Dysregulation Of Glucose Homeostasis Research Articles

Abstract RF02-02: BBO-10203, a first-in-class, orally bioavailable, selective covalent small molecule that inhibits RAS-driven PI3Kalpha activity without affecting glucose metabolism

Abstract PI3Kα is the most mutated kinase and the second most mutated oncogene in human cancer. Activation of PI3Ka can be achieved by receptor tyrosine kinases such as insulin receptor and insulin-like growth factor receptor 1 and/or by directly interacting with RAS family members. Previous elegant preclinical studies have established that RAS-driven PI3Ka activation is important in tumor cells but may not be involved in cell types controlling glucose metabolism. Alpelisib, a small molecule inhibitor of the kinase activity of PI3Ka, has been approved for the treatment of ER+ PIK3CA mutant breast cancer in combination with fulvestrant after endocrine therapy in advanced or metastatic breast cancer based on an improvement in PFS versus fulvestrant alone. Inhibition of PI3Ka activity by alpelisib in normal tissues resulted in a severe (G3/4) hyperglycemia rate of 37% with frequent dose interruptions and discontinuations. Additionally, preclinical studies have demonstrated that the dysregulation of glucose homeostasis resulting from PI3Ka kinase inhibition leads to hyperinsulinemia that increases pathway flux, rendering kinase inhibitors less effective. Here, we report on a novel covalent small molecule designed to inhibit RAS-mediated activation of the AKT pathway via PI3Ka without the resultant hyperglycemia associated with direct inhibition of PI3Ka kinase activity. BBO-10203 disrupts the physical interaction between RAS and PI3Ka in tumor cells resulting in potent signaling pathway inhibition. This agent selectively binds to PI3Ka and disrupts its interaction with K-,H-, and N-RAS with low single digit nanomolar potency (~5 nM). Breaking the interaction between these two oncogenes inhibits basal pAKT cellular levels (BT-474/KYSE-410 IC50: ~5 nM) in HER2 amplified (HER2amp) and wild-type or mutant PI3Ka cell lines. Even though BBO-10203 does not inhibit the kinase activity of PI3Ka, its effects on cancer cell signaling inhibition and transcriptional regulation highly resemble those of alpelisib. BBO-10203 displays excellent drug-like properties and oral bioavailability. Single dose treatment of KYSE-410 (HER2amp/KRASG12C) tumor bearing mice with increasing doses (1-100 mg/kg, PO) of BBO-10203 results in dose and time dependent inhibition of pAKT in vivo. Maximal inhibition (~80%) is achieved at 30 mg/kg and lasts for 24 hours. Repeated dose treatment of tumor bearing mice with BBO-10203 is well tolerated and results in significant efficacy in PIK3CA mutant as well as HER2amp human xenograft models. In the KYSE-410 xenograft model, BBO-10203 daily oral dosing of 30 mg/kg results in significant tumor regressions. Importantly, treatment with BBO-10203 does not affect insulin signaling in differentiated adipocytes in vitro, nor does it impact glucose metabolism in vivo at 3-times the maximal efficacious dose level in xenograft studies. In conclusion, we have identified a novel approach to inhibit the PI3Ka signaling pathway by blocking its interaction with, and activation by RAS. This approach can achieve strong pAKT inhibition in tumor cells without changes in glucose metabolism. Clinical investigation of BBO-10203 for the treatment of both ER+/PIK3CA mutant and HER2amp breast cancer is warranted. Citation Format: Pedro Beltran, Simanshu Dhirendra, Rui Xu, Ming Chen, Daniel Czyzyk, Sofia Donovan, Siyu Feng, Cindy Feng, Lijuan Fu, Felice Lightstone, Ken Lin, Anna Maciag, Dwight Nissley, Erin Riegler, Kerstin Sinkevicius, Andrew Stephen, James Stice, David Turner, Bin Wang, Keshi Wang, Yue Yang, Cathy Zhang, Frank McCormick, Eli Wallace. BBO-10203, a first-in-class, orally bioavailable, selective covalent small molecule that inhibits RAS-driven PI3Kalpha activity without affecting glucose metabolism [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr RF02-02.

