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Gut Microbiota–Decanoic Acid–Interleukin-17A Axis Orchestrates Hyperglycemia-Induced Osteoporosis in Male Mice

Hyperglycemia (HG) is a well-established risk factor for secondary osteoporosis, primarily due to suppressed osteoblast activity. While gut microbiota (GM) dysbiosis has been implicated in various diseases, its role in HG-induced osteoporosis remains poorly understood. Here, we demonstrate that HG mice develop low-turnover osteoporosis accompanied by reduced GM diversity. Fecal microbiota transplantation (FMT) from HG mice (GM HG -FMT) induced osteoporosis in recipient mice, independent of blood glucose levels. A depletion of Bifidobacterium pseudolongum was associated with bone loss, whereas supplementation with either microbiota of normoglycemic mice or B. pseudolongum alleviated osteoporosis in HG mice. Both HG and GM HG -FMT recipient mice exhibited elevated serum interleukin-17A (IL-17A) levels, and anti–IL-17A antibody treatment mitigated osteoporosis in the GM HG -FMT model. Furthermore, decanoic acid levels were elevated in the feces of HG mice and the serum of GM HG -FMT recipients. Decanoic acid promoted the differentiation of naive CD4 + T cells into T helper17 cells, leading to increased IL-17A production. These findings reveal a microbiome dysbiosis-driven decanoic acid/IL-17A axis in HG-induced osteoporosis and highlight the therapeutic potential of microbiome-associated targets. Article Highlights This study investigated the role of gut microbiota dysbiosis in hyperglycemia-induced osteoporosis, a condition with unclear mechanisms. We explored whether gut microbiota dysbiosis drives bone loss in hyperglycemia and identified key microbial and molecular pathways. Hyperglycemic mice showed disturbed gut microbiota symbiosis, decreased Bifidobacterium pseudolongum, and elevated decanoic acid, which promoted T helper 17 differentiation and interleukin-17A (IL-17A) production, leading to osteoporosis. Fecal microbiota transplantation from control mice, B. pseudolongum supplementation, and IL-17A blockade alleviated bone loss, highlighting both B. pseudolongum supplementation and IL-17A inhibition as potential therapeutic strategies for hyperglycemia-induced osteoporosis.

Maternal Obesity Programs Glucose Intolerance in Pregnant Female Offspring

Maternal obesity is a known risk factor for metabolic dysfunction in offspring; however, its effect on metabolism during pregnancy in female offspring remains unclear. This study investigated how maternal obesity, induced by high-fat (HF) feeding in C57BL/6J mice, affects the metabolic adaptation to pregnancy in female offspring. Dams were fed an HF diet (60% fat) or chow for 3 months before and during pregnancy. Offspring of HF diet–fed dams (OF-HFD) exhibited reduced fetal growth, followed by rapid postnatal catch-up and increased adult adiposity, compared with offspring of chow-fed dams (OF-CD), despite having similar baseline glucose and insulin levels. During pregnancy, OF-HFD exhibited diminished increases in maternal body fat, blood triglycerides, and insulin concentrations, accompanied by glucose intolerance. In cultured islets, glucose-stimulated insulin secretion was markedly reduced in pregnant OF-HFD, despite unchanged β-cell mass or proliferation. Hepatic triglyceride secretion was decreased, whereas liver insulin signaling was enhanced, suggesting alterations in lipid and glucose metabolism. Feeding OF-HFD an HF diet before and during pregnancy further impaired fetal growth. These findings indicate that maternal obesity impairs the metabolic adaptation to pregnancy in female offspring, characterized by insulin insufficiency and disrupted lipid homeostasis. This may initiate a transgenerational cycle of metabolic dysfunction, potentially increasing the risk of gestational diabetes in subsequent generations. Our findings underscore the need for more research to explore these mechanisms in humans and develop strategies to reduce the long-term effects of maternal obesity. Article Highlights Maternal high-fat (HF) diet induces adiposity in first-generation (F1) female offspring, impairing metabolic adaptations during pregnancy. F1 offspring from HF diet–fed dams show diminished fat gain and reduced serum triglycerides, disrupting nutrient availability for fetal growth. Impaired insulin production in F1 pregnancy leads to glucose intolerance, driven by reduced insulin secretion despite normal β-cell mass. Unlike male offspring, F1 females exhibit resistance to fat expansion under HF diet challenge, suggesting sex-specific programming. These findings underscore a transgenerational cycle of metabolic dysfunction, highlighting the need for interventions against maternal obesity.

