What's new about oral treatments in Multiple Sclerosis? Immunogenetics still under question

Evidence for novel cell defense mechanisms sustained by dimethyl fumarate in multiple sclerosis patients: the HuR/SOD2 cascade

BACKGROUND

Dimethyl fumarate (DMF) is an effective treatment for relapsing remitting Multiple Sclerosis (MS) and its mechanisms of action encompass immunomodulatory and cytoprotective effects. Despite DMF is known to activate the Nrf2 pathway, Nrf2-independent mechanisms have been also reported and new insights on the underlying molecular mechanisms are still emerging including transcriptional and post-transcriptional events. At this regard, we focused on a small family of RNA-binding proteins, the ELAV-like proteins, that play a pivotal role in post-transcriptional mechanisms and are involved in the pathogenesis of several psychiatric and neurologic disorders. HuR, the ubiquitously expressed member of the family, is implicated in many cellular functions, including survival, inflammation and proper functioning of the immune system. We previously documented the potential entanglement of HuR in MS pathogenesis. In the present work, we explored HuR protein levels in peripheral blood mononuclear cells (PBMCs) from MS patients before and after DMF treatment compared to healthy controls (HC). Considering that HuR may act on various targets, playing a protective role against oxidative stress, our main goals were to evaluate whether manganese-dependent superoxide dismutase transcript (SOD2) could represent a new molecular target of HuR and to study the potential influence of DMF treatment on this interaction.

METHODS

PBMCs from 20 patients with MS and 20 frequency-matched HC by sex and age were used to evaluate HuR, MnSOD (the protein coded by SOD2) and Nrf2 protein content by Western blot, before and after 12 months of DMF treatment. Immunoprecipitation experiments coupled with RNA extraction in PBMCs were performed to explore whether SOD2 mRNA could be physically bound by HuR and whether the expression of MnSOD protein could be affected by 12 months of DMF treatment.

RESULTS

In PBMCs, HuR protein binds SOD2 transcript in HC and in MS patients naïve to disease modifying treatment. The expression of MnSOD protein is positively affected by 12 months of DMF treatment. PBMCs from MS patients have a lower HuR and MnSOD protein content compared to matched HC (HuR: p<0.01, MnSOD: p<0.01). Of interest, 12 months of DMF treatment in MS patients restores the amount of both HuR protein and MnSOD enzyme to the levels observed in HC. We also confirmed that Nrf2 is an HuR target, and we report that its levels are significantly increased in MS patients naïve to disease modifying treatment and remain elevated following DMF administration.

CONCLUSION

SOD2 transcript is a new target of HuR protein. DMF induces an increased expression of HuR protein, which ultimately interacts more strongly with SOD2 transcript promoting the expression of this antioxidant protein. The activation of this molecular cascade can constitute an additional tool that the cells can exploit to counteract the oxidative stress associated with MS development, and can account for the multifaceted molecular mechanisms underlying DMF efficacy in MS.

In vivo detection of teriflunomide-derived fluorine signal during neuroinflammation using fluorine MR spectroscopy

Background: Magnetic resonance imaging (MRI) is indispensable for diagnosing neurological conditions such as multiple sclerosis (MS). MRI also supports decisions regarding the choice of disease-modifying drugs (DMDs). Determining in vivo tissue concentrations of DMDs has the potential to become an essential clinical tool for therapeutic drug monitoring (TDM). The aim here was to examine the feasibility of fluorine-19 (¹⁹F) MR methods to detect the fluorinated DMD teriflunomide (TF) during normal and pathological conditions.

Methods: We used ¹⁹F MR spectroscopy to detect TF in the experimental autoimmune encephalomyelitis (EAE) mouse model of multiple sclerosis (MS) in vivo. Prior to the in vivo investigations we characterized the MR properties of TF in vitro. We studied the impact of pH and protein binding as well as MR contrast agents.

Results: We could detect TF in vivo and could follow the ¹⁹F MR signal over different time points of disease. We quantified TF concentrations in different tissues using HPLC/MS and showed a significant correlation between ex vivo TF levels in serum and the ex vivo¹⁹F MR signal.

Conclusion: This study demonstrates the feasibility of ¹⁹F MR methods to detect TF during neuroinflammation in vivo. It also highlights the need for further technological developments in this field. The ultimate goal is to add ¹⁹F MR protocols to conventional ¹H MRI protocols in clinical practice to guide therapy decisions.

Immunosuppression in relapsing remitting multiple sclerosis: moving towards personalized treatment

INTRODUCTION

Therapeutic armamentarium in Multiple Sclerosis (MS) has radically changed in the last few decades due to the development of disease modifying treatments (DMTs) with highly selective mechanisms of action.

AREAS COVERED

In this review, the authors will focus on the current role of immunosuppressive DMTs in the management of the relapsing-remitting form of MS (RRMS), moving from the rationale of its use and looking at the possibility to design an idealistic scenario of a personalized approach for each single patient.

EXPERT OPINION

Questions remain open about whether initial high-efficacy immunosuppressive DMTs improve long-term outcomes, whether prolonged exposure to these agents increases adverse events and what the strongest early surrogate markers are for predicting long-term treatment responses to high-efficacy drugs. In this way, the immunosuppressive DMTs, are used to hit the immune system early and hard with the idealistic goal of striking the autoimmune activities before the neurological damage becomes irreversible.

