endothelin-1 and Demyelinating-Diseases

Pontine infarction is the major subtype of brainstem stroke causing severe neurological deficits. The pathophysiology and treatment of pontine infarction was rarely studied. A rat model of acute pontine infarction was established via injection of endothelin-1 in the pons. Single-cell RNA sequencing was applied to detect the cellular response in pontine infarction. Based on this finding, a potential treatment for pontine infarction targeting microglia was verified. Occlusion of penetrating artery caused by endothelin-1 led to pontine infarction. Single-cell RNA sequencing revealed a subtype of activated microglia, SPP1+ microglia, which were different from M1-like or M2-like depolarization. SPP1+ microglia interacted with oligodendrocytes and contributed to the demyelination of nerve tracts. Cyclin B1 regulated the proliferation of SPP1+ microglia. Cucurbitacin E, a cyclin B1 inhibitor, reduced the proliferation of SPP1+ microglia around the injured myelin sheath and alleviated the demyelination. Moreover, cucurbitacin E treatment decreased the ischemic infarction volume and neurological deficits after pontine infarction. SPP1+ microglia contributed to axonal demyelination in the pontine infarction, and inhibition of SPP1+ microglia provided neuroprotection for pontine infarction.

Topics: Animals; Brain Stem Infarctions; Cell Proliferation; Cyclin B1; Demyelinating Diseases; Endothelin-1; Microglia; Rats

Multiple sclerosis is a chronic inflammatory demyelinating disease of the central nervous system (CNS), characterized by accumulated motor disability. However, whether remyelination promotes motor recovery following demyelinating injury remains unclear. Damage to the internal capsule (IC) is known to result in motor impairment in multiple sclerosis and stroke. Here, we induced focal IC demyelination in mice by lysophosphatidylcholine (LPC) injection, and examined its effect on motor behavior. We also compared the effect of LPC-induced IC damage to that produced by endothelin-1 (ET1), a potent vasoconstrictor used in experimental stroke lesions. We found that LPC or ET1 injections induced asymmetric motor deficit at 7 days post-lesion (dpl), and that both lesion types displayed increased microglia/macrophage density, myelin loss, and axonal dystrophy. The motor deficit and lesion pathology remained in ET1-injected mice at 28 dpl. In contrast, LPC-injected mice regained motor function by 28 dpl, with corresponding reduction in activated microglia/macrophage density, and recovery of myelin staining and axonal integrity in lesions. These results suggest that LPC-induced IC demyelination results in acute motor deficit and subsequent recovery through remyelination, and may be used to complement future drug screens to identify drugs for promoting remyelination.

Topics: Animals; Axons; Demyelinating Diseases; Endothelin-1; Immunohistochemistry; Internal Capsule; Lysophosphatidylcholines; Macrophages; Male; Mice; Mice, Inbred C57BL; Microglia; Motor Skills Disorders; Myelin Sheath; Oligodendroglia; Recovery of Function; Stroke

Experimental autoimmune encephalitis (EAE) and virally induced demyelinating disease are two major experimental model systems used to study human multiple sclerosis. Although endothelin-1 level elevation was previously observed in the CNS of mice with EAE and viral demyelinating disease, the potential role of endothelin-1 in the development of these demyelinating diseases is unknown.. In this study, the involvement of endothelin-1 in the development and progression of demyelinating diseases was investigated using these two experimental models. Administration of endothelin-1 significantly promoted the progression of both experimental diseases accompanied with elevated inflammatory T cell responses. In contrast, administration of specific endothelin-1 inhibitors (BQ610 and BQ788) significantly inhibited progression of these diseases accompanied with reduced T cell responses to the respective antigens.. These results strongly suggest that the level of endothelin-1 plays an important role in the pathogenesis of immune-mediated CNS demyelinating diseases by promoting immune responses.

