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Furusho M, Terasaki M. Evidence for glia-mediated, age-dependent remodeling of myelin at the axon initial segment. J Comp Neurol 2024; 532:e25574. [PMID: 38411251 DOI: 10.1002/cne.25574] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Revised: 11/02/2023] [Accepted: 12/07/2023] [Indexed: 02/28/2024]
Abstract
Due to its proximity to the axon initial segment (AIS), the paranode of the first myelin segment can influence the threshold for action potentials and how a neuron participates in a neuronal circuit. Using serial section electron microscopy, we examined its three-dimensional (3D) organization in the ventral horn of the mouse spinal cord. The myelin loops of postnatal day 18 mice resemble those at the node of Ranvier. However, in 3-month-old mice, 13 of 22 para-AIS showed 4 types of alteration: (A) A cytoplasmic foot process, with ultrastructural characteristics of an astrocyte, was interposed between the axolemma and the myelin loops. (B) A thin extension of the inner tongue was present between the foot process and axolemma. (C) The foot process was absent. The inner tongue extension was a broad lamella from which a thin extension reached beyond the loops and spiraled around axon. (D) One set of loops was adjacent to the axon, and another was further back and underlain by compact myelin. We suggest that (A)-(C) are steps in a progression toward (D). In this progression, a glial process displaces the original loops, the inner tongue reactivates and extends beneath the foot process, then wraps around the axon to form a new set of loops. This is the first study of the 3D organization of myelin at the AIS and provides evidence for glia-mediated age-dependent remodeling at this critical region.
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Affiliation(s)
- Miki Furusho
- Department of Cell Biology, University of Connecticut Health Center, Farmington, Connecticut, USA
| | - Mark Terasaki
- Department of Cell Biology, University of Connecticut Health Center, Farmington, Connecticut, USA
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Pfeifer CW, Walsh JT, Santeford A, Lin JB, Beatty WL, Terao R, Liu YA, Hase K, Ruzycki PA, Apte RS. Dysregulated CD200-CD200R signaling in early diabetes modulates microglia-mediated retinopathy. Proc Natl Acad Sci U S A 2023; 120:e2308214120. [PMID: 37903272 PMCID: PMC10636339 DOI: 10.1073/pnas.2308214120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2023] [Accepted: 09/25/2023] [Indexed: 11/01/2023] Open
Abstract
Diabetic retinopathy (DR) is a neurovascular complication of diabetes. Recent investigations have suggested that early degeneration of the neuroretina may occur prior to the appearance of microvascular changes; however, the mechanisms underlying this neurodegeneration have been elusive. Microglia are the predominant resident immune cell in the retina and adopt dynamic roles in disease. Here, we show that ablation of retinal microglia ameliorates visual dysfunction and neurodegeneration in a type I diabetes mouse model. We also provide evidence of enhanced microglial contact and engulfment of amacrine cells, ultrastructural modifications, and transcriptome changes that drive inflammation and phagocytosis. We show that CD200-CD200R signaling between amacrine cells and microglia is dysregulated during early DR and that targeting CD200R can attenuate high glucose-induced inflammation and phagocytosis in cultured microglia. Last, we demonstrate that targeting CD200R in vivo can prevent visual dysfunction, microglia activation, and retinal inflammation in the diabetic mouse. These studies provide a molecular framework for the pivotal role that microglia play in early DR pathogenesis and identify a potential immunotherapeutic target for treating DR in patients.
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Affiliation(s)
- Charles W. Pfeifer
- John F. Hardesty, Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO63110
- Neurosciences Graduate Program, Roy and Diana Vagelos Division of Biology and Biomedical Sciences, Washington University School of Medicine, St. Louis, MO63110
| | - James T. Walsh
- John F. Hardesty, Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO63110
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO63110
| | - Andrea Santeford
- John F. Hardesty, Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO63110
| | - Joseph B. Lin
- John F. Hardesty, Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO63110
- Neurosciences Graduate Program, Roy and Diana Vagelos Division of Biology and Biomedical Sciences, Washington University School of Medicine, St. Louis, MO63110
| | - Wandy L. Beatty
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO63110
| | - Ryo Terao
- John F. Hardesty, Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO63110
- Department of Ophthalmology, Graduate School of Medicine, The University of Tokyo, Tokyo1138665, Japan
| | - Yizhou A. Liu
- John F. Hardesty, Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO63110
| | - Keitaro Hase
- John F. Hardesty, Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO63110
| | - Philip A. Ruzycki
- John F. Hardesty, Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO63110
- Department of Genetics, Washington University School of Medicine, St. Louis, MO63110
