diabetes

Exploring in vivo Treg function in T1D through the lens of expanded Tregs

PROJECT SUMMARY/ABSTRACT A critical barrier to optimally treating Type 1 Diabetes (T1D), an autoimmune disease in which the islet beta cells are destroyed by immune cells, is understanding how autoimmunity is regulated in vivo. Several lines of evidence suggest that defective CD4+FOXP3+ regulatory T cells (Treg) likely contribute to the loss of tolerance in T1D. Yet, less is known about how human Treg function in vivo. In the Sanford T-rex study in which adolescents diagnosed with T1D were treated with a single dose of polyclonal autologous in vitro expanded Treg (expTreg), we found that a lower degree of in vitro Treg expansion significantly correlated with better preservation of C- peptide (a biomarker of insulin secretion and beta cell function) a year after treatment. This correlation could not be explained by age, expTreg phenotype or in vitro expTreg suppressive function. However, we did identify an expTreg gene signature that correlated with better C-peptide preservation and this expTreg signature was consistently expressed over time within individuals. Further, lower- and higher- expTreg differed phenotypically and transcriptionally by signatures implicating metabolic, homing and suppressive functions. Together, these data suggest that intrinsic features of an individual’s Treg may contribute to the extent of in vitro Treg expansion. They also suggest that strong activation and expansion can differentially amplify or alter the state of Tregs, leading to changes in homing and function that may impact clinical response. Based on these findings, we hypothesize that Treg proliferative capacity is driven by the activation and metabolic state of Treg resulting in differential in vitro fold expansion, homing potential and in vivo suppressive function that impacts clinical outcome. We will test this hypothesis by leveraging existing primary human samples from both the T-rex clinical trial and the Benaroya Research Institute Registry and Repository that includes individuals with known degree of in vitro Treg expansion and known C-peptide decline. In Aim1, we will identify how activation states of pre- and post- expansion Treg and longitudinal Treg in T-rex participants contribute to proliferative capacity and outcome using cellular, transcriptomic and epigenetic assays. In Aim 2 we will determine how metabolic shifts during Treg in vitro fold expansion alter Treg suppressive function, thereby impacting clinical outcome. In Aim 3, we will compare the in vivo suppressive function of lower- versus higher-expTreg from clinical samples using a xenogeneic graft versus host disease (GvHD) mouse model in addition to assessing in vivo expTreg homing and function using the assays from Aims 1 and 2 and a novel in vitro assay of cell trafficking to pancreatic islets. Successful completion of these aims will reveal mechanisms regulating Treg proliferative capacity and in vivo function that impact clinical outcome. Understanding these mechanisms will guide development of next generation Treg activation and expansion protocols for Treg therapies and help tailor the Treg expansion process to an individual’s baseline Treg signature.

Metabolic Assessment of Metformin in Pregnancy (MoM-P)

