Model Of Type 2 Diabetes Research Articles

Berberine protects mice against type 2 diabetes by promoting PPARγ-FGF21-GLUT2-regulated insulin sensitivity and glucose/lipid homeostasis

Type 2 diabetes (T2D) is a chronic, burdensome disease that is characterized by disordered insulin sensitivity and disturbed glucose/lipid homeostasis. Berberine (BBR) has multiple therapeutic actions on T2D, including regulation of glucose and lipid metabolism, improvement of insulin sensitivity and energy expenditure. Recently, the function of BBR on fibroblast growth factor 21 (FGF21) has been identified. However, if BBR ameliorates T2D through FGF21, the underlying mechanisms remain unknown. Herein, we used T2D wild type (WT) and FGF21 global knockout (FKO) mice [mouse T2D model: established by high-fat diet (HFD) feeding plus streptozotocin (STZ) injection], and hepatocyte-specific peroxisome proliferator activated receptor γ (PPARγ) deficient (PPARγHepKO) mice, and cultured human liver carcinoma cells line, HepG2 cells, to characterize the role of BBR in glucose/lipid metabolism and insulin sensitivity. We found that BBR activated FGF21 expression by up-regulating PPARγ expression at the cellular level. Meanwhile, BBR ameliorated glucosamine hydrochloride (Glcn)-induced insulin resistance and increased glucose transporter 2 (GLUT2) expression in a PPARγ/FGF21-dependent manner. In T2D mice, BBR up-regulated the expression of PPARγ, FGF21 and GLUT2 in the liver, and GLUT2 in the pancreas. BBR also reversed T2D-induced insulin resistance, liver lipid accumulation, and damage in liver and pancreas. However, FGF21 deficiency diminished these effects of BBR on diabetic mice. Altogether, our study demonstrates that the therapeutic effects of BBR on T2D were partly accomplished by activating PPARγ-FGF21-GLUT2 signaling pathway. The discovery of this new pathway provides a deeper understanding of the mechanism of BBR for T2D treatment.

Non-invasive invivo measurements of metabolic alterations in the type 2 diabetic brain by 1H magnetic resonance spectroscopy.

Type 2 diabetes (T2D) is a complex chronic metabolic disorder characterized by hyperglycemia because of insulin resistance. Diabetes with chronic hyperglycemia may alter brain metabolism, including brain glucose and neurotransmitter levels; however, detailed, longitudinal studies of metabolic alterations in T2D are lacking. To shed insight, here, we characterized the consequences of poorly controlled hyperglycemia on neurochemical profiles that reflect metabolic alterations of the brain in both humans and animal models of T2D. Using invivo 1H magnetic resonance spectroscopy, we quantified 12 metabolites cross-sectionally in T2D patients and 20 metabolites longitudinally in T2D db/db mice versus db+ controls. We found significantly elevated brain glucose (91%, p < 0.001), taurine (22%, p = 0.02), glucose+taurine (56%, p < 0.001), myo-inositol (12%, p = 0.02), and choline-containing compounds (10%, p = 0.01) in T2D patients versus age- and sex-matched controls, findings consistent with measures in T2D db/db versus control db+ littermates. In mice, hippocampal and striatal neurochemical alterations in brain glucose, ascorbate, creatine, phosphocreatine, γ-aminobutyric acid, glutamate, glutamine, glutathione, glycerophosphoryl-choline, lactate, myo-inositol, and taurine persisted in db/db mice with chronic disease progression from 16 to 48 weeks of age, which were distinct from control db+ mice. Overall, our study demonstrates the utility of 1H magnetic resonance spectroscopy as a non-invasive tool for characterizing and monitoring brain metabolic changes with T2D progression.

Ancestry-attenuated effects of socioeconomic deprivation on type 2 diabetes disparities in the All of Us cohort

BackgroundDiabetes is a common disease with a major burden on morbidity, mortality, and productivity. Type 2 diabetes (T2D) accounts for roughly 90% of all diabetes cases in the USA and has a greater observed prevalence among those who identify as Black or Hispanic.MethodsThis study aimed to assess T2D racial and ethnic disparities using the All of Us Research Program data and to measure associations between genetic ancestry (GA), socioeconomic deprivation, and T2D. We used the All of Us Researcher Workbench to analyze T2D prevalence and model its associations with GA, individual-level (iSDI), and zip code-based (zSDI) socioeconomic deprivation indices among participant self-identified race and ethnicity (SIRE) groups.ResultsThe study cohort of 86,488 participants from the four largest SIRE groups in All of Us: Asian (n = 2311), Black (n = 16,282), Hispanic (n = 16,966), and White (n = 50,292). SIRE groups show characteristic genetic ancestry patterns, consistent with their diverse origins, together with a continuum of ancestry fractions within and between groups. The Black and Hispanic groups show the highest levels of socioeconomic deprivation, followed by the Asian and White groups. Black participants show the highest age- and sex-adjusted T2D prevalence (21.9%), followed by the Hispanic (19.9%), Asian (15.1%), and White (14.8%) groups. Minority SIRE groups and socioeconomic deprivation, both iSDI and zSDI, are positively associated with T2D, when the entire cohort is analyzed together. However, SIRE and GA both show negative interaction effects with iSDI and zSDI on T2D. Higher levels of iSDI and zSDI are negatively associated with T2D in the Black and Hispanic groups, and higher levels of iSDI and zSDI are negatively associated with T2D at high levels of African and Native American ancestry.ConclusionsSocioeconomic deprivation is associated with a higher prevalence of T2D in Black and Hispanic minority groups, compared to the majority White group. Nonetheless, socioeconomic deprivation is associated with reduced T2D risk within the Black and Hispanic groups. These results are paradoxical and have not been reported elsewhere, with possible explanations related to the nature of the All of Us data along with SIRE group differences in access to healthcare, diet, and lifestyle.