| | - Rajendra S. Apte
- John F. Hardesty, Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO63110
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO63110
- Department of Medicine, Washington University School of Medicine, St. Louis, MO63110
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Hayden MR. Brain Injury: Response to Injury Wound-Healing Mechanisms and Enlarged Perivascular Spaces in Obesity, Metabolic Syndrome, and Type 2 Diabetes Mellitus. MEDICINA (KAUNAS, LITHUANIA) 2023; 59:1337. [PMID: 37512148 PMCID: PMC10385746 DOI: 10.3390/medicina59071337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 07/15/2023] [Accepted: 07/18/2023] [Indexed: 07/30/2023]
Abstract
Embryonic genetic mechanisms are present in the brain and ready to be placed into action upon cellular injury, termed the response to injury wound-healing (RTIWH) mechanism. When injured, regional brain endothelial cells initially undergo activation and dysfunction with initiation of hemostasis, inflammation (peripheral leukocytes, innate microglia, and perivascular macrophage cells), proliferation (astrogliosis), remodeling, repair, and resolution phases if the injurious stimuli are removed. In conditions wherein the injurious stimuli are chronic, as occurs in obesity, metabolic syndrome, and type 2 diabetes mellitus, this process does not undergo resolution and there is persistent RTIWH with remodeling. Indeed, the brain is unique, in that it utilizes its neuroglia: the microglia cell, along with peripheral inflammatory cells and its astroglia, instead of peripheral scar-forming fibrocytes/fibroblasts. The brain undergoes astrogliosis to form a gliosis scar instead of a fibrosis scar to protect the surrounding neuropil from regional parenchymal injury. One of the unique and evolving remodeling changes in the brain is the development of enlarged perivascular spaces (EPVSs), which is the focus of this brief review. EPVSs are important since they serve as a biomarker for cerebral small vessel disease and also represent an impairment of the effluxing glymphatic system that is important for the clearance of metabolic waste from the interstitial fluid to the cerebrospinal fluid, and disposal. Therefore, it is important to better understand how the RTIWH mechanism is involved in the development of EPVSs that are closely associated with and important to the development of premature and age-related cerebrovascular and neurodegenerative diseases with impaired cognition.
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Affiliation(s)
- Melvin R Hayden
- Diabetes and Cardiovascular Disease Center, Department of Internal Medicine, Endocrinology Diabetes and Metabolism, University of Missouri School of Medicine, One Hospital Drive, Columbia, MO 65211, USA
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Mokhemer SA, Desouky MK, Abdelghany AK, Ibrahim MFG. Stem cells therapeutic effect in a reserpine-induced fibromyalgia rat model: A possible NLRP3 inflammasome modulation with neurogenesis promotion in the cerebral cortex. Life Sci 2023; 325:121784. [PMID: 37196857 DOI: 10.1016/j.lfs.2023.121784] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Revised: 05/06/2023] [Accepted: 05/14/2023] [Indexed: 05/19/2023]
Abstract
Fibromyalgia is a chronic pain syndrome with a multifactorial pathophysiology affecting 2-8 % of the population. AIMS To investigate the therapeutic effects of bone marrow mesenchymal stem cells (BMSCs) against fibromyalgia-related cerebral cortex damage and the possible underlying mechanisms of action. MATERIALS AND METHODS Rats were randomly allocated into three groups; control, fibromyalgia and fibromyalgia treated with BMSCs groups. Physical and behavioural assessments were performed. Cerebral cortices were collected for biochemical and histological assessment. KEY FINDINGS Fibromyalgia group showed behavioural changes indicating presence of pain, fatigue, depression, and sleep disturbances. Moreover, biochemical biomarkers alterations were demonstrated by a significant decrease in brain monoamines and GSH levels, but MDA, NO, TNF-alpha, HMGB-1, NLRP3, and caspase-1 levels significantly increased. Furthermore, histological assessment revealed structural and ultrastructural alterations indicating neuronal and neuroglial degeneration with microglia activation, an increase in mast cell number and IL-1β immune-expression. Additionally, a significant decrease in Beclin-1 immune-expression, and blood brain barrier disruption were noticed. Interestingly, BMSCs administration significantly improved behavioural alterations, restored the reduced brain monoamines and oxidative stress markers, and reduced TNF-alpha, HMGB-1, NLRP3, and caspase-1 levels. Profoundly, cerebral cortices demonstrated improved histological structure, significant decrease in mast cell number and IL-1β immune-expression, besides a significant increase in Beclin-1 and DCX immune-expression. SIGNIFICANCE For the best of our knowledge, this is the first study showing ameliorative effects for BMSCs treatment in fibromyalgia-related cerebral cortical damage. The neurotherapeutic effects of BMSCs could be attributed to NLRP3 inflammasome signaling pathway inhibition, mast cell deactivation, and stimulation of neurogenesis and autophagy.
