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Glia Oct 2020The presence of peripheral myelinating cells in the central nervous system (CNS) has gained the neurobiologist attention over the years. Despite the confirmed presence... (Review)
Review
The presence of peripheral myelinating cells in the central nervous system (CNS) has gained the neurobiologist attention over the years. Despite the confirmed presence of Schwann cells in the CNS in pathological conditions, and the long list of their beneficial effects on central remyelination, the cues that impede or allow Schwann cells to successfully conquer and remyelinate central axons remain partially undiscovered. A better knowledge of these factors stands out as crucial to foresee a rational therapeutic approach for the use of Schwann cells in CNS repair. Here, we review the diverse origins of Schwann cells into the CNS, both peripheral and central, as well as the CNS components that inhibit Schwann survival and migration into the central parenchyma. Namely, we analyze the astrocyte- and the myelin-derived components that restrict Schwann cells into the CNS. Finally, we highlight the unveiled mode of invasion of these peripheral cells through the central environment, using blood vessels as scaffolds to pave their ways toward demyelinated lesions. In short, this review presents the so far uncovered knowledge of this complex CNS-peripheral nervous system (PNS) relationship.
Topics: Animals; Cell Movement; Cell Survival; Central Nervous System; Demyelinating Diseases; Humans; Myelin Sheath; Peripheral Nervous System; Remyelination; Schwann Cells
PubMed: 32027054
DOI: 10.1002/glia.23788 -
Revue Neurologique Oct 2016Characteristics of the intermediate filament proteins (IFPs) expressed during the development and cell differentiation of peripheral neurons are here reviewed.... (Review)
Review
Characteristics of the intermediate filament proteins (IFPs) expressed during the development and cell differentiation of peripheral neurons are here reviewed. Neurofilament triplet proteins (NFPs), peripherin, α-internexin, synemin, syncoilin, nestin, vimentin and glial fibrillary acidic protein (GFAP) are each produced by different genes. NFPs, the most extensively studied, are thought to maintain axonal caliber, thus ensuring normal axonal transport, but this network is highly disrupted in several diseases, particularly motor neuron diseases. α-internexin has been proposed as the fourth NFP subunit. The relative plasticity of the peripherin network may account for its possible role during development, when axons have to find their targets, and when axons regenerate. In addition to their expression in muscle, other IFPs, such as syncoilin and synemin, are also expressed in neuronal tissues. Syncoilin modulates peripherin filament networks. Synemin M, associated with peripherin, is present in small unmyelinated fibers, whereas synemin L is produced in large neurons with myelinated fibers positive for the light-chain neurofilament (NF-L) subunit. Nestin is an IFP expressed in dividing cells during early stages of development in the central and peripheral nervous systems, and in muscles and other tissues. After differentiation, nestin is downregulated and replaced by tissue-specific IFPs. IFPs in glial cells are primarily composed of GFAP, although vimentin is also expressed; vimentin is also widely distributed in mesenchymal derivatives and established cell lines. In the peripheral nervous system, NFPs appear early in its development and progressively replace vimentin, which is expressed before NFPs in most, if not all, dividing neuroepithelial cells. In addition, in tissues undergoing an injury response, the unique and complex cell and tissue distribution of IFPs can be markedly modified.
Topics: Humans; Intermediate Filaments; Peripheral Nervous System; Peripheral Nervous System Diseases
PubMed: 27569989
DOI: 10.1016/j.neurol.2016.07.015 -
Frontiers in Immunology 2023The immune system has evolved to protect the host from infectious agents, parasites, and tumor growth, and to ensure the maintenance of homeostasis. Similarly, the... (Review)
Review
The immune system has evolved to protect the host from infectious agents, parasites, and tumor growth, and to ensure the maintenance of homeostasis. Similarly, the primary function of the somatosensory branch of the peripheral nervous system is to collect and interpret sensory information about the environment, allowing the organism to react to or avoid situations that could otherwise have deleterious effects. Consequently, a teleological argument can be made that it is of advantage for the two systems to cooperate and form an "integrated defense system" that benefits from the unique strengths of both subsystems. Indeed, nociceptors, sensory neurons that detect noxious stimuli and elicit the sensation of pain or itch, exhibit potent immunomodulatory capabilities. Depending on the context and the cellular identity of their communication partners, nociceptors can play both pro- or anti-inflammatory roles, promote tissue repair or aggravate inflammatory damage, improve resistance to pathogens or impair their clearance. In light of such variability, it is not surprising that the full extent of interactions between nociceptors and the immune system remains to be established. Nonetheless, the field of peripheral neuroimmunology is advancing at a rapid pace, and general rules that appear to govern the outcomes of such neuroimmune interactions are beginning to emerge. Thus, in this review, we summarize our current understanding of the interaction between nociceptors and, specifically, the myeloid cells of the innate immune system, while pointing out some of the outstanding questions and unresolved controversies in the field. We focus on such interactions within the densely innervated barrier tissues, which can serve as points of entry for infectious agents and, where known, highlight the molecular mechanisms underlying these interactions.