Topics: Animals; Cardiovirus Infections; Demyelinating Diseases; Endothelin-1; Female; Mice; Oligopeptides; T-Lymphocytes; Theilovirus

Maintenance of white matter integrity in health and disease is critical for a variety of neural functions. Ischemic stroke in the white matter frequently results in degeneration of oligodendrocytes (OLs) and myelin. Previously, we found that toll-like receptor 2 (TLR2) expressed in OLs provides cell-autonomous protective effects on ischemic OL death and demyelination in white matter stroke. Here, we identified high-mobility group box-1 (HMGB1) as an endogenous TLR2 ligand that promotes survival of OLs under ischemic stress. HMGB1 rapidly accumulated in the culture medium of OLs exposed to oxygen-glucose deprivation (OGD). This conditioned medium exhibited a protective activity against ischemic OL death that was completely abolished by immunodepletion of HMGB1. Knockdown of HMGB1 or application of glycyrrhizin, a specific HMGB1 inhibitor, aggravated OGD-induced OL death, and recombinant HMGB1 application reduced the extent of OL death in a TLR2-dependent manner. We confirmed that cytosolic translocation of HMGB1 and activation of TLR2-mediated signaling pathways occurred in a focal white matter stroke model induced by endothelin-1 injection. Animals with glycyrrhizin coinjection showed an expansion of the demyelinating lesion in a TLR2-dependent manner, accompanied by aggravation of sensorimotor behavioral deficits. These results indicate that HMGB1/TLR2 activates an autocrine trophic signaling pathways in OLs and myelin to maintain structural and functional integrity of the white matter under ischemic conditions.

Topics: Animals; Brain Ischemia; Cells, Cultured; Demyelinating Diseases; Endothelin-1; HMGB1 Protein; Male; Mice; Mice, Inbred C57BL; Myelin Sheath; Oligodendroglia; Signal Transduction; Stroke; Toll-Like Receptor 2; White Matter

Reactive astrogliosis is an essential and ubiquitous response to CNS injury, but in some cases, aberrant activation of astrocytes and their release of inhibitory signaling molecules can impair endogenous neural repair processes. Our lab previously identified a secreted intercellular signaling molecule, called endothelin-1 (ET-1), which is expressed at high levels by reactive astrocytes in multiple sclerosis (MS) lesions and limits repair by delaying oligodendrocyte progenitor cell (OPC) maturation. However, as ET receptors are widely expressed on neural cells, the cell- and receptor-specific mechanisms of OPC inhibition by ET-1 action remain undefined. Using pharmacological approaches and cell-specific endothelin receptor (EDNR) ablation, we show that ET-1 acts selectively through EDNRB on astrocytes--and not OPCs--to indirectly inhibit remyelination. These results demonstrate that targeting specific pathways in reactive astrocytes represents a promising therapeutic target in diseases with extensive reactive astrogliosis, including MS.

Topics: Animals; Astrocytes; Cell Differentiation; Demyelinating Diseases; Disease Models, Animal; Endothelin-1; Immunohistochemistry; Mice; Mice, Inbred C57BL; Mice, Mutant Strains; Microscopy, Electron, Transmission; Neural Stem Cells; Oligodendroglia; Receptor, Endothelin B; Regeneration

Oligodendrocyte progenitor cells (OPCs) can repair demyelinated lesions by maturing into myelin-producing oligodendrocytes. However, the OPC potential to differentiate can be prevented by inhibitory signals present in the pathological lesion environment. Identification of these signals is essential to promote OPC differentiation and lesion repair. We identified an endogenous inhibitor of remyelination, Endothelin-1 (ET-1), which is highly expressed in reactive astrocytes of demyelinated lesions. Using both gain- and loss-of-function approaches, we demonstrate that ET-1 drastically reduces the rate of remyelination. We also discovered that ET-1 acts mechanistically by promoting Notch activation in OPCs during remyelination through induction of Jagged1 expression in reactive astrocytes. Pharmacological inhibition of ET signaling prevented Notch activation in demyelinated lesions and accelerated remyelination. These findings reveal that ET-1 is a negative regulator of OPC differentiation and remyelination and is potentially a therapeutic target to promote lesion repair in demyelinated tissue.

