1
|
Ravi K, Paidas MJ, Saad A, Jayakumar AR. Astrocytes in rare neurological conditions: Morphological and functional considerations. J Comp Neurol 2021; 529:2676-2705. [PMID: 33496339 DOI: 10.1002/cne.25118] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2020] [Revised: 01/16/2021] [Accepted: 01/19/2021] [Indexed: 01/06/2023]
Abstract
Astrocytes are a population of central nervous system (CNS) cells with distinctive morphological and functional characteristics that differ within specific areas of the brain and are widely distributed throughout the CNS. There are mainly two types of astrocytes, protoplasmic and fibrous, which differ in morphologic appearance and location. Astrocytes are important cells of the CNS that not only provide structural support, but also modulate synaptic activity, regulate neuroinflammatory responses, maintain the blood-brain barrier, and supply energy to neurons. As a result, astrocytic disruption can lead to widespread detrimental effects and can contribute to the pathophysiology of several neurological conditions. The characteristics of astrocytes in more common neuropathologies such as Alzheimer's and Parkinson's disease have significantly been described and continue to be widely studied. However, there still exist numerous rare neurological conditions in which astrocytic involvement is unknown and needs to be explored. Accordingly, this review will summarize functional and morphological changes of astrocytes in various rare neurological conditions based on current knowledge thus far and highlight remaining neuropathologies where astrocytic involvement has yet to be investigated.
Collapse
Affiliation(s)
- Karthik Ravi
- University of Michigan, Ann Arbor, Michigan, USA
| | - Michael J Paidas
- Department of Obstetrics, Gynecology and Reproductive Sciences, University of Miami School of Medicine, Miami, Florida, USA
| | - Ali Saad
- Pathology and Laboratory Medicine, University of Miami School of Medicine, Miami, Florida, USA
| | - Arumugam R Jayakumar
- Department of Obstetrics, Gynecology and Reproductive Sciences, University of Miami School of Medicine, Miami, Florida, USA.,South Florida VA Foundation for Research and Education Inc, Miami, Florida, USA.,General Medical Research Neuropathology Section, R&D Service, Veterans Affairs Medical Centre, Miami, Florida, USA
| |
Collapse
|
2
|
Cline-Smith A, Axelbaum A, Shashkova E, Chakraborty M, Sanford J, Panesar P, Peterson M, Cox L, Baldan A, Veis D, Aurora R. Ovariectomy Activates Chronic Low-Grade Inflammation Mediated by Memory T Cells, Which Promotes Osteoporosis in Mice. J Bone Miner Res 2020; 35:1174-1187. [PMID: 31995253 PMCID: PMC8061311 DOI: 10.1002/jbmr.3966] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Revised: 12/23/2019] [Accepted: 01/16/2020] [Indexed: 12/27/2022]
Abstract
The loss of estrogen (E2 ) initiates a rapid phase of bone loss leading to osteoporosis in one-half of postmenopausal women, but the mechanism is not fully understood. Here, we show for the first time how loss of E2 activates low-grade inflammation to promote the acute phase of bone catabolic activity in ovariectomized (OVX) mice. E2 regulates the abundance of dendritic cells (DCs) that express IL-7 and IL-15 by inducing the Fas ligand (FasL) and apoptosis of the DC. In the absence of E2 , DCs become long-lived, leading to increased IL-7 and IL-15. We find that IL-7 and IL-15 together, but not alone, induced antigen-independent production of IL-17A and TNFα in a subset of memory T cells (TMEM ). OVX of mice with T-cell-specific ablation of IL15RA showed no IL-17A and TNFα expression, and no increase in bone resorption or bone loss, confirming the role of IL-15 in activating the TMEM and the need for inflammation. Our results provide a new mechanism by which E2 regulates the immune system, and how menopause leads to osteoporosis. The low-grade inflammation is likely to cause or contribute to other comorbidities observed postmenopause. © 2020 American Society for Bone and Mineral Research.
