Korean Red Ginseng extract ameliorates demyelination by inhibiting infiltration and activation of immune cells in cuprizone-administrated mice.

Background: Korean Red Ginseng (KRG), the steamed root of Panax ginseng, has pharmacological activities for immunological and neurodegenerative disorders. But, the role of KRGE in multiple sclerosis (MS) remains unclear. Purpose: To determine whether KRG extract (KRGE) could inhibit demyelination in corpus callosum (CC) of cuprizone (CPZ)-induced murine model of MS. Methods: Male adult mice were fed with a standard chow diet or a chow diet supplemented with 0.2% (w/w) CPZ ad libitum for six weeks to induce demyelination while were simultaneously administered with distilled water (DW) alone or KRGE-DW (0.004%, 0.02 and 0.1% of KRGE) by drinking. Results: Administration with KRGE-DW alleviated demyelination and oligodendrocyte degeneration associated with inhibition of infiltration and activation of resident microglia and monocyte-derived macrophages as well as downregulation of proinflammatory mediators in the CC of CPZ-fed mice. KRGE-DW also attenuated the level of infiltration of Th1 and Th17) cells, in line with inhibited mRNA expression of IFN-γ and IL-17, respectively, in the CC. These positive effects of KRGE-DW mitigated behavioral dysfunction based on elevated plus maze and the rotarod tests. Conclusion: The results strongly suggest that KRGE-DW may inhibit CPZ-induced demyelination due to its oligodendroglial protective and anti-inflammatory activities by inhibiting infiltration/activation of immune cells. Thus, KRGE might have potential in therapeutic intervention for MS.

An appraisal of emerging therapeutic targets for multiple sclerosis derived from current preclinical models.

INTRODUCTION: Multiple sclerosis (MS) is a chronic inflammatory, demyelinating, and neurodegenerative condition affecting the central nervous system (CNS). Although therapeutic approaches have become available over the last 20 years that markedly slow the progression of disease, there is no cure for MS. Furthermore, the capacity to repair existing CNS damage caused by MS remains very limited. AREAS COVERED: Several animal models are widely used in MS research to identify potential druggable targets for new treatment of MS. In this review, we look at targets identified since 2019 in studies using these models, and their potential for effecting a cure for MS. EXPERT OPINION: Refinement of therapeutic strategies targeting key molecules involved in the activation of immune cells, cytokine, and chemokine signaling, and the polarization of the immune response have dominated recent publications. While some progress has been made in identifying effective targets to combat chronic demyelination and neurodegeneration, much more work is required. Progress is largely limited by the gaps in knowledge of how the immune system and the nervous system interact in MS and its animal models, and whether the numerous targets present in both systems respond in the same way in each system to the same therapeutic manipulation.

A targeted extracellular vesicles loaded with montelukast in the treatment of demyelinating diseases.

The main pathological characteristics of demyelinating diseases are central nervous system (CNS) myelin damage, and the differentiation of oligodendrocyte precursor cells is the therapeutic target of myelin repair. Previous studies have found that a large number of platelet-derived growth factor receptor α(PDGFRα) positive oligodendrocyte progenitor cells (OPCs) accumulate in the lesion area of myelin injury, and differentiation is blocked. However, the therapeutic effects of drugs currently used clinically on OPCs differentiation and myelin repair are limited. The main reason is that it is difficult to reach the effective concentration of the drug in the lesion area. Therefore, efficiently delivering into the CNS lesion area is of great significance for the treatment of MS. Natural exosomes have good biocompatibility and are ideal drug carriers. The delivery of drugs to lesion areas can be achieved by giving the exosomes armed targeting ligand. Therefore, in this study, combining exosomes with PDGFA helps them accumulate in OPCs in vitro and in vivo. Further, load montelukast into exosomes to achieve targeted therapy for cuprizone-induced demyelination animal model. The implementation of this research will help provide effective treatments for demyelinating diseases and lay a theoretical foundation for its application in the clinical treatment of different demyelinating diseases.

