Experimental Autoimmune Encephalomyelitis Mice Research Articles

Inflammation-Targeted Biomimetic Nano-Decoys via Inhibiting the Infiltration of Immune Cells and Effectively Delivering Glucocorticoids for Enhanced Multiple Sclerosis Treatment.

Excessive infiltration of neutrophil and inflammatory cytokines accumulation as well as the inadequate delivery of drugs to the targeted site are key pathological cascades in multiple sclerosis (MS). Herein, inflammation-targeting biomimetic nano-decoys (TFMN) is developed that inhibit the infiltration of immune cells and effectively deliver glucocorticoids to lesions for enhanced MS treatment. Nano-decoys encapsulated with the glucocorticoid methylprednisolone (MPS) are prepared by coating neutrophil membrane (NM) on nanoparticles formed by the self-assembly of tannic acid and poloxamer188/pluronic68. Benefiting from the natural inflammation-targeting ability of activated neutrophil membranes, TFMN can target the lesion site and prevent neutrophils infiltration by adsorbing and neutralizing elevated neutrophil-related cytokines, subsequently modulating the inflammatory microenvironment in experimental autoimmune encephalomyelitis mice. TFMN exhibits a strong antioxidant capacity and scavenged excessive reactive oxygen species to enhance neuronal protection. Furthermore, at the inflammation site, perforin, discharged by cytotoxic T-lymphocytes, triggered the controlled release of MPS within the TFMN through perforin-formed pores in the NM. Simultaneously, this mechanism protected neurons from perforin-induced toxicity. The MPS liberated at the targeted site achieves optimal drug accumulation, thereby enhancing therapeutic efficacy. In conclusion, the innovative system shows potential for integrating various therapeutic agents, offering a novel strategy for CNS disorders.

Build muscles and protect myelin

Abstract Multiple sclerosis (MS) is a chronic and debilitating autoimmune disease of the central nervous system (CNS) in which a CNS-driven immune response destroys myelin, leading to wide range of symptoms including numbness and tingling, vision problems, mobility impairment, etc. Oligodendrocytes are the myelinating cells in the CNS, which are generated from oligodendroglial progenitor cells (OPCs) via differentiation. However, for multiple reasons, OPCs fail to differentiate to oligodendrocytes in MS and as a result, stimulating the differentiation of OPCs to oligodendrocytes is considered beneficial for MS. The β-hydroxy β-methylbutyrate (HMB) is a widely-used muscle-building supplement in human and recently it has been shown that low-dose HMB is capable of stimulating the differentiation of cultured OPCs to oligodendrocytes for remyelination. Moreover, other causes of autoimmune demyelination are the decrease and/or suppression of Foxp3-expressing anti-autoimmune regulatory T cells (Tregs) and upregulation of autoimmune T-helper 1(Th1) and Th17 cells. Experimental autoimmune encephalomyelitis (EAE) is an animal model of MS in which the autoimmune demyelination is nicely visible. It has been reported that in EAE mice, oral HMB upregulates Tregs and decreases Th1 and Th17 responses, leading to remyelination in the CNS. Here, we analyze these newly-described features of HMB, highlighting the putative promyelinating nature of this supplement.

Demyelination and neurodegeneration early in experimental autoimmune encephalomyelitis contribute to functional deficits in the anterior visual pathway

Impaired visual function is a prevalent feature of optic neuritis (ON) in multiple sclerosis (MS). Abnormal visual evoked potential (VEP) findings of increased latencies, reduced amplitudes and abnormal waveforms as well as decreased retinal nerve fiber layer (RNFL) assessed by optical coherence tomography (OCT) are hallmarks of ON-induced visual dysfunction. Here we utilized the experimental autoimmune encephalomyelitis (EAE) mouse model of MS to investigate the functional and pathological progression during early (before any clinical symptoms), peak (initial maximal clinical symptoms), and late (chronic disease for > 3 weeks) disease stages. Demyelination and initial stages of axon damage were observed in early EAE. Significant demyelination, inflammation, increased axon damage and impaired P1/N2 amplitudes and latencies by VEP were seen in middle and late EAE groups. A decrease in RNFL thickness by OCT was observed only during late EAE. NanoString analysis of optic nerves from late EAE indicated elevated inflammation-related genes, reduced myelin-related genes, and changes in axon degeneration-related genes. Early inflammatory demyelination and functional deficits of the visual pathway, if untreated, may lead to severe irrecoverable axon damage in EAE. These studies potentially help explain the progression of visual dysfunction during MS.