The amphiregulin/EGFR axis has limited contribution in controlling autoimmune diabetes

Conventional immunosuppressive functions of CD4+Foxp3+ regulatory T cells (Tregs) in type 1 diabetes (T1D) pathogenesis have been well described, but whether Tregs have additional non-immunological functions supporting tissue homeostasis in pancreatic islets is unknown. Within the last decade novel tissue repair functions have been ascribed to Tregs. One function is production of the epidermal growth factor receptor (EGFR) ligand, amphiregulin, which promotes tissue repair in response to inflammatory or mechanical tissue injury. However, whether such pathways are engaged during autoimmune diabetes and promote tissue repair is undetermined. Previously, we observed that upregulation of amphiregulin at the transcriptional level was associated with functional Treg populations in the non-obese diabetic (NOD) mouse model of T1D. From this we postulated that amphiregulin promoted islet tissue repair and slowed the progression of diabetes in NOD mice. Here, we report that islet-infiltrating Tregs have increased capacity to produce amphiregulin, and that both Tregs and beta cells express EGFR. Moreover, we show that amphiregulin can directly modulate mediators of endoplasmic reticulum stress in beta cells. Despite this, NOD amphiregulin deficient mice showed no acceleration of spontaneous autoimmune diabetes. Taken together, the data suggest that the ability for amphiregulin to affect the progression of autoimmune diabetes is limited.

Pharmacologic Inhibition of Myostatin With a Myostatin Antibody Improves the Skeletal Muscle and Bone Phenotype of Male Insulin-Deficient Diabetic Mice.

Type 1 diabetes (T1D) is associated with low bone and muscle mass, increased fracture risk, and impaired skeletal muscle function. Myostatin, a myokine that is systemically elevated in humans with T1D, negatively regulates muscle mass and bone formation. We investigated whether pharmacologic myostatin inhibition in a mouse model of insulin-deficient, streptozotocin (STZ)-induced diabetes is protective for bone and skeletal muscle. DBA/2J male mice were injected with low-dose STZ (diabetic) or vehicle (non-diabetic). Subsequently, insulin or palmitate Linbits were implanted and myostatin (REGN647-MyoAb) or control (REGN1945-ConAb) antibody was administered for 8 weeks. Body composition and contractile muscle function were assessed in vivo. Systemic myostatin, P1NP, CTX-I, and glycated hemoglobin (HbA1c) were quantified, and gastrocnemii were weighed and analyzed for muscle fiber composition and gene expression of selected genes. Cortical and trabecular parameters were analyzed (micro-computed tomography evaluations of femur) and cortical bone strength was assessed (three-point bending test of femur diaphysis). In diabetic mice, the combination of insulin/MyoAb treatment resulted in significantly higher lean mass and gastrocnemius weight compared with MyoAb or insulin treatment alone. Similarly, higher raw torque was observed in skeletal muscle of insulin/MyoAb-treated diabetic mice compared with MyoAb or insulin treatment. Additionally, muscle fiber cross-sectional area (CSA) was lower with diabetes and the combination treatment with insulin/MyoAb significantly improved CSA in type II fibers. Insulin, MyoAb, or insulin/MyoAb treatment improved several parameters of trabecular architecture (eg, bone volume fraction [BV/TV], trabecular connectivity density [Conn.D]) and cortical structure (eg, cortical bone area [Ct. Ar.], minimum moment of inertia [Imin]) in diabetic mice. Lastly, cortical bone biomechanical properties (stiffness and yield force) were also improved with insulin or MyoAb treatment. In conclusion, pharmacologic myostatin inhibition is beneficial for muscle mass, muscle function, and bone properties in this mouse model of T1D and its effects are both independent and additive to the positive effects of insulin. © 2023 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

A protein kinase C α and β inhibitor blunts hyperphagia to halt renal function decline and reduces adiposity in a rat model of obesity-driven type 2 diabetes