The Salvinorin Analogue, Ethoxymethyl Ether Salvinorin B, Promotes Remyelination in Preclinical Models of Multiple Sclerosis.

Multiple sclerosis is a neurodegenerative disease associated with demyelination and neuroinflammation in the central nervous system. There is an urgent need to develop remyelinating therapies to better treat multiple sclerosis and other demyelinating diseases. The kappa opioid receptor (KOR) has been identified as a potential target for the development of remyelinating therapies; however, prototypical KOR agonists, such as U50,488 have side effects, which limit clinical use. In the current study, we investigated a Salvinorin A analog, ethoxymethyl ether Salvinorin B (EOM SalB) in two preclinical models of demyelination in C57BL/6J mice. We showed that in cellular assays EOM SalB was G-protein biased, an effect often correlated with fewer KOR-mediated side effects. In the experimental autoimmune encephalomyelitis model, we found that EOM SalB (0.1-0.3 mg/kg) effectively decreased disease severity in a KOR-dependent manner and led to a greater number of animals in recovery compared to U50,488 treatment. Furthermore, EOM SalB treatment decreased immune cell infiltration and increased myelin levels in the central nervous system. In the cuprizone-induced demyelination model, we showed that EOM SalB (0.3 mg/kg) administration led to an increase in the number of mature oligodendrocytes, the number of myelinated axons and the myelin thickness in the corpus callosum. Overall, EOM SalB was effective in two preclinical models of multiple sclerosis and demyelination, adding further evidence to show KOR agonists are a promising target for remyelinating therapies.

Ethyl Pyruvate-Derived Transdifferentiation of Astrocytes to Oligodendrogenesis in Cuprizone-Induced Demyelinating Model.

Astrocytes redifferentiate into oligodendrogenesis, raising the possibility that astrocytes may be a potential target in the treatment of adult demyelinated lesion. Upon the basis of the improvement of behavior abnormality and demyelination by ethyl pyruvate (EP) treatment, we further explored whether EP affects the function of astrocytes, especially the transdifferentiation of astrocytes into oligodendrogenesis. The results showed that EP treatment increased the accumulation of astrocytes in myelin sheath and promoted the phagocytosis of myelin debris by astrocytes in vivo and in vitro. At the same time, EP treatment induced astrocytes to upregulate the expression of CNTF and BDNF in the corpus callosum and striatum as well as cultured astrocytes, accompanied by increased expression of nestin, Sox2, and ß-catenin and decreased expression of Notch1 by astrocytes. As a result, EP treatment effectively promoted the generation of NG2+ and PDGF-Ra+ oligodendrocyte precursor cells (OPCs) that, in part, express astrocyte marker GFAP. Further confirmation was performed by intracerebral injection of primary astrocytes labeled with carboxyfluorescein diacetate succinimidyl ester (CFSE). As expected, NG2+ OPCs expressing CFSE and Sox2 were elevated in the corpus callosum of mice treated with EP following transplantation, revealing that EP can convert astrocytes into myelinating cells. Our results indicate the possibility that EP lead to effective myelin repair in patients suffering from myelination deficit.Graphical Abstract The diagram of EP action for promoting myelin regeneration in CPZ model. EP promoted migration and enrichment of astrocytes to demyelinated tissue and induced astrocytes to express neurotrophic CNTF and BDNF as well as translation factor nestin, Sox2, and ß-catenin, which should contribute to astrocytes to differentiate of oligodendrogenesis. At the same time, EP promoted astrocytes to phagocytized myelin debris for removing the harmful substances of myelin regeneration.

Effect of Fasudil on remyelination following cuprizone-induced demyelination.

