Disentangling multiple sclerosis phenotypes through Mendelian disorders: A network approach.

BACKGROUND: The increasing knowledge about multiple sclerosis (MS) pathophysiology has reinforced the need for an improved description of disease phenotypes, connected to disease biology. Growing evidence indicates that complex diseases constitute phenotypical and genetic continuums with "simple," monogenic disorders, suggesting shared pathomechanisms. OBJECTIVES: The objective of this study was to depict a novel MS phenotypical framework leveraging shared physiopathology with Mendelian diseases and to identify phenotype-specific candidate drugs. METHODS: We performed an enrichment testing of MS-associated variants with Mendelian disorders genes. We defined a "MS-Mendelian network," further analyzed to define enriched phenotypic subnetworks and biological processes. Finally, a network-based drug screening was implemented. RESULTS: Starting from 617 MS-associated loci, we showed a significant enrichment of monogenic diseases (p < 0.001). We defined an MS-Mendelian molecular network based on 331 genes and 486 related disorders, enriched in four phenotypic classes: neurologic, immunologic, metabolic, and visual. We prioritized a total of 503 drugs, of which 27 molecules active in 3/4 phenotypical subnetworks and 140 in subnetwork pairs. CONCLUSION: The genetic architecture of MS contains the seeds of pathobiological multiplicities shared with immune, neurologic, metabolic and visual monogenic disorders. This result may inform future classifications of MS endophenotypes and support the development of new therapies in both MS and rare diseases.

Circulating U13 Small Nucleolar RNA as a Potential Biomarker in Huntington's Disease: A Pilot Study.

Plasma small RNAs have been recently explored as biomarkers in Huntington's disease (HD). We performed an exploratory study on nine HD patients, eight healthy subjects (HS), and five psychiatric patients (PP; to control for iatrogenic confounder effects) through an Affymetrix-Gene-Chip-miRNA-Array. We validated the results in an independent population of 23 HD, 15 pre-HD, 24 PP, 28 Alzheimer's disease (AD) patients (to control the disease-specificity) and 22 HS through real-time PCR. The microarray results showed higher levels of U13 small nucleolar RNA (SNORD13) in HD patients than controls (fold change 1.54, p = 0.003 HD vs. HS, and 1.44, p = 0.0026 HD vs. PP). In the validation population, a significant increase emerged with respect to both pre-HD and the control groups (p < 0.0001). SNORD13 correlated with the status of the mutant huntingtin carrier (r = 0.73; p < 0.001) and the disease duration (r = 0.59; p = 0.003). The receiver operating characteristic (ROC) curve analysis showed the high accuracy of SNORD13 in discriminating HD patients from other groups (AUC = 0.963). An interactome and pathway analysis on SNORD13 revealed enrichments for factors relevant to HD pathogenesis. We report the unprecedented finding of a potential disease-specific role of SNORD13 in HD. It seems to peripherally report a 'tipping point' in the pathogenic cascade at the neuronal level.

Proinflammatory mucosal-associated invariant CD8+ T cells react to gut flora yeasts and infiltrate multiple sclerosis brain.

The composition of the intestinal microbiota plays a critical role in shaping the immune system. Modern lifestyle, the inappropriate use of antibiotics, and exposure to pollution have significantly affected the composition of commensal microorganisms. The intestinal microbiota has been shown to sustain inappropriate autoimmune responses at distant sites in animal models of disease, and may also have a role in immune-mediated central nervous system (CNS) diseases such as multiple sclerosis (MS). We studied the composition of the gut mycobiota in fecal samples from 27 persons with MS (pwMS) and in 18 healthy donors (HD), including 5 pairs of homozygous twins discordant for MS. We found a tendency towards higher fungal abundance and richness in the MS group, and we observed that MS twins showed a higher rate of food-associated strains, such as Saccharomyces cerevisiae. We then found that in pwMS, a distinct population of cells with antibacterial and antifungal activity is expanded during the remitting phase and markedly decreases during clinically and/or radiologically active disease. These cells, named MAIT (mucosal-associated invariant T cells) lymphocytes, were significantly more activated in pwMS compared to HD in response to S. cerevisiae and Candida albicans strains isolated from fecal samples. This activation was also mediated by fungal-induced IL-23 secretion by innate immune cells. Finally, immunofluorescent stainings of MS post-mortem brain tissues from persons with the secondary progressive form of the disease showed that MAIT cells cross the blood-brain barrier (BBB) and produce pro-inflammatory cytokines in the brain. These results were in agreement with the hypothesis that dysbiosis of the gut microbiota might determine the inappropriate response of a subset of pathogenic mucosal T cells and favor the development of systemic inflammatory and autoimmune diseases.

