Multiple Sclerosis

Immunopathogenesis of multiple sclerosis: molecular and cellular mechanisms and new immunotherapeutic approaches

BACKGROUND

Multiple sclerosis (MS) is a central nervous system (CNS) demyelinating autoimmune disease with increasing global prevalence. It predominantly affects females, especially those of European descent. The interplay between environmental factors and genetic predisposition plays a crucial role in MS etiopathogenesis.

METHODS

We searched recent relevant literature on reputable databases, which include, PubMed, Embase, Web of Science, Scopus, and ScienceDirect using the following keywords: multiple sclerosis, pathogenesis, autoimmunity, demyelination, therapy, and immunotherapy.

RESULTS

Various animal models have been employed to investigate the MS etiopathogenesis and therapeutics. Autoreactive T cells within the CNS recruit myeloid cells through chemokine expression, leading to the secretion of inflammatory cytokines driving the MS pathogenesis, resulting in demyelination, gliosis, and axonal loss. Key players include T cell lymphocytes (CD4+ and CD8+), B cells, and neutrophils. Signaling dysregulation in inflammatory pathways and the immunogenetic basis of MS are essential considerations for any successful therapy to MS. Data indicates that B cells and neutrophils also have significant roles in MS, despite the common belief that T cells are essential. High neutrophil-to-lymphocyte ratios correlate with MS severity, indicating their contribution to disease progression. Dysregulated signaling pathways further exacerbate MS progression.

CONCLUSION

MS remains incurable, but disease-modifying therapies, monoclonal antibodies, and immunomodulatory drugs offer hope for patients. Research on the immunogenetics and immunoregulatory functions of gut microbiota is continuing to provide light on possible treatment avenues. Understanding the complex interplay between genetic predisposition, environmental factors, and immune dysregulation is critical for developing effective treatments for MS.

Knockdown of IFIT3 ameliorates multiple sclerosis via selectively regulating M1 polarization of microglia in an experimental autoimmune encephalomyelitis model

The key to the treatment of multiple sclerosis (MS) is to promote the transition from inflammation-induced demyelination to remyelination. Polarization of microglia towards M1 or M2 phenotype is critical in this transition. Interferon induced protein with tetratricopeptide repeats 3 (IFIT3) is involved in inflammatory reaction and up-regulated in M1-polarized macrophages. However, its effect on microglia during MS has not been reported. In this paper, we demonstrated the important role of IFIT3 in selectively regulating microglia polarization. The expression of IFIT3 was increased when microglia were polarized towards M1, but did not change under M2 polarization. The knockdown of IFIT3 selectively inhibited M1 polarization, while M2 polarization was not affected by IFIT3 silencing. Furthermore, the activation of signal transducer and activator of transcription 1 (STAT1) and nuclear factor kappa-B (NF-ĸB) signaling in M1 polarized microglia was suppressed by downregulating IFIT3. In experimental autoimmune encephalitis (EAE) mice, an animal model of MS, IFIT3 expression was upregulated. The disease progression, inflammatory infiltration and demyelination in the EAE mice were alleviated by silencing IFIT3. The inhibitory effects of IFIT3 knockdown on M1 polarization and STAT1 and NF-ĸB pathways were also confirmed in the spinal cord of EAE mice. In summary, our findings suggest that IFIT3 selectively intensified microglia polarization towards the pro-inflammatory M1 phenotype, and may contribute to the progression of MS.

Assessment of Functional Capacity of Immune System in Patients with Multiple Sclerosis using QuantiFERON Monitor

Background

The QuantiFERON®-Monitor (QFM) is an assay that measures interferon-γ production and was developed to provide an objective marker of complex immune response. In this study, we evaluated the use of the QFM test in patients with two forms of multiple sclerosis (MS), relapsing-remitting form treated with fingolimod (fMS) and secondarily progressive form not treated pharmacologically (pMS), and in healthy controls (HC). We hypothesized that IFN-γ levels would be lower in those subjects who are relatively more immunosuppressed and higher in those with normal or activated immune function.

Methods

This single-center observational study was conducted from November 2020 to October 2021 and compared results in three groups of patients: 86 healthy controls, 96 patients with pMS, and 78 fMS. Combination of lyophilized stimulants was added to 1 ml heparinized whole blood within 8 hr of collection. Plasmatic IFN-γ was measured using the ELISA kit for the QFM and data were obtained in IU/ml.