Dysfunction of the adhesion G protein-coupled receptor latrophilin 1 (ADGRL1/LPHN1) increases the risk of obesity

Obesity is one of the diseases with severe health consequences and rapidly increasing worldwide prevalence. Understanding the complex network of food intake and energy balance regulation is an essential prerequisite for pharmacological intervention with obesity. G protein-coupled receptors (GPCRs) are among the main modulators of metabolism and energy balance. They, for instance, regulate appetite and satiety in certain hypothalamic neurons, as well as glucose and lipid metabolism and hormone secretion from adipocytes. Mutations in some GPCRs, such as the melanocortin receptor type 4 (MC4R), have been associated with early-onset obesity. Here, we identified the adhesion GPCR latrophilin 1 (ADGRL1/LPHN1) as a member of the regulating network governing food intake and the maintenance of energy balance. Deficiency of the highly conserved receptor in mice results in increased food consumption and severe obesity, accompanied by dysregulation of glucose homeostasis. Consistently, we identified a partially inactivating mutation in human ADGRL1/LPHN1 in a patient suffering from obesity. Therefore, we propose that LPHN1 dysfunction is a risk factor for obesity development.

Tyrosine nitration of glucagon impairs its function: Extending the role of heme in T2D pathogenesis

New studies raise the possibility that the higher glucagon (GCG) level present in type 2 diabetes (T2D) is a compensatory mechanism to enhance β-cell function, rather than induce dysregulated glucose homeostasis, due to an important role for GCG that acts directly within the pancreas on insulin secretion by intra-islet GCG signaling. However, in states of poorly controlled T2D, pancreatic α cell mass increases (overproduced GCG) in response to insufficient insulin secretion, indicating decreased local GCG activity. The reason for this decrease is not clear. Recent evidence has uncovered a new role of heme in cellular signal transduction, and its mechanism involves reversible binding of heme to proteins. Considering that protein tyrosine nitration in diabetic islets increases and glucose-stimulated insulin secretion (GSIS) decreases, we speculated that heme modulates GSIS by transient interaction with GCG and catalyzing its tyrosine nitration, and the tyrosine nitration may impair GCG activity, leading to loss of intra-islet GCG signaling and markedly impaired insulin secretion. Data presented here elucidate a novel role for heme in disrupting local GCG signaling in diabetes. Heme bound to GCG and induced GCG tyrosine nitration. Two tyrosine residues in GCG were both sensitive to the nitrating species. Further, GCG was also demonstrated to be a preferred target peptide for tyrosine nitration by co-incubation with BSA. Tyrosine nitration impaired GCG stimulated cAMP-dependent signaling in islet β cells and decreased insulin release. Our results provided a new role of heme for impaired GSIS in the pathological process of diabetes.

Liraglutide prevents cellular senescence in human retinal endothelial cells (HRECs) mediated by SIRT1: an implication in diabetes retinopathy.

Diabetes mellitus (DM) is a chronic metabolic disorder affecting millions of people worldwide, characterized by dysregulated glucose homeostasis and hyperglycemia. Diabetic retinopathy (DR) is one of the serious multisystemic complications. Aging is an important risk factor for DR. Endothelial sirtuin 1 (SIRT1) plays an important role in regulating the pathophysiology of glucose metabolism, cellular senescence, and aging. Liraglutide, an analog of Glucagon-like peptide 1 (GLP-1), has been widely used in the treatment of DM. However, the effects of Liraglutide on DR are less reported. Here, we investigated whether treatment with Liraglutide has beneficial effects on high glucose (HG)-induced injury in human retinal microvascular endothelial cells (HRECs). First, we found that exposure to HG reduced the expression of glucagon-like peptide 1 receptor 1 (GLP-1R). Additionally, Liraglutide ameliorated HG-induced increase in the expression of vascular endothelial growth factor-A (VEGF-A) and interleukin 6 (IL-6). Importantly, Liraglutide ameliorated cellular senescence and increased telomerase activity in HG-challenged HRECs. Liraglutide also reduced the levels of p53 and p21. Mechanistically, Liraglutide restored the expression of SIRT1 against HG. In contrast, the knockdown of SIRT1 abolished the protective effects of Liraglutide in cellular senescence of HRECs. Our findings suggest that Liraglutide might possess a benefit on DR mediated by SIRT1.

E-Cigarette Exposure Alters Neuroinflammation Gene and Protein Expression in a Murine Model: Insights from Perinatally Exposed Offspring and Post-Birth Mothers.