Disruption of blood-brain barrier and endothelial-to-mesenchymal transition are attenuated by Astragalus polysaccharides mediated through upregulation of ETS1 expression in experimental autoimmune encephalomyelitis

Blood-brain barrier (BBB) breakdown, an early hallmark of multiple sclerosis (MS), remains crucial for MS progression. Our previous works have confirmed that Astragalus polysaccharides (APS) can significantly ameliorate demyelination and disease progression in experimental autoimmune encephalomyelitis (EAE) mice. However, it remains unclear whether APS protects BBB and the potential mechanism. In this study, we found that APS effectively reduced BBB leakage in EAE mice, which was accompanied by a decreased level of endothelial-to-mesenchymal transition (EndoMT) in the central nervous system (CNS). We further induced EndoMT in the mouse brain endothelial cells (bEnd.3) by interleukin-1β (IL-1β) in vitro. The results showed that APS treatment could inhibit IL-1β-induced EndoMT and endothelial cell dysfunction. In addition, the transcription factor ETS1 is a central regulator of EndoMT related to the compromise of BBB. We tested the regulation of APS on ETS1 and identified the expression of ETS1 was upregulated in both EAE mice and bEnd.3 cells by APS. ETS1 knockdown facilitated EndoMT and endothelial cell dysfunction, which completely abolished the regulatory effect of APS. Collectively, APS treatment could protect BBB integrity by inhibiting EndoMT, which might be associated with upregulating ETS1 expression. Our findings indicated that APS has potential value in the prevention of MS.

Immunofluorescence Staining of Murine Spinal Cord Sections to Evaluate Microglial Activation and Astrogliosis.

Microglia and astrocytes are the main components of the central nervous system (CNS). Upon activation, microglia is able to phagocyte cell debris, pathogens, and toxins; astrocytes support neuronal functions, blood-brain barrier (BBB) homeostasis, and neurotransmitter uptake and metabolism. Furthermore, both cell types can produce cytokines and chemokines. Aging impacts microglia and astrocytes by promoting the production of pro-inflammatory cytokines, impairing microglial phagocytosis and motility and astrocyte glutamate uptake. During neurodegenerative and neuroinflammatory diseases, the aging process may be accelerated contributing to the alteration of CNS glial cells functions. Multiple sclerosis (MS) is an autoimmune, demyelinating disease in which immunosenescence can promote the conversion from relapsing-remitting form to progressive disease. The murine model of experimental autoimmune encephalomyelitis (EAE) allows to investigate MS pathogenesis. Furthermore, EAE can be developed as acute or progressive, mimicking different forms of human MS. Microglia and astrocytes report morphological and functional changes during neuroinflammation that can be investigated in different ways. We here present a protocol for the study of glial cell activation in the spinal cord tissue of EAE mice.

Prebiotic inulin controls Th17 cells mediated central nervous system autoimmunity through modulating the gut microbiota and short chain fatty acids

ABSTRACT Multiple sclerosis (MS) is an autoimmune disease characterized by inflammatory demyelination occurring in the central nervous system (CNS). Inulin is a common prebiotic that can improve metabolic disorders by modulating the gut microbiota. However, its capacity to affect CNS autoimmunity is poorly recognized. Experimental autoimmune encephalomyelitis (EAE) is a classical mouse model of MS. Herein, we found that oral administration of inulin ameliorated the severity EAE in mice, accompanied by reductions in inflammatory cell infiltration and demyelination in the CNS. These reductions were associated with decreased proportion and numbers of Th17 cells in brain and spleen. Consistent with the findings, the serum concentrations of IL-17, IL-6, and TNF-α were reduced in inulin treated EAE mice. Moreover, the proliferation of auto-reactive lymphocytes, against MOG35-55 antigen, was attenuated ex vivo. Mechanistically, inulin treatment altered the composition of gut microbiota. It increased Lactobacillus and Dubosiella whereas decreased g_Prevotellaceae_NK3B31_group at the genus level, alongside with elevated concentration of butyric acid in fecal content and serum. In vitro, butyrate, but not inulin, could inhibit the activation of MOG35-55 stimulated lymphocytes. Furthermore, fecal microbiota transplantation assay confirmed that fecal contents of inulin-treated normal mice had an ameliorative effect on EAE mice. In contrast, antibiotic cocktail (ABX) treatment diminished the therapeutic effect of inulin in EAE mice as well as the reduction of Th17 cells, while supplementation with Lactobacillus reuteri restored the amelioration effect. These results confirmed that the attenuation of inulin on Th17 cells and inflammatory demyelination in EAE mice was dependent on its modulation on gut microbiota and metabolites. Our findings provide a potential therapeutic regimen for prebiotic inulin supplementation in patients with multiple sclerosis.

