Effect of Fasudil on remyelination following cuprizone-induced demyelination

Particulate matter exposure and neurodegenerative diseases: A comprehensive update on toxicity and mechanisms

Exposure to particulate matter (PM) has been associated with a range of health impacts, including neurological abnormalities that affect neurodevelopment, neuroplasticity, and behavior. Recently, there has been growing interest in investigating the possible relationship between PM exposure and the onset and progression of neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, Huntington's disease, and multiple sclerosis. However, the precise mechanism by which PM affects neurodegeneration is still unclear, even though several epidemiological and animal model studies have provided mechanistic insights. This article presents a review of the current research on the neurotoxicity of PM and its impact on neurodegenerative diseases. This review summarizes findings from epidemiological and animal model studies collected through searches in Google Scholar, PubMed, Web of Science, and Scopus. This review paper also discusses the reported effects of PM exposure on the central nervous system and highlights research gaps and future directions. The information presented in this review may inform public health policies aimed at reducing PM exposure and may contribute to the development of new treatments for neurodegenerative diseases. Further mechanistic and therapeutic research will be needed to fully understand the relationship between PM exposure and neurodegenerative diseases.

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.

Therapeutic effect of combination vitamin D3 and siponimod on remyelination and modulate microglia activation in cuprizone mouse model of multiple sclerosis

Stimulation of remyelination is critical for the treatment of multiple sclerosis (MS) to alleviate symptoms and protect the myelin sheath from further damage. The current study aimed to investigate the possible therapeutic effects of combining vitamin D3 (Vit D3) and siponimod (Sipo) on enhancing remyelination and modulating microglia phenotypes in the cuprizone (CPZ) demyelination mouse model. The study was divided into two stages; demyelination (first 5 weeks) and remyelination (last 4 weeks). In the first 5 weeks, 85 mice were randomly divided into two groups, control (n = 20, standard rodent chow) and CPZ (n = 65, 0.3% CPZ mixed with chow for 6 weeks, followed by 3 weeks of standard rodent chow). At week 5, the CPZ group was re-divided into four groups (n = 14) for remyelination stages; untreated CPZ (0.2 ml of CMC orally), CPZ+Vit D3 (800 IU/kg Vit D3 orally), CPZ+Sipo (1.5 mg/kg Sipo orally), and CPZ+Vit D3 (800 IU/kg Vit D3) + Sipo (1.5 mg/kg Sipo orally). Various behavioral tasks were performed to evaluate motor performance. Luxol Fast Blue (LFB) staining, the expression level of myelin basic protein (MBP), and M1/M2 microglia phenotype genes were assessed in the corpus callosum (CC). The results showed that the combination of Vit D3 and Sipo improved behavioral deficits, significantly promoted remyelination, and modulated expression levels of microglia phenotype genes in the CC at early and late remyelination stages. These results demonstrate for the first time that a combination of Vit D3 and Sipo can improve the remyelination process in the cuprizone (CPZ) mouse model by attenuating the M1 microglia phenotype. This may help to improve the treatment of MS patients.

Design and development of novel fasudil derivatives as potent antibreast cancer agent that improves intestinal flora and intestinal barrier function in rats

This study was conducted to develop novel fasudil derivatives after incorporation of substituted thiazoles as potent anti-breast cancer (BC) agents. The compounds were developed using a facile synthetic route in excellent yields. The entire set of developed compounds was tested for inhibitory activity against rho-associated coiled-coil kinase (ROCK; ROCK1 and ROCK2) kinase, where they exhibit potent and selective inhibition of ROCK1 as compared to ROCK2. The most potent ROCK2 inhibitor, compound 6h significantly inhibited the viability of BC cells (MCF-7). It also causes inhibition of migration and invasion of MCF-7 cells. Moreover, the anti-BC activity of compound 6h was studied in 7,12 dimethyl Benz(a)anthracene (DMBA)-induced BC in female Sprague Dawley rats. Results suggest that it causes significant improvement in the bodyweight of the animals with a reduction in oxidative stress in the liver and mammary tissues of rats. It showed improvement in the intestinal barrier function of rats by restoring the level of Diamine oxidase, d-lactate, and endotoxin. In western blot analysis, it showed improvement in (ZO-1), occludin, and claudin-1 in the colon tissue of the rat as compared to the DMBA group. Our study demonstrated the development of the novel class of fasudil derivatives potent anti-BC agent that improves intestinal flora and intestinal barrier function in rats.