Response to oxidative stress of peripheral blood mononuclear cells from multiple sclerosis patients and healthy controls

The complex scenario of multiple sclerosis (MS) pathology involves several mechanisms, including oxidative stress response. The heat shock proteins (HSPs) are important for the protection of the cells; however, their role in MS is not clear. The present research is focused on the response of peripheral blood mononuclear cells (PBMCs) to oxidative stress and to the involvement of HSP70-2 (a protein coded by the HSPA1B gene, located in the MHC class III). To this aim, we challenged PBMCs from MS patients and healthy controls with hydrogen peroxide. Specifically, PBMCs mitochondrial activity, HSP70-2 protein expression and the production of intracellular reactive oxygen species were assessed. These parameters were also related to the HSP70-2 rs1061581 polymorphism, which is linked to the risk of developing MS. Moreover, mitochondrial activity and HSP70-2 protein levels were also related to disease severity. Overall, our results indicate that PBMCs, from both MS patients and healthy controls, may display a similar response towards an oxidative insult; within this context, HSP70-2 does not seem to be central in the protection of PBMCs. Nevertheless, the HSP70-2 rs1061581 polymorphism is related to ROS levels and appears to have a role in the different expression of HSP70-2 under oxidative stimulus.

Serum Exosome MicroRNAs Predict Multiple Sclerosis Disease Activity after Fingolimod Treatment

We and others have previously demonstrated the potential for circulating exosome microRNAs to aid in disease diagnosis. In this study, we sought the possible utility of serum exosome microRNAs as biomarkers for disease activity in multiple sclerosis patients in response to fingolimod therapy. We studied patients with relapsing-remitting multiple sclerosis prior to and 6 months after treatment with fingolimod. Disease activity was determined using gadolinium-enhanced magnetic resonance imaging. Serum exosome microRNAs were profiled using next-generation sequencing. Data were analysed using univariate/multivariate modelling and machine learning to determine microRNA signatures with predictive utility. Accordingly, we identified 15 individual miRNAs that were differentially expressed in serum exosomes from post-treatment patients with active versus quiescent disease. The targets of these microRNAs clustered in ontologies related to the immune and nervous systems and signal transduction. While the power of individual microRNAs to predict disease status post-fingolimod was modest (average 77%, range 65 to 91%), several combinations of 2 or 3 miRNAs were able to distinguish active from quiescent disease with greater than 90% accuracy. Further stratification of patients identified additional microRNAs associated with stable remission, and a positive response to fingolimod in patients with active disease prior to treatment. Overall, these data underscore the value of serum exosome microRNA signatures as non-invasive biomarkers of disease in multiple sclerosis and suggest they may be used to predict response to fingolimod in future clinical practice. Additionally, these data suggest that fingolimod may have mechanisms of action beyond its known functions.

Genome-wide DNA methylation changes in CD19+ B cells from relapsing-remitting multiple sclerosis patients

Multiple Sclerosis (MS) is an inflammatory and neurodegenerative disease of the central nervous system. The inflammatory process in MS is driven by both T and B cells and current therapies are targeted to each of these cell types. Epigenetic mechanisms may provide a valuable link between genes and environment. DNA methylation is the best studied epigenetic mechanism and is recognized as a potential contributor to MS risk. The objective of this study was to identify DNA methylation changes associated with MS in CD19+ B-cells. We performed an epigenome-wide association analysis of DNA methylation in the CD19+ B-cells from 24 patients with relapsing-remitting MS on various treatments and 24 healthy controls using Illumina 450 K arrays. A large differentially methylated region (DMR) was observed at the lymphotoxin alpha (LTA) locus. This region was hypermethylated and contains 19 differentially methylated positions (DMPs) spanning 860 bp, all of which are located within the transcriptional start site. We also observed smaller DMRs at 4 MS-associated genes: SLC44A2, LTBR, CARD11 and CXCR5. These preliminary findings suggest that B-cell specific DNA-methylation may be associated with MS risk or response to therapy, specifically at the LTA locus. Development of B-cell specific epigenetic therapies is an attractive new avenue of research in MS treatment. Further studies are now required to validate these findings and understand their functional significance.

DNA methylation changes in CD4+ T cells isolated from multiple sclerosis patients on dimethyl fumarate

Background

Dimethyl fumarate is an oral treatment for multiple sclerosis, whose mechanism of action is not fully understood.

Objective

To investigate the effects of dimethyl fumarate on DNA methylation in the CD4⁺ T cells of multiple sclerosis patients.

Methods

We performed Illumina EPIC arrays to investigate the DNA methylation profiles of CD4⁺ T cells derived from multiple sclerosis patients before and after dimethyl fumarate treatment.

Results

Treatment with dimethyl fumarate resulted in 97% of differentially methylated positions showing hypermethylation. Four genes, SNORD1A, SHTN1, MZB1 and TNF had a differentially methylated region located within the transcriptional start site.

Conclusion

This study investigates the effect of dimethyl fumarate on DNA methylation in multiple sclerosis patients.