The use of E-cigarettes, often considered a safer alternative to traditional smoking, has been associated with high rates of cellular toxicity, genetic alterations, and inflammation. Neuroinflammatory impacts of cigarette smoking during pregnancy have been associated with increased risks of adverse childhood health outcomes; however, it is still relatively unknown if the same propensity is conferred on offspring by maternal vaping during gestation. Results from our previous mouse inhalation studies suggest such a connection. In this earlier study, pregnant C57BL/6 mice were exposed daily to inhaled E-cig aerosols (i.e., propylene glycol and vegetable glycerin, [PG/VG]), with or without nicotine (16 mg/mL) by whole-body inhalation throughout gestation (3 h/d; 5 d/week; total ~3-week) and continuing postnatally from post-natal day (PND) 4-21. As neuroinflammation is involved in the dysregulation of glucose homeostasis and weight gain, this study aimed to explore genes associated with these pathways in 1-mo.-old offspring (equivalent in humans to 12-18 years of age). Results in the offspring demonstrated a significant increase in glucose metabolism protein levels in both treatment groups compared to filtered air controls. Gene expression analysis in the hypothalamus of 1 mo. old offspring exposed perinatally to E-cig aerosols, with and without nicotine, revealed significantly increased gene expression changes in multiple genes associated with neuroinflammation. In a second proof-of-principal parallel study employing the same experimental design, we shifted our focus to the hippocampus of the postpartum mothers. We targeted the mRNA levels of several neurotrophic factors (NTFs) indicative of neuroinflammation. While there were suggestive changes in mRNA expression in this study, levels failed to reach statistical significance. These studies highlight the need for ongoing research on E-cig-induced alterations in neuroinflammatory pathways.

Fingerprinting hyperglycemia using predictive modelling approach based on low-cost routine CBC and CRP diagnostics

Hyperglycemia is an outcome of dysregulated glucose homeostasis in the human body and may induce chronic elevation of blood glucose levels. Lifestyle factors such as overnutrition, physical inactivity, and psychosocials coupled with systemic low-grade inflammation have a strong negative impact on glucose homeostasis, in particular, insulin sensitivity. Together, these factors contribute to the pathophysiology of diabetes (DM) and expanding landscape of its prevalence regionally and globally. The rapid rise in the prevalence of type 2 diabetes, therefore, underscores the need for its early diagnosis and treatment. In this work, we have evaluated the discriminatory capacity of different diagnostic markers including inflammatory biomolecules and RBC (Red Blood Cell) indices in predicting the risk of hyperglycemia and borderline hyperglycemia. For that, 208,137 clinical diagnostic entries obtained over five years from Chugtai Labs, Pakistan, were retrospectively evaluated. The dataset included HbA1c (n = 142,011), complete blood count (CBC, n = 84,263), fasting blood glucose (FBG, n = 35,363), and C-reactive protein (CRP, n = 9035) tests. Our results provide four glycemic predictive models for two cohorts HbA1c and FBG) each having an overall predictive accuracy of more than 80% (p-value < 0.0001). Next, multivariate analysis (MANOVA) followed by univariate analysis (ANOVA) was employed to identify predictors with significant discriminatory capacity for different levels of glycemia. We show that the interplay between inflammation, hyperglycemic-induced derangements in RBC indices, and altered glucose homeostasis could be employed for prognosticating hyperglycemic outcomes. Our results then conclude a glycemic predictor with high sensitivity and specificity, employing inflammatory markers coupled with RBC indices, to predict glycemic outcomes (ROC p-value < 0.0001). Taken together, this study outlines a predictor of glycemic outcomes which could assist as a prophylactic intervention in predicting the early onset of hyperglycemia and borderline hyperglycemia.

Engineered exosomes as a prospective therapy for diabetic foot ulcers.

Diabetic foot ulcer (DFU), characterized by high recurrence rate, amputations and mortality, poses a significant challenge in diabetes management. The complex pathology involves dysregulated glucose homeostasis leading to systemic and local microenvironmental complications, including peripheral neuropathy, micro- and macro-angiopathy, recurrent infection, persistent inflammation and dysregulated re-epithelialization. Novel approaches to accelerate DFU healing are actively pursued, with a focus on utilizing exosomes. Exosomes are natural nanovesicles mediating cellular communication and containing diverse functional molecular cargos, including DNA, mRNA, microRNA (miRNA), lncRNA, proteins, lipids and metabolites. While some exosomes show promise in modulating cellular function and promoting ulcer healing, their efficacy is limited by low yield, impurities, low loading content and inadequate targeting. Engineering exosomes to enhance their curative activity represents a potentially more efficient approach for DFUs. This could facilitate focused repair and regeneration of nerves, blood vessels and soft tissue after ulcer development. This review provides an overview of DFU pathogenesis, strategies for exosome engineering and the targeted therapeutic application of engineered exosomes in addressing critical pathological changes associated with DFUs.

High Fat Diet and High Sucrose Intake Divergently Induce Dysregulation of Glucose Homeostasis through Distinct Gut Microbiota-Derived Bile Acid Metabolism in Mice.