Anti-LINGO-1 improved remyelination and neurobehavioral deficit in cuprizone-induced demyelination

Objective(s):

Central nervous system demyelination is the main feature of multiple sclerosis (MS). The most important unmet need in MS is use of treatments that delay the progression of the disease. Leucine-rich repeat and Immunoglobulin-like domain containing NOGO receptor-interacting protein 1(LINGO-1) have been known as inhibitors of oligodendrocyte differentiation and myelination.

Materials and Methods:

We investigated LINGO-1 antibody effects on remyelination and neurobehavioral deficit using cuprizone-induced demyelination. Animals were randomly divided into three groups (n = 10): (1) Control group; received the regular diet, (2) CPZ group; normal saline was injected intraperitoneally, and (3) Treatment group; LINGO-1 antibody (10 mg/kg) was injected IP once every six days for 3 weeks. We assessed the level of myelin basic protein (MBP), neurofilament heavy chain (NF200), and Brain-derived neuroprotective factor (BDNF) in the corpus callosum (CC) by immunostaining against MBP, NF200, and BDNF.

Results:

We found decreased levels of MBP, NF200, and BDNF in demyelinated CC, and anti-LINGO-1 treatment improved demyelinated structures. Furthermore, motor impairment was measured by Open-field (OFT) and Balance beam tests. In the treatment group, motor impairment was significantly improved.

Conclusion:

These results provide evidence that LINGO-1 antibody can improve remyelination and neurobehavioral deficit.

Trifluoperazine reduces cuprizone-induced demyelination via targeting Nrf2 and IKB in mice

Multiple sclerosis (MS) is one of the most common neurodegenerative diseases. In this disease, the immune system attacks oligodendrocyte cells and the myelin sheath of myelinated neurons in the central nervous system, causing their destruction. These conditions lead to impaired conduction of nerve impulses and are manifested by symptoms such as weakness, fatigue, visual and motor disorders. This study aimed to evaluate the ability of trifluoperazine (TF) to improve cuprizone-induced behavioral and histopathological changes in the prefrontal cortex of C57BL/6 male mice. Demyelination was induced by adding 0.2% cuprizone (CPZ) to the standard animal diet for 6 weeks. Three doses of TF (0.5, 1 and 2 mg/kg/day; i.p.) were given once daily for the last 2 weeks of treatment. Treatment with CPZ induced a weight loss during 6 weeks of treatment compared to the control group, which was reversed by the administration of TF. Behavioral tests (pole test and rotarod performance test) showed a decrease in motor coordination and balance in the group treated with CPZ (P < 0.01). Treatment with TF during the last two weeks was able to improve these motor deficiencies. Histopathological examination also evidenced an increase in demyelination in the CPZ group, which was improved by TF administration. In addition, CPZ intake significantly decreased the cerebral cortex levels of p-Nrf2 (P < 0.001) and increased the levels of p-IKB (P < 0.001) and, these changes were normalized in the TF groups. TF administration also reversed the increased levels of nitrite and the reduced activity of the antioxidant enzyme superoxide dismutase associated with CPZ exposure. TF can to reduce the harmful effects of CPZ by reducing the demyelination and modulating the Nrf2 and NF-kB signaling pathways.

Role of RhoA/ROCK signaling in Alzheimer's disease

Rho-associated coiled-coil kinase (ROCK), a serine/threonine kinase regulated by the small GTPase RhoA, is involved in regulating cell migration, proliferation, and survival. Numerous studies have shown that the RhoA/ROCK signaling pathway can promote Alzheimer's disease (AD) occurrence. ROCK activation increases β-secretase activity and promotes amyloid-beta (Aβ) production; moreover, Aβ further activates ROCK. This is suggestive of a possible positive feedback role for Aβ and ROCK. Moreover, ROCK activation promotes the formation of neurofibrillary tangles and abnormal synaptic contraction. Additionally, ROCK activation can promote the neuroinflammatory response by activating microglia and astrocytes to release inflammatory cytokines. Therefore, ROCK is a promising drug target in AD; further, there is a need to elucidate the specific mechanism of action.