BACKGROUND: Multiple sclerosis is characterized by demyelination/remyelination, neuroinflammation, and neurodegeneration. Cuprizone (CPZ)-induced toxic demyelination is an experimental animal model commonly used to study demyelination and remyelination in the central nervous system. Fasudil is one of the most thoroughly studied Rho kinase inhibitors. METHODS: Following CPZ exposure, the degree of demyelination in the brain of male C57BL/6 mice was assessed by Luxol fast blue, Black Gold II, myelin basic protein immunofluorescent staining, and Western blot. The effect of Fasudil on behavioral change was determined using elevated plus maze test and pole test. The possible mechanisms of Fasudil action were examined by immunohistochemistry, flow cytometry, ELISA, and dot blot. RESULTS: Fasudil improved behavioral abnormalities, inhibited microglia-mediated neuroinflammation, and promoted astrocyte-derived nerve growth factor and ciliary neurotrophic factor, which should contribute to protection and regeneration of oligodendrocytes. In addition, Fasudil inhibited the production of myelin oligodendrocyte glycoprotein antibody and the infiltration of peripheral CD4+ T cells and CD68+ macrophages, which appears to be related to the integrity of the blood-brain barrier. CONCLUSION: These results provide evidence for the therapeutic potential of Fasudil in CPZ-induced demyelination. However, how Fasudil acts on microglia, astrocytes, and immune cells remains to be further explored.

Ethyl pyruvate enhances spontaneous remyelination by targeting microglia phagocytosis.

Ethyl pyruvate (EP), a simple derivative of the endogenous energy substrate pyruvate, provides strong anti-inflammatory and anti-oxidative properties. but its role in remyelination has not been explored. In this study, EP efficiently improved the behavioural performance and histological demyelination in cuprizone (CPZ)-induced mouse model. In terms of action, EP treatment enhanced microglia migration, increased the phagocytosis of myelin debris by BV2 microglia and primary microglia, induced cell proliferation and subsequent cell death. At the same time, EP induced microglia to exhibit M2 phenotype, representing decreased iNOS/TNF-α and increased Arg-1/IL-10. In addition, EP decreased microglia enrichment in myelin sheath, and declined TLR4/p-NF-kb/p65 and IL-1ß and IL-6, inhibiting microglia-mediated neuroinflammation. As a result, EP treatment promoted the generation of oligodendrocyte progenitor cells (OPCs) and the differentiation from maturation to mature oligodendrocytes, which may be related to the up-regulation of Sox2. Given these data, we provided the proof-of-experiment that EP should be beneficial in multiple sclerosis or demyelinating lesions. However, further studies on the possibility to use EP as therapeutic application are warranted.

Hydroxyfasudil alleviates demyelination through the inhibition of MOG antibody and microglia activation in cuprizone mouse model.

Multiple sclerosis (MS) is an immune-mediated demyelinating disease of the central nervous system characterized by oligodendrocyte loss and progressive neurodegeneration. The cuprizone (CPZ)-induced demyelination is widely used to investigate the demyelination/remyelination. Here, we explored the therapeutic effects of Hydroxyfasudil (HF), an active metabolite of Fasudil, in CPZ model. HF improved behavioral abnormality and reduced myelin damage in the corpus callosum. Splenic atrophy and myelin oligodendrocyte glycoprotein (MOG) antibody were observed in CPZ model, which were partially restored and obviously inhibited by HF, therefore reducing pathogenic binding of MOG antibody to oligodendrocytes. HF inhibited the percentages of CD4+IL-17+ T cells from splenocytes and infiltration of CD4+ T cells and CD68+ macrophages in the brain. HF also declined microglia-mediated neuroinflammation, and promoted the production of astrocyte-derived brain derived neurotrophic factor (BDNF) and regeneration of NG2+ oligodendrocyte precursor cells. These results provide potent evidence for the therapeutic effects of HF in CPZ-induced demyelination.

Protective and therapeutic role of Bilobalide in cuprizone-induced demyelination.