Type 2 diabetes (T2D) and its complications can have debilitating, sometimes fatal consequences for afflicted individuals. The disease can be difficult to control, and therapeutic strategies to prevent T2D-induced tissue and organ damage are needed. Here we describe the results of administering a potent and selective inhibitor of Protein Kinase C (PKC) family members PKCα and PKCβ, Cmpd 1, in the ZSF1 obese rat model of hyperphagia-induced, obesity-driven T2D. Although our initial intent was to evaluate the effect of PKCα/β inhibition on renal damage in this model setting, Cmpd 1 unexpectedly caused a marked reduction in the hyperphagic response of ZSF1 obese animals. This halted renal function decline but did so indirectly and indistinguishably from a pair feeding comparator group. However, above and beyond this food intake effect, Cmpd 1 lowered overall animal body weights, reduced liver vacuolation, and reduced inguinal adipose tissue (iWAT) mass, inflammation, and adipocyte size. Taken together, Cmpd 1 had strong effects on multiple disease parameters in this obesity-driven rodent model of T2D. Further evaluation for potential translation of PKCα/β inhibition to T2D and obesity in humans is warranted.

SAT069 Targeting Human β-Cell G Protein-coupled Receptors To Alter Cytokine-mediated Caspase Activation

Abstract Disclosure: K. Rodrigues dos Santos: None. N. Mukherjee: None. L.F. Barella: None. F. Armoo: None. D.L. Eizirik: None. A.T. Templin: None. M.A. Kalwat: None. In type 1 diabetes (T1D) autoimmune destruction of pancreatic islet β-cells causes a lack of insulin, leading to hyperglycemia. The development of therapies that can prevent β-cell death is critical. β-cell proliferation and survival pathways are affected by signaling through G protein-coupled receptors (GPCRs). Using high-depth RNA-seq, we found altered expression of 123 different GPCRs in human islets exposed to cytokines (IL1β 50U/ml + IFNγ 1000U/ml, 48 h) to model the T1D milieu. We hypothesized these candidates may be exploited for β-cell protection. Among the candidates, adenosine receptors (ADORA1 and ADORA2A), calcium-sensing receptor (CASR), and metabotropic glutamate receptor 4 (GRM4) stood out. Cytokines decreased the expression of ADORA1 and CASR, but increased ADORA2A and GRM4. To gauge the impact of agonizing/antagonizing these receptors, we pre-treated human EndoC-β H1 β-cells or islets with receptor ligands and co-treated with cytokines (IL1β 50U/ml + IFNγ or IL1β + 1000U/ml IFNγ + 1000U/ml TNFɑ, 48 h) and measured glucose-stimulated insulin secretion, cell viability, and gene expression. Each cytokine combination induced target gene expression (e.g. CXCL10), but only the combination of IL1β + IFNγ + TNFɑ reduced glucose-stimulated insulin secretion. Preliminary experiments indicated that adenosine receptor ligands had little impact in our assays. However, ligands for CASR and GRM4 exhibited significant suppression of cytokine-induced caspase 3/7 activation in EndoC-βH1 cells. Interestingly, suppressed caspase activation did not result in observable impacts on live/dead cell ratios or live-cell analysis using Incucyte in EndoC-βH1 cells. Consistently, we also observed cytokine-mediated cell death in the presence of the pan-caspase inhibitor ZVAD-fmk. We conclude that a variety of β-cell GPCR-mediated signaling pathways may converge to prevent cytokine-induced caspase activation, but additional measures are needed to enable protection from eventual cell death. Our results and this line of investigation is significant because understanding mechanisms of GPCR-cytokine crosstalk in β-cells will inform strategies to protect islets in other models of T1D. Funding: JDRF 1-INO-2022-1113-A-N and Diabetes Research Connection #33. Presentation: Saturday, June 17, 2023

SAT071 Inhibition Of 12 Lipoxygenase In A Humanized Mouse Model Of Type 1 Diabetes Delays Progression Of Hyperglycemia

