ABSTRACT
Clonal hematopoiesis, a condition in which individual hematopoietic stem cell clones generate a disproportionate fraction of blood leukocytes, correlates with higher risk for cardiovascular disease. The mechanisms behind this association are incompletely understood. Here, we show that hematopoietic stem cell division rates are increased in mice and humans with atherosclerosis. Mathematical analysis demonstrates that increased stem cell proliferation expedites somatic evolution and expansion of clones with driver mutations. The experimentally determined division rate elevation in atherosclerosis patients is sufficient to produce a 3.5-fold increased risk of clonal hematopoiesis by age 70. We confirm the accuracy of our theoretical framework in mouse models of atherosclerosis and sleep fragmentation by showing that expansion of competitively transplanted Tet2-/- cells is accelerated under conditions of chronically elevated hematopoietic activity. Hence, increased hematopoietic stem cell proliferation is an important factor contributing to the association between cardiovascular disease and clonal hematopoiesis.
Subject(s)
Atherosclerosis/pathology , Clonal Hematopoiesis , Hematopoietic Stem Cells/pathology , Aging/pathology , Animals , Apolipoproteins E/genetics , Atherosclerosis/genetics , Bone Marrow/metabolism , Cell Proliferation , Clonal Evolution , Disease Models, Animal , Female , Humans , Mice , Mice, Inbred C57BL , Models, Biological , Sleep Deprivation/pathologyABSTRACT
Autonomic nerves control organ function through the sympathetic and parasympathetic branches, which have opposite effects. In the bone marrow, sympathetic (adrenergic) nerves promote hematopoiesis; however, how parasympathetic (cholinergic) signals modulate hematopoiesis is unclear. Here, we show that B lymphocytes are an important source of acetylcholine, a neurotransmitter of the parasympathetic nervous system, which reduced hematopoiesis. Single-cell RNA sequencing identified nine clusters of cells that expressed the cholinergic α7 nicotinic receptor (Chrna7) in the bone marrow stem cell niche, including endothelial and mesenchymal stromal cells (MSCs). Deletion of B cell-derived acetylcholine resulted in the differential expression of various genes, including Cxcl12 in leptin receptor+ (LepR+) stromal cells. Pharmacologic inhibition of acetylcholine signaling increased the systemic supply of inflammatory myeloid cells in mice and humans with cardiovascular disease.
Subject(s)
Acetylcholine , Hematopoiesis , Animals , B-Lymphocytes , Cholinergic Agents , Hematopoiesis/genetics , Mice , Stem Cell NicheABSTRACT
Diet profoundly influences physiology. Whereas over-nutrition elevates risk for disease via its influence on immunity and metabolism, caloric restriction and fasting appear to be salutogenic. Despite multiple correlations observed between diet and health, the underlying biology remains unclear. Here, we identified a fasting-induced switch in leukocyte migration that prolongs monocyte lifespan and alters susceptibility to disease in mice. We show that fasting during the active phase induced the rapid return of monocytes from the blood to the bone marrow. Monocyte re-entry was orchestrated by hypothalamic-pituitary-adrenal (HPA) axis-dependent release of corticosterone, which augmented the CXCR4 chemokine receptor. Although the marrow is a safe haven for monocytes during nutrient scarcity, re-feeding prompted mobilization culminating in monocytosis of chronologically older and transcriptionally distinct monocytes. These shifts altered response to infection. Our study shows that diet-in particular, a diet's temporal dynamic balance-modulates monocyte lifespan with consequences for adaptation to external stressors.