PROJECT SUMMARY The objective of the “Metabolic Assessment of Metformin in Pregnancy “(MoM-P) proposal is to assess the physiological effect of metformin on maternal and neonatal metabolism during pregnancy in individuals developing gestational diabetes (GDM). Metformin is increasingly being used for medical treatment of GDM not adequately treated with nutrition and physical activity. There is inconsistency among various organizations (Society for Maternal Fetal Medicine, American College of Obstetrics and Gynecology and the American Diabetes Association) as to metformin’s role in the medical management of GDM. We will examine the metabolic action of metformin in GDM pregnancies and effect on mothers and their offspring. We plan to recruit 50 participants from Massachusetts General Hospital (MGH) for Specific Aims 1, 2 and 3 and 100 participants from Ohio State University college of Medicine (OSUCOM) for Specific Aims 2 and 3. Participants for the study will have been diagnosed with GDM requiring medical management of GDM as part of the DECIDE multicenter randomized controlled trial. The primary site for DECIDE is OSUCOM, with Dr. Mark Landon as the PI. The MoM-P study will recruit participants from the DECIDE trial at MGH and OSUCOM. The MoM-P study aims are: Aim 1: To establish metformin’s effects on endogenous (primarily hepatic) glucose production (EGP) and insulin sensitivity in late pregnancy. We hypothesize that metformin does not lower EGP in pregnancy and hence the need of additional insulin in the medical management of GDM. We will perform infusion of a stable isotope of glucose (6,6 2H2 glucose) to estimate EGP and a HOMA-IR prior to initiation of medical management and again at 37 weeks gestation. Aim 2: Metformin increases GDF15 levels in human GDM pregnancy and is associated with lower nutrient intake, gestational weight gain (GWG) and increased resting energy expenditure (REE). We hypothesize that metformin increases GDF15 concentrations which lead to GI upset, lower caloric intake/GWG and increases REE. In DECIDE participants randomized to metformin vs. insulin, we will measure GDF15 and examine the relationship to ASA-nutrition records, REE with indirect calorimetry and maternal body composition using air displacement plethysmography (ADP) prior to initiation of medication and again at 37 weeks. Aim 3: To compare fetal growth and body composition in neonates exposed and unexposed to metformin in utero. We hypothesize that metformin treatment of GDM decreases fetal weight: 1) directly based on metformin’s effect on neonatal metabolism (fetal AMPK and mTOR pathways) and 2) indirectly by lowering maternal nutritional intake, fat free mass (FFM) and increasing maternal REE, resulting in decreased neonatal FFM and increased fat mass in childhood. In DECIDE participants, we will measure neonatal body composition with 72 hours of delivery using pediatric ADP and a planned follow-up of children at 2 years in the DECIDE protocol with estimates of male and female children’s body composition.

Circulating extracellular vesicles as functional indicators of maternal mental and physical health in pregnancy and postpartum

Women with high levels of adverse childhood experiences (ACEs) are at significantly greater risk for negative health outcomes in pregnancy and postpartum, including gestational diabetes, PTB, and depressed mood. However, we still lack biomarkers or a sufficient understanding of causal mechanisms. Extracellular vesicles (EVs) are one of the most dynamic and abundant biological signals secreted into maternal circulation, largely produced by the placenta – where levels increase 4-5-fold during pregnancy. Similarly, removal of the placenta at delivery produces a dramatic drop in maternal EV concentration. Across species, we and others have identified significant EV changes during pregnancy associated with homeostatic regulation, including glucose and glucocorticoid levels, supporting key roles for EVs in maternal health. However, longitudinal studies in human pregnancy and postpartum have not been conducted. We know little as to the mechanisms controlling EV secretion or the roles for EVs in maternal pregnancy and postpartum health. Our decade’s long work identified the X-linked gene, O-glycosyltransferase (OGT), in mouse and human placenta as a master gage of the maternal milieu, where OGT regulation of annexin A1 (AA1) is key to EV cargo loading and secretion from the placenta. We recently reported that placental OGT levels positively correlate with maternal EV concentration. How this association may contribute toward postpartum health, including regulating maternal stress physiology and mood in humans is not known. We hypothesize that increased ACEs, similar to stress in preclinical models, are negatively associated with a cell’s ability to secrete EVs important to maintain homeostasis in the face of the challenges of pregnancy and postpartum, producing an increasingly unhealthy state. Therefore, the goals of these proposed studies in both mice and humans are as follows: 1) To identify cellular mechanisms involved in EV secretion important to maternal health outcomes utilizing the placenta as a tool to genetically target OGT in mice and examine maternal homeostatic control related to EV concentration and composition during pregnancy; 2) To examine the functional ability for a dynamic elevation in maternal EV concentration to improve homeostatic regulation in pregnancy and postpartum using chemogenetic activation (DREADDs) of placenta trophoblast cells in pregnancy, and by EV transfer by tail vein injection postpartum; and 3) To examine in women changes in maternal EVs in a longitudinal pregnancy and postpartum study in association with maternal glucose and cortisol changes, we will examine markers of physical (glucose challenge test), HPA stress (hair cortisol & stress- stimulated salivary cortisol) and psychological (Hamilton Rating Scale for Depression, Perceived Stress Scale) health across pregnancy and the postpartum period in 150 healthy women with varying degrees of exposure to ACEs as measured using the ACE Questionnaire (ACE-Q).