Multiple sclerosis genetic and non-genetic factors interact through the transient transcriptome.

A clinically actionable understanding of multiple sclerosis (MS) etiology goes through GWAS interpretation, prompting research on new gene regulatory models. Our previous investigations suggested heterogeneity in etiology components and stochasticity in the interaction between genetic and non-genetic factors. To find a unifying model for this evidence, we focused on the recently mapped transient transcriptome (TT), that is mostly coded by intergenic and intronic regions, with half-life of minutes. Through a colocalization analysis, here we demonstrate that genomic regions coding for the TT are significantly enriched for MS-associated GWAS variants and DNA binding sites for molecular transducers mediating putative, non-genetic, determinants of MS (vitamin D deficiency, Epstein Barr virus latent infection, B cell dysfunction), indicating TT-coding regions as MS etiopathogenetic hotspots. Future research comparing cell-specific transient and stable transcriptomes may clarify the interplay between genetic variability and non-genetic factors causing MS. To this purpose, our colocalization analysis provides a freely available data resource at www.mscoloc.com .

Multiple Sclerosis and SARS-CoV-2: Has the Interplay Started?

Current knowledge on Multiple Sclerosis (MS) etiopathogenesis encompasses complex interactions between the host's genetic background and several environmental factors that result in dysimmunity against the central nervous system. An old-aged association exists between MS and viral infections, capable of triggering and sustaining neuroinflammation through direct and indirect mechanisms. The novel Coronavirus, SARS-CoV-2, has a remarkable, and still not fully understood, impact on the immune system: the occurrence and severity of both acute COVID-19 and post-infectious chronic illness (long COVID-19) largely depends on the host's response to the infection, that echoes several aspects of MS pathobiology. Furthermore, other MS-associated viruses, such as the Epstein-Barr Virus (EBV) and Human Endogenous Retroviruses (HERVs), may enhance a mechanistic interplay with the novel Coronavirus, with the potential to interfere in MS natural history. Studies on COVID-19 in people with MS have helped clinicians in adjusting therapeutic strategies during the pandemic; similar efforts are being made for SARS-CoV-2 vaccination campaigns. In this Review, we look over 18 months of SARS-CoV-2 pandemic from the perspective of MS: we dissect neuroinflammatory and demyelinating mechanisms associated with COVID-19, summarize pathophysiological crossroads between MS and SARS-CoV-2 infection, and discuss present evidence on COVID-19 and its vaccination in people with MS.

Intestinal Permeability and Circulating CD161+CCR6+CD8+T Cells in Patients With Relapsing-Remitting Multiple Sclerosis Treated With Dimethylfumarate.

Background: The changes of the gut-brain axis have been recently recognized as important components in multiple sclerosis (MS) pathogenesis. Objectives: To evaluate the effects of DMF on intestinal barrier permeability and mucosal immune responses. Methods: We investigated intestinal permeability (IP) and circulating CD161+CCR6+CD8+T cells in 25 patients with MS, who met eligibility criteria for dimethyl-fumarate (DMF) treatment. These data, together with clinical/MRI parameters, were studied at three time-points: baseline (before therapy), after one (T1) and 9 months (T2) of treatment. Results: At baseline 16 patients (64%) showed altered IP, while 14 cases (56%) showed active MRI. During DMF therapy we found the expected decrease of disease activity at MRI compared to T0 (6/25 at T1, p = 0.035 and 3/25 at T2, p < 0.00), and a reduction in the percentage of CD161+CCR6+CD8+ T cells (16/23 at T2; p < 0.001). The effects of DMF on gut barrier alterations was variable, without a clear longitudinal pattern, while we found significant relationships between IP changes and drop of MRI activity (p = 0.04) and circulating CD161+CCr6+CD8+ T cells (p = 0.023). Conclusions: The gut barrier is frequently altered in MS, and the CD161+ CCR6+CD8+ T cell-subset shows dynamics which correlate with disease course and therapy.