Subject(s)
Bone Marrow , Monocytes , Mice , Animals , Bone Marrow Cells , Fasting , Chemokines/metabolismABSTRACT
Glial cells and central nervous system (CNS)-infiltrating leukocytes contribute to multiple sclerosis (MS). However, the networks that govern crosstalk among these ontologically distinct populations remain unclear. Here, we show that, in mice and humans, CNS-resident astrocytes and infiltrating CD44hiCD4+ T cells generated interleukin-3 (IL-3), while microglia and recruited myeloid cells expressed interleukin-3 receptor-É (IL-3RÉ). Astrocytic and T cell IL-3 elicited an immune migratory and chemotactic program by IL-3RÉ+ myeloid cells that enhanced CNS immune cell infiltration, exacerbating MS and its preclinical model. Multiregional snRNA-seq of human CNS tissue revealed the appearance of IL3RA-expressing myeloid cells with chemotactic programming in MS plaques. IL3RA expression by plaque myeloid cells and IL-3 amount in the cerebrospinal fluid predicted myeloid and T cell abundance in the CNS and correlated with MS severity. Our findings establish IL-3:IL-3RA as a glial-peripheral immune network that prompts immune cell recruitment to the CNS and worsens MS.
Subject(s)
Multiple Sclerosis , Animals , Humans , Mice , Central Nervous System , Interleukin-3 , Microglia , Neuroglia/metabolismABSTRACT
The nervous and immune systems are intricately linked1. Although psychological stress is known to modulate immune function, mechanistic pathways linking stress networks in the brain to peripheral leukocytes remain poorly understood2. Here we show that distinct brain regions shape leukocyte distribution and function throughout the body during acute stress in mice. Using optogenetics and chemogenetics, we demonstrate that motor circuits induce rapid neutrophil mobilization from the bone marrow to peripheral tissues through skeletal-muscle-derived neutrophil-attracting chemokines. Conversely, the paraventricular hypothalamus controls monocyte and lymphocyte egress from secondary lymphoid organs and blood to the bone marrow through direct, cell-intrinsic glucocorticoid signalling. These stress-induced, counter-directional, population-wide leukocyte shifts are associated with altered disease susceptibility. On the one hand, acute stress changes innate immunity by reprogramming neutrophils and directing their recruitment to sites of injury. On the other hand, corticotropin-releasing hormone neuron-mediated leukocyte shifts protect against the acquisition of autoimmunity, but impair immunity to SARS-CoV-2 and influenza infection. Collectively, these data show that distinct brain regions differentially and rapidly tailor the leukocyte landscape during psychological stress, therefore calibrating the ability of the immune system to respond to physical threats.
Subject(s)
Brain , Fear , Leukocytes , Motor Neurons , Neural Pathways , Stress, Psychological , Animals , Bone Marrow Cells/cytology , Bone Marrow Cells/immunology , Brain/cytology , Brain/physiology , COVID-19/immunology , Chemokines/immunology , Disease Susceptibility , Fear/physiology , Glucocorticoids/metabolism , Humans , Leukocytes/cytology , Leukocytes/immunology , Lymphocytes/cytology , Lymphocytes/immunology , Lymphoid Tissue/cytology , Lymphoid Tissue/immunology , Mice , Monocytes/cytology , Monocytes/immunology , Motor Neurons/cytology , Motor Neurons/physiology , Neutrophils/cytology , Neutrophils/immunology , Optogenetics , Orthomyxoviridae Infections/immunology , Paraventricular Hypothalamic Nucleus/physiology , SARS-CoV-2/immunology , Stress, Psychological/immunology , Stress, Psychological/physiopathologyABSTRACT
Communication within the glial cell ecosystem is essential for neuronal and brain health1-3. The influence of glial cells on the accumulation and clearance of ß-amyloid (Aß) and neurofibrillary tau in the brains of individuals with Alzheimer's disease (AD) is poorly understood, despite growing awareness that these are therapeutically important interactions4,5. Here we show, in humans and mice, that astrocyte-sourced interleukin-3 (IL-3) programs microglia to ameliorate the pathology of AD. Upon recognition of Aß deposits, microglia increase their expression of IL-3Rα-the specific receptor for IL-3 (also known as CD123)-making them responsive to IL-3. Astrocytes constitutively produce IL-3, which elicits transcriptional, morphological, and functional programming of microglia to endow them with an acute immune response program, enhanced motility, and the capacity to cluster and clear aggregates of Aß and tau. These changes restrict AD pathology and cognitive decline. Our findings identify IL-3 as a key mediator of astrocyte-microglia cross-talk and a node for therapeutic intervention in AD.