A novel MRI method for noninvasive imaging of bone quality in type 2 diabetes

ABSTRACT: Type 2 diabetes mellitus (T2DM) affects 500 million of the global population, which is expected to increase to 800 million in 20 years. One of the multiple complications involved with T2DM is the significantly increased bone fracture risk and post-fracture mortality. Dual-energy X-ray absorptiometry (DXA) scans are routinely performed to measure bone mineral density (BMD) and associated fracture risk. However, T2DM patients often show preserved or even elevated BMD despite the significantly increased fracture risk. This mismatch between the BMD measurement and actual fracture risk hampers the accurate assessment of fracture risk and the appropriate treatment of T2DM that considers patient bone health. The lack of an accurate fracture risk assessment tool also confounds the evaluation of the bone health effect of antidiabetic drugs, including recently highlighted glucagon-like peptide-1 receptor agonists (e.g., semaglutide) and sodium-glucose cotransporter-2 inhibitors. Previous studies have suggested that bone quality, rather than bone quantity, as represented by BMD, is a crucial factor contributing to fracture risk in T2DM settings. Collagen crosslinking via advanced glycation end-products (AGEs) in cortical bone has been identified as a distinctive bone quality characteristic of T2DM patients, which explains the increased bone fragility. Although this finding is highly promising for improving the bone health management of T2DM patients, currently, no non-invasive method can monitor collagen crosslinking in the bones. This proposal aims to develop an ultrashort echo time (UTE) MRI-based method for measuring the degree of bone collagen crosslinking by quantifying magnetization transfer between water and collagen in the bone. This method, termed UTE-quantitative magnetization transfer (UTE-qMT) MRI, measures not only the quantity of macromolecules (e.g., collagen) in the bone but also the rates of exchange between water and macromolecular protons, which are related to the degree of collagen crosslinking. The proposal will develop and optimize the accelerated UTE-qMT method for reliably measuring the exchange rate in Aim 1. The optimized technique will be validated by correlating exchange rates with AGE-driven collagen crosslinking and subsequent compromise of bone mechanical properties in Aim 2. Finally, the optimized UTE-qMT MRI method will be translated to animal and human studies to demonstrate its clinical feasibility for investigating the effect of antidiabetic drugs on bone health in patients with T2DM in Aim 3. The successful completion of these aims will enable rapid and accurate assessment of bone fracture risk in patients with T2DM. Furthermore, noninvasively probing bone quality can also accurately assess the effect of antidiabetic drugs on bone health and aid in screening novel T2DM therapeutics for their impact on bone health.

Characterizing adipocyte heterogeneity in response to metabolic stress

Project Summary Adipose tissue is a central player in metabolism, storing energy healthily under normal conditions but becoming dysfunctional when overloaded. This can lead to the development of metabolic disease, most notably insulin resistance and type 2 diabetes (T2D). Understanding the contribution of adipose tissue to these complications requires knowledge of the individual cell types within adipose tissue and how they respond to different metabolic conditions. My previous work used single nucleus RNA sequencing to profile the cell types in adipose tissue and identified a number of subpopulations of white adipocytes that are differentially associated with clinical characteristics such as body mass index. In this grant, I now aim to better understand how a diverse array of stimuli influences adipocyte development and specification, the role that intra-individual variation plays in the response to these stimuli, and a better understanding of the relationship of adipocyte state to the development of metabolic disease. To do this, I propose using a model in which I can study human adipocyte development and function in mice to perform experiments such as high fat diet and cold exposure that are well-characterized in mice but not in humans. By performing experiments using cells from humans with a range of starting clinical characteristics, I can determine what changes will happen in response to a stimuli in all individuals verses those that only occur in specific populations. The experience that I have in characterizing adipocytes and adipose tissue both at the bench and computationally make me uniquely positioned to answer these questions. Taken together, these studies can test the behavior of adipocyte subpopulations from different people and under different conditions, ultimately leading to a better understanding of how subpopulations develop and, eventually, how we can target these populations to treat metabolic disease.