MAIT Cells and Microbiota in Multiple Sclerosis and Other Autoimmune Diseases.

The functions of mucosal-associated invariant T (MAIT) cells in homeostatic conditions include the interaction with the microbiota and its products, the protection of body barriers, and the mounting of a tissue-repair response to injuries or infections. Dysfunction of MAIT cells and dysbiosis occur in common chronic diseases of inflammatory, metabolic, and tumor nature. This review is aimed at analyzing the changes of MAIT cells, as well as of the microbiota, in multiple sclerosis and other autoimmune disorders. Common features of dysbiosis in these conditions are the reduced richness of microbial species and the unbalance between pro-inflammatory and immune regulatory components of the gut microbiota. The literature concerning MAIT cells in these disorders is rather complex, and sometimes not consistent. In multiple sclerosis and other autoimmune conditions, several studies have been done, or are in progress, to find correlations between intestinal permeability, dysbiosis, MAIT cell responses, and clinical biomarkers in treated and treatment-naïve patients. The final aims are to explain what activates MAIT cells in diseases not primarily infective, which interactions with the microbiota are potentially pathogenic, and their dynamics related to disease course and disease-modifying treatments.

Circulating hsa-miR-323b-3p in Huntington's Disease: A Pilot Study.

The momentum of gene therapy in Huntington's disease (HD) deserves biomarkers from easily accessible fluid. We planned a study to verify whether plasma miRNome may provide useful peripheral "reporter(s)" for the management of HD patients. We performed an exploratory microarray study of whole non-coding RNA profiles in plasma from nine patients with HD and 13 matched controls [eight healthy subjects (HS) and five psychiatric patients (PP) to minimize possible iatrogenic impact on the profile of non-coding RNAs]. We found an HD-specific signature: downregulation of hsa-miR-98 (fold change, -1.5, p = 0.0338 HD vs. HS, and fold change, 1.5, p = 0.0045 HD vs. PP) and upregulation of hsa-miR-323b-3p (fold change, 1.5, p = 0.0007 HD vs. HS, and fold change, 1.5, p = 0.0111 HD vs. PP). To validate this result in an independent cohort, we quantify by digital droplet PCR (ddPCR) the presence of the two microRNA in the plasma of 33 HD patients and 49 matched controls (25 HS and 24 PP patients). We were able to confirm that hsa-miR-323b-3p was upregulated in HD and premanifest HD vs. HS and PP: the median values (first-third quartile) were 4.1 (0.9-10.53) and 5.8 (1.9-10.70) vs. 0.69 (0.3-2.75) and 1.4 (0.78-2.70), respectively, p < 0.05. No significant difference was found for hsa-miR-98. To evaluate the biological plausibility of the hsa-miR-323b-3p as a component of the disease pathophysiology, we performed a bioinformatic analysis based on its targetome and the huntingtin (HTT) interactome. We found a statistically significant overconnectivity between the targetome of hsa-miR-323b-3p and the HTT interactome (p = 1.48e-08). Furthermore, there was a significant transcription regulation of the HTT interactome by the miR-323b-3p targetome (p = 0.02). The availability of handy, reproducible, and minimally invasive biomarkers coming from peripheral miRNome may be valuable to characterize the illness progression, to indicate new therapeutic targets, and to monitor the effect of disease-modifying treatments. Our data deserve further studies with larger sample size and longitudinal design.

A Case of Double Standard: Sex Differences in Multiple Sclerosis Risk Factors.

Multiple sclerosis is a complex, multifactorial, dysimmune disease prevalent in women. Its etiopathogenesis is extremely intricate, since each risk factor behaves as a variable that is interconnected with others. In order to understand these interactions, sex must be considered as a determining element, either in a protective or pathological sense, and not as one of many variables. In particular, sex seems to highly influence immune response at chromosomal, epigenetic, and hormonal levels. Environmental and genetic risk factors cannot be considered without sex, since sex-based immunological differences deeply affect disease onset, course, and prognosis. Understanding the mechanisms underlying sex-based differences is necessary in order to develop a more effective and personalized therapeutic approach.