A high calorie diet such as excessive fat and sucrose intake is always accompanied by impaired glucose homeostasis such as T2DM (type 2 diabetes mellitus). However, it remains unclear how fat and sucrose individually affect host glucose metabolism. In this study, mice were fed with high fat diet (HFD) or 30% sucrose in drinking water (HSD) for 24 weeks, and glucose metabolism, gut microbiota composition, as well as bile acid (BA) profile were investigated. In addition, the functional changes of HFD or HSD-induced gut microbiota were further verified by fecal microbiota transplantation (FMT) and ex vivo culture of gut bacteria with BAs. Our results showed that both HFD and HSD caused dysregulated lipid metabolism, while HFD feeding had a more severe effect on impaired glucose homeostasis, accompanied by reduced hyocholic acid (HCA) levels in all studied tissues. Meanwhile, HFD had a more dramatic influence on composition and function of gut microbiota based on α diversity indices, β diversity analysis, as well as the abundance of secondary BA producers than HSD. In addition, the phenotypes of impaired glucose homeostasis and less formation of HCA caused by HFD can be transferred to recipient mice by FMT. Ex vivo culture with gut bacteria and BAs revealed HFD-altered gut bacteria produced less HCA than HSD, which might closely associate with reduced relative abundance of C7 epimerase-coding bacteria g_norank/unclassified_f_Eggerthellaceae and bile salt hydrolase-producing bacteria Lactobacillus and Bifidobacterium in HFD group. Our findings revealed that the divergent effects of different high-calorie diets on glucose metabolism may be due to the gut microbiota-mediated generation and metabolism of BAs, highlighting the importance of dietary management in T2DM.

Discovery and Clinical Proof-of-Concept of RLY-2608, a First-in-Class Mutant-Selective Allosteric PI3Kα Inhibitor That Decouples Antitumor Activity from Hyperinsulinemia.

Treatments for PIK3CA-mutant cancers are limited by toxicities associated with the inhibition of WT PI3Kα. Molecular dynamics, cryo-electron microscopy, and DNA-encoded libraries were used to develop RLY-2608, a first-in-class inhibitor that demonstrates mutant selectivity in patients. This marks the advance of clinical mutant-selective inhibition that overcomes limitations of orthosteric PI3Kα inhibitors. See related commentary by Gong and Vanhaesebroeck, p. 204 . See related article by Varkaris et al., p. 227 . This article is featured in Selected Articles from This Issue, p. 201.

Abstract 15706: Common- and Rare-Variant Genetic Architecture of Heart Failure Across the Allele Frequency Spectrum

Background: Heart failure (HF) is a complex trait influenced by environmental and genetic factors. Genome-wide association studies (GWAS) have found common genetic variants associated with HF risk, but the extent that common and rare variants explain risk and implicate similar genes and pathways in HF remains less understood. Methods: For common variants, we meta-analyze existing GWAS of all-cause HF with data from the Million Veteran Program, including 207,346 individuals with HF and 2,151,210 without in diverse populations. We examine rare coding variants in the Penn Medicine BioBank (PMBB) using gene-collapsing association studies and burden heritability regression. We test for an interaction between a polygenic risk score (PRS) based on our GWAS meta-analysis and truncating variants in TTN (TTNtv). Results: GWAS meta-analysis identified 176 risk loci (146 previously unreported), implicating known risk factors for HF and genes involved in cardiac development. New signals at GIPR/ GLP1R highlight potential contributions of dysregulated glucose homeostasis and metabolism in HF. Gene collapsing studies identified associations between HF and rare loss-of-function variants in TTN (OR 2.94, 95% CI 2.43-3.56) and MYBPC3 (OR 7.71, 95% CI 3.97-14.97) at exome-wide significance. HF heritability mediated through common variants (4.5%) was significantly higher than for rare variants (1.8%), but rare variant heritability was further enriched in cardiomyopathy genes compared to common variants (27-fold vs. 3.4-fold). We found a significant interaction between a new multi-ancestry HF-associated PRS (AUC 0.72, 95% CI 0.72-0.73) and TTNtv carrier status (interaction OR 1.32, 95% CI 1.06-1.64). Conclusions: Common and rare variants contribute to HF heritability. Common variant HF heritability is highly polygenic, while rare variant burden heritability appears more concentrated in core cardiomyopathy genes. HF risk conferred by TTNtv carrier status is further increased by an individual’s polygenic contribution. Our results support the continued inclusion of cardiomyopathy genes in rare-variant genetic testing panels for HF but suggest a meaningful polygenic component to HF exists that is not currently captured by clinical genetic testing.