Collapse
Affiliation(s)
- Anna Cline-Smith
- Department of Molecular Microbiology & Immunology, Saint Louis University School of Medicine, St. Louis, MO, USA
| | - Ariel Axelbaum
- Department of Molecular Microbiology & Immunology, Saint Louis University School of Medicine, St. Louis, MO, USA
| | - Elena Shashkova
- Department of Molecular Microbiology & Immunology, Saint Louis University School of Medicine, St. Louis, MO, USA
| | - Mousumi Chakraborty
- Department of Molecular Microbiology & Immunology, Saint Louis University School of Medicine, St. Louis, MO, USA
| | - Jessie Sanford
- Department of Molecular Microbiology & Immunology, Saint Louis University School of Medicine, St. Louis, MO, USA
| | - Prabhjyot Panesar
- Department of Molecular Microbiology & Immunology, Saint Louis University School of Medicine, St. Louis, MO, USA
| | - Macey Peterson
- Department of Molecular Microbiology & Immunology, Saint Louis University School of Medicine, St. Louis, MO, USA
| | - Linda Cox
- Division of Bone and Mineral Diseases, Washington University School of Medicine in St. Louis, St. Louis, MO, USA
| | - Angel Baldan
- Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, MO, USA
| | - Deborah Veis
- Division of Bone and Mineral Diseases, Washington University School of Medicine in St. Louis, St. Louis, MO, USA
| | - Rajeev Aurora
- Department of Molecular Microbiology & Immunology, Saint Louis University School of Medicine, St. Louis, MO, USA
| |
Collapse
|
3
|
Naveed M, Zhou QG, Han F. Cerebrovascular inflammation: A critical trigger for neurovascular injury? Neurochem Int 2019; 126:165-177. [PMID: 30890409 DOI: 10.1016/j.neuint.2019.03.011] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Revised: 03/05/2019] [Accepted: 03/12/2019] [Indexed: 02/07/2023]
Abstract
The cerebrovascular system is not only inert bystandard that support the metabolic demands of the brain but also elicit the barrier functions against risk factors mediated neurovascular injury. The onsets of cerebrovascular inflammation are considered as stimuli that can provoke the host defense system and trigger the development of neurological disorders. Homeostasis of the brain function is regulated by the movement of endothelial, glial, and neuronal cells within the neurovascular unit (NVU), which acts as a "platform" for the coordinated action of anti- and pro-inflammatory mechanisms. The cerebrovascular system plays an integral role in the inflammatory response by either producing or expressing a variety of cytokines, adhesion molecules, metalloproteinases, and serine proteases. Excessive inflammatory cytokine production can further be affecting the blood-brain barrier (BBB) integrity and lead to brain tissue damage. In this review, we summarize the more recent evidence highlighting the importance of cerebrovascular injury in terms of risk prediction, and the mechanisms mediating the upregulation of inflammatory mediators in cerebrovascular dysfunction and neurodegeneration.
Collapse
Affiliation(s)
- Muhammad Naveed
- Key Laboratory of Cardiovascular and Cerebrovascular Medicine, School of Pharmacy, Nanjing Medical University, Nanjing, 211166, Jiangsu Province, PR China
| | - Qi-Gang Zhou
- Department of Clinical Pharmacology, School of Pharmacy, Nanjing Medical University, Nanjing, 211166, Jiangsu Province, PR China; Sir Run Run Hospital, Nanjing Medical University, Nanjing, 211166, Jiangsu Province, PR China
| | - Feng Han
- Key Laboratory of Cardiovascular and Cerebrovascular Medicine, School of Pharmacy, Nanjing Medical University, Nanjing, 211166, Jiangsu Province, PR China.
| |
Collapse
|
4
|
Recent advances in the mechanisms of neuroinflammation and their roles in neurodegeneration. Neurochem Int 2018; 120:13-20. [PMID: 30016687 DOI: 10.1016/j.neuint.2018.07.003] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Revised: 06/07/2018] [Accepted: 07/13/2018] [Indexed: 12/11/2022]
Abstract
Neuroinflammation is associated with the pathogenesis of many neurological disorders including Parkinson's disease, Alzheimer's disease, Amyotrophic lateral sclerosis and Huntington disease. Current studies in this area have advanced the mechanism of neuroinflammation and its role in neurodegeneration. Studies from epidemiologic, clinical and animal models also contributed in the various new mechanisms of neuroinflammation. In this line, activation of monocytes is an important emerging mechanism that has a, profound role in neuroinflammation and neurodegeneration. Ion channels, matrix metalloproteases and microRNAs are also found to be the key players in the pathogenesis of neuroinflammation. In particular, microRNA-32 regulates microglia-mediated neuroinflammation and thus neurodegeneration. Notably, some important studies describe the role of Th17 cells in neuroinflammation, but, very little knowledge is available about their mechanism of action. Particularly, the role of autophagy gets emphasized, which plays a very critical role in protein aggregation and neurodegeneration. In this review, we highlight and discuss the mechanisms of these mediators of inflammation by which they contribute to the disease progression. In conclusion, we focus on the various newer molecular mechanisms that are associated with the basic understanding of neuroinflammation in neurodegeneration.
Collapse
|