Subject(s)
Alzheimer Disease/metabolism , Astrocytes/physiology , Interleukin-3/metabolism , Microglia/physiology , Animals , Cell Communication , Cells, Cultured , Humans , Mice , Mice, Inbred C57BL , Mice, Knockout , Neural Stem Cells/physiologyABSTRACT
The biochemical response to food intake must be precisely regulated. Because ingested sugars and fats can feed into many anabolic and catabolic pathways1, how our bodies handle nutrients depends on strategically positioned metabolic sensors that link the intrinsic nutritional value of a meal with intermediary metabolism. Here we describe a subset of immune cells-integrin ß7+ natural gut intraepithelial T lymphocytes (natural IELs)-that is dispersed throughout the enterocyte layer of the small intestine and that modulates systemic metabolism. Integrin ß7- mice that lack natural IELs are metabolically hyperactive and, when fed a high-fat and high-sugar diet, are resistant to obesity, hypercholesterolaemia, hypertension, diabetes and atherosclerosis. Furthermore, we show that protection from cardiovascular disease in the absence of natural IELs depends on the enteroendocrine-derived incretin GLP-12, which is normally controlled by IELs through expression of the GLP-1 receptor. In this metabolic control system, IELs modulate enteroendocrine activity by acting as gatekeepers that limit the bioavailability of GLP-1. Although the function of IELs may prove advantageous when food is scarce, present-day overabundance of diets high in fat and sugar renders this metabolic checkpoint detrimental to health.
Subject(s)
Cardiovascular Diseases/metabolism , Disease Progression , Intestine, Small/cytology , Intraepithelial Lymphocytes/metabolism , Animals , Atherosclerosis/genetics , Atherosclerosis/metabolism , Atherosclerosis/prevention & control , Cardiovascular Diseases/genetics , Cardiovascular Diseases/prevention & control , Disease Models, Animal , Eating , Enterocytes/cytology , Enterocytes/metabolism , Female , Glucagon-Like Peptide 1/metabolism , Glucagon-Like Peptide-1 Receptor/metabolism , Integrin beta Chains/genetics , Integrin beta Chains/metabolism , Male , Metabolic Syndrome/genetics , Metabolic Syndrome/metabolism , Metabolic Syndrome/prevention & control , MiceABSTRACT
Sleep is integral to life1. Although insufficient or disrupted sleep increases the risk of multiple pathological conditions, including cardiovascular disease2, we know little about the cellular and molecular mechanisms by which sleep maintains cardiovascular health. Here we report that sleep regulates haematopoiesis and protects against atherosclerosis in mice. We show that mice subjected to sleep fragmentation produce more Ly-6Chigh monocytes, develop larger atherosclerotic lesions and produce less hypocretin-a stimulatory and wake-promoting neuropeptide-in the lateral hypothalamus. Hypocretin controls myelopoiesis by restricting the production of CSF1 by hypocretin-receptor-expressing pre-neutrophils in the bone marrow. Whereas hypocretin-null and haematopoietic hypocretin-receptor-null mice develop monocytosis and accelerated atherosclerosis, sleep-fragmented mice with either haematopoietic CSF1 deficiency or hypocretin supplementation have reduced numbers of circulating monocytes and smaller atherosclerotic lesions. Together, these results identify a neuro-immune axis that links sleep to haematopoiesis and atherosclerosis.