SAT043 Chronically High Cerebrospinal Fluid Glucose Levels Impair Memory In Male Mice

Abstract Disclosure: M.U. Raza: None. K.H. Chhabra: None. Diabetes doubles the risk of cognitive decline and Alzheimer’s disease (AD). Whether this is mediated by an increase in blood glucose or cerebrospinal fluid (CSF) glucose levels, or by other metabolic factors such as changes in plasma insulin levels is unclear. To clarify the contribution of high blood glucose versus high CSF glucose levels toward increasing the risk of cognitive decline in mice, we have developed a method through which glucose concentration can be increased selectively in CSF. We implanted 8 weeks old male mice (n= 7-8 / group) with cannula attached to osmotic minipumps to directly infuse either artificial CSF (aCSF/sham group) or 50% glucose solution (treatment group) into the right lateral ventricle for eight weeks at a flow rate of 0.25ul/hr. CSF glucose was measured two and eight weeks after initiating the infusion in these mice. We also performed oral glucose tolerance tests (OGTT) in these mice to assess their peripheral glucose metabolism and uptake. Moreover, these mice were tested through the Morris water maze (MWM) to investigate the effects of high CSF glucose on learning and memory. Mice in the treatment group showed a significant increase (p&amp;lt;0.0001, unpaired t-test) in CSF glucose levels (mean=328±30.15 and 358±15.03mg/dl post-2, and 8 weeks of implantation, respectively) as compared to the sham group (mean=56±2.63 and 73±8.61mg/dl post-2, and 8 weeks of implantation, respectively). There was no significant change in body weight and food intake during the study. In OGTT, the treatment group showed significantly lower blood glucose levels (p&amp;lt;0.05, two-way ANOVA repeated measures design, Bonferroni’s multiple comparisons) at 15 minutes post-gavage (mean=336.3±24.41mg/dl) as compared to the sham group (mean=478.6±30.06 mg/dl). Mice in the treatment group made significantly fewer entries to the correct quadrant (i.e. the quadrant where the hidden platform was placed during training) (mean=12.43±1.55 entries, p&amp;lt;0.05, unpaired t-test) in the MWM test, as compared to the sham group (mean=18.4±1.84 entries). Additionally, mice in the treatment group were significantly less likely to revisit the correct quadrant (mean=10.7±1.50 revisits, p&amp;lt;0.05, unpaired t-test) than the mice in the sham group (mean=16.8±1.78 revisits). Importantly, there was no significant difference in the overall locomotor activity between the groups as measured through the open field test. To summarize, we have developed a method to test the effects of high CSF glucose levels on learning and memory in mice. Our results show that high CSF glucose levels for up to two months cause memory deficits in mice. This mouse model of chronically high CSF glucose presents a useful tool to investigate how diabetes-associated dysregulation of glucose homeostasis in the brain may contribute to AD and other neurodegenerative disorders. Presentation: Saturday, June 17, 2023

Salsalate: a pleotropic anti-inflammatory drug in the treatment of diabetes, obesity, and metabolic diseases.

Type two Diabetes Mellitus (T2DM) is a rising epidemic. Available therapeutic strategies have provided glycaemic control via HbA1c reduction but fail to provide clinically meaningful reduction in microvascular and macrovascular (cardiac, renal, ophthalmological, and neurological) complications. Inflammation is strongly linked to the pathogenesis of T2DM. Underlying inflammatory mechanisms include oxidative stress, endoplasmic reticulum stress amyloid deposition in the pancreas, lipotoxicity, and glucotoxicity. Molecular signalling mechanisms in chronic inflammation linked to obesity and diabetes include JANK, NF-kB, and AMPK pathways. These activated pathways lead to a production of various inflammatory cytokines, such as Interleukin (IL-6), tumor necrosis factor (TNF)-alpha, and C-reactive protein (CRP), which create a chronic low-grade inflammation and ultimately dysregulation of glucose homeostasis in the liver, skeletal muscle, and smooth muscle. Anti-inflammatory agents are being tested as anti-diabetic agents such as the IL-1b antagonist, Anakinra, the IL-1b inhibitor, Canakinuma, the IL-6 antagonists such as Tocilizumab, Rapamycin (Everolimus), and the IKK-beta kinase inhibitor, Salsalate. Salsalate is a century old safe anti-inflammatory drug used in the treatment of arthritis. Long-term safety and efficacy of Salsalate in the treatment of T2DM have been evaluated, which showed improved fasting plasma glucose and reduced HbA1C levels as well as reduced pro-inflammatory markers in T2DM patients. Current publication summarizes the literature review of pathophysiology of role of inflammation in T2DM and clinical efficacy and safety of Salsalate in the treatment of T2DM.