Topics: Animals; Astrocytes; Calcium-Binding Proteins; Cell Count; Cell Differentiation; Demyelinating Diseases; Disease Models, Animal; Drug Delivery Systems; Endothelin-1; Gene Expression Regulation; Glial Fibrillary Acidic Protein; Green Fluorescent Proteins; Intercellular Signaling Peptides and Proteins; Jagged-1 Protein; Lipopolysaccharides; Membrane Proteins; Mice; Mice, Inbred C57BL; Mice, Transgenic; Oligopeptides; Platelet Endothelial Cell Adhesion Molecule-1; Receptors, Notch; Serrate-Jagged Proteins; Stem Cells

White matter is frequently involved in ischemic stroke, and progressive ischemic white matter injuries are associated with various neurologic dysfunctions in the elderly population. Demyelination and oligodendrocyte (OL) loss are prominent features of ischemic white matter injury. Endothelin-1 injection into the internal capsule resulted in a localized demyelinating lesion in mice, where loss of OL lineage cells and inflammatory cell infiltration were observed accompanied by upregulation of toll-like receptor 2 (TLR2). Intriguingly, the extent of demyelinating pathology was markedly larger in TLR2 deficient mice than that of wild-type (WT) mice. TLR2 deficient mice showed enhanced OL death and decreased phosphorylation of ERK1/2 compared with WT animals. Cultured OLs from TLR2 deficient mice were more vulnerable to oxygen-glucose deprivation than WT OLs. Applying TLR2 agonists Pam3CSK4 or Zymosan after oxygen-glucose deprivation substantially rescued WT OL death with augmentation of ERK1/2 phosphorylation. Treatment with Pam3CSK4 also reduced the extent of endothelin-1 induced ischemic demyelination in vivo. Our data indicate TLR2 may provide endogenous protective effects on ischemic demyelination and OL degeneration.

Topics: Animals; Cell Death; Cells, Cultured; Demyelinating Diseases; Endothelin-1; Leukoencephalopathies; Lipopeptides; Male; MAP Kinase Signaling System; Mice; Mice, Inbred C57BL; Mice, Knockout; Oligodendroglia; Phosphorylation; Toll-Like Receptor 2; Up-Regulation

Following acute and chronic neurodegenerative disorders, a cascade of pathological events including inflammatory response, excitotoxicity and oxidative stress induces secondary tissue loss in both gray and white matter. Axonal damage and demyelination are important components of the white matter demise during these diseases. In spite of this, a few studies have addressed the patterns of inflammatory response, axonal damage and demyelination following focal ischemic damage to the central nervous system (CNS). In the present study, we describe the patterns of inflammatory response, axonal damage and myelin impairment following microinjections of 10 pmol of endothelin-1 into the rat striatum. Animals were perfused at 1 day, 3 days and 7 days after injection. 20 mum sections were stained by hematoxylin and immunolabeled for neutrophils (anti-MBS-1), activated macrophages/microglia (anti-ED1), damaged axons (anti-betaAPP) and myelin (anti-MBP). The evolution of acute inflammation was quantitatively assessed by cell counts in different survival times. There was recruitment of both neutrophils and macrophages to the damaged striatal parenchyma with maximum recruitment at 1 day and 7 days, respectively. Progressive myelin impairment in the striatal white matter tracts has been observed mainly at later survival times. beta-APP+ endbulbs were not present in all evaluated time points. These results suggest that progress myelin impairment in the absence of damage to axonal cylinder is a feature of white matter pathology following endothelin-1-induced focal striatal ischemia.