Multiple sclerosis (MS) is a chronic demyelinating disease of the central nervous system characterized by recurrent and progressive demyelination, neuroinflammation and oligodendrocyte loss. The cuprizone (CPZ) model is characterized by primary and reversible demyelination, accompanied by oligodendrocyte loss and neuroinflammation. In the current study, we explored the efficiency of Bilobalide in the demyelination and remyelination. The results demonstrate that Bilobalide improved behavioral abnormality and promoted remyelination in the corpus callosum by using Luxol Fast Blue, Black Gold II and myelin basic protein (MBP) staining. We for the first time found that CPZ caused the splenic atrophy and induced the formation of myelin oligodendrocyte glycoprotein (MOG) antibody, which was attenuated by Bilobalide. Thus, Bilobalide decreased the loss of O4+ oligodendrocytes possibly through MOG antibody-dependent cell cytotoxicity. Bilobalide also prevented the infiltration of CD4+ T cells, CD68+ macrophages and B220+ B cells within the brain, and reduced the inflammatory microenvironment mediated with Iba1+iNOS+ and Iba1+NF-kB+ microglia after CPZ challenge, accompanied by the inhibition of IL-1ß and IL-6 in the brain. These results identify a potent therapeutic efficiency for Bilobalide and highlight clear pleiotropic effects of the compound beyond specific autoantibody and inflammatory microenvironment in CPZ-mediated demyelination.

Dynamic Balance of Microglia and Astrocytes Involved in the Remyelinating Effect of Ginkgolide B.

Multiple sclerosis (MS) is an inflammatory demyelinating disorder in the central nervous system (CNS), in which remyelination failure results in persistent neurologic impairment. Ginkgolide B (GB), a major terpene lactone and active component of Ginkgo biloba, has neuroprotective effects in several models of neurological diseases. Here, our results show, by using an in vivo cuprizone (CPZ)-induced demyelinating model, administration of GB improved behavior abnormalities, promoted myelin generation, and significantly regulated the dynamic balance of microglia and astrocytes by inhibiting the expression of TLR4, NF-κB and iNOS as well as IL-1ß and TNF-α, and up-regulating the expression of Arg-1 and neurotrophic factors. GB treatment also induced the generation of oligodendrocyte precursor cells (OPCs). In vitro cell experiments yielded the results similar to those of the in vivo model. The dynamic balance by decreasing microglia-mediated neuroinflammation and promoting astrocyte-derived neurotrophic factors should contribute to endogenous remyelination. Despite GB treatment may represent a novel strategy for promoting myelin recovery, the precise mechanism of GB targeting microglia and astrocytes remains to be further explored.

Brain-derived neurotrophic factor deficiency restricts proliferation of oligodendrocyte progenitors following cuprizone-induced demyelination.

Brain-derived neurotrophic factor (BDNF) is a member of the neurotrophin family of growth factors that through its neurotrophic tyrosine kinase, receptor, type 2 (TrkB) receptor, increases 5-bromo-2-deoxyuridine incorporation in oligodendrocyte progenitor cells (OPCs) in culture. Roles in vivo are less well understood; however, increases in numbers of OPCs are restricted in BDNF+/- mice following cuprizone-elicited demyelination. Here, we investigate whether these blunted increases in OPCs are associated with changes in proliferation. BDNF+/+ and BDNF+/- mice were fed cuprizone-containing or control feed. To assess effects on OPC numbers, platelet-derived growth factor receptor alpha (PDGFRα)+ or NG2+ cells were counted. To monitor DNA synthesis, 5-ethynyl-2'-deoxyuridine (EdU) was injected intraperitoneally and colocalized with PDGFRα+ cells. Alternatively, proliferating cell nuclear antigen (PCNA) was colocalized with PDGFRα or NG2. Labeling indices were determined in the BDNF+/+ and BDNF+/- animals. After 4 or 5 weeks of control feed, BDNF+/- mice exhibit similar numbers of OPCs compared with BDNF+/+ animals. The labeling indices for EdU and PCNA also were not significantly different, suggesting that neither the DNA synthesis phase (S phase) nor the proliferative pool size was different between genotypes. In contrast, when mice were challenged by cuprizone for 4 or 5 weeks, increases in OPCs observed in BDNF+/+ mice were reduced in the BDNF+/- mice. This difference in elevations in cell number was accompanied by decreases in EdU labeling and PCNA labeling without changes in cell death, indicating a reduction in the DNA synthesis and the proliferative pool. Therefore, levels of BDNF influence the proliferation of OPCs resulting from a demyelinating lesion.