Abstract Disclosure: T. Nargis: None. A. Chakraborty: None. K. Figatner: None. D. Maloney: None. M. Boxer: None. S.A. Tersey: None. R.G. Mirmira: None. Type 1 diabetes (T1D) is an autoimmune disorder characterized by islet inflammation (insulitis). We have recently shown that a key mediator of inflammatory signaling in the islet beta cell is the enzyme 12-lipoxygenase (12-LOX), which generates proinflammatory eicosanoids that augment dysfunctional insulin secretion and beta-cell visibility to the immune system. Whereas inhibition of 12-LOX offers an opportunity to modify T1D progression by altering how the beta cell responds to insulitis, a barrier to testing inhibitors in preclinical models is the specificity of next generation inhibitors toward the human enzyme. To generate a preclinical platform for the study of human-specific 12-LOX inhibitors, we developed a mouse model in which the mouse-equivalent Alox15 coding region was replaced with the human ALOX12 gene, while retaining the mouse upstream control region. These mice (hALOX12) were developed on both the C57BL/6J and NOD genetic backgrounds, then subjected to treatment with the human 12-LOX inhibitor VLX-1005 to evaluate diabetes progression. C57BL/6J-wildtype and C57BL/6J-hALOX12 mice were confirmed to express exclusively mouse Alox15 and human ALOX12, respectively, using RNA isolated from islets. To test susceptibility to toxin-induced diabetes, C57BL/6J-wildtype and C57BL/6J-hALOX12 were subjected to multiple low-dose streptozotocin (STZ) to induce diabetes. Both wildtype and humanized mice exhibited gradual and equivalent hyperglycemia (within 25 days) following STZ injection. Following intraperitoneal VLX-1005 therapy (30 mg/kg), whereas C57BL/6J-wildtype mice developed diabetes (with a delay of 10 days) following STZ, C57BL/6J-hALOX12 mice showed complete protection against STZ-induced diabetes and exhibited significantly better glucose tolerance compared to vehicle- or VLX-1005-injected wildtype controls and vehicle-injected C57BL/6J-hALOX12 mice. Next, hALOX12 mice were backcrossed onto the NOD.ShiltJ background model of autoimmune T1D. NOD-hALOX12 mice received either vehicle or VLX-1005 (30 mg/kg) orally during the prediabetic phase (6-10 weeks of age) and were followed for diabetes incidence. Mice receiving VLX-1005 showed a significant delay with only 30% of female and 7% of male mice developing diabetes over 25 weeks of age. Pancreatic sections from the mice treated with VLX-1005 showed reduced insulitis and increased beta cell mass compared to vehicle controls. In summary, the hALOX12 mouse model serves as a preclinical translational platform to interrogate effects of next generation 12-LOX inhibitors and demonstrates the potential of VLX-1005 to modify T1D disease progression. Presentation: Saturday, June 17, 2023

Angelica polysaccharides relieve blood glucose levels in diabetic KKAy mice possibly by modulating gut microbiota: an integrated gut microbiota and metabolism analysis

BackgroundAngelica polysaccharides (AP) have numerous benefits in relieving type 2 diabetes (T2D). However, the underlying mechanisms have yet to be fully understood. Recent many reports have suggested that altering gut microbiota can have adverse effects on the host metabolism and contribute to the development of T2D. Here, we successfully established the T2D model using the male KKAy mice with high-fat and high-sugar feed. Meanwhile, the male C57BL/6 mice were fed with a normal feed. T2D KKAy mice were fed either with or without AP supplementation. In each group, we measured the mice's fasting blood glucose, weight, and fasting serum insulin levels. We collected the cecum content of mice, the gut microbiota was analyzed by targeted full-length 16S rRNA metagenomic sequencing and metabolites were analyzed by untargeted-metabolomics.ResultsWe found AP effectively alleviated glycemic disorders of T2D KKAy mice, with the changes in gut microbiota composition and function. Many bacteria species and metabolites were markedly changed in T2D KKAy mice and reversed by AP. Additionally, 16 altered metabolic pathways affected by AP were figured out by combining metagenomic pathway enrichment analysis and metabolic pathway enrichment analysis. The key metabolites in 16 metabolic pathways were significantly associated with the gut microbial alteration. Together, our findings showed that AP supplementation could attenuate the diabetic phenotype. Significant gut microbiota and gut metabolite changes were observed in the T2D KKAy mice and AP intervention.ConclusionsAdministration of AP has been shown to improve the composition of intestinal microbiota in T2D KKAy mice, thus providing further evidence for the potential therapeutic application of AP in the treatment of T2D.

In vivo retinal imaging is associated with cognitive decline, blood-brain barrier disruption and neuroinflammation in type 2 diabetic mice.

Type 2 diabetes (T2D) is associated with chronic inflammation and neurovascular changes that lead to functional impairment and atrophy in neural-derived tissue. A reduction in retinal thickness is an early indicator of diabetic retinopathy (DR), with progressive loss of neuroglia corresponding to DR severity. The brain undergoes similar pathophysiological events as the retina, which contribute to T2D-related cognitive decline. This study explored the relationship between retinal thinning and cognitive decline in the LepR db/db model of T2D. Diabetic db/db and non-diabetic db/+ mice aged 14 and 28 weeks underwent cognitive testing in short and long-term memory domains and in vivo retinal imaging using optical coherence tomography (OCT), followed by plasma metabolic measures and ex vivo quantification of neuroinflammation, oxidative stress and microvascular leakage. At 28 weeks, mice exhibited retinal thinning in the ganglion cell complex and inner nuclear layer, concomitant with diabetic insulin resistance, memory deficits, increased expression of inflammation markers and cerebrovascular leakage. Interestingly, alterations in retinal thickness at both experimental timepoints were correlated with cognitive decline and elevated immune response in the brain and retina. These results suggest that changes in retinal thickness quantified with in vivo OCT imaging may be an indicator of diabetic cognitive dysfunction and neuroinflammation.