Topics: Amyloid beta-Peptides; Animals; Axons; Biomarkers; Brain Ischemia; Cerebral Arteries; Chemotaxis, Leukocyte; Corpus Striatum; Demyelinating Diseases; Disease Progression; Encephalitis; Endothelin-1; Male; Microcirculation; Microglia; Microinjections; Myelin Basic Protein; Nerve Fibers, Myelinated; Neutrophils; Rats; Rats, Wistar

Inflammatory response, axonal damage and demyelination are important components of the pathophysiology of acute neurodegenerative diseases. We have investigated the outcome of these pathological events following an excitotoxic or an ischemic damage to the spinal nucleus of adult rats at 1 and 7 days postinjury. Microinjections of 80 nmol of NMDA or 40 pmol of endothelin-1 into the rat spinal nucleus induced differential histopathological events. NMDA injection induced intense tissue loss in the gray matter (GM) without significant tissue loss in the white matter (WM). There was a mild inflammatory response, with recruitment of a few neutrophils and macrophages. Axonal damage was present in the GM following NMDA injection, with negligible axonal damage in the WM. Myelin impairment was apparent at 7 days. Microinjections of endothelin-1 into the same region induced lesser tissue loss than NMDA injections, concomitant with an intense inflammatory response characterized by recruitment of macrophages, but not of neutrophils. There were more axonal damage and early myelin impairment after endothelin-1 injection. These results were confirmed by quantitative analysis. Microcysts were present in the WM of the trigeminothalamic tract at 7 days following injection of endothelin-1. These results show that an ischemic damage to the spinal nucleus affects both GM and WM with more bystander inflammation, axonal damage and myelin impairment, while excitotoxic damage induces effects more restricted to the GM. These pathological events may occur following acute damage to the human brain stem and can be an important contributing factor to the underlying functional deficits.

Topics: Amyloid beta-Protein Precursor; Analysis of Variance; Animals; Axons; Brain Ischemia; Cell Count; Demyelinating Diseases; Ectodysplasins; Endothelin-1; Inflammation; Male; Myelin Basic Protein; N-Methylaspartate; Neurotoxins; Rats; Rats, Wistar; Time Factors; Trigeminal Nucleus, Spinal

In this study stereotaxic injections of the vasoconstrictive peptide endothelin-1 (ET-1) were used to create infarcts in the white matter of the internal capsule underlying sensorimotor cortex in rats. Resulting deficits were assessed using established sensorimotor tests conducted on each rat before and after the ET-1-induced infarct. After a 14-day survival period, histological examination revealed tissue necrosis and demyelination in the infarcted white matter of ET-1-injected rats, but not saline-injected control rats. Infarcts resulted in measurable sensorimotor deficits in rats that received ET-1 injections. The same sensorimotor tests showed no deficits in surgical-control rats. The present model of white matter infarct should be valuable in examining the underlying mechanisms of subcortical ischemic stroke and to evaluate potential therapeutic interventions.

Topics: Animals; Behavior, Animal; Brain Infarction; Demyelinating Diseases; Disease Models, Animal; Endothelin-1; Forelimb; Internal Capsule; Male; Necrosis; Psychomotor Performance; Rats; Rats, Sprague-Dawley; Vibrissae

The role of endothelin-1 (ET-1) in the development of experimental autoimmune encephalomyelitis (EAE) was studied by the blocking the action of ET-1 with a receptor antagonist, BQ-123. Intrathecal administration of BQ-123 significantly ameliorated EAE progression at the peak stage of EAE (p<0.05). By immunohistochemistry, ED-1-positive macrophages in EAE lesions were identified as major producers of ET-1, whereas the immunoreactivity of ET-1 on brain cells, such as astrocytes, was dramatically increased in accordance with the progression of EAE. This study points to a putative pro-1nflammatory role for ET-1 in the pathogenesis of EAE. One possible application for the ET-1 receptor antagonist might be helpful in the therapy of autoimmune neurological disorders.

Topics: Animals; Antihypertensive Agents; Astrocytes; Blood Vessels; Demyelinating Diseases; Disease Models, Animal; Encephalitis; Encephalomyelitis, Autoimmune, Experimental; Endothelin Receptor Antagonists; Endothelin-1; Female; Glial Fibrillary Acidic Protein; Immunohistochemistry; Injections, Spinal; Male; Nerve Degeneration; Peptides, Cyclic; Rats; Rats, Inbred Lew; Receptors, Endothelin; Spinal Cord; Treatment Outcome