Microvascular Homeostasis Is Compromised in Pancreatic Islets in a Mouse Model of β-Cell Loss and Low-Grade Inflammation

Vascular dysfunction is considered a consequence of diabetes. However, in pancreatic islets, some hemodynamic changes occur before the onset of symptoms. The underlying mechanisms driving islet vascular abnormalities have not been fully characterized, but islet pericyte dysfunction seems to be an early event in the pathogenesis of type 1 diabetes in humans. It remains to be investigated, however, how abnormal pericyte physiology affects their ability to regulate islet blood flow and vascular permeability. To address this issue, we treated mice with multiple subdiabetogenic doses of the β-cell toxin streptozotocin (STZ; 50 mg/kg) and recorded islet vascular responses when animals developed glucose intolerance but were still not diabetic (average fed glycemia <200 mg/dL). At this stage, pericyte coverage of islet capillaries was abnormal, with capillaries either lacking pericytes or being covered by dysfunctional mural cells, which compromised islet vasomotor responses recorded ex vivo in living pancreas slices. These functional defects interfered with proper regulation of blood flow and compromised islet vascular integrity, because large fluorescent dextrans (500 kDa) could leak from peripheral islet vessels in the exteriorized pancreas of STZ-treated mice. Our study supports that the loss of functional pericyte coverage of islet capillaries is part of a pathogenic process occurring in islets before diabetes onset, associated with a loss of functional β-cell mass and inflammation. Article Highlights Pericyte dysfunction is an early event in type 1 diabetes in humans, but how it affects islet microvascular homeostasis in vivo is unknown. We sought to determine whether vascular integrity and blood flow regulation in islets were impaired in a model of partial β-cell loss and inflammation. Islet capillaries lost functional pericyte coverage shortly after low-dose streptozotocin, compromising vascular stability and local control of blood flow. Strategies that preserve vascular niches in islets could be of important therapeutic potential.

Dual-Input Regulation of β-Cell Proliferation by ATF6α and Glucose via E2F1

Finding ways to increase β-cell mass is a key goal of diabetes research. During elevated insulin demand, β-cells turn on endoplasmic reticulum (ER) stress response pathways, and some β-cells enter the cell cycle. ER stress response protein activating transcription factor 6 (ATF6α) induces β-cell proliferation, but only in high glucose. The mechanism by which ATF6α increases proliferation, and the reasons for glucose dependence, remain unknown. Here we show that ATF6α activation in mouse and human islet cells increases expression of E2F1, a key cell cycle driver. E2F1 was required for ATF6α-induced proliferation in high glucose. However, E2F1 remained inactive in normal glucose, possibly because retinoblastoma (Rb), a direct E2F1 inhibitor, was in its dephosphorylated, active state. Indeed, inducing Rb phosphorylation by overexpressing cyclin-dependent kinase 4 (CDK4) allowed ATF6α to increase E2F1 activity and β-cell proliferation in normal glucose. E2F1 expression increased in an ATF6α-dependent manner during generalized ER stress by thapsigargin treatment. Importantly, in human β-cells, ATF6α failed to synergize with high glucose to induce proliferation, but the synergy was rescued by adding back CDK6. Taken together, this study establishes a new dual-input β-cell proliferation regulatory mechanism integrating ER load with current glycemic conditions via CDK4/6, in which Rb phosphorylation serves as a glucose sensor that permits ATF6α-driven proliferation. Article Highlights Endoplasmic reticulum stress response mediator activating transcription factor 6 (ATF6α) increases pancreatic β-cell proliferation in a glucose-dependent manner, but the mechanism remains unknown. ATF6α activation upregulated mRNA and protein expression of E2F1, a key G1/S phase transition regulator; however, E2F1 activity only increased in high glucose. Glucose dependence of E2F1 activity was mediated by cyclin-dependent kinase 4/6 phosphorylation of retinoblastoma (Rb) protein, derepressing E2F1 in high glucose. Generalized endoplasmic reticulum stressor thapsigargin increased E2F1 abundance in an ATF6-dependent manner. ATF6α increased E2F1 expression in human β-cells and increased human β-cell proliferation when cyclin-dependent kinase 6 (CDK6) was coexpressed.