Discussion of spinal cord neurons apoptosis and neuroprotection mechanism of NGF gene transfection mediated by recombinant adenovirus in EAE mice

To investigate the spinal cord neuron apoptosis and neuroprotective mechanism of nerve growth factorganismsor (NGF) gene mediated by recombinant adenovirus (Ad-NGF) via peripheral transfection in mice with experimental autoimmune encephalomyelitis (EAE). Forty healthy female C57BL/6 mice were randomly divided into a control group, adenovirus (AdV) group, EAE group, and Ad-NGF transfection group; the control group received no treatment; the AdV group received adenovirus injection via the tail vein; the EAE and Ad-NGF transfection groups were induced with experimental autoimmune encephalomyelitis (EAE) using myelin oligodendrocyte glycoprotein 35–55 (MOG35-55), Ad-NGF transfection group received Ad-NGF injection via the tail vein, and daily neurological impairment scores were obtained. AQThe TUNEL method was employed to observe spinal neuron apoptosis in each group of mice; protein immunoblotting (western blot) and RT-PCR were used to measure NGF levels in the spinal cord tissues of each group, and western blotting was used to assess levels of cleaved caspase-3, Bax, and Bcl-2. ELISA and RT-PCR were employed to detect protein and mRNA levels of neuron-specific enolase (NSE) in spinal cord tissues, respectively. The control group and AdV mice did not develop symptoms. Compared to the EAE group, in the Ad-NGF transfection group, neurological function scores, TUNEL-positive cell counts, the ratio of NeuN + TUNEL to NeuN, levels of Bax and cleaved caspase-3 apoptotic proteins were significantly reduced, while Bcl-2 protein expression was increased. Expression levels of NGF, NGF-mRNA, NSE, and NSE-mRNA in spinal cord tissues were significantly elevated (P < 0.01). Immunofluorescence labeling revealed a significant punctate aggregation of apoptotic cells in spinal neurons of the EAE group, while the aggregation phenomenon was less pronounced in the Ad-NGF transfection group. Ad-NGF transfected by the periphery has a protective effect on spinal cord neurons in EAE mice by up-regulation NGF level, down-regulating apoptotic protein Caspase-3 in spinal cord neurons, inhibiting spinal cord neuron apoptosis and promoting NSE expression.

The Protective Effect of Astragalus Polysaccharide on Experimental Autoimmune Encephalomyelitis in Mice by Activating the AMPK/JAK/STAT3/Arginase-1 Signaling Pathway.