Results

The results showed that controls had nearly 2-fold higher levels of IFN-γ (QFM score) in median (q25, q75) 228.00 (112.20, 358.67) than the MS patient groups: pMS 144.80 (31.23, 302.00); fMS 130.50 (39.95, 217.07) which is statistically significant difference P-value: HC vs. pMS = 0.0071; HC vs. fMS = 0.0468. This result was also confirmed by a validation analysis to exclude impact of variable factors, such as disease duration and Expanded Disability Status Scale scores.

Conclusions

Results showed that controls had higher levels of IFN-γ production than the MS patient groups and suggest that MS patients included in this study have a lower ability of immune system activation than HC. Results confirm that fingolimod is able to suppress production of IFN-γ. The fact that the QFM score of MS patients is significantly lower than that of HC may indicate a dysfunctional state of the immune system in baseline conditions.

Immune cells transcriptome-based drug repositioning for multiple sclerosis

Objective

Finding target genes and target pathways of existing drugs for drug repositioning in multiple sclerosis (MS) based on transcriptomic changes in MS immune cells.

Materials and Methods

Based on transcriptome data from Gene Expression Omnibus (GEO) database, differentially expressed genes (DEGs) in MS patients without treatment were identified by bioinformatics analysis according to the type of immune cells, as well as DEGs in MS patients before and after drug administration. Hub target genes of the drug for MS were analyzed by constructing the protein-protein interaction network, and candidate drugs targeting 2 or more hub target genes were obtained through the connectivity map (CMap) database and Drugbank database. Then, the enriched pathways of MS patients without treatment and the enriched pathways of MS patients before and after drug administration were intersected to obtain the target pathways of the drug for MS, and the candidate drugs targeting 2 or more target pathways were obtained through Kyoto Encyclopedia of Genes and Genomes (KEGG) database.

Results

We obtained 50 hub target genes for CD4⁺ T cells in Fingolimod for MS, 15 hub target genes for Plasmacytoid dendritic cells (pDCs) and 7 hub target genes for Peripheral blood mononuclear cells (PBMC) in interferon-β (IFN-β) for MS. 6 candidate drugs targeting two or more hub targets (Fostamatinib, Copper, Artenimol, Phenethyl isothiocyanate, Aspirin and Zinc) were obtained. In addition, we obtained 4 target pathways for CD19⁺ B cells and 15 target pathways for CD4⁺ T cells in Fingolimod for MS, 7 target pathways for pDCs and 6 target pathways for PBMC in IFN-β for MS, most of which belong to the immune system and viral infectious disease pathways. We obtained 69 candidate drugs targeting two target pathways.

Conclusion

We found that applying candidate drugs that target both the “PI3K-Akt signaling pathway” and “Chemokine signaling pathway” (e.g., Nemiralisib and Umbralisib) or applying tyrosine kinase inhibitors (e.g., Fostamatinib) may be potential therapies for the treatment of MS.

Glucagon-Like Peptide-1 Receptor Agonists as Potential Myelination-Inducible and Anti-Demyelinating Remedies

Glucagon-like peptide-1 receptor agonists (GLP-1RAs) were developed as insulinotropic and anti-hyperglycemic agents for the treatment of type 2 diabetes, but their neurotrophic and neuroprotective activities have been receiving increasing attention. Myelin plays a key role in the functional maintenance of the central and peripheral nervous systems, and recent in vivo and in vitro studies have shed light on the beneficial effects of GLP-1RAs on the formation and protection of myelin. In this article, we describe the potential efficacy of GLP-1RAs for the induction of axonal regeneration and remyelination following nerve lesions and the prevention and alleviation of demyelinating disorders, particularly multiple sclerosis.

Differences in MS clinical and epidemiological characteristics between Ashkenazi and non-Ashkenazi Jewish patients in Israel: a retrospective single center study

The prevalence and severity of Multiple Sclerosis (MS) varies across different ethnicities, with a tendency to a more severe phenotype in non-Caucasian populations.  Our objective was to evaluate the differences in disease phenotype between Ashkenazi Jewish and Non-Ashkenazi Jewish patients in Israel. We conducted a single center retrospective cohort study in which subjects were assigned to Ashkenazi or Non-Ashkenazi groups according to self-reported ancestry and disease severity was assessed using the expanded disability status (EDSS), MS severity score (MSSS), progression index (PI) and MRI metrics. 330 Ashkenazi Jewish (AJ) and 207 Non-Ashkenazi Jewish patients (Non-AJ) were included. Non-AJ had a younger age of disease onset (32.7 years vs. 35.7 years, p = 0.05), with a lower proportion of females (62.3% vs. 73.3%, p = 0.01). These differences were maintained within the subgroup of Israeli native patients. Ethnicity was a significant predictor of MSSS (β = 0.601, p = 0.003), with a higher estimate than that of other epidemiological factors. To conclude, Non-AJ patients had an earlier age of onset and a more disabling disease as well as having a more balanced female to male ratio compared to AJ patients. These findings demonstrate variability of disease phenotype within Caucasian patient's dependent on their ethnicity despite equivalent access to healthcare services.