Reworking GWAS Data to Understand the Role of Nongenetic Factors in MS Etiopathogenesis.

Genome-wide association studies have identified more than 200 multiple sclerosis (MS)-associated loci across the human genome over the last decade, suggesting complexity in the disease etiology. This complexity poses at least two challenges: the definition of an etiological model including the impact of nongenetic factors, and the clinical translation of genomic data that may be drivers for new druggable targets. We reviewed studies dealing with single genes of interest, to understand how MS-associated single nucleotide polymorphism (SNP) variants affect the expression and the function of those genes. We then surveyed studies on the bioinformatic reworking of genome-wide association studies (GWAS) data, with aggregate analyses of many GWAS loci, each contributing with a small effect to the overall disease predisposition. These investigations uncovered new information, especially when combined with nongenetic factors having possible roles in the disease etiology. In this context, the interactome approach, defined as "modules of genes whose products are known to physically interact with environmental or human factors with plausible relevance for MS pathogenesis", will be reported in detail. For a future perspective, a polygenic risk score, defined as a cumulative risk derived from aggregating the contributions of many DNA variants associated with a complex trait, may be integrated with data on environmental factors affecting the disease risk or protection.

Oxidative Status in Multiple Sclerosis and Off-Targets of Antioxidants: The Case of Edaravone.

BACKGROUND: MS is a chronic inflammatory disease of the CNS leading to demyelination and neurodegeneration, with a complex and still to be clarified aetiology. Several data, coming from patients' samples and from animal models, show that Oxidative Status (OS) plays an important role in MS pathogenesis. Overproduction of reactive oxidative species by macrophages/microglia can bring about cellular injury and ensuing cell death by oxidizing cardinal cellular components. Oxidized molecules are present in active MS lesions and are associated with neurodegeneration. METHODS: We undertook a structured search of bibliographic databases for peer-reviewed research literature focusing on OS in MS. The contents of the selected papers were described in the context of a conceptual framework. A special emphasis was given to the results of our study in the field. RESULTS: The results of our three recent studies were put in the context and discussed taking into account the literature on the topic. Oxidative damage underpinned an imbalance shared by MS and neurodegenerative diseases such as Alzheimer and Parkinson diseases. In people with clinically isolated syndrome (an early phase of MS) oxidative stress proved to contribute to disease pathophysiology and to provide biomarkers that may help predict disease evolution. A drug screening platform based on multiple assays to test the remyelinating potential of library of approved compounds showed two anti-oxidants, edaravone and 5-methyl-7- methoxyisoflavone, as active drugs. Moreover, an analysis of 'structure activity relationship' showed off-targets sites of these compounds that accounted for their remyelinating activity, irrespective of their antioxidant action. CONCLUSION: Overall, edaravone emerges as a candidate to treat complex disease such as MS, where inflammation, oxidative stress and neurodegeneration contribute to disease progression, together or individually, in different phases and disease types. Furthermore, approaches based on drug repositioning seem to maintain the promise of helping discover novel treatment for complex diseases, where molecular targets are largely unknown.

SARS-CoV-2 meta-interactome suggests disease-specific, autoimmune pathophysiologies and therapeutic targets.

Background: Severe coronavirus disease 2019 (COVID-19) is associated with multiple comorbidities and is characterized by an auto-aggressive inflammatory state leading to massive collateral damage. To identify preventive and therapeutic strategies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), it is important to ascertain the molecular interactions between virus and host, and how they translate into disease pathophysiology. Methods: We matched virus-human protein interactions of human coronaviruses and other respiratory viruses with lists of genes associated with autoimmune diseases and comorbidities associated to worse COVID-19 course. We then selected the genes included in the statistically significant intersection between SARS-CoV-2 network and disease associated gene sets, identifying a meta-interactome. We analyzed the meta-interactome genes expression in samples derived from lungs of infected humans, and their regulation by IFN-ß. Finally, we performed a drug repurposing screening to target the network's most critical nodes. Results: We found a significant enrichment of SARS-CoV-2 interactors in immunological pathways and a strong association with autoimmunity and three prognostically relevant conditions (type 2 diabetes, coronary artery diseases, asthma), that present more independent physiopathological subnetworks. We observed a reduced expression of meta-interactome genes in human lungs after SARS-CoV-2 infection, and a regulatory potential of type I interferons. We also underscored multiple repurposable drugs to tailor the therapeutic strategies. Conclusions: Our data underscored a plausible genetic background that may contribute to the distinct observed pathophysiologies of severe COVID-19. Also, these results may help identify the most promising therapeutic targets and treatments for this condition.