Lysyl Oxidase Promotes Actin-Dependent Neutrophil Activation and Cytotoxicity Toward Retinal Endothelial Cells in Diabetes

Activated neutrophils contribute to retinal endothelial cell (EC) death and capillary degeneration associated with early diabetic retinopathy (DR), a major vision-threatening complication of diabetes. However, the factors and mechanisms driving neutrophil activation and cytotoxicity in diabetes remain insufficiently understood. Here, we show that lysyl oxidase (LOX), a matrix cross-linking and stiffening enzyme that increases retinal EC susceptibility to activated neutrophils, simultaneously activates neutrophils in its soluble form. Specifically, treatment of diabetic mice with LOX inhibitor β-aminopropionitrile (BAPN) prevented the diabetes-induced increase in neutrophil activation (extracellular release of neutrophil elastase and superoxide) and cytotoxicity toward cocultured mouse retinal ECs. Mouse neutrophils and differentiated (neutrophil-like) human HL-60 cells treated with recombinant LOX alone exhibited significant activation and cytotoxicity. Mechanistically, this LOX-induced neutrophil activation was associated with biphasic F-actin remodeling, with the initial and rapid (∼10 min) F-actin depolymerization followed by a significant increase in F-actin polymerization and polarization. Preventing the initial F-actin depolymerization blocked LOX-induced neutrophil activation and cytotoxicity toward cocultured retinal ECs. Finally, this biphasic F-actin remodeling was found to be essential for LOX-induced membrane aggregation of azurophilic granule marker CD63 and NADPH organizer p47 phox, which are associated with extracellular release of neutrophil elastase and superoxide, respectively. By revealing a previously unrecognized causal link between LOX and actin-dependent neutrophil activation in diabetes, these findings provide fresh mechanistic insights into the proinflammatory role of LOX in early DR that goes beyond its canonical matrix-stiffening effects. Article Highlights Activated neutrophils kill retinal endothelial cells (ECs) in early diabetic retinopathy, but how neutrophils become activated in diabetes is not well understood. We found that lysyl oxidase (LOX), whose matrix-localized form activates retinal ECs, can also directly activate neutrophils in its soluble form. LOX-induced release of neutrophil elastase and superoxide is mediated by actin remodeling and membrane aggregation of azurophilic granules. The dual ability of LOX to activate neutrophils (in its soluble form) and retinal ECs (in its matrix-localized form) implicates it as a key proinflammatory target for early diabetic retinopathy.