Safety and efficacy of bexarotene in patients with relapsing-remitting multiple sclerosis (CCMR One): a randomised, double-blind, placebo-controlled, parallel-group, phase 2a study

BACKGROUND

Progressive disability in multiple sclerosis occurs because CNS axons degenerate as a late consequence of demyelination. In animals, retinoic acid receptor RXR-gamma agonists promote remyelination. We aimed to assess the safety and efficacy of a non-selective retinoid X receptor agonist in promoting remyelination in people with multiple sclerosis.

METHODS

This randomised, double-blind, placebo-controlled, parallel-group, phase 2a trial (CCMR One) recruited patients with relapsing-remitting multiple sclerosis from two centres in the UK. Eligible participants were aged 18-50 years and had been receiving dimethyl fumarate for at least 6 months. Via a web-based system run by an independent statistician, participants were randomly assigned (1:1), by probability-weighted minimisation using four binary factors, to receive 300 mg/m2 of body surface area per day of oral bexarotene or oral placebo for 6 months. Participants, investigators, and outcome assessors were masked to treatment allocation. MRI scans were done at baseline and at 6 months. The primary safety outcome was the number of adverse events and withdrawals attributable to bexarotene. The primary efficacy outcome was the patient-level change in mean lesional magnetisation transfer ratio between baseline and month 6 for lesions that had a baseline magnetisation transfer ratio less than the within-patient median. We analysed the primary safety outcome in the safety population, which comprised participants who received at least one dose of their allocated treatment. We analysed the primary efficacy outcome in the intention-to-treat population, which comprised all patients who completed the study. This study is registered in the ISRCTN Registry, 14265371, and has been completed.

FINDINGS

Between Jan 17, 2017, and May 17, 2019, 52 participants were randomly assigned to receive either bexarotene (n=26) or placebo (n=26). Participants who received bexarotene had a higher mean number of adverse events (6·12 [SD 3·09]; 159 events in total) than did participants who received placebo (1·63 [SD 1·50]; 39 events in total). All bexarotene-treated participants had at least one adverse event, which included central hypothyroidism (n=26 vs none on placebo), hypertriglyceridaemia (n=24 vs none on placebo), rash (n=13 vs one on placebo), and neutropenia (n=10 vs none on placebo). Five (19%) participants on bexarotene and two (8%) on placebo discontinued the study drug due to adverse events. One episode of cholecystitis in a placebo-treated participant was the only serious adverse event. The change in mean lesional magnetisation transfer ratio was not different between the bexarotene group (0·25 percentage units [pu; SD 0·98]) and the placebo group (0·09 pu [0·84]; adjusted bexarotene-placebo difference 0·16 pu, 95% CI -0·39 to 0·71; p=0·55).

INTERPRETATION

We do not recommend the use of bexarotene to treat patients with multiple sclerosis because of its poor tolerability and negative primary efficacy outcome. However, statistically significant effects were seen in some exploratory MRI and electrophysiological analyses, suggesting that other retinoid X receptor agonists might have small biological effects that could be investigated in further studies.

FUNDING

Multiple Sclerosis Society of the United Kingdom.

Isoflavone diet ameliorates experimental autoimmune encephalomyelitis through modulation of gut bacteria depleted in patients with multiple sclerosis

The gut microbiota is a potential environmental factor that influences the development of multiple sclerosis (MS). We and others have demonstrated that patients with MS and healthy individuals have distinct gut microbiomes. However, the pathogenic relevance of these differences remains unclear. Previously, we showed that bacteria that metabolize isoflavones are less abundant in patients with MS, suggesting that isoflavone-metabolizing bacteria might provide protection against MS. Here, using a mouse model of MS, we report that an isoflavone diet provides protection against disease, which is dependent on the presence of isoflavone-metabolizing bacteria and their metabolite equol. Notably, the composition of the gut microbiome in mice fed an isoflavone diet exhibited parallels to healthy human donors, whereas the composition in those fed an isoflavone-free diet exhibited parallels to patients with MS. Collectively, our study provides evidence that dietary-induced gut microbial changes alleviate disease severity and may contribute to MS pathogenesis.