Inhibition of hyaluronan synthesis prevents β-cell loss in obesity-associated type 2 diabetes

Pancreatic β-cell dysfunction and death are central to the pathogenesis of type 2 diabetes (T2D). We identified a novel role for the inflammatory extracellular matrix polymer hyaluronan (HA) in this pathophysiology. Low concentrations of HA were present in healthy pancreatic islets. However, HA substantially accumulated in cadaveric islets of T2D patients and islets of the db/db mouse model of T2D in response to hyperglycemia. Treatment with 4-methylumbelliferone (4-MU), an inhibitor of HA synthesis, or the deletion of the main HA receptor CD44, preserved glycemic control and insulin concentrations in db/db mice despite ongoing weight gain, indicating a critical role for this pathway in T2D pathogenesis. 4-MU treatment and the deletion of CD44 likewise preserved glycemic control in other settings of β-cell injury including streptozotocin treatment and islet transplantation. Mechanistically, we found that 4-MU increased the expression of the apoptosis inhibitor survivin, a downstream transcriptional target of CD44 dependent on HA/CD44 signaling, on β-cells such that caspase 3 activation did not result in β-cell apoptosis. These data indicated a role for HA accumulation in diabetes pathogenesis and suggested that it may be a viable target to ameliorate β-cell loss in T2D. These data are particularly exciting, because 4-MU is already an approved drug (also known as hymecromone), which could accelerate translation of these findings to clinical studies.

Boosting glycolysis to combat fragile bone in type 1 diabetes

Individuals with type 1 diabetes (T1D) have an increased risk of osteoporosis and fracture. In this issue of Cell Chemical Biology, Ji etal.1 show that impaired glucose metabolism in the bone-forming osteoblast drives diabetic osteoporosis in Akita mice, a mouse model of T1D.

Restoring connexin-36 function in diabetogenic environments precludes mouse and human islet dysfunction.

The secretion of insulin from β-cells in the islet of Langerhans is governed by a series of metabolic and electrical events, which can fail during the progression of type 2 diabetes (T2D). β-cells are electrically coupled via connexin-36 (Cx36) gap junction channels, which coordinates the pulsatile dynamics of [Ca2+ ] and insulin release across the islet. Factors such as pro-inflammatory cytokines and free fatty acids disrupt gap junction coupling under in vitro conditions. Here we test whether gap junction coupling and coordinated [Ca2+ ] dynamics are disrupted in T2D, and whether recovery of gap junction coupling can recover islet function. We examine islets from donors with T2D, from db/db mice, and islets treated with pro-inflammatory cytokines (TNF-α, IL-1β, IFN-ɣ) or free fatty acids (palmitate). We modulate gap junction coupling using Cx36 over-expression or pharmacological activation via modafinil. We also develop a peptide mimetic (S293) of the c-terminal regulatory site of Cx36 designed to compete against its phosphorylation. Cx36 gap junction permeability and [Ca2+ ] dynamics were disrupted in islets from both human donors with T2D and db/db mice, and in islets treated with pro-inflammatory cytokines or palmitate. Cx36 over-expression, modafinil treatment and S293 peptide all enhanced Cx36 gap junction coupling and protected against declines in coordinated [Ca2+ ] dynamics. Cx36 over-expression and S293 peptide also reduced apoptosis induced by pro-inflammatory cytokines. Critically, S293 peptide rescued gap junction coupling and [Ca2+ ] dynamics in islets from both db/db mice and a sub-set of T2D donors. Thus, recovering or enhancing Cx36 gap junction coupling can improve islet function in diabetes. KEY POINTS: Connexin-36 (Cx36) gap junction permeability and associated coordination of [Ca2+ ] dynamics is diminished in human type 2 diabetes (T2D) and mouse models of T2D. Enhancing Cx36 gap junction permeability protects against disruptions to the coordination of [Ca2+ ] dynamics. A novel peptide mimetic of the Cx36 c-terminal regulatory region protects against declines in Cx36 gap junction permeability. Pharmacological elevation in Cx36 or Cx36 peptide mimetic recovers [Ca2+ ] dynamics and glucose-stimulated insulin secretion in human T2D and mouse models of T2D.

