEP cycle is an inhibitory pathway that lowers Ca2+ influx stimulated by amino acids.

Disclosure

E. Jin: None. H.R. Foster: None. E. Potapenko: None. E.R. Knuth: None. M.J. Merrins: None.

Funding

The Merrins laboratory gratefully acknowledges support from the NIH/NIDDK (R01DK113103 and R01DK127637 to MJM) and the United States Department of Veterans Affairs Biomedical Laboratory Research and Development Service (I01BX005113 to MJM). ERK received a predoctoral fellowship from the NIH/NIDDK (F31DK134171).
1743-P: STING Mediates Glucose-Induced Insulin Secretion through Pax6
Authors: ZHANG ZIYUE , QIAO JINGTING , LIU YANG , LIU MING
Published: June 2024

Introduction & Objective: Previous studies have shown that stimulator of interferon genes (STING) plays an important role in regulating glucose homeostasis, including insulin secretion. This study aimed to investigate the role of STING in glucose-induced insulin secretion.

Methods: Rat pancreatic β-cell line INS-1 cells and islets from adult wide-type (WT) mice were cultured with high-glucose (33.3 mmol/L) and low-glucose (2.8 mmol/L) and the expression of STING was detected by RT-PCR and western blotting. Glucose-stimulated insulin secretion (GSIS) tests were measured in islets from global STING knockout (KO) mice or high-glucose-induced islets of WT mice. The involvement of STING and Pax6 was evaluated by infecting islets with STING-overexpression adeno-associated virus (AAV-STING) or AAV-Pax6 in vitro.

Results: STING was highly expressed in pancreatic islets and INS-1 cells, but its levels were reduced in high-glucose-induced islets and INS-1 cells compared to controls. Overexpression of STING could restore GSIS in high-glucose-induced islets of WT mice. In addition, the expression levels of several genes involved in insulin secretion, including Pax6, Abcc8, Kir6.2, were significantly reduced in high-glucose induced islets of WT mice and were increased when STING expression was restored. Moreover, GSIS was significantly decreased in islets from STING KO mice, and the overexpression of either STING or Pax6 resulted in an increased expression of Pax6, Abcc8, Kir6.2 and improved GSIS.

Conclusion: This study provides the first in vitro experimental evidence supporting that STING may play an important role in glucose-induced insulin secretion through transcription factor Pax6.

Disclosure

Z. Zhang: None. J. Qiao: None. Y. Liu: None. M. Liu: None.

Funding

National Natural Science Foundation of China (82220108014, 81830025, 82200892), National Key R&D Program of China (2022YFE0131400, 2019YFA0802502), Key project of Tianjin Municipal Health Commission(TJWJ2021ZD001), Tianjin Key Medical Discipline (Specialty)Construction Project (TJYXZDXK-030A), Tianjin Medical University General Hospital Clinical Research Program (22ZYYLCZD02), Tianjin Municipal Education Commission (2021KJ209)
1744-P: Exenatide Activates PPARd to Promote Mitochondrial Function for Insulin Secretion in Islet ß-Cells
Authors: LIU ZHIGU , CHEN YALAN , LIN BEISI , SU YANNA , PENG YUEYUE , CHEN DANRUI , YANG YANLING , XU FEN , LIANG HUA , YAN JINHUA , XU WEN
Published: June 2024

Aim: Glucagon-like peptide 1 receptor agonists can lower blood glucose by increasing glucose-stimulated insulin secretion (GSIS). However, related molecular mechanisms remain to be further explored.

Methods: C57BL/6J mice were treated with exenatide, GW501516 (GW, a PPARδ agonist) or saline for 8 weeks after a 12-week high-fat diet (HFD) challenge. Phenotypic evaluations were performed during and after the interventions. In vitro, mouse pancreatic β cells (NIT1) were treated with palmitic acid (PA), PA+exendin-4 (Exe), PA+GW, PA+GSK0660 (GSK, a PPARδ antagonist), and PA+GSK+Exe, respectively. PPARδ knockout (KO) NIT1 cells were constructed using CRISPR/Cas9 method. The KO cells were also treated by PA and PA+Exe. After a 24-hour incubation, GSIS tests were performed, and PPARδ expression and mitochondrial function were also detected.

Results: Compared with HFD mice treated with saline, exenatide and GW treatments lowered body weight and fasting blood glucose, improved glucose tolerance and insulin sensitivity. Moreover, normal mitochondrial morphology in pancreatic islets of exenatide and GW treated mice were found with Transmission electron microscopy, while significantly abnormal mitochondria were noted in saline group. In vitro, compared with PA treatment alone, NIT1 cells treated by PA+Exe and PA+GW showed enhanced GSIS, along with increased PPARδ expression, lower ADP/ATP ratio and lactic acid levels, more mitochondrial DNA and higher mitochondrial membrane potential. However, opposite results were found in cells treated with PA+GSK. In addition, in PA+GSK+Exe group, GSK weakened the effects of Exe on GSIS and mitochondrial function. KO cells treated with PA showed similar changes in GSIS and mitochondrial function as PA+GSK treated cells. Importantly, adding Exe couldn’t completely reverse the impairment.

Conclusion: Exenatide protects GSIS function in islet β cells by enhancing mitochondrial function through promoting PPARδ expression.

Disclosure

Z. Liu: None. Y. Chen: None. B. Lin: None. Y. Su: None. Y. Peng: None. D. Chen: None. Y. Yang: None. F. Xu: None. H. Liang: None. J. Yan: None. W. Xu: None.

Funding

Natural Science Foundation of Guangdong Province (2022A1515012364?