Subject(s)
Atherosclerosis/prevention & control , Hematopoiesis/physiology , Sleep/physiology , Animals , Antigens, Ly/metabolism , Atherosclerosis/metabolism , Atherosclerosis/pathology , Bone Marrow Cells/metabolism , Female , Hematopoiesis/drug effects , Hypothalamic Area, Lateral/metabolism , Macrophage Colony-Stimulating Factor/biosynthesis , Macrophage Colony-Stimulating Factor/deficiency , Macrophage Colony-Stimulating Factor/metabolism , Male , Mice , Monocytes/drug effects , Monocytes/metabolism , Myelopoiesis/drug effects , Neutrophils/metabolism , Orexin Receptors/deficiency , Orexin Receptors/metabolism , Orexins/biosynthesis , Orexins/deficiency , Orexins/metabolism , Orexins/pharmacology , Sleep/drug effects , Sleep Deprivation/metabolism , Sleep Deprivation/physiopathology , Sleep Deprivation/prevention & controlABSTRACT
BACKGROUND: Diabetes mellitus is a prevalent public health problem that affects about one-third of the US population and leads to serious vascular complications with increased risk for coronary artery disease. How bone marrow hematopoiesis contributes to diabetes mellitus complications is incompletely understood. We investigated the role of bone marrow endothelial cells in diabetic regulation of inflammatory myeloid cell production. METHODS: In 3 types of mouse diabetes mellitus, including streptozotocin, high-fat diet, and genetic induction using leptin-receptor-deficient db/db mice, we assayed leukocytes, hematopoietic stem and progenitor cells (HSPC). In addition, we investigated bone marrow endothelial cells with flow cytometry and expression profiling. RESULTS: In diabetes mellitus, we observed enhanced proliferation of HSPC leading to augmented circulating myeloid cell numbers. Analysis of bone marrow niche cells revealed that endothelial cells in diabetic mice expressed less Cxcl12, a retention factor promoting HSPC quiescence. Transcriptome-wide analysis of bone marrow endothelial cells demonstrated enrichment of genes involved in epithelial growth factor receptor (Egfr) signaling in mice with diet-induced diabetes mellitus. To explore whether endothelial Egfr plays a functional role in myelopoiesis, we generated mice with endothelial-specific deletion of Egfr (Cdh5CreEgfrfl/fl). We found enhanced HSPC proliferation and increased myeloid cell production in Cdh5CreEgfrfl/fl mice compared with wild-type mice with diabetes mellitus. Disrupted Egfr signaling in endothelial cells decreased their expression of the HSPC retention factor angiopoietin-1. We tested the functional relevance of these findings for wound healing and atherosclerosis, both implicated in complications of diabetes mellitus. Inflammatory myeloid cells accumulated more in skin wounds of diabetic Cdh5CreEgfrfl/fl mice, significantly delaying wound closure. Atherosclerosis was accelerated in Cdh5CreEgfrfl/fl mice, leading to larger and more inflamed atherosclerotic lesions in the aorta. CONCLUSIONS: In diabetes mellitus, bone marrow endothelial cells participate in the dysregulation of bone marrow hematopoiesis. Diabetes mellitus reduces endothelial production of Cxcl12, a quiescence-promoting niche factor that reduces stem cell proliferation. We describe a previously unknown counterregulatory pathway, in which protective endothelial Egfr signaling curbs HSPC proliferation and myeloid cell production.
Subject(s)
Bone Marrow Cells/metabolism , Endothelial Cells/metabolism , Myelopoiesis , Animals , Diabetes Mellitus, Experimental , Disease Models, Animal , Epidermal Growth Factor/metabolism , ErbB Receptors/metabolism , Gene Expression Profiling , Gene Expression Regulation , Male , Mice , Models, Biological , Myeloid Cells/metabolism , Myelopoiesis/genetics , Signal Transduction , TranscriptomeABSTRACT
Many aspects of human health and disease display daily rhythmicity. The brain's suprachiasmic nucleus, which interprets recurring external stimuli, and autonomous molecular networks in peripheral cells together, set our biological circadian clock. Disrupted or misaligned circadian rhythms promote multiple pathologies including chronic inflammatory and metabolic diseases such as atherosclerosis. Here, we discuss studies suggesting that circadian fluctuations in the vessel wall and in the circulation contribute to atherogenesis. Data from humans and mice indicate that an impaired molecular clock, disturbed sleep, and shifting light-dark patterns influence leukocyte and lipid supply in the circulation and alter cellular behavior in atherosclerotic lesions. We propose that a better understanding of both local and systemic circadian rhythms in atherosclerosis will enhance clinical management, treatment, and public health policy.