Additive Effects of Dorzagliatin and Glucagon-Like Peptide 1 Receptor Agonism in a Novel Mouse Model of GCK -MODY and in Obese db/db Mice

Glucokinase (GK) catalyzes the key regulatory step in glucose-stimulated insulin secretion (GSIS). Correspondingly, hetero- and homozygous mutations in human GCK cause maturity-onset diabetes of the young ( GCK -MODY) and permanent neonatal diabetes mellitus, respectively. To explore the possible utility of GK activators (GKAs) and of glucagon-like peptide 1 (GLP-1) receptor agonists in these diseases, we have developed a novel hypomorphic Gck allele in mice encoding an aberrantly spliced mRNA. In islets from homozygous knock-in (Gck KI/KI ) mice, GK immunoreactivity was reduced by >85%, and GSIS eliminated. Homozygous Gck KI/KI mice displayed frank diabetes (fasting blood glucose >18 mmol/L; HbA 1c ∼108 mmol/mol), ketosis, and nephropathy. Heterozygous Gck KI/+ mice were glucose intolerant (HbA 1c ∼37 mmol/mol). Abnormal glucose-stimulated Ca 2+ dynamics in Gck KI/+ islets were completely reversed by the GKA dorzagliatin, which was largely inactive in homozygous Gck KI/KI mouse islets. The GLP-1 receptor agonist exendin-4 improved glucose tolerance in male Gck KI/+ mice, an action potentiated by dorzagliatin. Sex-dependent additive effects of these agents were also observed on insulin secretion in vitro. Similar additive effects of the drugs were observed in obese hyperglycemic db/db mice. Combined treatment with GKA and incretin mimetics may thus be useful in GCK -MODY and in more common forms of type 2 diabetes. Article Highlights Glucokinase (GK) deficiency can drive maturity-onset diabetes of the young ( GCK -MODY) in heterozygotes and permanent neonatal diabetes in homozygotes. We describe a hypomorphic Gck allele that results in aberrant splicing in islets and liver lowering GK activity by ∼85%. Whereas heterozygous mutant mice are mildly hyperglycemic, homozygotes have frank diabetes but survive to adulthood. Dorzagliatin potentiates the effects of glucagon–like receptor-1 receptor activation sex dependently in heterozygous Gck mice and in obese hyperglycemic db/db mice. Combined use of these drugs may be useful in some forms of GCK -MODY and in obesity-related type 2 diabetes.

Flt3L-Derived Antigen-Presenting Cell Transfer in Neonatal NOD Mice Reduces the Incidence of Type 1 Diabetes

Type 1 diabetes (T1D) is an autoimmune disease characterized by progressive stages culminating in T-cell–mediated destruction of the β-cells at the islets of Langerhans. The immune mechanisms that initiate T1D are not fully resolved but likely involve an interaction between proinflammatory antigen-presenting cells (APCs) and autoreactive T cells that initiate immune infiltration and activation. Previous studies have tested the use of tolerogenic APCs in adult female NOD mice to delay or prevent T1D with only slight to intermediate success. Moreover, immune infiltration begins as early as age 4 weeks; therefore, targeting autoreactive T cells with tolerogenic APCs in adult mice may not impact later stages of diabetes. Thus, we hypothesize that the transfer of tolerogenic APCs at the neonatal stage prior to priming and immune infiltration will result in effective protection from autoimmunity. Our studies demonstrate that immature APCs travel to the pancreatic draining lymph nodes, alter the cytokine milieu in young mice, divert autoreactive CD4 + T cells to anergy, and drastically decrease proliferation and function of cytotoxic lymphocytes in adult prediabetic mice, leading to a significant reduction in the incidence of T1D. Article Highlights Neonatal transfer of immature dendritic cell–enriched Flt3L splenocytes significantly reduces the incidence of type 1 diabetes in female NOD mice. Early time points are associated with accumulation of anergic T cells. In adult mice, there is a reduction in CD4 T helper 1 cells and reduced proliferation and perforin of CD8 T cells. Our work demonstrates how targeting the neonatal window of tolerance alters autoimmunity outcome.