Dapagliflozin impedes endothelial cell senescence by activating the SIRT1 signaling pathway in type 2 diabetes

BackgroundSodium-glucose cotransporter 2 inhibitors (SGLT2i) clinically reduce atherosclerosis and lower blood pressure. However, their impact on endothelial dysfunction in type 2 diabetes (T2D) remains unclear. In this study, we investigated the protective effect and underlying mechanism of the SGLT2 inhibitor dapagliflozin in diabetes. MethodsVascular reactivity was measured to assess the vasoprotective effect of dapagliflozin in a mouse model of high glucose (HG)-induced T2D. Pulse wave velocity was measured to quantify arterial stiffness. Protein expression was assessed by western blotting and immunofluorescence, oxidative stress was evaluated using dihydroethidium, nitric oxide was evaluated using the Griess reaction, and cellular senescence was assessed based on senescence-associated beta-galactosidase (SA‐β‐gal) activity and the expression of senescence markers. Furthermore, the endothelial nitric oxide synthase (eNOS) acetylation status was determined and eNOS interactions with SIRT1 were evaluated by coimmunoprecipitation assays. ResultsDapagliflozin protected against impaired endothelium-dependent vasorelaxation and improved arterial stiffness in the mouse model of T2D; mouse aortas had significantly reduced levels of senescence activity and senescence-associated inflammatory factors. HG-induced increases in senescence activity, protein marker levels, and oxidative stress in vitro were all ameliorated by dapagliflozin. The decreases in eNOS phosphorylation and nitric oxide (NO) production in senescent endothelial cells were restored by dapagliflozin. SIRT1 expression was reduced in HG-induced senescent endothelial cells, and dapagliflozin restored SIRT1 expression. SIRT1 inhibition diminished the antisenescence effects of dapagliflozin. Coimmunoprecipitation showed that SIRT1 was physically associated with eNOS, suggesting that the effects of dapagliflozin are dependent on SIRT1 activation. ConclusionThese findings indicate that dapagliflozin protects against endothelial cell senescence by regulating SIRT1 signaling in diabetic mice.

Cdk5-Mediated Brain Unfolded Protein Response Upregulation Associated with Cognitive Impairments in Type 2 Diabetes and Ameliorative Action of NAC.

The role of cyclin-dependent kinase 5 (Cdk5) in the normal functioning of the central nervous system and synaptic plasticity is well established. However, dysregulated kinase activity can have a significant impact on neurodegeneration and cognitive impairment. Cdk5 hyperactivation is linked to diabetes-associated neurodegeneration, but the underlying mechanism is not fully understood. Our study reveals that oxidative stress can lead to Cdk5 hyperactivity, which in turn is linked to neurodegeneration and cognitive impairment. Specifically, our experiments with N2A cells overexpressing Cdk5 and its activators p35 and p25 show ER stress, resulting in activation of the unfolded protein response (UPR) pathway. We identified Cdk5 as the epicenter of this regulatory process, leading to the activation of the CDK5-IRE1-XBP1 arm of UPR. Moreover, our study demonstrated that Cdk5 hyperactivation can lead to ER stress and activation of the UPR pathway, which may contribute to cognitive impairments associated with diabetes. Our findings also suggest that antioxidants such as NAC and GSH can decrease deregulated Cdk5 kinase activity and rescue cells from UPR-mediated ER stress. The accumulation of phosphorylated Tau protein in AD brain protein has been widely described earlier. Notably, we observed that oral treatment with NAC decreased Cdk5 kinase activity in the hippocampus, attenuated high levels of phospho-tau (ser396), and ameliorated memory and learning impairments in a type 2 diabetic (T2D) mouse model. Additionally, the high-fat-induced T2D model exhibits elevated phospho-tau levels, which are rescued by the NAC treatment. Taken together, these results suggest that targeting Cdk5 may be a promising therapeutic strategy for treating diabetes-associated cognitive impairments.

Metabolomics and Lipidomics Studies in Pediatric Type 1 Diabetes: Biomarker Discovery for the Early Diagnosis and Prognosis

Aim. Type 1 diabetes (T1D) is an autoimmune disease with heterogeneous risk factors. Metabolic perturbations in the pathogenesis of the disease are remarkable to illuminate the interaction between genetic and environmental factors and how islet immunity and overt diabetes develop. This review aimed to integrate the metabolic changes of T1D to identify potential biomarkers for predicting disease progression based on recent metabolomics and lipidomics studies with parallel methodologies. Methods. A total of 18 metabolomics and lipidomics studies of childhood T1D during the last 15 years were reviewed. The metabolic fingerprints consisting of 41 lipids and/or metabolite classes of subjects with islet autoantibodies, progressors of T1D, and T1D children were mapped in four-time dimensions based on a tentative effect-score rule. Results. From birth, high-risk T1D subjects had decreased unsaturated triacylglycerols, unsaturated phosphatidylcholines (PCs), sphingomyelins (SMs), amino acids, and metabolites in the tricarboxylic acid (TCA) cycle. On the contrary, lysophosphatidylcholines (LPCs) and monosaccharides increased. And LPCs and branched-chain amino acids (BCAAs) were elevated before the appearance of islet autoantibodies but were lowered after seroconversion. Choline-related lipids (including PCs, SMs, and LPCs), BCAAs, and metabolites involved in the TCA cycle were identified as consensus biomarkers potentially predicting the development of islet autoimmunity and T1D. Decreased LPCs and amino acids indicated poor glycemic control of T1D, while elevated lysophosphatidylethanolamines and saturated PCs implied good glycemic control. Further pathway analysis revealed that biosynthesis of aminoacyl-tRNA, BCAAs, and alanine, aspartate, and glutamate metabolism were significantly enriched. Moreover, established cohort studies and predictive statistical models of pediatric T1D were also summarized. Conclusion. The metabolic profile of high-risk T1D subjects and patients demonstrated significant changes compared with healthy controls. This integrated analysis provides a comprehensive overview of metabolic features and potential biomarkers in the pathogenesis and progression of T1D.