Progress in the Application of Drugs for the Treatment of Multiple Sclerosis

Multiple sclerosis (MS) is an autoimmune and chronic inflammatory demyelinating disease of the central nervous system (CNS), which gives rise to focal lesion in CNS and cause physical disorders. Although environmental factors and susceptibility genes are reported to play a role in the pathogenesis of MS, its etiology still remains unclear. At present, there is no complete cure, but there are drugs that decelerate the progression of MS. Traditional therapies are disease-modifying drugs that control disease severity. MS drugs that are currently marketed mainly aim at the immune system; however, increasing attention is being paid to the development of new treatment strategies targeting the CNS. Further, the number of neuroprotective drugs is presently undergoing clinical trials and may prove useful for the improvement of neuronal function and survival. In this review, we have summarized the recent application of drugs used in MS treatment, mainly introducing new drugs with immunomodulatory, neuroprotective, or regenerative properties and their possible treatment strategies for MS. Additionally, we have presented Food and Drug Administration-approved MS treatment drugs and their administration methods, mechanisms of action, safety, and effectiveness, thereby evaluating their treatment efficacy.

Amelioration of clinical course and demyelination in the cuprizone mouse model in relation to ketogenic diet

Ketogenic diet (KD) is defined as a high-fat, low-carbohydrate diet with appropriate amounts of protein, which has broad neuroprotective effects. However, the mechanisms of ameliorating the demyelination and of the neuroprotective effects of KD have not yet been completely elucidated. Therefore, the present study investigated the protection mechanism of KD treatment in the cuprizone (bis-cyclohexanone oxalydihydrazone, CPZ)-induced demyelination mice model, with special emphasis on neuroinflammation. After the KD treatment, an increased ketone body level in the blood of mice was detected, and a significant increase in the distance traveled within the central area was observed in the open field test, which reflected the increased exploration and decreased anxiety of mice that received CPZ. The results of Luxol fast blue and myelin basic protein (MBP) immunohistochemistry staining for the evaluation of the myelin content within the corpus callosum revealed a noticeable increase in the number of myelinated fibers and myelin score after KD administration in these animals. Concomitant, the protein expressions of glial fibrillary acidic protein (GFAP, an astrocyte marker), ionized calcium-binding adaptor molecule 1 (Iba-1, a microglial marker), CD68 (an activated microglia marker) and CD16/32 (a M1 microglial marker) were down-regulated, while the expression of oligodendrocyte lineage transcription factor 2 (OLIG2, an oligodendrocyte precursor cells marker) was up-regulated by the KD treatment. In addition, the KD treatment not only reduced the level of the C-X-C motif chemokine 10 (CXCL10), which is correlated to the recruitment of activated microglia, but also inhibited the production of proinflammatory cytokines, including interleukin 1β (IL-1β) and tumor necrosis factor-α (TNF-α), which are closely correlated to the M1 phenotype microglia. It is noteworthy, that the expression levels of histone deacetylase 3 (HADC3) and nod-like receptor pyrin domain containing 3 (NLRP3) significantly decreased after KD administration. In conclusion, these data demonstrate that KD decreased the reactive astrocytes and activated the microglia in the corpus callosum, and that KD inhibited the HADC3 and NLRP3 inflammasome signaling pathway in CPZ-treated mice. This suggests that the inhibition of the HADC3 and NLRP3 signaling pathway may be a novel mechanism by which KD exerts its protective actions for the treatment of demyelinating diseases.

Astrocytes: a double-edged sword in neurodegenerative diseases

Astrocytes play multifaceted and vital roles in maintaining neurophysiological function of the central nervous system by regulating homeostasis, increasing synaptic plasticity, and sustaining neuroprotective effects. Astrocytes become activated as a result of inflammatory responses during the progression of pathological changes associated with neurodegenerative disorders. Reactive astrocytes (neurotoxic A1 and neuroprotective A2) are triggered during disease progression and pathogenesis due to neuroinflammation and ischemia. However, only a limited body of literature describes morphological and functional changes of astrocytes during the progression of neurodegenerative diseases. The present review investigated the detrimental and beneficial roles of astrocytes in neurodegenerative diseases reported in recent studies, as these cells have promising therapeutic potential and offer new approaches for treatment of neurodegenerative diseases.