This study aimed to investigate the protective effect and mechanism of Astragalus polysaccharide (APS) on autoimmune encephalomyelitis. C57BL/6 mice were randomly divided into the blank control group, EAE group, and APS intervention group (n=15/group). The Experimental Autoimmune Encephalomyelitis (EAE) mouse model was established by active immunization. The pathological changes in the spinal cord were evaluated by Hematoxylin-eosin (HE) and Luxol Fast Blue (LFB) staining. The number of CD11b+ Gr-1+ myeloid-derived suppressor cells (MDSCs) in the spleen tissues of mice in each group was determined by immunofluorescence staining. The expression of Arginase-1 in the spinal cord and spleen of each group was detected by immunofluorescence double staining. The TNF-α, IL-6, and Arginase-1 levels in the spleen were detected by ELISA assay. A western blot was used to detect the protein expression of the AMPK/JAK/STAT3/Arginase-1 signaling pathway. After the intervention of APS, the incidence of autoimmune encephalomyelitis in mice of the APS group was significantly lower than that in the EAE group, and the intervention of APS could significantly delay the onset time in the EAE mice, and the score of neurological function deficit in mice was significantly lower than that in EAE group (P < 0.05). APS intervention could reduce myelin loss and improve the inflammatory response of EAE mice. Moreover, it could induce the expression of CD11b+ GR-1 + bone MDSCs in the spleen and increase the expression of Arginase-1 in the spinal cord and spleen. This study further demonstrated that APS can protect EAE mice by activating the AMPK/JAK/STAT3/Arginase-1 signaling pathway. After the intervention of APS, myelin loss and inflammatory response of EAE mice were effectively controlled. APS promoted the secretion of Arginase-1 by activating MDSCs and inhibited CD4+T cells by activating AMPK/JAK/STAT3/Arginase-1 signaling pathway, thus improving the clinical symptoms and disease progression of EAE mice.

Upregulated expression of ubiquitin ligase TRIM21 promotes PKM2 nuclear translocation and astrocyte activation in experimental autoimmune encephalomyelitis.

Reactive astrocytes play critical roles in the occurrence of various neurological diseases such as multiple sclerosis. Activation of astrocytes is often accompanied by a glycolysis-dominant metabolic switch. However, the role and molecular mechanism of metabolic reprogramming in activation of astrocytes have not been clarified. Here, we found that PKM2, a rate-limiting enzyme of glycolysis, displayed nuclear translocation in astrocytes of EAE (experimental autoimmune encephalomyelitis) mice, an animal model of multiple sclerosis. Prevention of PKM2 nuclear import by DASA-58 significantly reduced the activation of mice primary astrocytes, which was observed by decreased proliferation, glycolysis and secretion of inflammatory cytokines. Most importantly, we identified the ubiquitination-mediated regulation of PKM2 nuclear import by ubiquitin ligase TRIM21. TRIM21 interacted with PKM2, promoted its nuclear translocation and stimulated its nuclear activity to phosphorylate STAT3, NF-κB and interact with c-myc. Further single-cell RNA sequencing and immunofluorescence staining demonstrated that TRIM21 expression was upregulated in astrocytes of EAE. TRIM21 overexpressing in mice primary astrocytes enhanced PKM2-dependent glycolysis and proliferation, which could be reversed by DASA-58. Moreover, intracerebroventricular injection of a lentiviral vector to knockdown TRIM21 in astrocytes or intraperitoneal injection of TEPP-46, which inhibit the nuclear translocation of PKM2, effectively decreased disease severity, CNS inflammation and demyelination in EAE. Collectively, our study provides novel insights into the pathological function of nuclear glycolytic enzyme PKM2 and ubiquitination-mediated regulatory mechanism that are involved in astrocyte activation. Targeting this axis may be a potential therapeutic strategy for the treatment of astrocyte-involved neurological disease.

Effects of long-term magnesium L-threonate supplementation on neuroinflammation, demyelination and blood–brain barrier integrity in mice with neuromyelitis optica spectrum disorder

In clinical practice, we found cerebrospinal fluid magnesium concentration significantly lower in neuromyelitis optica spectrum disorder (NMOSD) patients compared to controls with non-autoimmune encephalitis neurological diseases. To investigate the effects and potential mechanisms of long-term magnesium supplementation on neuroinflammation, demyelination, and blood–brain barrier (BBB) integrity in NMOSD, we used two models: (1) NMOSD mouse model, which was induced by intraperitoneal injection of purified NMO-IgG to experimental autoimmune encephalomyelitis (EAE) mice, and (2) cultured human cerebral microvascular endothelial cells/D3 (hCMEC/D3). In the NMOSD mouse model, Magnesium L-threonate (MgT) pretreatment alleviated NMO-IgG–induced effects, including AQP4 loss, leukocyte infiltration, astrocyte and microglia activation, demyelination, decreased tight junction (TJ) protein expression, and neurological deficits. In vitro, MgT pretreatment ameliorated NMO-IgG induced damage to TJ protein expression in a (transient receptor potential melastatin 7) TRPM7-dependent manner. Magnesium supplementation shows potential protective effects against NMOSD, suggesting it may be a novel therapeutic approach for this condition. The beneficial effects appear to be mediated through preservation of blood–brain barrier integrity and reduction of neuroinflammation and demyelination.