A Novel Mitochondrial-Targeted Inhibitor of NLRP3 Inflammasome Activation

PROJECT ABSTRACT Inflammasomes are multiprotein complexes of the innate immune system that assemble upon detecting specific molecular patterns associated with pathogens and cellular damage. Once assembled, activated inflammasomes trigger a cascade of downstream events that culminate in cell death and inflammation. Aberrant activation of the NLRP3 inflammasome contributes to the pathogenesis of numerous inflammatory and degenerative diseases, including gout, atherosclerosis, type 2 diabetes, and Alzheimer’s disease. Despite its central role in innate immunity and inflammation, there are no FDA-approved therapies that directly target the NLRP3 inflammasome. Current strategies rely on biologics that inhibit downstream pro-inflammatory cytokines produced from inflammasome activation, such as interleukin-1β (IL-1β), but do not block upstream inflammasome assembly or pyroptotic cell death, highlighting a critical unmet need for selective small-molecule inhibitors with novel mechanisms of action. To address this gap, we identified a covalent small molecule, Compound-2 (C-2), that robustly inhibits NLRP3 inflammasome activation in murine and human immune cells. C-2 suppresses multiple downstream events triggered by inflammasome activation, including IL-1β secretion and pyroptosis, with no apparent toxicity. Chemoproteomic profiling revealed that C-2 interacts with SLC25A3, a mitochondrial phosphate and copper transporter, suggesting a previously unrecognized regulatory node in inflammasome signaling. This R21 project aims to (1) elucidate the mechanism by which C-2 suppresses NLRP3 activation and (2) define the molecular interaction between C-2 and SLC25A3 and its functional consequences. Our studies will integrate biochemical, cellular, and in vivo approaches to uncover a novel mitochondrial mechanism of inflammasome regulation and validate C-2 as a first-in-class inflammasome inhibitor. Successful completion of this project will lay the foundation for future therapeutic development targeting mitochondrial- inflammasome crosstalk in inflammatory disease.

Targeting the brain to improve obesity and type 2 diabetes

The increasing prevalence of obesity and type 2 diabetes (T2D) and associated morbidity and mortality emphasizes the need for a more complete understanding of the mechanisms mediating energy homeostasis to accelerate the identification of new medications. Recent reports indicate that obesity medication, 5-hydroxytryptamine (5-HT, serotonin)2C receptor (5-HT2CR) agonist lorcaserin improves glycemic control in association with weight loss in obese patients with T2D. We examined whether lorcaserin has a direct effect on insulin sensitivity and how this effect is achieved. We clarify that lorcaserin dose-dependently improves glycemic control in a mouse model of T2D without altering body weight. Examining the mechanism of this effect, we reveal a necessary and sufficient neurochemical mediator of lorcaserin’s glucoregulatory effects, via activation of brain pro-opiomelanocortin (POMC) peptides. We observed that lorcaserin reduces hepatic glucose production and improves insulin sensitivity. These data suggest that lorcaserin’s action within the brain represents a mechanistically novel treatment for T2D: findings of significance to a prevalent global disease.

Importance of perinatal hormones and diet on hypothalamic development and lifelong metabolic regulation

Inclusive Data Science

A single person can be the source of billions of data points, whether these are generated from everyday internet use, healthcare records, wearable sensors or participation in experimental research. This vast amount of data can be used to make predictions about people and systems: what is the probability this person will develop diabetes in the next year? Will commit a crime? Will be a good employee? Is of a particular ethnicity? Predictions are simply represented by a number, produced by an algorithm. A single number in itself is not biased. How that number was generated, interpreted and subsequently used are all processes deeply susceptible to human bias and prejudices. This session will explore a philosophical perspective of data ethics and discuss practical steps to reducing statistical bias. There will be opportunity in the last section of the session for attendees to discuss and troubleshoot ethical questions from their own analyses in a ‘Data Clinic’.