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Affiliation(s)
- Sahar A Mokhemer
- Department of Histology and Cell Biology, Faculty of Medicine, Minia University, 61511 El-Minia, Egypt.
| | - Maha K Desouky
- Department of Anatomy, Faculty of Medicine, Minia University, 61511 El-Minia, Egypt
| | - Asmaa K Abdelghany
- Animal and Poultry Management and Wealth Development Department, Faculty of Veterinary Medicine, Beni-Suef University, Beni-Suef 62511, Egypt
| | - Manar Fouli Gaber Ibrahim
- Department of Histology and Cell Biology, Faculty of Medicine, Minia University, 61511 El-Minia, Egypt
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Kumari A, Srivastava A, Jagdale P, Ayanur A, Khanna VK. Lambda-cyhalothrin enhances inflammation in nigrostriatal region in rats: Regulatory role of NF-κβ and JAK-STAT signaling. Neurotoxicology 2023; 96:101-117. [PMID: 37060950 DOI: 10.1016/j.neuro.2023.04.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Revised: 04/03/2023] [Accepted: 04/11/2023] [Indexed: 04/17/2023]
Abstract
The risk to develop neurobehavioural abnormalities in humans on exposure to lambda-cyhalothrin (LCT) - a type II synthetic pyrethroid has enhanced significantly due to its extensive uses in agriculture, homes, veterinary practices and public health programs. Earlier, we found that the brain dopaminergic system is vulnerable to LCT and affects motor functions in rats. In continuation to this, the present study is focused to unravel the role of neuroinflammation in LCT-induced neurotoxicity in substantia nigra and corpus striatum in rats. Increase in the mRNA expression of proinflammatory cytokines (TNF- α, IL-1β, IL-6) and iNOS whereas decrease in anti-inflammatory cytokine (IL-10) was distinct both in substantia nigra and corpus striatum of rats treated with LCT (0.5, 1.0, 3.0 mg/kg body weight, p.o, for 45 days) as compared to control rats. Further, LCT-treated rats exhibited increased levels of glial fibrillary acidic protein (GFAP) and ionized calcium-binding adapter molecule 1 (Iba-1), the glial marker proteins both in substantia nigra and corpus striatum as compared to controls. Exposure of rats to LCT also caused alterations in the levels of heat shock protein 60 (HSP60) and mRNA expression of toll-like receptors (TLR2 and TLR4) in the substantia nigra and corpus striatum. An increase in the phosphorylation of key proteins involved in NF-kβ (P65, Iκβ, IKKα, IKKβ) and JAK/STAT (STAT1, STAT3) signaling and alteration in the protein levels of JAK1 and JAK2 was prominent in LCT-treated rats. Histological studies revealed damage of dopaminergic neurons and reactive gliosis as evidenced by the presence of darkly stained pyknotic neurons and decrease in Nissl substance and an increase in infiltration of immune cells both in substantia nigra and corpus striatum of LCT-treated rats. Presence of reactive microglia and astrocytes in LCT-treated rats was also distinct in ultrastructural studies. The results exhibit that LCT may damage dopaminergic neurons in the substantia nigra and corpus striatum by inducing inflammation as a result of stimulation of neuroglial cells involving activation of NF-κβ and JAK/STAT signaling.
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Affiliation(s)
- Anima Kumari
- Developmental Toxicology Laboratory, Area - Systems Toxicology & Health Risk Assessment, CSIR - Indian Institute of Toxicology Research, Vishvigyan Bhawan, 31 Mahatma Gandhi Marg, Lucknow 226 001, Uttar Pradesh, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Anugya Srivastava
- Developmental Toxicology Laboratory, Area - Systems Toxicology & Health Risk Assessment, CSIR - Indian Institute of Toxicology Research, Vishvigyan Bhawan, 31 Mahatma Gandhi Marg, Lucknow 226 001, Uttar Pradesh, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Pankaj Jagdale
- Central Pathology Laboratory, Area - Regulatory Toxicology, CSIR - Indian Institute of Toxicology Research, Vishvigyan Bhawan, 31 Mahatma Gandhi Marg, Lucknow 226 001, Uttar Pradesh, India
| | - Anjaneya Ayanur
- Central Pathology Laboratory, Area - Regulatory Toxicology, CSIR - Indian Institute of Toxicology Research, Vishvigyan Bhawan, 31 Mahatma Gandhi Marg, Lucknow 226 001, Uttar Pradesh, India
| | - Vinay Kumar Khanna
- Developmental Toxicology Laboratory, Area - Systems Toxicology & Health Risk Assessment, CSIR - Indian Institute of Toxicology Research, Vishvigyan Bhawan, 31 Mahatma Gandhi Marg, Lucknow 226 001, Uttar Pradesh, India.