Dysregulation of miR-223, miR-146a, and miR-193a Expression Profile in Acute and Chronic Phases of Experimental Autoimmune Encephalomyelitis in C57BL/6 Mice.

Multiple sclerosis (MS) is a chronic autoimmune disease with an unknown etiology. The purpose of this research was to assess miR-223, miR-146a, and miR-193a in acute and chronic phases of experimental autoimmune encephalomyelitis (EAE) mice to consider the possible role of these genes in the pathogenesis of MS. EAE induction was given by myelin oligodendrocyte glycoprotein peptide on female C57BL/6 mice. Clinical scores and other criteria were followed daily until day 21 for the acute group and day 77 for the chronic group. At the end of the course, inflammation and demyelination of the central nervous system (CNS) were assessed by histological analysis. MicroRNA expression levels were assessed by real-time PCR. EAE development attenuated in the chronic group, and histological analysis showed less infiltration and demyelination in the chronic group compared to the acute group. The upper expression of miR-223 is demonstrated in the acute phase of EAE. Moreover, the expression levels of miR-146a and miR-193a decreased in the chronic phase of EAE. MiR-223 showed a highly coordinated elevation in the acute phase both in vivo and in vitro. MiR-146a shares a pathway with miR-223 through effecting IL-6 expression. Further studies are needed to reveal their impact on EAE and possible applications as drug targets and biomarkers.

CD8+T cell infiltration-associated barrier function of brain endothelial cells is enhanced by Astragalus polysaccharides via inhibiting PI3K/AKT signaling pathway.

Pathogenic CD8+T cells play an essential role in neuroinflammation and neural injury, which leads to the progression of inflammatory neurological disorders. Thus, blocking the infiltration of CD8+T cells is necessary for the treatment of neuroinflammatory diseases. Our previous study demonstrated that Astragalus polysaccharides (APS) could significantly reduce the infiltration of CD8+T cells in experimental autoimmune encephalomyelitis (EAE) mice. However, the mechanism by which APS suppress CD8+T cell infiltration remains elusive. In this study, we further found that APS could reduce the CD8+T cell infiltration in EAE and lipopolysaccharide (LPS)-induced neuroinflammatory model. Furthermore, we established the mouse brain endothelial cell (bEnd.3) inflammatory injury model by interleukin-1β (IL-1β) or LPS in vitro. The results showed that APS treatment downregulated the expression of vascular cell adhesion molecule1 (VCAM1) to decrease the adhesion of CD8+T cells to bEnd.3 cells. APS also upregulated the expression of zonula occluden-1 (ZO-1) and vascular endothelial cadherin (VE-cadherin) to reduce the trans-endothelial migration of CD8+T cells. The PI3K/AKT signaling pathway might mediate this protective effect of APS on bEnd.3 cells against inflammatory injury. In addition, we demonstrated the protective effect of APS on the integrity of brain endothelial cells in an LPS-induced neuroinflammatory model. In summary, our results indicate that APS can reduce peripheral CD8+T cell infiltration via enhancing the barrier function of brain endothelial cells, it may be a potential for the prevention of neuroinflammatory diseases.

Matrine protects against experimental autoimmune encephalomyelitis through modulating microglial ferroptosis