Identification of 3H-benzo[b] [1,4] diazepine derivatives as PPARα agonists by in silico studies and biochemical evaluation

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in the world, whose pathologic features include dysregulated glucose homeostasis and lipid accumulation. Peroxisome proliferators-activated receptor α (PPARα) is a key regulator of fatty acid metabolism and ketogenesis due to its regulatory pathways involve activating fatty acid uptake, accelerating fatty acid oxidation, inhibiting gluconeogenesis, and suppressing inflammation and fibrosis. Therefore, PPARα is considered as a potential target for the treatment of NAFLD and some agonists have entered clinical trials, which drove us to discover more novel PPARα agonists. In current work, new 3H-benzo[b] [1,4] diazepine PPARα agonists were identified from the ChemDiv database by pharmacophore modeling, molecular docking, derivative structure search, and bioassays, where compound LY-2 and its derivatives (LY-10∼LY-19) were discovered to promote the expression of PPARα downstream gene, carnitine palmitoyl transterase-1 α (cpt1α). Among these active compounds, the EC50 value of LY-2 against increasing cpt1α was 2.169 μΜ. Furthermore, the effect of LY-2 on cpt1α was weakened when PPARα knock down, which confirmed that it is a PPARα agonist again. Finally, the results from molecular dynamics simulations and binding free energy calculations showed that π-π stacking and hydrogen bonding interactions played key roles in the binding of LY-2 and PPARα protein and their complex maintained a stable structure to facilitate LY-2 to have a better binding affinity with PPARα protein. Taken together, compound LY-2 might be a novel lead compound for the development of potent PPARα agonists. Communicated by Ramaswamy H. Sarma

Overexpression of Plg-RKT protects against adipose dysfunction and dysregulation of glucose homeostasis in diet-induced obese mice

ABSTRACT The plasminogen receptor, Plg-RKT, is a unique cell surface receptor that is broadly expressed in cells and tissues throughout the body. Plg-RKT localizes plasminogen on cell surfaces and promotes its activation to the broad-spectrum serine protease, plasmin. In this study, we show that overexpression of Plg-RKT protects mice from high fat diet (HFD)-induced adipose and metabolic dysfunction. During the first 10 weeks on the HFD, the body weights of mice that overexpressed Plg-RKT (Plg-RKT-OEX) were lower than those of control mice (CagRosaPlgRKT). After 10 weeks on the HFD, CagRosaPlgRKT and Plg-RKT-OEX mice had similar body weights. However, Plg-RKT-OEX mice showed a more metabolically favourable body composition phenotype. Plg-RKT-OEX mice also showed improved glucose tolerance and increased insulin sensitivity. We found that the improved metabolic functions of Plg-RKT-OEX mice were mechanistically associated with increased energy expenditure and activity, decreased proinflammatory adipose macrophages and decreased inflammation, elevated brown fat thermogenesis, and higher expression of adipose PPARγ and adiponectin. These findings suggest that Plg-RKT signalling promotes healthy adipose function via multiple mechanisms to defend against obesity-associated adverse metabolic phenotypes.

Circulating Sphingolipids and Glucose Homeostasis: An Update.

Sphingolipids are a family of lipid molecules produced through different pathways in mammals. Sphingolipids are structural components of membranes, but in response to obesity, they are implicated in the regulation of various cellular processes, including inflammation, apoptosis, cell proliferation, autophagy, and insulin resistance which favors dysregulation of glucose metabolism. Of all sphingolipids, two species, ceramides and sphingosine-1-phosphate (S1P), are also found abundantly secreted into the bloodstream and associated with lipoproteins or extracellular vesicles. Plasma concentrations of these sphingolipids can be altered upon metabolic disorders and could serve as predictive biomarkers of these diseases. Recent important advances suggest that circulating sphingolipids not only serve as biomarkers but could also serve as mediators in the dysregulation of glucose homeostasis. In this review, advances of molecular mechanisms involved in the regulation of ceramides and S1P association to lipoproteins or extracellular vesicles and how they could alter glucose metabolism are discussed.

P-610 Lipid metabolism mediated the effect of glucose homeostasis and insulin resistance on IVF/ICSI outcomes in PCOS women