Subject(s)
Atherosclerosis/metabolism , Circadian Rhythm , Animals , Atherosclerosis/physiopathology , Atherosclerosis/prevention & control , Healthy Lifestyle , Humans , Lipid Metabolism , SleepABSTRACT
Cardiovascular disease (CVD) is the number one cause of global mortality and atherosclerosis is the underlying cause of most CVD. However, the molecular mechanisms by which cardiovascular risk factors promote the development of atherosclerosis are not well understood. The development of new efficient therapies to directly block or slow disease progression will require a better understanding of these mechanisms. Accumulating evidence supports a role for endoplasmic reticulum (ER) stress in all stages of the developing atherosclerotic lesion however, it was not clear how ER stress may contribute to disease progression. Recent findings have shown that ER stress signaling through glycogen synthase kinase (GSK)-3α may significantly contribute to macrophage lipid accumulation, inflammatory cytokine production and M1macrophage polarization. In this review we summarize our knowledge of the potential role of ER stress-GSK3 signaling in the development and progression of atherosclerosis as well as the possible therapeutic implications of this pathway.
Subject(s)
Atherosclerosis/metabolism , Endoplasmic Reticulum Stress/physiology , Glycogen Synthase Kinase 3/metabolism , Animals , Humans , Risk Factors , Signal Transduction/physiologyABSTRACT
Glucosamine is an essential substrate for N-linked protein glycosylation. However, elevated levels of glucosamine can induce endoplasmic reticulum (ER) stress. Glucosamine-induced ER stress has been implicated in the development of diabetic complications, including atherosclerosis and hepatic steatosis. In this study, we investigate the potential relationship between the effects of glucosamine on lipid-linked oligosaccharide (LLO) biosynthesis, N-linked glycosylation, and ER homeostasis. Mouse embryonic fibroblasts (MEFs) were cultured in the presence of 0-5 mM glucosamine for up to 18 h, and LLO biosynthesis was monitored by fluorescence-assisted carbohydrate electrophoresis. ER stress was determined by quantification of unfolded protein response (UPR) gene expression. We found that exposure of MEFs to ≥1 mM glucosamine significantly impaired the biosynthesis of mature (Glc3Man9GlcNAc2) LLOs before the activation of the UPR, which resulted in the accumulation of an LLO intermediate (Man3GlcNAc2). The addition of 4-phenylbutyric acid (4-PBA), a chemical chaperone, was able to alleviate ER stress but did not rescue LLO biosynthesis. Other ER stress-inducing agents, including dithiothreitol and thapsigargin, had no effect on LLO levels. Together, these data suggest that elevated concentrations of glucosamine induce ER stress by interfering with lipid-linked oligosaccharide biosynthesis and N-linked glycosylation. We hypothesize that this pathway represents a causative link between hyperglycemia and the development of diabetic complications.