β-Hydroxybutyrylation Links Ketone Metabolism to Mitochondrial Remodeling in Diabetic Cardiomyopathy

Diabetic cardiomyopathy (DbCM) is characterized by metabolic remodeling and energetic stress independent of coronary artery disease. Increased reliance on fatty acid and ketone body metabolism has been observed in DbCM, but the regulatory mechanisms linking altered substrate use to myocardial dysfunction remain poorly understood. In particular, lysine β-hydroxybutyrate (Kbhb), a ketone body–derived, posttranslational modification, has emerged as a potentially critical regulator but has not been fully investigated. We conducted a comprehensive multiomics study integrating metabolomics, transcriptomics, proteomics, and Kbhb-specific proteomics on myocardial tissues in a well-established mouse model of DbCM. Kbhb-modified proteins were systematically mapped and quantified, followed by motif, subcellular localization, and protein-protein interaction analyses. DbCM cardiac tissue exhibited coordinated upregulations of fatty acid β-oxidation, ketone metabolism, and tricarboxylic acid cycle activity at the transcriptomic, proteomic, and metabolomic levels. Kbhb profiling revealed extensive mitochondrial protein modification, with Atp5f1a-K239 identified as a key modification site strongly correlated with β-hydroxybutyrate and isocitric acid concentrations. This study identifies Kbhb as a potential metabolic-epigenetic modifier linking ketone body availability to the regulation of mitochondrial proteins in DbCM. Our findings provide novel insights into metabolic-epigenetic cross talk and identify potential therapeutic targets for interventions to restore mitochondrial function in alleviating diabetic heart disease. Article Highlights We performed a multiomics study to better understand dysfunctions in diabetic cardiomyopathy (DbCM) and specifically identify links between lysine β-hydroxybutyrylation (Kbhb), a ketone body–derived, posttranslational modification, and cardiac dysfunction. DbCM cardiac tissue exhibited coordinated upregulations of fatty acid β-oxidation, ketone metabolism, and tricarboxylic acid cycle activity at the transcriptomic, proteomic, and metabolomic levels. Mitochondrial proteins showed that high Kbhb modification and modification of the Atp5f1a-K239 site were strongly correlated with high β-hydroxybutyrate and isocitric acid concentrations. This study identifies Kbhb modification of mitochondrial proteins as a potential mechanism linking ketone body availability to mitochondrial function in DbCM.

miR-432 Exacerbates Obesity-Induced Dysregulation of Glucose and Lipid Homeostasis

miRNAs are key regulators of metabolic homeostasis, yet their role in obesity-associated dysfunction remains incompletely understood. Here, we identify miR-432 as a driver of systemic metabolic dysregulation. Serum miRNA profiling revealed a positive correlation between miR-432 expression and obesity/type 2 diabetes mellitus. Functionally, adipose-specific miR-432 exacerbated high-fat diet–induced obesity and insulin resistance. Similarly, hepatic-specific miR-432 aggravated hepatic steatosis and systemic glucose dysregulation, while skeletal muscle–specific miR-432 disrupted glucose homeostasis without affecting body composition. Mechanistically, miR-432 disrupted insulin sensitivity by inhibiting the PIK3R3/AKT pathway and perturbed lipid homeostasis by suppressing the PIK3R3/PPAR-α axis. Notably, obesity-induced miR-432 upregulation was predominantly localized in adipocytes and driven by the CDK5/PPAR-γ axis. Furthermore, adipocyte-derived exosomal miR-432 was identified as a mediator of systemic metabolic dysfunction, facilitating intertissue cross talk in obesity. Collectively, our data demonstrate that miR-432 exacerbates obesity-induced dysregulation of glucose and lipid metabolism. Article Highlights miR-432 overexpression in adipose tissue, liver, and skeletal muscle exacerbates high-fat diet–induced disruption of metabolic homeostasis. miR-432 impairs glucose homeostasis by suppressing the PIK3R3/AKT pathway and disrupts lipid homeostasis via inhibition of the PIK3R3/PPAR-α axis or directly suppressing PPAR-α. Obesity-induced elevation of miR-432 is predominantly localized in adipocytes and driven by the CDK5/PPAR-γ axis. Adipocyte-derived exosomal miR-432 mediates systemic metabolic dysfunction, establishing an intertissue regulatory network.