Abstract Study question To investigate the potential mediation role of lipid metabolism on the effect of glucose metabolism on IVF/ICSI outcomes in PCOS women. Summary answer Lipid metabolism indicators were possible mediators of the effect of glucose metabolism indicators on IVF/ICSI early reproductive outcomes in PCOS women. What is known already Women with PCOS have high incidences of dyslipidemia, obesity, impaired glucose tolerance (IGT), diabetes, and insulin resistance (IR) and are fragile to female infertility. The causality between dyslipidemia, glucose homeostasis dysregulation, and IR has been widely discussed. Dyslipidemia may be an intermediate biological mechanism for the associations between abnormal glucose metabolism and potential disorders of oocytogenesis and embryogenesis in PCOS women. Study design, size, duration We retrospectively analyzed 917 PCOS women aged between 20 – 45 years old who underwent their first fresh IVF/ICSI cycle with autologous oocytes during 2018 – 2020 at a reproductive center. Participants/materials, setting, methods Data on baseline reproductive and cycle characteristics were collected from the internal database derived from the electronic medical records. The pregnancy outcomes were collected by well-trained follow-up staff from telephone interviews. Associations between glucose and lipid metabolism indicators and IVF/ICSI outcomes were explored using multivariable generalized linear regressions. Mediation analyses were conducted to examine the role of lipid metabolism on the association between glucose metabolism and IVF/ICSI outcomes. Main results and the role of chance Significant dose-dependent relationships were found between glucose metabolism indicators and IVF/ICSI early reproductive outcomes, as well as between glucose metabolism indicators and lipid metabolism indicators (all P &amp;lt; 0.05). Also, we found significant dose-dependent relationships between lipid metabolism indicators and IVF/ICSI early reproductive outcomes (all P &amp;lt; 0.05). The mediation analysis indicated that elevated FPG, 2hPG, FPI, 2hPI, HbA1c, and HOMA2-IR were significantly associated with decreased retrieved oocyte count, MII oocyte count, normal fertilization count, normal cleavage count, high-quality embryo count, or blastocyst formation count after controlling for lipid metabolism indicators. Serum TG mediated 6.0 – 31.0% of the associations; serum TC mediated 6.1 – 10.8% of the associations; serum HDL-C mediated 9.4 – 43.6% of the associations; serum LDL-C mediated 4.2 – 18.2% of the associations; and BMI mediated 26.7 – 97.7% of the associations. Limitations, reasons for caution Given the retrospective nature, bias in data collection cannot be excluded. Besides, we did not consider any adjunctive therapy, including diet, exercise, or medication (i.e., metformin) before or during IVF treatment. The possible random errors in single measurements may also lead to certain imprecise estimates of association. Wider implications of the findings Our study emphasizes a mediation role of lipid metabolism in the impact of glucose metabolism on oocytogenesis and embryogenesis in PCOS women, suggesting that the monitoring and management of preconception lipid metabolism, glucose homeostasis, and IR are essential for improving the IVF/ICSI outcomes of PCOS women. Trial registration number Not Applicable

1512-P: The Novel Roles of Intracellular Calcium and Phosphoinositides in Insulin Signaling and Metabolic Disease

Insulin resistance is closely associated with elevated intracellular Ca2+ concentration under ectopic lipid accumulation and hyperglycemia-induced intracellular stress conditions. We recently identified that obesity impairs intracellular Ca2+ homeostasis, which prevents membrane localization of PH domain-containing proteins such as AKT, PLCδ, and IRS through the formation of Ca2+-phosphoinositides (PIPs), resulting in dysregulation of glucose homeostasis and insulin resistance. It is unclear, however, whether insulin sensitivity can be improved by targeting intracellular Ca2+ overload. Therefore, we screened nine angiotensin-II-receptor blockers (ARBs), a class of antihypertensive agents, for beneficial effects on palmitic acid (PA)-induced insulin resistance in human HepG2 cells. Two of the ARBs attenuated PA-induced intracellular Ca2+ overload by inhibiting dysregulated store-operated channel (SOC)-mediated Ca2+ entry into cells, which ameliorated insulin resistance by promoting insulin-stimulated membrane localization of AKT and by increasing the phosphorylation of AKT and its downstream substrates in PA-treated HepG2 cells. Furthermore, certain ARBs ameliorated obesity-induced insulin resistance, hepatic steatosis, and tissue inflammation in mice fed a high-fat diet. Meanwhile, certain ARBs normalized intracellular Ca2+ homeostasis by regulating obesity-associated SOC-mediated Ca2+ entry, which rescued impaired insulin signaling in liver and muscle tissues by promoting postprandial membrane localization of AKT and IRS2. These findings underscore the contribution of dysregulated intracellular Ca2+ homeostasis to the pathophysiology of insulin resistance and suggest a therapeutic strategy to use specific ARBs to ameliorate insulin resistance. Disclosure J.Lee: None. Y.Jung: None. S.Im: None. D.Lee: None. H.Lee: None. I.Hong: None. O.Kim: None. B.Oh: None. Funding Korean Ministry of Health &amp; Welfare (HI14C1135 to B-C.O.); Basic Science Research Program (2021R1I1A1A01051429 to O-H.K.); Mid-Career Researcher Program (2019R1A2C2008130, 2022R1A2C2092700 to B-C.O.); National Research Foundation of Korea (2021R1A5A203033)