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Hayden MR. Overview and New Insights into the Metabolic Syndrome: Risk Factors and Emerging Variables in the Development of Type 2 Diabetes and Cerebrocardiovascular Disease. Medicina (B Aires) 2023; 59:medicina59030561. [PMID: 36984562 PMCID: PMC10059871 DOI: 10.3390/medicina59030561] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2023] [Revised: 03/04/2023] [Accepted: 03/10/2023] [Indexed: 03/16/2023] Open
Abstract
Metabolic syndrome (MetS) is considered a metabolic disorder that has been steadily increasing globally and seems to parallel the increasing prevalence of obesity. It consists of a cluster of risk factors which traditionally includes obesity and hyperlipidemia, hyperinsulinemia, hypertension, and hyperglycemia. These four core risk factors are associated with insulin resistance (IR) and, importantly, the MetS is known to increase the risk for developing cerebrocardiovascular disease and type 2 diabetes mellitus. The MetS had its early origins in IR and syndrome X. It has undergone numerous name changes, with additional risk factors and variables being added over the years; however, it has remained as the MetS worldwide for the past three decades. This overview continues to add novel insights to the MetS and suggests that leptin resistance with hyperleptinemia, aberrant mitochondrial stress and reactive oxygen species (ROS), impaired folate-mediated one-carbon metabolism with hyperhomocysteinemia, vascular stiffening, microalbuminuria, and visceral adipose tissues extracellular vesicle exosomes be added to the list of associated variables. Notably, the role of a dysfunctional and activated endothelium and deficient nitric oxide bioavailability along with a dysfunctional and attenuated endothelial glycocalyx, vascular inflammation, systemic metainflammation, and the important role of ROS and reactive species interactome are discussed. With new insights and knowledge regarding the MetS comes the possibility of new findings through further research.
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Affiliation(s)
- Melvin R Hayden
- Department of Internal Medicine, Endocrinology Diabetes and Metabolism, Diabetes and Cardiovascular Disease Center, University of Missouri School of Medicine, One Hospital Drive, Columbia, MO 65211, USA
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Ultrastructural Remodeling of the Blood-Brain Barrier and Neurovascular Unit by Lipopolysaccharide-Induced Neuroinflammation. Int J Mol Sci 2023; 24:ijms24021640. [PMID: 36675154 PMCID: PMC9862046 DOI: 10.3390/ijms24021640] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Revised: 01/09/2023] [Accepted: 01/12/2023] [Indexed: 01/18/2023] Open
Abstract
The blood-brain barrier (BBB) is an interface primarily comprised of brain endothelial cells (BECs), separating the central nervous system (CNS) from the systemic circulation while carefully regulating the transport of molecules and inflammatory cells, and maintaining the required steady-state environment. Inflammation modulates many BBB functions, but the ultrastructural cytoarchitectural changes of the BBB with inflammation are understudied. Inflammation was induced in male 8-10-week-old CD-1 mice with intraperitoneal lipopolysaccharide (LPS), using a regimen (3 mg/kg at 0, 6, and 24 h) that caused robust BBB disruption but had minimal lethality at the study timepoint of 28 h. Perfusion-fixed brains were collected and the frontal cortical layer III regions were analyzed using a transmission electron microscopy (TEM). The LPS-treated mice had pronounced ultrastructural remodeling changes in BECs that included plasma membrane ruffling, increased numbers of extracellular microvesicles, small exosome formation, aberrant BEC mitochondria, increased BEC transcytosis, while tight junctions appeared to be unaltered. Aberrant pericytes were contracted with rounded nuclei and a loss of their elongated cytoplasmic processes. Surveilling microglial cells were attracted to the neurovascular unit (NVU) of BECs, and astrocyte detachment and separation were associated with the formation of a perivascular space and pericapillary edema. The LPS treatment resulted in numerous ultrastructural aberrant remodeling changes to the neurovascular unit's BECs, microglia, pericytes, and astrocytes. In summary, a disturbance of the NVU morphology is a consequence of LPS treatment.
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Reactive Microgliosis in Sepsis-Associated and Acute Hepatic Encephalopathies: An Ultrastructural Study. Int J Mol Sci 2022; 23:ijms232214455. [PMID: 36430933 PMCID: PMC9696099 DOI: 10.3390/ijms232214455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Revised: 11/17/2022] [Accepted: 11/19/2022] [Indexed: 11/23/2022] Open
Abstract
Sepsis and acute liver failure are associated with severe endogenous intoxication. Microglia, which are the resident immune brain cells, play diverse roles in central nervous system development, surveillance, and defense, as well as contributing to neuroinflammatory reactions. In particular, microglia are fundamental to the pathophysiology of reactive toxic encephalopathies. We analyzed microglial ultrastructure, morphotypes, and phagocytosis in the sensorimotor cortex of cecal ligation and puncture (CLP) and acetaminophen-induced liver failure (AILF) Wistar rats. A CLP model induced a gradual shift of ~50% of surveillant microglia to amoeboid hypertrophic-like and gitter cell-like reactive phenotypes with active phagocytosis and frequent contacts with damaged neurons. In contrast, AILF microglia exhibited amoeboid, rod-like, and hypertrophic-like reactive morphotypes with minimal indications for efficient phagocytosis, and were mostly in contact with edematous astrocytes. Close interactions of reactive microglia with neurons, astrocytes, and blood-brain barrier components reflect an active contribution of these cells to the tissue adaptation and cellular remodeling to toxic brain damage. Partial disability of reactive microglia may affect the integrity and metabolism in all tissue compartments, leading to failure of the compensatory mechanisms in acute endogenous toxic encephalopathies.