Topics: Humans; Nociceptors; Sensory Receptor Cells; Pain; Peripheral Nervous System; Myeloid Cells
PubMed: 37006298
DOI: 10.3389/fimmu.2023.1127571 -
The Journal of Hand Surgery May 2023Peripheral neuropathy can affect sensory, motor, or autonomic nerves and manifest with a variety of symptoms. Tuberculosis as a major infectious disease that often...
Peripheral neuropathy can affect sensory, motor, or autonomic nerves and manifest with a variety of symptoms. Tuberculosis as a major infectious disease that often affects many organs of the body. However, primary involvement of peripheral nerves is unusual. Peripheral neuropathy in patients with tuberculosis often is associated with other comorbidities, such as immunocompromised states, diabetes mellitus, malnutrition, and some antitubercular medications. This report describes the rare finding of peripheral tubercular neuritis with caseating abscesses of right median and radial nerve in a healthy 24-year man.
Topics: Male; Humans; Peripheral Nervous System Diseases; Neuritis; Peripheral Nerves; Radial Nerve; Tuberculosis
PubMed: 36922292
DOI: 10.1016/j.jhsa.2023.02.002 -
Advanced Biology Sep 2022Schwann cells (SCs) are the most abundant cell type in the nerves in the peripheral nervous system and compose a family of subtypes that are endowed with a variety of... (Review)
Review
Schwann cells (SCs) are the most abundant cell type in the nerves in the peripheral nervous system and compose a family of subtypes that are endowed with a variety of different functions. SCs facilitate the transmission of neural impulses, provide nutrients and protection for neurons, guide axons in nerve repair, and regulate immune functions. In the context of cancer, recent studies have revealed an active role of SCs in promoting cancer cell invasion, modulating immune responses, and transmitting pain sensation.
Topics: Axons; Neoplasms; Nerve Regeneration; Peripheral Nervous System; Schwann Cells
PubMed: 35666078
DOI: 10.1002/adbi.202200089 -
Current Opinion in Neurobiology Aug 2016The remarkable interaction between glial cells and axons is crucial for nervous system development and homeostasis. Alterations in this continuous communication can... (Review)
Review
The remarkable interaction between glial cells and axons is crucial for nervous system development and homeostasis. Alterations in this continuous communication can cause severe pathologies that can compromise the integrity of the nervous system. The most dramatic consequence of this interaction is the generation of the myelin sheath, made by myelinating glial cells: Schwann cells in the peripheral nervous system and oligodendrocytes in the central nervous system. In this review I will focus on signals coming from axons in the first part and then on those from Schwann cells that promote the formation and the maintenance of peripheral myelin. I will discuss their inter-relationship together with seminal and important advances recently made.
Topics: Axons; Humans; Myelin Sheath; Oligodendroglia; Peripheral Nervous System; Schwann Cells
PubMed: 27089429
DOI: 10.1016/j.conb.2016.03.006 -
Trends in Endocrinology and Metabolism:... Oct 2023The peripheral nervous system (PNS) relays information between organs and tissues and the brain and spine to maintain homeostasis, regulate tissue functions, and respond... (Review)
Review
The peripheral nervous system (PNS) relays information between organs and tissues and the brain and spine to maintain homeostasis, regulate tissue functions, and respond to interoceptive and exteroceptive signals. Glial cells perform support roles to maintain nerve function, plasticity, and survival. The glia of the central nervous system (CNS) are well characterized, but PNS glia (PNSG) populations, particularly tissue-specific subtypes, are underexplored. PNSG are found in large nerves (such as the sciatic), the ganglia, and the tissues themselves, and can crosstalk with a range of cell types in addition to neurons. PNSG are also subject to phenotypic changes in response to signals from their local tissue environment, including metabolic changes. These topics and the importance of PNSG in metabolically active tissues, such as adipose, muscle, heart, and lymphatic tissues, are outlined in this review.