0503 Respiratory Effort During Sleep And Prevalent Diabetes In Obstructive Sleep Apnea

Abstract Introduction Obstructive sleep apnea (OSA) and type 2 diabetes (T2Dia) is a frequent clinical association. Beyond OSA-related hypoxic burden, increased respiratory effort (RE) is one of the main features of OSA and contributes to sympathetic overactivity that in turn might participate to glucose homeostasis dysregulation. The independent contribution of RE to the OSA-T2Dia pathogenesis remains to be demonstrated. The study aims to determine the impact of metrics assessing sleep RE derived from the sleep mandibular jaw movements (MJM) signal on the prevalence of T2Dia in a large cohort of patients addressed for in-laboratory conventional polysomnography (PSG) with suspicion of OSA. Methods An interpretable machine learning model was built to predict T2Dia from clinical data, PSG indices, and MJM-derived parameters (including the time spent with increased RE, expressed in % of TST). The analysis included 1128 subjects, randomly assigned to training (n=853) and validation (n=275) subsets with equal T2Dia prevalence of 11%. Results The risk stratification model based on 19 input features including increased RE showed good performance for predicting prevalent T2Dia (sensitivity=0.81, specificity=0.89). Post-hoc interpretation using the Shapley additive explanation (SHAP) method revealed that increased RE was the most important risk factor of T2Dia after other clinical factors for T2Dia (i.e., sex, BMI and average SpO2), ahead of standard PSG metrics (including the apnea-hypopnea index and oxygen desaturation index). Conclusion These findings suggested that the proportion of sleep time spent with increased RE automatically derived from MJM is a potential new reliable metric to predict prevalent T2Dia in patients with OSA. Support (if any)

Uses of Papaya Leaf and Seaweed Supplementations for Controlling Glucose Homeostasis in Diabetes.

Studies from laboratory animal models and complementary medical practices have implied that nutrients from special plants or herbs contain antidiabetic, antioxidant, anti-obese, anti-hypertensive, and anti-inflammatory properties. Seaweed and tropical papaya, which are widely available in Asian and Pacific countries, have been used as home remedies for centuries. The bioactive extracts from these plants contain vitamins A, C, B and E complexes, as well as polysaccharides, phenolic compounds, essential fatty acids, flavonoids, saponins, fucoidan, and phlorotannin. In this review, the authors examine the pathogenesis of diabetes characterized by hyperglycemia due to the dysregulation of glucose homeostasis, antidiabetic/antihyperglycemic seaweed or/and papaya derived bioactive phytochemicals and their proposed mechanisms of action in the management of Type 2 Diabetes Mellitus (T2DM). The authors also propose combining papaya and seaweed to enhance their antidiabetic effects, leveraging the advantages of herb-to-herb combination. Papaya and seaweed have demonstrated antidiabetic effects through in vitro assays, cellular models, and animal studies despite the limited clinical trials. Nutraceuticals with antidiabetic effects, such as secondary metabolites isolated from seaweed and papaya, could be combined for a synergistic effect on T2DM management. However, the application of these compounds in their purified or mixed forms require further scientific studies to evaluate their efficacy against diabetes-related complications, such as hyperlipidemia, elevated free radicals, pro-inflammatory molecules, insulin insensitivity, and the degeneration of pancreatic beta cells.

Obesity and Type 2 Diabetes: Adiposopathy as a Triggering Factor and Therapeutic Options

Obesity and type 2 diabetes (T2DM) are major public health concerns associated with serious morbidity and increased mortality. Both obesity and T2DM are strongly associated with adiposopathy, a term that describes the pathophysiological changes of the adipose tissue. In this review, we have highlighted adipose tissue dysfunction as a major factor in the etiology of these conditions since it promotes chronic inflammation, dysregulated glucose homeostasis, and impaired adipogenesis, leading to the accumulation of ectopic fat and insulin resistance. This dysfunctional state can be effectively ameliorated by the loss of at least 15% of body weight, that is correlated with better glycemic control, decreased likelihood of cardiometabolic disease, and an improvement in overall quality of life. Weight loss can be achieved through lifestyle modifications (healthy diet, regular physical activity) and pharmacotherapy. In this review, we summarized different effective management strategies to address weight loss, such as bariatric surgery and several classes of drugs, namely metformin, GLP-1 receptor agonists, amylin analogs, and SGLT2 inhibitors. These drugs act by targeting various mechanisms involved in the pathophysiology of obesity and T2DM, and they have been shown to induce significant weight loss and improve glycemic control in obese individuals with T2DM.