Subject(s)
Endoplasmic Reticulum Stress/drug effects , Fibroblasts/drug effects , Glucosamine/pharmacology , Glycosylation/drug effects , Lipopolysaccharides/biosynthesis , Animals , Cell Line , Dithiothreitol/pharmacology , Enzyme Inhibitors/pharmacology , Fibroblasts/metabolism , Mice , Phenylbutyrates/pharmacology , Thapsigargin/pharmacology , Unfolded Protein Response/drug effectsABSTRACT
OBJECTIVE: Glycogen synthase kinase (GSK)-3α/ß has been implicated in the pathogenesis of diabetes mellitus, cancer, Alzheimer, and atherosclerosis. The tissue- and homolog-specific functions of GSK3α and ß in atherosclerosis are unknown. This study examines the effect of hepatocyte or myeloid cell deletion of GSK3α or GSK3ß on atherosclerosis in low-density lipoprotein receptor (LDLR)(-/-) mice. APPROACH AND RESULTS: We ablated GSK3α or GSK3ß expression in hepatic or myeloid cells of LDLR(-/-) mice, and mice were fed a high-fat diet for 10 weeks. GSK3α or GSK3ß deficiency in hepatic or myeloid cells did not affect metabolic parameters, including plasma lipid levels. Hepatic deletion of GSK3α or GSK3ß did not affect the development of atherosclerosis or hepatic lipid content. Myeloid deletion of GSK3α, but not of GSK3ß, reduced atherosclerotic lesion volume and lesion complexity. Mice lacking GSK3α in myeloid cells had a less inflammatory and more anti-inflammatory plasma cytokine profile. Macrophages within atherosclerotic lesions of myeloid GSK3α-deficient mice, but not of GSK3ß-deficient mice, displayed reduced expression of markers associated with M1 macrophage polarization and enhanced expression of the M2 markers. Finally, bone marrow-derived macrophages were isolated and differentiated into classical M1 macrophages or alternative M2 macrophages in vitro. GSK3α deletion, but not GSK3ß deletion, attenuated the expression of genes associated with M1 polarization while promoting the expression of genes associated with M2 polarization by modulating STAT3 and STAT6 activation. CONCLUSIONS: Our findings suggest that deletion of myeloid GSK3α attenuates the progression of atherosclerosis by promoting an M2 macrophage phenotype.
Subject(s)
Atherosclerosis/genetics , Gene Deletion , Gene Expression Regulation , Glycogen Synthase Kinase 3/genetics , Macrophages/cytology , Animals , Atherosclerosis/physiopathology , Cells, Cultured , Cytokines/metabolism , Disease Models, Animal , Hepatocytes/metabolism , Mice , Mice, Knockout , Myeloid Cells/metabolism , PhenotypeABSTRACT
Studies have implicated signaling through glycogen synthase kinase (GSK) 3α/ß in the activation of pro-atherogenic pathways and the accelerated development of atherosclerosis. By using a mouse model, we examined the role of GSK3α in the development and progression of accelerated atherosclerosis. We crossed Gsk3a/GSK3α-knockout mice with low-density lipoprotein receptor (Ldlr) knockout mice. Five-week-old Ldlr(-/-);Gsk3a(+/+), Ldlr(-/-);Gsk3a(+/-), and Ldlr(-/-);Gsk3a(-/-) mice were fed a chow diet or a high-fat diet for 10 weeks and then sacrificed. GSK3α deficiency had no detectible effect on any measured parameters in chow-fed mice. High-fat-diet fed Ldlr(-/-) mice that were deficient for GSK3α had significantly less hepatic lipid accumulation and smaller atherosclerotic lesions (60% smaller in Ldlr(-/-);Gsk3a(+/-) mice, 80% smaller in Ldlr(-/-);Gsk3a(-/-) mice; P < 0.05), compared with Ldlr(-/-);Gsk3a(+/+) controls. GSK3α deficiency was associated with a significant increase in plasma IL-10 concentration and IL-10 expression in isolated macrophages. A twofold to threefold enhancement in endoplasmic reticulum stress-induced IL-10 expression was observed in Thp-1-derived macrophages that were pretreated with the GSK3α/ß inhibitor CT99021. Together, these results suggest that GSK3α plays a pro-atherogenic role, possibly by mediating the effects of endoplasmic reticulum stress in the activation of pro-atherogenic pathways.