Killing of Human β-Cells by CD8 + T Cells Triggers Inflammatory Paracrine Signaling and Neighboring β-Cell Dysfunction

Type 1 diabetes is a progressive autoimmune disease characterized by the selective destruction of insulin-producing β-cells by CD8 + T cells. Although the mechanisms of antigen-specific β-cell killing are well established, the broader consequences of this targeted destruction on neighboring β-cells that escape direct T-cell receptor (TCR)–mediated attack remain poorly understood. Here, we developed a coculture model of HLA-A2–expressing human β-cells cultured as pseudoislets and CD8 + T cells specific for the INS 15-24 epitope. Using this new in vitro model, we demonstrate that 1 ) β-cell death induced by CD8 + T cells strictly depends on TCR-HLA class I interactions and 2 ) neighboring β-cells that evade direct T-cell contact do not alter β-cell identity or glucose-stimulated insulin secretion. However, they exhibit increased expression of inflammatory markers, reduced insulin content, and impaired protein translation. The robust, versatile, and readily applicable model described here represents a strong basis to further address paracrine signaling that extend beyond direct cytotoxicity. Article Highlights In type 1 diabetes, CD8 + T cells destroy pancreatic β-cells. Since most β-cells avoid direct T-cell contact, we asked whether bystander effects drive their dysfunction and loss. We asked whether CD8 + T cells can damage β-cells indirectly via bystander inflammation. By developing and using a chimeric pseudoislet model, we show that β-cell killing requires direct CD8 + T-cell contact, contact-free β-cells are impacted by inflammation, that these effects are reproduced using conditioned medium from activated CD8 + T cells, and that insulin secretion is preserved with reduced storage and impaired protein translation. Our model provides a platform to dissect type 1 diabetes pathogenesis and test therapies to preserve β-cells.

Obstructive Sleep Apnea, Resting Heart Rate, and Glycemic Variability in Adults With Maturity-Onset Diabetes of the Young

Obstructive sleep apnea (OSA) is a common condition strongly linked to increased cardiovascular risk and poor glycemic control. Little is known about OSA, cardiovascular risk, and glycemia in maturity-onset diabetes of the young (MODY), an inherited form of diabetes, which is different than both type 1 and type 2 diabetes. We assessed OSA, resting heart rate (RHR), an important prognostic marker of cardiovascular disease, and glycemic variability among the most common subtypes of MODY, glucokinase (GCK)-MODY, and transcription factor (TF)-related MODY (HNF1A, HNF4A, and HNF1B). Adults with GCK-MODY ( n = 63) and TF-related MODY ( n = 60) and control adults without diabetes ( n = 65) were screened for OSA by home sleep test. Glycemic variability (continuous glucose monitoring) and RHR (wearable sleep-activity tracker) were concomitantly assessed for 2 weeks at home. Data from 188 individuals (2,853 recorded days) were analyzed. Individuals with TF-related MODY, compared with those with GCK-MODY or control individuals, had more OSA (48.3%, 27.0%, and 30.8%, respectively; P = 0.033), higher RHR (72.8 ± 10.8, 65.2 ± 7.9, and 67.3 ± 7.7 bpm, respectively; P < 0.001), and higher glycemic variability (coefficient of variation of glucose 31.6 ± 6.0%, 17.3 ± 4.5%, and 17.5 ± 4.0%, respectively; P < 0.001). Greater severity of OSA and higher RHR were associated with higher glycemic variability. These findings may have important clinical implications for cardiovascular risk assessment in MODY. Article Highlights Obstructive sleep apnea (OSA) has been strongly linked to increased cardiovascular risk and poor glycemic control in the general population. Resting heart rate (RHR) is a prognostic marker of cardiovascular morbidity and mortality and has been linked to dysglycemia. Little is known about OSA, RHR, and glycemia in maturity-onset diabetes of the young (MODY), an inherited form of diabetes with discrete clinical features. Adults with transcription factor–related MODY (HNF1A, HNF4A, and HNF1B) had more OSA and higher RHR and greater glycemic variability compared with those with glucokinase-MODY or control adults without diabetes, which may have important clinical implications for future cardiovascular risk.