1850-PUB: Immune Silencing of Beta Cells for Transplantation Informed by Naturally Occurring Immune-Privileged Cells

To cure Type 1 Diabetes (T1D) is necessary to restore the lost beta-cells while ensuring their long-lasting survival. This could be done by transplantation of primary or stem cell-derived islets. However, any replacement will irrevocably succumb to the same autoimmune attack that killed the original beta-cells. Moreover, a mismatch between donor cells and recipient patients adds an allo-graft rejection against transplanted cells. Thus, it is of the utmost importance to develop strategies to protect transplanted pancreatic islets from immune attack. Unfortunately, many approaches aiming at restoring tolerance by manipulating immune cells have been tested and, although safe, have shown only limited efficacy. We recently discovered the existence of immune privileged tissue-resident stem cells and found that their ability to resist direct attack by T cells was not dependent on a physical barrier. Instead, it was a cell-autonomous process that allowed cloaking from immune cells. We identified a molecular pathway that reduces antigen presentation allowing protection from T cells while preserving enough MHC class I to not trigger a Natural Killer (NK) cell response. We have exploited such molecular circuits to provide similar protection to beta-cells for transplantation. Since this mechanism of protection is cell intrinsic, changes in the immune system should not jeopardize their survival. Preliminary data engineering beta-cell-like cells demonstrated that targeting this pathway leads to protection both in the Non-Obese Diabetic (NOD) model of T1D as well as in a model of CD8+ T cell-mediated autoimmune attack against beta-cells. Here we report novel candidate genes to engineer beta-cells for transplantation that can allow them to become immune silent. Disclosure J.Agudo: None. X.Sanchez: None. Funding American Diabetes Association (1-20-ACE-08 to J.A.)

1555-P: Novel Imaging Platform Highlights the Disconnect between ß-Cell Mass and Glucose Control in the Onset of Type 1 Diabetes

The age of onset of Type 1 Diabetes (T1D) presents considerable variation from patient to patient. Some become insulin dependent in a just few weeks, while others may take months or years. In either, immune system-β-cell interactions conspire to lead to loss of β-cells and insulin secretion. The molecular and cellular events involved have been the focus of intense research efforts, but most longitudinal studies during the onset of T1D have been limited to biomarkers (circulating autoantibodies, C-peptide⋯), without direct β-cell assessment. Despite data indicating that patients can retain functional β-cells years after the onset of the disease, one school of thought is that there is a precipitous loss of β-cells just preceding the time of clinical onset, triggering the hyperglycemia observed in T1D patients. A counter-view supported by recent studies suggests that insulin secretion is reduced even before β-cell loss. These assessments are traditionally performed through histo-morphometry. The process is time-consuming, prone to errors and costly. Using an NOD line with a SfGFP reporter attached to the C-peptide, we have designed a platform allowing the in toto imaging of β-cell mass in a model of T1D. After a 15-minute IPGTT to capture the peak of insulin secretion, pancreata were harvested and imaged on a cohort of animals at a time of early onset of T1D. A comparison of classical histo-morphometry and in toto imaging revealed a tight correlation between both approaches. Using the new platform allowed the rapid classification of large cohorts of animals based on the β-cell mass and glucose response. The results highlighted a significant disconnect between mass and function in a subset of mice: Some animals presenting near-normal mass while being glucose intolerant while others displaying a drastically reduced mass but still responding normally to a glucose challenge. These findings emphasize the role of islet dysfunction during the onset of T1D even before β-cell death. Disclosure C.Cras-méneur: None. R.J.Seeley: Board Member; Fractyl Health, Inc., Consultant; Novo Nordisk, Eli Lilly and Company, Research Support; Novo Nordisk, Fractyl Health, Inc., AstraZeneca, Eli Lilly and Company. P.Arvan: None. Funding National Institute of Diabetes and Digestive and Kidney Diseases (P30DK020572)

296-LB: Loss of SERCA2 Induces Mitochondrial Dysfunction, Increases ß-Cell Senescence, and Accelerates Type 1 Diabetes Development