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The Mighty Mitochondria Are Unifying Organelles and Metabolic Hubs in Multiple Organs of Obesity, Insulin Resistance, Metabolic Syndrome, and Type 2 Diabetes: An Observational Ultrastructure Study. Int J Mol Sci 2022; 23:ijms23094820. [PMID: 35563211 PMCID: PMC9101653 DOI: 10.3390/ijms23094820] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 04/22/2022] [Accepted: 04/24/2022] [Indexed: 12/25/2022] Open
Abstract
Mitochondria (Mt) are essential cellular organelles for the production of energy and thermogenesis. Mt also serve a host of functions in addition to energy production, which include cell signaling, metabolism, cell death, and aging. Due to the central role of Mt in metabolism as metabolic hubs, there has been renewed interest in how Mt impact metabolic pathways and multiple pathologies. This review shares multiple observational ultrastructural findings in multiple cells and organs to depict aberrant mitochondrial (aMt) remodeling in pre-clinical rodent models. Further, it is intended to show how remodeling of Mt are associated with obesity, insulin resistance, metabolic syndrome (MetS), and type 2 diabetes mellitus (T2DM). Specifically, Mt remodeling in hypertensive and insulin-resistant lean models (Ren2 rat models), lean mice with streptozotocin-induced diabetes, obesity models including diet-induced obesity, genetic leptin-deficient ob/ob, and leptin receptor-deficient db/db diabetic mice are examined. Indeed, aMt dysfunction and damage have been implicated in multiple pathogenic diseases. Manipulation of Mt such as the induction of Mt biogenesis coupled with improvement of mitophagy machinery may be helpful to remove leaky damaged aMt in order to prevent the complications associated with the generation of superoxide-derived reactive oxygen species and the subsequent reactive species interactome. A better understanding of Mt remodeling may help to unlock many of the mysteries in obesity, insulin resistance, MetS, T2DM, and the associated complications of diabetic end-organ disease.
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Hayden MR, Tyagi SC. Impaired Folate-Mediated One-Carbon Metabolism in Type 2 Diabetes, Late-Onset Alzheimer's Disease and Long COVID. MEDICINA (KAUNAS, LITHUANIA) 2021; 58:16. [PMID: 35056324 PMCID: PMC8779539 DOI: 10.3390/medicina58010016] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Revised: 12/18/2021] [Accepted: 12/21/2021] [Indexed: 12/25/2022]
Abstract
Impaired folate-mediated one-carbon metabolism (FOCM) is associated with many pathologies and developmental abnormalities. FOCM is a metabolic network of interdependent biosynthetic pathways that is known to be compartmentalized in the cytoplasm, mitochondria and nucleus. Currently, the biochemical mechanisms and causal metabolic pathways responsible for the initiation and/or progression of folate-associated pathologies have yet to be fully established. This review specifically examines the role of impaired FOCM in type 2 diabetes mellitus, Alzheimer's disease and the emerging Long COVID/post-acute sequelae of SARS-CoV-2 (PASC). Importantly, elevated homocysteine may be considered a biomarker for impaired FOCM, which is known to result in increased oxidative-redox stress. Therefore, the incorporation of hyperhomocysteinemia will be discussed in relation to impaired FOCM in each of the previously listed clinical diseases. This review is intended to fill gaps in knowledge associated with these clinical diseases and impaired FOCM. Additionally, some of the therapeutics will be discussed at this early time point in studying impaired FOCM in each of the above clinical disease states. It is hoped that this review will allow the reader to better understand the role of FOCM in the development and treatment of clinical disease states that may be associated with impaired FOCM and how to restore a more normal functional role for FOCM through improved nutrition and/or restoring the essential water-soluble B vitamins through oral supplementation.
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Affiliation(s)
- Melvin R. Hayden
- Departments of Internal Medicine, Endocrinology Diabetes and Metabolism Diabetes and Cardiovascular Disease Center, University of Missouri School of Medicine, Columbia, MO 65212, USA
| | - Suresh C. Tyagi
- Department of Physiology, University of Louisville School of Medicine, Louisville, KY 40202, USA;
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Hayden MR, Banks WA. Deficient Leptin Cellular Signaling Plays a Key Role in Brain Ultrastructural Remodeling in Obesity and Type 2 Diabetes Mellitus. Int J Mol Sci 2021; 22:5427. [PMID: 34063911 PMCID: PMC8196569 DOI: 10.3390/ijms22115427] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 05/13/2021] [Accepted: 05/15/2021] [Indexed: 12/11/2022] Open
Abstract
The triad of obesity, metabolic syndrome (MetS), Type 2 diabetes mellitus (T2DM) and advancing age are currently global societal problems that are expected to grow over the coming decades. This triad is associated with multiple end-organ complications of diabetic vasculopathy (maco-microvessel disease), neuropathy, retinopathy, nephropathy, cardiomyopathy, cognopathy encephalopathy and/or late-onset Alzheimer's disease. Further, obesity, MetS, T2DM and their complications are associated with economical and individual family burdens. This review with original data focuses on the white adipose tissue-derived adipokine/hormone leptin and how its deficient signaling is associated with brain remodeling in hyperphagic, obese, or hyperglycemic female mice. Specifically, the ultrastructural remodeling of the capillary neurovascular unit, brain endothelial cells (BECs) and their endothelial glycocalyx (ecGCx), the blood-brain barrier (BBB), the ventricular ependymal cells, choroid plexus, blood-cerebrospinal fluid barrier (BCSFB), and tanycytes are examined in female mice with impaired leptin signaling from either dysfunction of the leptin receptor (DIO and db/db models) or the novel leptin deficiency (BTBR ob/ob model).