Subject(s)
Atherosclerosis/metabolism , Fatty Liver/metabolism , Glycogen Synthase Kinase 3/deficiency , Glycogen Synthase Kinase 3/genetics , Liver/pathology , Receptors, LDL/genetics , Animals , Atherosclerosis/genetics , Body Weight , Diet, High-Fat , Female , Genotype , Glycogen Synthase Kinase 3/metabolism , Glycogen Synthase Kinase 3 beta , Macrophages/metabolism , Mice , Mice, Inbred C57BL , Mice, Knockout , Mice, Transgenic , Receptors, LDL/deficiency , Signal TransductionABSTRACT
Evidence suggests a causative role for endoplasmic reticulum (ER) stress in the development of atherosclerosis. This study investigated the potential role of glycogen synthase kinase (GSK)-3α/ß in proatherogenic ER stress signaling. Thp1-derived macrophages were treated with the ER stress-inducing agents, glucosamine, thapsigargin, or palmitate. Using small-molecule inhibitors of specific unfolded protein response (UPR) signaling pathways, we found that protein kinase R-like ER kinase (PERK), but not inositol requiring enzyme 1 or activating transcription factor 6, is required for the activation of GSK3α/ß by ER stress. GSK3α/ß inhibition or siRNA-directed knockdown attenuated ER stress-induced expression of distal components of the PERK pathway. Macrophage foam cells within atherosclerotic plaques and isolated macrophages from ApoE(-/-) mice fed a diet supplemented with the GSK3α/ß inhibitor valproate had reduced levels of C/EBP homologous protein (CHOP). GSK3α/ß inhibition blocked ER stress-induced lipid accumulation and the upregulation of genes associated with lipid metabolism. In primary mouse macrophages, PERK inhibition blocked ER stress-induced lipid accumulation, whereas constitutively active S9A-GSK3ß promoted foam cell formation and CHOP expression, even in cells treated with a PERK inhibitor. These findings suggest that ER stress-PERK-GSK3α/ß signaling promotes proatherogenic macrophage lipid accumulation.
Subject(s)
Foam Cells/cytology , Foam Cells/metabolism , Glycogen Synthase Kinase 3/metabolism , eIF-2 Kinase/metabolism , Animals , Atherosclerosis/metabolism , Atherosclerosis/pathology , Biological Transport/drug effects , Cell Line , Endoplasmic Reticulum Stress/drug effects , Female , Foam Cells/drug effects , Foam Cells/enzymology , Gene Expression Regulation/drug effects , Glycogen Synthase Kinase 3/antagonists & inhibitors , Glycogen Synthase Kinase 3 beta , Humans , Lipid Metabolism/drug effects , Lipids/biosynthesis , Mice , Mice, Inbred C57BL , Protein Kinase Inhibitors/pharmacology , Signal Transduction/drug effects , Transcription Factor CHOP/metabolism , Unfolded Protein Response/drug effectsABSTRACT
Glucosamine sulfate is a dietary supplement that is marketed as a treatment for osteoarthritis. Recent evidence from animal and cell culture models have suggested that glucosamine treatment can promote the misfolding of proteins and the activation of the unfolded protein response (UPR). We investigated whether glucosamine sulfate supplementation activates the UPR in circulating leukocytes of human subjects. Cultured Thp1 human monocytes were exposed to increasing concentrations of glucosamine (0, 0.25, 1.0, 4.0 mmol · L(-1)) for 18 h. We observed a dose-dependent increase in intracellular glucosamine levels as well as the activation of UPR. To test the effect of glucosamine sulfate supplementation in humans, 14 healthy human subjects took 1500 mg · day(-1) glucosamine sulfate for 14 days. Metabolic parameters and blood samples were collected before and after supplementation. In humans, glucosamine sulfate supplementation did not alter metabolic parameters including lipid levels and glucose tolerance. Further, glucosamine sulfate supplementation did not affect intracellular glucosamine levels or activate the UPR in the leukocytes of human subjects. Our results indicate that in healthy human subjects, the recommended dose of glucosamine sulfate (1500 mg · day(-1)) for 14 days does not significantly alter intracellular glucosamine levels and does not activate the UPR in circulating leukocytes.