Type 1 diabetes (T1D) results from immune-mediated destruction of pancreatic β-cells. Senescence and activation of a senescence-associated secretory phenotype (SASP) in β-cells may contribute to T1D pathogenesis; however, the mechanisms responsible for this phenotype are not well understood. We hypothesized that loss of endoplasmic reticulum (ER) Ca2+ induces mitochondrial dysfunction and drives the development of β-cell senescence during T1D. To test this hypothesis, we generated sarco/ER Ca2+-ATPase 2 (SERCA2) haploinsufficient mice on the NOD background (NOD-S2+/-). NOD-S2+/- mice displayed accelerated T1D onset compared to NOD-WT mice (14 wks vs 18 wks; p≤ 0.0001 female and 21 wks vs 24.5 wks male; p&amp;lt;0.05). As expected, basal ER Ca2+ levels were reduced in NOD-S2+/- islets, but basal mitochondrial Ca2+ levels were elevated compared to NOD-WT islets. Basal cytoplasmic Ca2+ levels remained unchanged. Single cell RNA sequencing showed an increase in immune cell markers in the NOD-S2+/- islets at 6 wks of age, with signatures of ER stress and mitochondrial dysfunction at both 6 and 10 wks of age. Islets from prediabetic female NOD-S2+/- mice showed decreased glucose-stimulated O2 consumption, reduced ATP production, and decreased mitochondrial membrane potential. Additionally, protein expression of ATP synthase and Complex III was decreased in female NOD-S2+/- islets, but mitochondrial content was unchanged. There was an increased expression of multiple markers of senescence and SASP in NOD-S2+/- islets between 6 and 12 wks of age compared to NOD-WT islets. Lastly, in vivo allosteric activation of SERCA decreased insulitis and delayed diabetes onset in WT NOD mice. Our results show that SERCA2 deficiency leads to mitochondrial dysfunction, β-cell senescence, and accelerated T1D development. In future studies, we will test whether senolytic agents can delay diabetes onset and rescue mitochondrial health in models of T1D and SERCA2 deficiency. Disclosure S. A. Weaver: Employee; Eli Lilly and Company. R. N. Bone: None. D. J. Acri: None. J. Kim: None. T. Kono: None. R. Dahl: None. D. L. Eizirik: None. F. Syed: None. C. Evans-molina: Advisory Panel; Provention Bio, Inc., DiogenX, Avotres Inc., Neurodon, MaiCell Therapeutics, Other Relationship; Isla Technology, Bristol-Myers Squibb Company, Nimbus Therapeutics, Research Support; Lilly, Astellas Pharma Inc. Funding National Institute of Diabetes and Digestive and Kidney Diseases (F31DK134168, R01DK093954, R01DK127308, R01DK127236, UC4DK104166, U01DK127786); U.S. Department of Veterans Affairs (I01BX001733, 2I01BX001733-05); JDRF (3-PDF-2017-385-A-N, 3-IND-2022-1235-I-X); National Center for Advancing Translational Sciences (UL1TR002529)

1233-P: The Association between Subgingival Microbiome, Subclinical Cardiovascular Disease, and Type 1 Diabetes

Background: Dysbiosis in the subgingival microbiome is the root cause of periodontal disease, a risk factor of cardiovascular disease (CVD), but its association with subclinical CVD, particularly among those with type 1 diabetes (T1D) is unclear. Methods: We included 283 subjects with (n=141) and without (n=142) T1D. We performed 16S rDNA sequencing on subgingival plaque samples and identified amplicon sequence variants. Subclinical CVD was measured by carotid intima-media thickness (cIMT), pulse wave velocity (PWV), and brachial artery distensibility (BrachD). Results: Beta diversity differed between T1D and the nondiabetes (ND) group (F = 1.66, P=0.024). As shown in Figure 1, in the stratified generalized linear model (adjusted for age, gender, race, smoking, alcohol drinking, BMI, and additionally HbA1c in the T1D model), we observed 4 taxa in the T1D group and 28 taxa in the ND group to be associated with cIMT (all Padj&amp;lt; 0.05). Moreover, 8 and 17 taxa were associated with BrachD (lower value suggests worse status) in T1D and ND groups, and 6 and 5 for PWV (all Padj &amp;lt; 0.05). Some associations were in opposite directions by diabetes status, especially for cIMT. Conclusion: We observed differences in the subgingival microbiome profile between those with and without T1D. Subgingival microbiome taxa were associated with subclinical CVD measures, with some differences observed by diabetes status. Disclosure M. Xiao: None. A. Sarkar: None. J.K. Snell-Bergeon: None. S. Chandrasekaran: None. L.R. Johnson: None. B.R. Burkhardt: None. J. Petrosino: None. A.C. Alman: None. Funding National Institutes of Health (5R01DE026480)