A metabolic function of the hippocampal sharp wave-ripple

The hippocampal formation has been implicated in both cognitive functions as well as the sensing and control of endocrine states. To identify a candidate activity pattern which may link such disparate functions, we simultaneously measured electrophysiological activity from the hippocampus and interstitial glucose concentrations in the body of freely behaving rats. We found that clusters of sharp wave-ripples (SPW-Rs) recorded from both dorsal and ventral hippocampus reliably predicted a decrease in peripheral glucose concentrations within ~10 minutes. This correlation was less dependent on circadian, ultradian, and meal-triggered fluctuations, it could be mimicked with optogenetically induced ripples, and was attenuated by pharmacogenetically suppressing activity of the lateral septum, the major conduit between the hippocampus and subcortical structures. Our findings demonstrate that a novel function of the SPW-R is to modulate peripheral glucose homeostasis and offer a mechanism for the link between sleep disruption and blood glucose dysregulation seen in type 2 diabetes and obesity.

Ablation of Necroptosis Protects Diabetes Associated Cognitive Deficits & Lipotoxicity Induced Neuro-Glia Changes

Hippocampal neurovascular coupling and spatial working memory impairment in a rodent model of type 2 diabetes: impact of dietary nitrate intervention

Metabolic syndrome status and fitness determine the association of insulin resistance with abnormal brain functional dynamics and cognition in pre-diabetes

Modeling of increased excitability of nociceptive neurons due to diabetes-induced upregulation of somatic T-type Ca2+ current

Neuroprotective potential of Chebulinic acid in streptozotocin-induced diabetes-associated cognitive decline: behavioral and biochemical evidences

Regulation of the apoptosis/autophagy switch by propionic acid in ventromedial hypothalamus of rats with type 2 diabetes mellitus

Trans-resveratrol effects on diabetes-induced apoptosis in retinal pigment epithelium in Wistar rats

Type 1 diabetes mediated microvascular dysfunction and impaired behavioral performance in mice

Aggression control by type 2 diabetes risk gene Dusp8

FENS Forum 2024

Antioxidant effect of combined administration of metformin and propionate in a rat model of type 2 diabetes mellitus

FENS Forum 2024

The effect of diabetes on myelin homeostasis

FENS Forum 2024

Impact of type 2 diabetes and high-intensity interval exercise on neurogenesis, angiogenesis, and the accumulation of lipid droplets in the hippocampus

FENS Forum 2024

Impaired modulation of trigeminal caudal nucleus somatosensory responses by the locus coeruleus in a mouse model of diabetes: Participation of GABAergic and glycinergic neurons

FENS Forum 2024

Memory-enhancing activities of the aqueous extract of Sclerocarya birrea, Nauclea latifolia, and Piper longum mixture on diabetes-induced cognitive dysfunction

FENS Forum 2024

Non-canonical anti-inflammatory effects of sitagliptin, a drug for type 2 diabetes, in microglia

FENS Forum 2024

Prediabetes and type 2 diabetes affect tau phosphorylation patterns in murine models of Alzheimer’s disease

FENS Forum 2024

Reduced light exposure as a lifestyle measure for the alleviation of diabetes-induced anxiety – the link with oxidative stress

FENS Forum 2024

Retinal and behavioral characterization of a streptozotocin-induced diabetes type 2 model in the search of early symptoms of Alzheimer’s disease

FENS Forum 2024

Structural and functional alterations in the retina of a model of Alzheimer’s disease and type 2 diabetes

FENS Forum 2024

Subchronic administration of the antidiabetic drug metformin mitigates cognitive impairments in a mouse model of type 2 diabetes mellitus

FENS Forum 2024

Type one diabetes modifies tau phosphorylation patterns and worsens cognitive impairment in the APP/PS1 mouse model of Alzheimer’s disease

FENS Forum 2024