Development and Validation of a Type 1 Diabetes Multi-Ancestry Polygenic Score

Polygenic scores strongly predict type 1 diabetes risk, but most scores were developed in European-ancestry populations. In this study, we leveraged recent multiancestry genome-wide association studies to create a Type 1 Diabetes Multi-Ancestry Polygenic Score (T1D MAPS). We trained the score in the Mass General Brigham (MGB) Biobank (372 individuals with type 1 diabetes) and tested the score in the All of Us program (86 individuals with type 1 diabetes). We evaluated the area under the receiver operating characteristic curve (AUC), and we compared the AUC to two published single-ancestry scores for European (EUR) and African (AFR) populations: T1D Genetic Risk Score 2 (GRS2 EUR ) and T1D GRS AFR. We also developed an updated score (T1D MAPS2) that combines T1D GRS2 EUR and T1D MAPS. Among individuals with non-European ancestry, the AUC of T1D MAPS was 0.90, significantly higher than T1D GRS2 EUR (0.82) and T1D GRS AFR (0.82). Among individuals with European ancestry, the AUC of T1D MAPS was slightly lower than T1D GRS2 EUR (0.89 vs. 0.91). However, T1D MAPS2 performed equivalently to T1D GRS2 EUR in European ancestry (0.91 vs. 0.91) and performed better in non-European ancestry (0.90 vs. 0.82). Overall, these findings advance the accuracy of type 1 diabetes genetic risk prediction across diverse populations. Article Highlights Type 1 diabetes polygenic scores are highly predictive of disease risk, but their performance varies based on genetic ancestry. Can we develop a polygenic score that accurately predicts type 1 diabetes risk across diverse populations? Our novel polygenic score performs similar to existing scores in European populations, and it demonstrates superior performance in non-European populations. This polygenic score will improve prediction of type 1 diabetes risk in genetically diverse populations.

Cerebrospinal Fluid Fatty Acids, Hypothalamic Inflammation, and Weight Loss in Human Obesity: A Longitudinal Study

Preclinical studies show that dietary or central administration of monounsaturated fatty acids (MUFAs) and polyunsaturated fatty acids (PUFAs) can reduce food intake, enhance energy expenditure, and attenuate hypothalamic inflammation (HI), whereas saturated fatty acids (SFAs) promote weight gain, HI, and neuronal injury. However, whether hypothalamic exposure to different fatty acids similarly influences HI and body weight in humans remains unclear. In this longitudinal study, we compared cerebrospinal fluid (CSF) free fatty acid (FFA) profiles between 19 normal-weight control participants and 44 individuals with obesity, both at baseline and 1 year after bariatric surgery (BS). We also examined associations between CSF FFA composition, MRI-based markers of HI (i.e., increased hypothalamic mean diffusivity [MD] and volume), and postoperative weight loss. At baseline, individuals with obesity had similar CSF concentrations of total FFA, SFA, and MUFA compared with control participants but significantly lower PUFA levels, mainly due to reduced docosahexaenoic acid (DHA) levels. BS did not substantially alter CSF FFA profiles. Lower baseline CSF DHA levels were associated with higher hypothalamic MD and independently predicted less weight loss at 1 year. Postoperative increases in CSF DHA levels correlated with reductions in hypothalamic MD. These findings suggest brain DHA level may influence hypothalamic microstructure and contribute to body weight regulation in human obesity. Article Highlights Whether hypothalamic exposure to free fatty acid (FFA) species contributes to obesity and hypothalamic inflammation (HI) in humans is not yet defined. We compared cerebrospinal fluid FFA profiles between normal-weight control participants and individuals with obesity, before and after bariatric surgery (BS), and examined their associations with postoperative weight trajectories and neuroimaging biomarkers of HI. Individuals with obesity had reduced cerebrospinal fluid levels of docosahexaenoic acid (DHA) before and after BS. Lower cerebrospinal fluid DHA levels correlated with biomarkers of HI and were independently associated with less weight loss after BS. The findings highlight the potential of DHA in modulating hypothalamic function.