Multiple sclerosis (MS) is an inflammatory demyelination neurodegenerative disease of the central nervous system (CNS). Ferroptosis has been implicated in a range of brain disorders, and iron-loaded microglia are frequently found in affected brain regions. However, the molecular mechanisms linking ferroptosis with MS have not been well-defined. The present study seeks to bridge this gap and investigate the impact of matrine (MAT), a herbal medicine with immunomodulatory capacities, on the regulation of oxidative stress and ferroptosis in the CNS of mice with experimental autoimmune encephalomyelitis (EAE), an animal model of MS. CNS of EAE mice contained elevated levels of ferroptosis-related molecules, e.g., MDA, LPCAT3 and PTGS2, but decreased expression of antioxidant molecules, including GSH and SOD, GPX4 and SLC7A11. This pathogenic process was reversed by MAT treatment, together with significant reduction of disease severity and CNS inflammatory demyelination. Furthermore, the expression of PTGS2 and LOX was largely increased in microglia of EAE mice, accompanied with increased production of IL-6 and TNF-α, indicating a proinflammatory phenotype of microglia that undergo oxidative stress/ferroptosis, and their expression was significantly reduced after MAT treatment. Together, our results indicate that ferroptosis/inflammation plays an important role in the pathogenesis of CNS autoimmunity, and inhibiting ferroptosis-induced microglial activation/inflammation could be a novel mechanism underlying the therapeutic effects of MAT on CNS inflammatory demyelination in EAE.

Non-saponin from Panax ginseng maintains blood-brain barrier integrity by inhibiting NF-κB and p38 MAP kinase signaling pathways to prevent the progression of experimental autoimmune encephalomyelitis

BackgroundThe non-saponin (NS) fraction is an important active component of Panax ginseng, with multifunctional pharmacological activities including neuroprotective, immune regulatory, anti-inflammatory, and antioxidant effects. However, the effects of NSs on multiple sclerosis (MS), a chronic and autoimmune demyelinating disorder, have not yet been demonstrated. Purposeand Methods: The goal of the present study was to demonstrate the pharmacological actions of NSs on movement dysfunctions and the related mechanisms of action using an experimental autoimmune encephalomyelitis (EAE) mouse model of MS. ResultsNSs (p.o.) alleviated movement dysfunctions in EAE mice related to reduced demyelination in the lumbar spinal cord (LSC). NSs attenuated the recruitment of microglia (CD11b+/CD45low) and macrophages (CD11b+/CD45high) in LSCs from EAE model mice, consistent with the decreased mRNA expression levels of the main proinflammatory mediators (IL-1β, COX-2, MCP-1, MIP-1α, and RANTES). NSs blocked the migration of Th17 cells (CD4+/IL17A+) and mRNA expression levels of IL-17A (product of Th17 cells) in LSCs from EAE mice. NSs suppressed alterations in blood-brain barrier (BBB) components, such as astrocytes and cell adhesion molecules, associated with inhibiting NF-κB and p38 MAPK pathways in LSCs of EAE mice and lipopolysaccharide-induced bEND.3 cells. ConclusionsNSs could attenuate movement dysfunctions and related pathological/inflammatory changes by reducing BBB permeability through NF-κB and p38 MAPK pathway inhibition in LSCs of EAE model mice. These are the first results suggesting that NSs can be potential therapeutic agents for MS by reducing BBB permeability.

Single-Cell RNA Sequencing Reveals Transcriptional Landscape of Neutrophils and Highlights the Role of TREM-1 in EAE.

Neutrophils, underestimated in multiple sclerosis (MS), are gaining increased attention for their significant functions in patients with MS and the experimental autoimmune encephalomyelitis (EAE) animal model. However, the precise role of neutrophils in cervical lymph nodes (CLNs), the primary CNS-draining lymph nodes where the autoimmune response is initiated during the progression of EAE, remains poorly understood. Applying single-cell RNA sequencing (scRNA-seq), we constructed a comprehensive immune cell atlas of CLNs during development of EAE. Through this atlas, we concentrated on and uncovered the transcriptional landscape, phenotypic and functional heterogeneity of neutrophils, and their crosstalk with immune cells within CLNs in the neuroinflammatory processes in EAE. Notably, we observed a substantial increase in the neutrophil population in EAE mice, with a particular emphasis on the significant rise within the CLNs. Neutrophils in CLNs were categorized into 3 subtypes, and we explored the specific roles and developmental trajectories of each distinct neutrophil subtype. Neutrophils were found to engage in extensive interactions with other immune cells, playing crucial roles in T-cell activation. Moreover, our findings highlighted the strong migratory ability of neutrophils to CLNs, partly regulated by triggering the receptor expressed on myeloid cells 1 (TREM-1). Inhibiting TREM1 with LR12 prevents neutrophil migration both in vivo and in vitro. In addition, in patients with MS, we confirmed an increase in peripheral neutrophils with an upregulation of TREM-1. Our research provides a comprehensive and precise single-cell atlas of CLNs in EAE, highlighting the role of neutrophils in regulating the periphery immune response. In addition, TREM-1 emerged as an essential regulator of neutrophil migration to CLNs, holding promise as a potential therapeutic target in MS.