The Contribution of Gut Barrier Changes to Multiple Sclerosis Pathophysiology.

The gut barrier consists of several components, including the mucus layer, made of mucins and anti-bacterial molecule, the epithelial cells, connected by tight junction proteins, and a mixed population of cells involved in the interplay with microbes, such as M cells, elongations of "antigen presenting cells" dwelling the lamina propria, intraepithelial lymphocytes and Paneth cells secreting anti-bacterial peptides. Recently, the influence of intestinal permeability (IP) changes on organs far from gut has been investigated, and IP changes in multiple sclerosis (MS) have been described. A related topic is the microbiota dysfunction that underpins the development of neuroinflammation in animal models and human diseases, including MS. It becomes now of interest to better understand the mechanisms through which IP changes contribute to pathophysiology of neuroinflammation. The following aspects seem of relevance: studies on other biomarkers of IP alterations; the relationship with known risk factors for MS development, such as vitamin D deficiency; the link between blood brain barrier and gut barrier breakdown; the effects of IP increase on microbial translocation and microglial activation; the parallel patterns of IP and neuroimmune changes in MS and neuropsychiatric disorders, that afflict a sizable proportion of patients with MS. We will also discuss the therapeutic implications of IP changes, considering the impact of MS-modifying therapies on gut barrier, as well as potential approaches to enhance or protect IP homeostasis.

Drug Holiday of Interferon Beta 1b in Multiple Sclerosis: A Pilot, Randomized, Single Blind Study of Non-inferiority.

Introduction: To compare a schedule with cyclic withdrawal (CW) of interferon beta (IFN-b) 1b, respect to the full regimen (FR), in relapsing-remitting MS (RR-MS). Methods: Participants were randomly assigned to CW or FR schedule and monthly monitored with brain MRI scans for 12 months (three of run-in and 9 of treatment). CW schedule included drug withdrawal for 1 month after two of treatment for a total of three quarters over the 9-month treatment period. The assessing neurologist and the expert neuroradiologists were blind. After the blind phase of the study all participants took their indicated disease modifying therapies in a prospectively planned, open-label extension phase (up to 120 months). Results: Of 60 randomized subjects 56 (29 in FR and 27 in CW group) completed the single-blind phase: the two groups were comparable, except for a non-significant difference in the number of contrast-enhanced lesions (CEL) at the end of run-in. The two-sided 90% CI for the ratio between median number of cumulative CEL was 0.29-1.07, allowing to significantly reject the null hypothesis of a ratio ≥1.2 and to meet the primary end-point of non-inferiority (the threshold and the ratio between median were chosen according to the non-normal distribution of the data). The differences (CW vs. FR) were also non-significant for secondary end points: mean cumulative number of T2-weighted new and enlarging lesions (3.48 ± 5.34 vs. 3.86 ± 6.76); mean number and volume (cm3) of black holes (1.24 ± 1.61 vs. 2.71 ± 4.56; 489.11 ± 1488.12 vs. 204.48 ± 396.98); number of patients with at least an active scan (21 vs. 22); mean relapse rate (0.52 ± 0.89 vs. 0.34 ± 0.66), relapse risk ratio adjusted for baseline variables (2.15 [0.64-7.18]), EDSS score (1.0 [1-1.56] vs. 1.5 [1-1.78]), proportion of patients with antibodies anti-IFN (5 [21%] vs. 8 [36%]). Fifty-four patients (27 for each study arm) completed the open-label phase. The annualized RR, EDSS, proportion of patients shifting to progressive disease and hazard ratio of shifting, adjusting for baseline covariates, were comparable between the two study groups. Conclusions: A calendar with CW was non-inferior than FR at the beginning of IFN-b therapy, and may not affect the long-term outcome. Clinical Trial Registration: www.ClinicalTrials.gov, identifier: NCT00270816.