Gestational Diabetes Mellitus Alters Placental Precursor mRNA Splicing

Gestational diabetes mellitus (GDM) is defined as hyperglycemia first identified during pregnancy and can lead to adverse maternal and neonatal outcomes. The molecular mechanisms leading to these outcomes are currently poorly understood. While transcriptomics of GDM placentas has been previously studied, the effect on precursor mRNA splicing remains largely unknown. This study explores the impact of GDM on placental splicing and identifies its regulatory mechanisms. Using RNA sequencing data from Norwegian and Chinese cohorts, we uncovered thousands of differential splicing events. Pathway enrichment analysis revealed significant associations with metabolic and diabetes-related pathways. Splicing factor motif and cross-linking and immunoprecipitation sequencing analyses highlighted serine/arginine-rich splicing factor 10 (SRSF10) as a key regulator in this process, with its binding enriched at misspliced exons. Silencing SRSF10 in placental cells mirrored GDM-associated missplicing in key genes. These findings underscore splicing dysregulation as a critical process in GDM pathogenesis, suggesting that targeting SRSF10 could be a potential therapeutic approach to mitigate the deleterious effects of GDM. Article Highlights Gestational diabetes mellitus (GDM) causes hyperglycemia during pregnancy and adverse maternal and neonatal outcomes. Bulk placental gene expression has been reported largely unchanged. RNA sequencing of Norwegian and Chinese GDM placentas reveals hundreds of differential splicing events enriched for metabolic- and diabetes-related pathways. Motif enrichment and cross-linking and immunoprecipitation sequencing integration identify serine/arginine splicing factor 10 as a key regulator of GDM-associated missplicing. Silencing serine/arginine splicing factor 10 in placental models recapitulates the GDM-associated missplicing program.

Neural Regulation of Blood Glucose in Acute Stress: A Report on Research Supported by Pathway to Stop Diabetes

There is significant evidence that acute stress, a challenge to an organism’s homeostasis, has dramatic effects on metabolic control. Acute stress impairs blood glucose control in people with both type 1 and type 2 diabetes. In addition, growing evidence suggests that metabolic responses to stress in people without diabetes may be a crucial determinant of health. Acute dysregulation of blood glucose in the hospital setting, including both hyper- and hypoglycemia, predicts short- and long-term morbidity and mortality in patients with critical illnesses. Animal studies indicate that exposure to physiological and psychological stressors activates a highly conserved network of neural circuits that ultimately coordinate the functions of multiple organs to increase blood glucose. In this article, we provide an overview of the neural populations and circuits that increase blood glucose in response to acute stress, including our research funded by the American Diabetes Association Pathway to Stop Diabetes program, highlighting the impacts on clinical outcomes and opportunities for the development of therapies for diabetes. This article is part of a series of perspectives that report on research funded by the American Diabetes Association Pathway to Stop Diabetes program. Article Highlights Internal and external stressors rapidly increase blood glucose, a highly conserved metabolic response. Multiple stress-modulated neural populations in the brain stem, hypothalamus, and forebrain contribute to regulation of the hypothalamo-pituitary-adrenal axis and sympathetic nervous system to elicit hyperglycemia. Exaggerated or diminished glucose responses to acute stress are associated with increased risk of type 2 diabetes and poor health outcomes. A greater understanding of the neural circuitry contributing to stress hyperglycemia and how these circuits are disrupted has the potential to provide new approaches to improve glycemic control.