AtRA Attenuates High Salt-Driven EAE Mainly Through Suppressing Th17-Like Regulatory T Cell Response Mediated by the Inhibition of IL-23R Signaling Pathway.

High salt diet (HSD) is implicated in numerous disorders, which boosts Th17 cell development and weakens immunosuppressive function of regulatory T cells (Treg cells) Treg cells, leading to the exacerbation of EAE. However, little is known regarding the harness of excessive proinflammatory responses evoked by HSD. Here we show that atRA, a key vitamin A metabolite with multifaceted immunoregulatory properties has the potential in inhibiting the proinflammatory reaction of high salt. Treatment with atRA in vivo elicited the Treg generation in cervical and axillary lymph nodes (CALs), and in CNS of experimental autoimmune encephalomyelitis (EAE). Meanwhile, the proportion of Th17-like Treg cells (RORγt-positive or GM-CSF-positive Treg cells) decreased in CALs. atRA also inhibited IL-17A expression in CD4+ effector T cells. In-vitro mechanistic studies showed that atRA inhibit IL-23R but not SGK1 expression in Treg cells and this results in maintained immunosuppressive function of Treg cells even in the presence of IL-6 and high salt. Furthermore, treatment of EAE with anti-IL-23R mAb attenuated HSD-provoked EAE progress. This was associated with a reduction in the number of CNS-infiltrating Th17 cells and an increase of CAL-Treg cells. Mechanically, treatment with atRA significantly promoted LP-CD103+CD11c+ dendritic cells, a subgroup of cells most closely involved in endogenous retinoic acid metabolism, and enhanced intestinal Aldh1a1 and Rdh10 expression from HSD-fed EAE mice. Interestingly, anti-IL-23R mAb administration also reduced IL-23R expression in Treg cells, along with the increased proportion of LP-CD103+CD11c+ dendritic cells and Rdh10 mRNA expression. In conclusion, administration of atRA might be a way to combat the proinflammatory effects of HSD. Meanwhile, systematic inhibition of IL-23R also had a moderate therapeutic potential in inhibiting inflammatory effects of high salt, which may serve as a basis for the identification of novel therapeutic strategies against HSD-driven autoimmune disorders.

Deferoxamine preconditioning of canine stem cell derived extracellular vesicles alleviates inflammation in an EAE mouse model through STAT3 regulation

Extracellular vesicles (EVs) from mesenchymal stem cells (MSCs), specifically those preconditioned with deferoxamine (DFO) in canine adipose tissue-derived MSCs (cAT-MSCs), were explored for treating autoimmune diseases. This study assessed the effects of DFO-preconditioned EVs (EVDFO) in an experimental autoimmune encephalomyelitis (EAE) mouse model. cAT-MSCs were treated with DFO for 48 h, after which EVs were isolated. EAE mice received intranasal EV or EVDFO treatments and were euthanized following histopathologic analysis; RNA and protein expression levels were measured. Histologically, EV and EVDFO groups showed a significant reduction in inflammatory cell infiltration and demyelination. Immunofluorescence revealed increased CD206 and Foxp3 expression, indicating elevated M2 macrophages and regulatory T (Treg) cells, particularly in the EVDFO group. Treg cells also notably increased in the spleen of EVDFO -treated mice. STAT3 and pSTAT3 proteins were upregulated in the EAE groups compared to the naïve group. However, following EV treatment, STAT3 expression decreased compared to the EAE group, whereas pSTAT3 expression was similar in both the EV and EAE groups. In conclusion, EVDFO treatment resulted in reduced STAT3 expression, suggesting its role in T cell regulation and the potential of EVDFO in modulating the STAT3 pathway for reducing inflammation more effectively than non-preconditioned EVs.