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Affiliation(s)
- Melvin R. Hayden
- Departments of Internal Medicine, Endocrinology Diabetes and Metabolism, Diabetes and Cardiovascular Disease Center, University of Missouri-Columbia School of Medicine, One Hospital Drive, Columbia, MO 65212, USA;
| | - William A. Banks
- Geriatrics Research, Education and Clinical Center, Veterans Affairs Puget Sound Health Care System, 1660 S. Columbian Way, 810C/Bldg 1, Seattle, WA 98108, USA
- Department of Medicine, Division of Gerontology and Geriatric Medicine, University of Washington, Seattle, WA 98108, USA
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ASSESSMENT OF HYPERREFLECTIVE FOCI AFTER BEVACIZUMAB OR DEXAMETHASONE TREATMENT ACCORDING TO DURATION OF MACULAR EDEMA IN PATIENTS WITH BRANCH RETINAL VEIN OCCLUSION. Retina 2021; 41:355-365. [PMID: 32349101 DOI: 10.1097/iae.0000000000002826] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
PURPOSE To evaluate the association between hyperreflective foci (HRF) on spectral domain optical coherence tomography and therapeutic effect of intravitreal bevacizumab (IVB) or intravitreal dexamethasone implants (IVD) according to macular edema (ME) duration in branch retinal vein occlusion. METHODS Consecutive treatment-naive patients received IVB or IVD for at least 6 months. Each group was subdivided according to ME duration (<3 months vs. ≥3 months). Hyperreflective foci and best-corrected visual acuity were compared. RESULTS Of 139 eyes (139 patients), 69 received IVB and 70 received IVD. At baseline, eyes with ME ≥ 3 months had more outer and total retinal HRF than eyes with ME < 3 months (P < 0.001 and P = 0.001). At 6 months, the IVD group exhibited a greater reduction in outer retinal HRF than the IVB group in both ME duration subgroups (P = 0.015 and P < 0.001). In the ME ≥ 3 months group, IVD resulted in greater best-corrected visual acuity improvement than IVB (P = 0.017). CONCLUSION Increased outer retinal HRF at baseline in eyes with ME ≥ 3 months together with a greater reduction in HRF at 6 months and better visual outcomes after IVD suggests that the inflammatory aspect of disease should be considered in the treatment of ME. Thus, IVD injection could be more appropriate for patients with a longer ME duration after branch retinal vein occlusion.
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Wiciński M, Wódkiewicz E, Górski K, Walczak M, Malinowski B. Perspective of SGLT2 Inhibition in Treatment of Conditions Connected to Neuronal Loss: Focus on Alzheimer's Disease and Ischemia-Related Brain Injury. Pharmaceuticals (Basel) 2020; 13:ph13110379. [PMID: 33187206 PMCID: PMC7697611 DOI: 10.3390/ph13110379] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2020] [Revised: 10/22/2020] [Accepted: 11/05/2020] [Indexed: 12/15/2022] Open
Abstract
Sodium-glucose co-transporter 2 inhibitors (SGLT2i) are oral anti-hyperglycemic agents approved for the treatment of type 2 diabetes mellitus. Some reports suggest their presence in the central nervous system and possible neuroprotective properties. SGLT2 inhibition by empagliflozin has shown to reduce amyloid burden in cortical regions of APP/PS1xd/db mice. The same effect was noticed regarding tau pathology and brain atrophy volume. Empagliflozin presented beneficial effect on cognitive function, which may be connected to an increase in cerebral brain-derived neurotrophic factor. Canagliflozin and dapagliflozin may possess acetylcholinesterase inhibiting activity, resembling in this matter Alzheimer’s disease-registered therapies. SGLT2 inhibitors may prove to impact risk factors of atherosclerosis and pathways participating both in acute and late stage of stroke. Their mechanism of action can be related to induction in hepatocyte nuclear factor-1α, vascular endothelial growth factor-A, and proinflammatory factors limitation. Empagliflozin may have a positive effect on preservation of neurovascular unit in diabetic mice, preventing its aberrant remodeling. Canagliflozin seems to present some cytostatic properties by limiting both human and mice endothelial cells proliferation. The paper presents potential mechanisms of SGLT-2 inhibitors in conditions connected with neuronal damage, with special emphasis on Alzheimer’s disease and cerebral ischemia.