Subject(s)
Dietary Supplements , Endoplasmic Reticulum Stress/drug effects , Glucosamine/adverse effects , Leukocytes/drug effects , Unfolded Protein Response/drug effects , Administration, Oral , Adult , Cell Line , Female , Glucosamine/metabolism , Glucose/metabolism , Humans , Leukocytes/metabolism , Lipids/blood , Male , Middle Aged , Young AdultABSTRACT
Atherosclerosis remains the leading cause of death globally. Although its focal pathology is atheroma that develops in arterial walls, atherosclerosis is a systemic disease involving contributions by many organs and tissues. It is now established that the immune system causally contributes to all phases of atherosclerosis. Recent and emerging evidence positions the nervous system as a key modulator of inflammatory processes that underly atherosclerosis. This neuro-immune crosstalk, we are learning, is bidirectional, and immune regulated afferent signaling is becoming increasingly recognized in atherosclerosis. Here, we summarize data and concepts that link the immune and nervous systems in atherosclerosis by focusing on two important sites, the arterial vessel and the bone marrow.
ABSTRACT
BACKGROUND: Scientific evidence highlights the influence of biological sex on the relationship between stress and metabolic dysfunctions. However, there is limited understanding of how diet and stress concurrently contribute to metabolic dysregulation in both males and females. Our study aimed to investigate the combined effects of high-fat diet (HFD) induced obesity and repeated stress on fear-related behaviors, metabolic, immune, and hypothalamic outcomes in male and female mice. METHODS: To investigate this, we used a highly reliable rodent behavioral model that faithfully recapitulates key aspects of post-traumatic stress disorder (PTSD)-like fear. We subjected mice to footshock stressor followed by a weekly singular footshock stressor or no stressor for 14 weeks while on either an HFD or chow diet. At weeks 10 and 14 we conducted glucose tolerance and insulin sensitivity measurements. Additionally, we placed the mice in metabolic chambers to perform indirect calorimetric measurements. Finally, we collected brain and peripheral tissues for cellular analysis. RESULTS: We observed that HFD-induced obesity disrupted fear memory extinction, increased glucose intolerance, and affected energy expenditure specifically in male mice. Conversely, female mice on HFD exhibited reduced respiratory exchange ratio (RER), and a significant defect in glucose tolerance only when subjected to repeated stress. Furthermore, the combination of repeated stress and HFD led to sex-specific alterations in proinflammatory markers and hematopoietic stem cells across various peripheral metabolic tissues. Single-nuclei RNA sequencing (snRNAseq) analysis of the ventromedial hypothalamus (VMH) revealed microglial activation in female mice on HFD, while male mice on HFD exhibited astrocytic activation under repeated stress. CONCLUSIONS: Overall, our findings provide insights into complex interplay between repeated stress, high-fat diet regimen, and their cumulative effects on health, including their potential contribution to the development of PTSD-like stress and metabolic dysfunctions, emphasizing the need for further research to fully understand these interconnected pathways and their implications for health.
In our study, we attempted to investigate how the combination of diet, stress, and sex can affect various aspects of health in mice. Specifically, we aimed to elucidate the neurobiology of underlying stress and metabolic dysfunction with a focus on sex-specific differences. We recognize that stress and metabolic disorders often co-occur and exhibit distinct patterns between sexes. In the present study, we observed that male mice fed a high-fat diet exhibited an inability to extinguish fear memory, mirroring a hallmark symptom observed in PTSD patients. We also observed sex-specific differences in metabolic and immune function in response to the diet and stress challenge. We uncovered that both repeated stress and a HFD can induce alterations in the quantity and types of immune cells present in various peripheral tissues, suggesting potential pathways through which metabolic diseases may develop. Our investigation further revealed that the ventromedial hypothalamus, responsible for regulating metabolism and stress behavior, exhibited distinct transcriptomic activity patterns in males and females. These findings shed light on the complex connections between high fat diet, stress levels, and overall health, emphasizing the importance of continued research in this area.