Tyrosine Kinase Receptors Axl and MerTK Mediate the Beneficial Effect of Electroacupuncture in a Cuprizone-Induced Demyelinating Model

Electroacupuncture has been shown to promote remyelination in a demyelinating model of multiple sclerosis (MS) through enhanced microglial clearance of degraded myelin debris. However, the mechanisms involved in this process are yet to be clearly elucidated. It has been revealed that TAM receptor tyrosine kinases (Tyro3, Axl, and MerTK) play pivotal roles in regulating multiple features of microglia, including the phagocytic function and myelin clearance. Therefore, the aim of this study is to further confirm whether electroacupuncture improves functional recovery in this model and to characterise the involvement of the TAM receptor during this process. In addition to naive control mice, a cuprizone-induced demyelinating model was established, and long-term electroacupuncture treatment was administrated. To evaluate the efficiency of functional recovery following demyelination, we performed beam-walking test and rotarod performance test; to objectify the degree of remyelination, we performed transmission electron microscopy and protein quantification of mature oligodendrocyte markers. Oil Red O staining was used to evaluate the deposit of myelin debris. We confirmed that, in cuprizone-treated mice, electroacupuncture significantly ameliorates motor-coordinative dysfunction and counteracts demyelinating processes, with less deposit of myelin debris accumulating in the corpus callosum. Surprisingly, mRNA expression of TAM receptors was significantly upregulated after electroacupuncture treatment, and we further confirmed an increased protein expression of Axl and MerTK after electroacupuncture treatment, indicating their involvement during electroacupuncture treatment. Finally, LDC1267, a selective TAM kinase inhibitor, abolished the therapeutic effect of electroacupuncture on motor-coordinative dysfunction. Overall, our data demonstrate that electroacupuncture could mitigate the progression of demyelination by enhancing the TAM receptor expression to facilitate the clearance of myelin debris. Our results also suggest that electroacupuncture may be a potential curative treatment for MS patients.

Effect of Sox10 on remyelination of the hippocampus in cuprizone-induced demyelinated mice

OBJECTIVE

The low number of oligodendrocytes (OLs) in the hippocampus of patients with schizophrenia suggests that hippocampal demyelination is changed in this condition. Sox10 is expressed throughout OL development. The effect of Sox10 on myelin regeneration is unknown. This study aimed to analyze changes in Sox10 expression in the hippocampus and its regulatory role in hippocampal myelin regeneration in a mouse model of demyelination.

METHODS

Mice were fed 0.2% cuprizone (CPZ) for six weeks to establish the acute demyelinating model (CPZ mice). Behavioral changes of these mice were assessed via open field and tail suspension tests. The ultrastructure of the myelin sheaths in the hippocampus was observed by transmission electron microscopy. The expression levels of myelin sheath-related proteins and the transcription factor Sox10 were detected via immunohistochemistry and Western blots. Furthermore, Sox10-overexpressing adeno-associated virus was injected into the hippocampus after establishing the demyelinating model to investigate effects of Sox10 on remyelination.

RESULTS

CPZ mice showed abnormal behavioral changes, a large number of pathological changes in the myelin sheaths, and significantly reduced protein expression of the myelin sheath markers myelin basic protein and proteolipid protein. This confirmed that the demyelinating model was successfully established. Meanwhile, the protein expression of the oligodendrocyte precursor cell marker neural/glial antigen 2 (NG2) increased, whereas Sox10 expression decreased. After Sox10 overexpression in the hippocampus, the abnormal behavior was improved, the ultrastructure of the myelin sheaths was restored, and the expression of myelin sheath protein was reversed. NG2 expression was upregulated.

CONCLUSION

Overexpression of Sox10 promotes hippocampal remyelination after CPZ-induced acute demyelination.

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.