The Distribution of GPR17-Expressing Cells Correlates with White Matter Inflammation Status in Brain Tissues of Multiple Sclerosis Patients

In multiple sclerosis (MS), oligodendrocyte precursor cells (OPCs) are recruited to the site of injury to remyelinate damaged axons; however, in patients this process is often ineffective due to defects in OPC maturation. The membrane receptor GPR17 timely regulates the early stages of OPC differentiation; however, after reaching its highest levels in immature oligodendrocytes, it has to be downregulated to allow terminal maturation. Since, in several animal models of disease GPR17 is upregulated, the aim of this work was to characterize GPR17 alterations in MS patients. We developed immunohistochemistry and immunofluorescence procedures for the detection of GPR17 in human tissues and stained post-mortem MS brain lesions from patients with secondary progressive MS and control subjects. The inflammatory activity in each lesion was evaluated by immunohistochemistry for the myelin protein MOG and the HLA antigen to classify them as active, chronic inactive or chronic active. Hence, we assessed the distribution of GPR17-positive cells in these lesions compared to normal appearing white matter (NAWM) and white matter (WM) of control subjects. Our data have shown a marked increase of GPR17-expressing oligodendroglial cells accumulating at NAWM, in which moderate inflammation was also found. Furthermore, we identified two distinct subpopulations of GPR17-expressing oligodendroglial cells, characterized by either ramified or rounded morphology, that differently populate the WM of healthy controls and MS patients. We concluded that the coordinated presence of GPR17 in OPCs at the lesion sites and inflamed NAWM areas suggests that GPR17 could be exploited to support endogenous remyelination through advanced pharmacological approaches.

Glial cell activation and altered metabolic profile in the spinal-trigeminal axis in a rat model of multiple sclerosis associated with the development of trigeminal sensitization

Trigeminal neuralgia is often an early symptom of multiple sclerosis (MS), and it generally does not correlate with the severity of the disease. Thus, whether it is triggered simply by demyelination in specific central nervous system areas is currently questioned. Our aims were to monitor the development of spontaneous trigeminal pain in an animal model of MS, and to analyze: i) glial cells, namely astrocytes and microglia in the central nervous system and satellite glial cells in the trigeminal ganglion, and ii) metabolic changes in the trigeminal system. The subcutaneous injection of recombinant MOG_1-125 protein fragment to Dark Agouti male rats led to the development of relapsing-remitting EAE, with a first peak after 13 days, a remission stage from day 16 and a second peak from day 21. Interestingly, orofacial allodynia developed from day 1 post injection, i.e. well before the onset of EAE, and worsened over time, irrespective of the disease phase. Activation of glial cells both in the trigeminal ganglia and in the brainstem, with no signs of demyelination in the latter tissue, was observed along with metabolic alterations in the trigeminal ganglion. Our data show, for the first time, the spontaneous development of trigeminal sensitization before the onset of relapsing-remitting EAE in rats. Additionally, pain is maintained elevated during all stages of the disease, suggesting the existence of parallel mechanisms controlling motor symptoms and orofacial pain, likely involving glial cell activation and metabolic alterations which can contribute to trigger the sensitization of sensory neurons.

Amifostine ameliorates induction of experimental autoimmune encephalomyelitis: Effect on reactive oxygen species/NLRP3 pathway

Multiple sclerosis (MS) is an autoimmune disease for which conventional treatments have limited efficacy or side effects. Free radicals are primarily involved in blood-brain barrier disruption and induce neuronal and axonal damage, thus promoting the development of MS. Amifostine, a radioprotective drug used as a cytoprotective agent, attenuates oxidative stress and improves radiation damage by acting as a direct scavenger of reactive oxygen and nitrogen species. The aim of this study was to evaluate the effects of amifostine on MS in a mouse model of experimental autoimmune encephalomyelitis (EAE), which was developed by immunizing C57BL/6 mice with myelin oligodendrocyte glycoprotein and pertussis toxin. EAE mice received intraperitoneal injections of amifostine prior to onset of clinical symptoms and were monitored up to day 15 post induction. We observed abnormal clinical behavioral scores and a decrease in body weight. Histological analysis showed severe inflammatory infiltration and demyelination in the brain and spinal cord lumbar enlargements where significant upregulation of the mRNA expression of the pro-inflammatory cytokines interleukin-6 and interleukin-8, downregulation of the anti-inflammatory cytokine interleukin-10, and obvious microgliosis were also observed. Amifostine treatment potently reversed these abnormal changes. The anti-inflammatory effect of amifostine was associated with the inhibition of reactive oxygen species generation. Furthermore, the expression of proteins involved in the NLRP3 signaling pathway and pyroptosis was decreased. In conclusion, our study showed that amifostine ameliorates induction of experimental autoimmune encephalomyelitis via anti-inflammatory and anti-pyroptosis effects, providing further insights into the use of amifostine for the treatment of MS.