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Rifaai RA, Mokhemer SA, Saber EA, El-Aleem SAA, El-Tahawy NFG. Neuroprotective effect of quercetin nanoparticles: A possible prophylactic and therapeutic role in alzheimer's disease. J Chem Neuroanat 2020; 107:101795. [PMID: 32464160 DOI: 10.1016/j.jchemneu.2020.101795] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2020] [Revised: 03/29/2020] [Accepted: 04/14/2020] [Indexed: 12/11/2022]
Abstract
BACKGROUND Alzheimer's disease (AD) is the most common cause of dementia in elderly. Quercetin is a well-known flavonoid with low bioavailability. Recently, quercetin nanoparticles (QNPs) has been shown to have a better bioavailability. AIMS This study aimed to investigate the protective and therapeutic effects of QNPs in Aluminum chloride (AlCl3) induced animal model of AD. MATERIALS AND METHODS AD was induced in rats by oral administration of AlCl3 (100 mg/kg/day) for 42 days. QNPs (30 mg/kg) was given along with AlCl3 in the prophylactic group and following AD induction in the treated group. Hippocampi were harvested for assessments of the structural and ultrastructural changes using histological and histochemical approaches. RESULTS AND DISCUSSION AD hippocampi showed a prominent structural and ultrastructural disorders both neuronal and extraneuronal. Including neuronal degeneration, formation of APs and NFTs, downregulation of tyrosine hydroxylase (TH), astrogliosis and inhibition of the proliferative activity (all P ≤ 0.05). Electron microscopy showed signs of neuronal degeneration with microglia and astrocyte activation and disruption of myelination and Blood Brain Barrier (BBB). Interestingly, QNPs administration remarkably reduced the neuronal degenerative changes, APs and NFTs formation (all P ≤ 0.05). Furthermore, it showed signs of regeneration (all P ≤ 0.05) and upregulation of TH. The effect was profound in the prophylactic group. Thus, QNPs reduced the damaging effect of AlCl3 on hippocampal neurons at the molecular, cellular and subcellular levels. CONCLUSION For the best of our knowledge this is the first study to show a prophylactic and therapeutic effect for QNPs in AD model. This might open the gate for further research and provide a new line for therapeutic intervention in AD.
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Affiliation(s)
- Rehab Ahmed Rifaai
- Department of Histology and Cell Biology, Minia University- Faculty of Medicine, Egypt
| | - Sahar Ahmed Mokhemer
- Department of Histology and Cell Biology, Minia University- Faculty of Medicine, Egypt
| | - Entesar Ali Saber
- Department of Histology and Cell Biology, Minia University- Faculty of Medicine, Egypt; Delegated to Deraya University, New Minia City, Egypt
| | - Seham A Abd El-Aleem
- Department of Histology and Cell Biology, Minia University- Faculty of Medicine, Egypt.
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Hayden MR. Type 2 Diabetes Mellitus Increases The Risk of Late-Onset Alzheimer's Disease: Ultrastructural Remodeling of the Neurovascular Unit and Diabetic Gliopathy. Brain Sci 2019; 9:brainsci9100262. [PMID: 31569571 PMCID: PMC6826500 DOI: 10.3390/brainsci9100262] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Revised: 09/17/2019] [Accepted: 09/27/2019] [Indexed: 12/11/2022] Open
Abstract
Type 2 diabetes mellitus (T2DM) and late-onset Alzheimer’s disease–dementia (LOAD) are increasing in global prevalence and current predictions indicate they will only increase over the coming decades. These increases may be a result of the concurrent increases of obesity and aging. T2DM is associated with cognitive impairments and metabolic factors, which increase the cellular vulnerability to develop an increased risk of age-related LOAD. This review addresses possible mechanisms due to obesity, aging, multiple intersections between T2DM and LOAD and mechanisms for the continuum of progression. Multiple ultrastructural images in female diabetic db/db models are utilized to demonstrate marked cellular remodeling changes of mural and glia cells and provide for the discussion of functional changes in T2DM. Throughout this review multiple endeavors to demonstrate how T2DM increases the vulnerability of the brain’s neurovascular unit (NVU), neuroglia and neurons are presented. Five major intersecting links are considered: i. Aging (chronic age-related diseases); ii. metabolic (hyperglycemia advanced glycation end products and its receptor (AGE/RAGE) interactions and hyperinsulinemia-insulin resistance (a linking linchpin); iii. oxidative stress (reactive oxygen–nitrogen species); iv. inflammation (peripheral macrophage and central brain microglia); v. vascular (macrovascular accelerated atherosclerosis—vascular stiffening and microvascular NVU/neuroglial remodeling) with resulting impaired cerebral blood flow.
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Affiliation(s)
- Melvin R Hayden
- Diabetes and Cardiovascular Center, University of Missouri School of Medicine, Columbia, MO 65212, USA.
- Division of Endocrinology and Metabolism, Department of Medicine, University of Missouri, Columbia, MO 65212, USA.