Topics: Humans; Neuroglia; Peripheral Nervous System; Neurons; Homeostasis; Central Nervous System
PubMed: 37591710
DOI: 10.1016/j.tem.2023.07.004 -
Development (Cambridge, England) Nov 2019During the development of the peripheral nervous system, axons and myelinating Schwann cells form a unique symbiotic unit, which is realized by a finely tuned network of... (Review)
Review
During the development of the peripheral nervous system, axons and myelinating Schwann cells form a unique symbiotic unit, which is realized by a finely tuned network of molecular signals and reciprocal interactions. The importance of this complex interplay becomes evident after injury or in diseases in which aspects of axo-glial interaction are perturbed. This Review focuses on the specific interdependence of axons and Schwann cells in peripheral nerve development that enables axonal outgrowth, Schwann cell lineage progression, radial sorting and, finally, formation and maintenance of the myelin sheath.
Topics: Animals; Axons; Cell Differentiation; Cell Lineage; Cell Separation; Gene Expression Regulation, Developmental; Mice; Myelin Sheath; Nerve Regeneration; Neuroglia; Peripheral Nerves; Peripheral Nervous System; Rats; Schwann Cells; Signal Transduction
PubMed: 31719044
DOI: 10.1242/dev.151704 -
Tropical Biomedicine Sep 2021Ever since the first reported case series on SARS-CoV-2-induced neurological manifestation in Wuhan, China in April 2020, various studies reporting similar as well as... (Review)
Review
Ever since the first reported case series on SARS-CoV-2-induced neurological manifestation in Wuhan, China in April 2020, various studies reporting similar as well as diverse symptoms of COVID-19 infection relating to the nervous system were published. Since then, scientists started to uncover the mechanism as well as pathophysiological impacts it has on the current understanding of the disease. SARS-CoV-2 binds to the ACE2 receptor which is present in certain parts of the body which are responsible for regulating blood pressure and inflammation in a healthy system. Presence of the receptor in the nasal and oral cavity, brain, and blood allows entry of the virus into the body and cause neurological complications. The peripheral and central nervous system could also be invaded directly in the neurogenic or hematogenous pathways, or indirectly through overstimulation of the immune system by cytokines which may lead to autoimmune diseases. Other neurological implications such as hypoxia, anosmia, dysgeusia, meningitis, encephalitis, and seizures are important symptoms presented clinically in COVID-19 patients with or without the common symptoms of the disease. Further, patients with higher severity of the SARS-CoV-2 infection are also at risk of retaining some neurological complications in the long-run. Treatment of such severe hyperinflammatory conditions will also be discussed, as well as the risks they may pose to the progression of the disease. For this review, articles pertaining information on the neurological manifestation of SARS-CoV-2 infection were gathered from PubMed and Google Scholar using the search keywords "SARS-CoV-2", "COVID-19", and "neurological dysfunction". The findings of the search were filtered, and relevant information were included.
Topics: Angiotensin-Converting Enzyme 2; Anosmia; COVID-19; Central Nervous System; Dysgeusia; Encephalitis, Viral; Humans; Meningitis, Viral; Nervous System Diseases; Peripheral Nervous System; SARS-CoV-2; Seizures
PubMed: 34608117
DOI: 10.47665/tb.38.3.086 -
Current Opinion in Neurobiology Feb 2017In the vertebrate nervous system, the fast conduction of action potentials is potentiated by the myelin sheath, a multi-lamellar, lipid-rich structure that also provides... (Review)
Review
In the vertebrate nervous system, the fast conduction of action potentials is potentiated by the myelin sheath, a multi-lamellar, lipid-rich structure that also provides vital trophic and metabolic support to axons. Myelin is elaborated by the plasma membrane of specialized glial cells, oligodendrocytes in the central nervous system (CNS) and Schwann cells (SCs) in the peripheral nervous system (PNS). The diseases that result from damage to myelin or glia, including multiple sclerosis and Charcot-Marie-Tooth disease, underscore the importance of these cells for human health. Therefore, an understanding of glial development and myelination is crucial in addressing the etiology of demyelinating diseases and developing patient therapies. In this review, we discuss new insights into the roles of mechanotransduction and cytoskeletal rearrangements as well as activity dependent myelination and axonal maintenance by glia. Together, these discoveries advance our knowledge of myelin and glia in nervous system health and plasticity throughout life.
Topics: Axons; Humans; Mechanotransduction, Cellular; Neuroglia; Neurology; Peripheral Nervous System
PubMed: 27930937
DOI: 10.1016/j.conb.2016.11.003