Bipedal hopping as a new measure to detect subtle sensorimotor impairment in people with multiple sclerosis

BACKGROUND

Bipedal hopping has the potential to detect subtle multiple sclerosis (MS)-related impairments, especially among patients who "pass" typical movement tests. In this narrative review, we outline the biomechanics of bipedal hopping and propose its usefulness as a novel outcome measure for people with MS having mild disability.

METHODS

We summarize articles that (1) examined the biomechanics of jumping or hopping and (2) tested the validity and/or reliability of hopping tests. We consolidated consistencies and gaps in research and opportunities for future development of the bipedal hop test.

RESULTS

Bipedal hopping requires immense power, coordination, balance, and ability to reduce co-contraction; movement components typically affected by MS. These impairments can be measured and differentiated by examining specific variables, such as hop length (power), symmetry (coordination), center of pressure (balance), and coefficient of variability (co-contraction/spasticity). Bipedal hopping challenges these aspects of movement and exposes sensorimotor impairments that may not have been apparent during walking.

CONCLUSIONS

Testing of bipedal hopping on an instrumented walkway may detect and monitor sensorimotor control in people with MS who do not currently present with clinical deficits. Early measurement is imperative for precise rehabilitation prescription to slow disability progression prior to onset of measurable gait impairment.Implications for rehabilitationJumping and hopping tests detect lower limb and balance impairments in children, athletes, and older adults.Bipedal hop test measures multiple domains: power, coordination, balance, and muscle timing.Bipedal hop test may expose subtle sensorimotor impairments in people with multiple sclerosis.Multiple variables measured can discern type of sensorimotor impairment to direct personalized rehabilitation programs.

Upregulation of Tolerogenic Pathways by the Hydrogen Sulfide Donor GYY4137 and Impaired Expression of H2S-Producing Enzymes in Multiple Sclerosis

The aim of this study was to examine the in vitro effects of the slow-releasing H2S donor GYY4137 on the immune cells involved in the pathogenesis of the central nervous system (CNS) autoimmune disease, multiple sclerosis (MS). GYY4137 specifically potentiated TGF-β expression and production in dendritic cells and significantly reduced IFN-γ and IL-17 production in the lymph node and spinal cord T cells obtained from mice immunized with CNS antigens. Both the proportion of FoxP3+ regulatory CD4+ T cells in the lymph node cells, and the percentage of IL-17+ CD4+ T cells in the spinal cord cells were reduced upon culturing with GYY4137. Interestingly, the peripheral blood mononuclear cells obtained from the MS patients had a lower expression of the H2S-producing enzyme, 3-mercaptopyruvate-sulfurtransferase (MPST), in comparison to those obtained from healthy donors. A significant inverse correlation between the expression of MPST and several pro-inflammatory factors was also observed. Further studies on the relevance of the observed results for the pathogenesis and therapy of MS are warranted.

Innate Immune System and Multiple Sclerosis. Granulocyte Numbers Are Reduced in Patients Affected by Relapsing-Remitting Multiple Sclerosis during the Remission Phase

BACKGROUND

Multiple sclerosis (MS) is a neurodegenerative disease that affects the central nervous system. The cause of MS is still unknown, and the role of innate immunity is still poorly understood.

OBJECTIVE

The goal of this study was to understand whether, compared to healthy controls, the elements of innate immunity are altered in the blood of MS patients in the remitting phase.

METHODS

A total of 77 naïve MS patients and 50 healthy controls were included in this cohort study. Peripheral blood samples were collected and analyzed. All the calculations were performed with the statistical system R (r-project.org).

RESULTS

The results showed that MS patients had significantly lower relative representations of granulocytes than healthy controls, while the relative representations of monocytes remained unchanged. CD64- and PD-L1-positive granulocytes exhibited a nonsignificant decreasing trend, while granulocytes with other membrane markers remained noticeably unchanged.

CONCLUSION

The results of this study suggest that studies of the causes of MS and its treatment should also be focused on the elements of the innate immune response.