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Hayden MR. Hypothesis: Astrocyte Foot Processes Detachment from the Neurovascular Unit in Female Diabetic Mice May Impair Modulation of Information Processing-Six Degrees of Separation. Brain Sci 2019; 9:brainsci9040083. [PMID: 31013991 PMCID: PMC6523904 DOI: 10.3390/brainsci9040083] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Revised: 04/08/2019] [Accepted: 04/10/2019] [Indexed: 01/12/2023] Open
Abstract
Astrocytes via their foot processes (ACfp) are specialized connecting cells, and they structurally connect the neurovascular unit (NVU) mural cells to neurons. Astrocytes provide homeostatic mechanisms for structural connections and provide communication between the NVU and regional neurons for functional hyperemia in regions of increased neuronal activity (neurovascular coupling). Previously, our group has demonstrated a detachment, separation, and retraction of ACfp in diabetic db/db females (DBC). It was hypothesized that a loss of adherent ACfp/NVU could result in the known impaired cognition in DBC. Additionally hypothesized was that empagliflozin treatment could protect DBC ACfp/NVU remodeling. This study demonstrates a significant loss of ACfp/NVU numbers in DBC and a protection of this loss by empagliflozin treatment (DBE). The number of intact ACfp/NVU was 6.45 ± 1.1 in control heterozygous (CKC) vs. 1.88 ± 0.72 in DBC (p < 0.05) and 5.86 ± 0.88 in DBE vs. DBC (p < 0.05) by visually hand-counting the capillary NVUs (22 in CKC, 25 in DBC, and 22 in DBE). These findings suggest that empagliflozin provides neuroprotection via the prevention of ACfp separation in DBE as compared to diabetic DBC. Furthermore, a loss of ACfp/NVU numbers in DBC may correspond with a negative modulation of informational processing, and the protection of ACfp/NVU numbers could provide a protective modulation in DBE models.
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Affiliation(s)
- Melvin R Hayden
- Diabetes and Cardiovascular Center, University of Missouri School of Medicine, Columbia, MO 65212, USA.
- Division of Endocrinology and Metabolism, Department of Medicine, University of Missouri, Columbia, MO 65212, USA.
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Hayden MR, Grant DG, Aroor AR, DeMarco VG. Empagliflozin Ameliorates Type 2 Diabetes-Induced Ultrastructural Remodeling of the Neurovascular Unit and Neuroglia in the Female db/ db Mouse. Brain Sci 2019; 9:brainsci9030057. [PMID: 30866531 PMCID: PMC6468773 DOI: 10.3390/brainsci9030057] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Revised: 03/04/2019] [Accepted: 03/05/2019] [Indexed: 11/21/2022] Open
Abstract
Type 2 diabetes is associated with diabetic cognopathy. Anti-hyperglycemic sodium glucose transporter 2 (SGLT2) inhibitors have shown promise in reducing cognitive impairment in mice with type 2 diabetes mellitus. We recently described marked ultrastructural (US) remodeling of the neurovascular unit (NVU) in type 2 diabetic db/db female mice. Herein, we tested whether the SGLT-2 inhibitor, empagliflozin (EMPA), protects the NVU from abnormal remodeling in cortical gray and subcortical white matter. Ten-week-old female wild-type and db/db mice were divided into lean controls (CKC, n = 3), untreated db/db (DBC, n = 3), and EMPA-treated db/db (DBE, n = 3). Empagliflozin was added to mouse chow to deliver 10 mg kg−1 day−1 and fed for ten weeks, initiated at 10 weeks of age. Brains from 20-week-old mice were immediately immersion fixed for transmission electron microscopic study. Compared to CKC, DBC exhibited US abnormalities characterized by mural endothelial cell tight and adherens junction attenuation and/or loss, pericyte attenuation and/or loss, basement membrane thickening, glia astrocyte activation with detachment and retraction from mural cells, microglia cell activation with aberrant mitochondria, and oligodendrocyte–myelin splitting, disarray, and axonal collapse. We conclude that these abnormalities in the NVU were prevented in DBE. Empagliflozin may provide neuroprotection in the diabetic brain.
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Affiliation(s)
- Melvin R Hayden
- Diabetes and Cardiovascular Center, School of Medicine, University of Missouri, Columbia, MO 65212, USA.
- Division of Endocrinology and Metabolism, Department of Medicine, University of Missouri, Columbia, MO 65212, USA.
| | - DeAna G Grant
- Electron Microscopy Core Facility, University of Missouri, Columbia, MO 65212, USA.
| | - Annayya R Aroor
- Diabetes and Cardiovascular Center, School of Medicine, University of Missouri, Columbia, MO 65212, USA.
- Division of Endocrinology and Metabolism, Department of Medicine, University of Missouri, Columbia, MO 65212, USA.
- Research Service, Harry S. Truman Memorial Veterans Hospital, Columbia, MO 65201, USA.
| | - Vincent G DeMarco
- Diabetes and Cardiovascular Center, School of Medicine, University of Missouri, Columbia, MO 65212, USA.
- Division of Endocrinology and Metabolism, Department of Medicine, University of Missouri, Columbia, MO 65212, USA.
- Research Service, Harry S. Truman Memorial Veterans Hospital, Columbia, MO 65201, USA.
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO 65212, USA.
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