Circulating platelets modulate oligodendrocyte progenitor cell differentiation during remyelination

Revealing unknown cues that regulate oligodendrocyte progenitor cell (OPC) function in remyelination is important to optimise the development of regenerative therapies for multiple sclerosis (MS). Platelets are present in chronic non-remyelinated lesions of MS and an increase in circulating platelets has been described in experimental autoimmune encephalomyelitis (EAE) mice, an animal model for MS. However, the contribution of platelets to remyelination remains unexplored. Here we show platelet aggregation in proximity to OPCs in areas of experimental demyelination. Partial depletion of circulating platelets impaired OPC differentiation and remyelination, without altering blood-brain barrier stability and neuroinflammation. Transient exposure to platelets enhanced OPC differentiation in vitro, whereas sustained exposure suppressed this effect. In a mouse model of thrombocytosis (Calr+/-), there was a sustained increase in platelet aggregation together with a reduction of newly-generated oligodendrocytes following toxin-induced demyelination. These findings reveal a complex bimodal contribution of platelet to remyelination and provide insights into remyelination failure in MS.

Circulating platelets modulate oligodendrocyte progenitor cell differentiation during remyelination.

Revealing unknown cues that regulate oligodendrocyte progenitor cell (OPC) function in remyelination is important to optimise the development of regenerative therapies for multiple sclerosis (MS). Platelets are present in chronic non-remyelinated lesions of MS and an increase in circulating platelets has been described in experimental autoimmune encephalomyelitis (EAE) mice, an animal model for MS. However, the contribution of platelets to remyelination remains unexplored. Here we show platelet aggregation in proximity to OPCs in areas of experimental demyelination. Partial depletion of circulating platelets impaired OPC differentiation and remyelination, without altering blood-brain barrier stability and neuroinflammation. Transient exposure to platelets enhanced OPC differentiation in vitro, whereas sustained exposure suppressed this effect. In a mouse model of thrombocytosis (Calr+/-), there was a sustained increase in platelet aggregation together with a reduction of newly-generated oligodendrocytes following toxin-induced demyelination. These findings reveal a complex bimodal contribution of platelet to remyelination and provide insights into remyelination failure in MS.

The Antidepressant- and Anxiolytic-Like Effects of the Phosphodiesterase Type-5 Inhibitor Tadalafil are Associated with the Modulation of the Gut-Brain Axis During CNS Autoimmunity.

Multiple Sclerosis (MS) is a debilitating disease that severely affects the central nervous system (CNS). Apart from neurological symptoms, it is also characterized by neuropsychiatric comorbidities, such as anxiety and depression. Phosphodiesterase-5 inhibitors (PDE5Is) such as Sildenafil and Tadalafil have been shown to possess antidepressant-like effects, but the mechanisms underpinning such effects are not fully characterized. To address this question, we used the EAE model of MS, behavioral tests, immunofluorescence, immunohistochemistry, western blot, and 16S rRNA sequencing. Here, we showed that depressive-like behavior in Experimental Autoimmune Encephalomyelitis (EAE) mice is due to neuroinflammation, reduced synaptic plasticity, dysfunction in glutamatergic neurotransmission, glucocorticoid receptor (GR) resistance, increased blood-brain barrier (BBB) permeability, and immune cell infiltration to the CNS, as well as inflammation, increased intestinal permeability, and immune cell infiltration in the distal colon. Furthermore, 16S rRNA sequencing revealed that behavioral dysfunction in EAE mice is associated with changes in the gut microbiota, such as an increased abundance of Firmicutes and Saccharibacteria and a reduction in Proteobacteria, Parabacteroides, and Desulfovibrio. Moreover, we detected an increased abundance of Erysipelotrichaceae and Desulfovibrionaceae and a reduced abundance of Lactobacillus johnsonii. Surprisingly, we showed that Tadalafil likely exerts antidepressant-like effects by targeting all aforementioned disease aspects. In conclusion, our work demonstrated that anxiety- and depressive-like behavior in EAE is associated with a plethora of neuroimmune and gut microbiota-mediated mechanisms and that Tadalafil exerts antidepressant-like effects probably by targeting these mechanisms. Harnessing the knowledge of these mechanisms of action of Tadalafil is important to pave the way for future clinical trials with depressed patients.