A cell type-specific transcriptomic approach to map B cell and monocyte type I interferon-linked pathogenic signatures in Multiple Sclerosis.

Alteration in endogenous Interferon (IFN) system may profoundly impact immune cell function in autoimmune diseases. Here, we provide evidence that dysregulation in IFN-regulated genes and pathways are involved in B cell- and monocyte-driven pathogenic contribution to Multiple Sclerosis (MS) development and maintenance. In particular, by using an Interferome-based cell type-specific approach, we characterized an increased susceptibility to an IFN-linked caspase-3 dependent apoptotic cell death in both B cells and monocytes of MS patients that may arise from their chronic activation and persistent stimulation by activated T cells. Ongoing caspase-3 activation functionally impacts on MS monocyte properties influencing the STAT-3/IL-16 axis, thus, driving increased expression and massive release of the bio-active IL-16 triggering and perpetuating CD4+ T cell migration. Importantly, our analysis also identified a previously unknown multi-component defect in type I IFN-mediated signaling and response to virus pathways specific of MS B cells, impacting on induction of anti-viral responses and Epstein-barr virus infection control in patients. Taking advantage of cell type-specific transcriptomics and in-depth functional validation, this study revealed pathogenic contribution of endogenous IFN signaling and IFN-regulated cell processes to MS pathogenesis with implications on fate and functions of B cells and monocytes that may hold therapeutic potential.

Genome-Wide Multiple Sclerosis Association Data and Coagulation.

The emerging concept of a crosstalk between hemostasis, inflammation, and immune system prompt recent works on coagulation cascade in multiple sclerosis (MS). Studies on MS pathology identified several coagulation factors since the beginning of the disease pathophysiology: fibrin deposition with breakdown of blood brain barrier, and coagulation factors within active plaques may exert pathogenic role, especially through the innate immune system. Studies on circulating coagulation factors showed complex imbalance involving several components of hemostasis cascade (thrombin, factor X, factor XII). To analyze the role of the coagulation process in connection with other pathogenic pathways, we implemented a systematic matching of genome-wide association studies (GWAS) data with an informative and unbiased network of coagulation pathways. Using MetaCore (version 6.35 build 69300, 2018) we analyzed the connectivity (i.e., direct and indirect interactions among two networks) between the network of the coagulation process and the network resulting from feeding into MetaCore the MS GWAS data. The two networks presented a remarkable over-connectivity: 958 connections vs. 561 expected by chance; z-score = 17.39; p-value < 0.00001. Moreover, genes coding for cluster of differentiation 40 (CD40) and plasminogen activator, urokinase (PLAU) shared both networks, pointed to an integral interplay between coagulation cascade and main pathogenic immune effectors. In fact, CD40 pathways is especially operative in B cells, that are currently a major therapeutic target in MS field. The potential interaction of PLAU with a signal of paramount importance for B cell pathogenicity, such as CD40, suggest new lines of research and pave the way to implement new therapeutic targets.

DNA damage signatures in peripheral blood cells as biomarkers in prodromal huntington disease.

Easily accessible biomarkers in Huntington disease (HD) are actively searched. We investigated telomere length and DNA double-strand breaks (histone variant pγ-H2AX) as predictive disease biomarkers in peripheral blood mononuclear cells (PBMC) from 25 premanifest subjects, 58 HD patients with similar CAG expansion in the huntingtin gene (HTT), and 44 healthy controls (HC). PBMC from the pre-HD and HD groups showed shorter telomeres (p < 0.0001) and a significant increase of pγ-H2AX compared to the controls (p < 0.0001). The levels of pγ-H2AX correlated robustly with the presence of the mutated gene in pre-HD and HD. The availability of a potentially reversible biomarker (pγ-H2AX) in the premanifest stage of HD, negligible in HC, provides a novel tool to monitor premanifest subjects and find patient-specific drugs. Ann Neurol 2018;00:1-6 ANN NEUROL 2019;85:296-301.

Analysis of coding and non-coding transcriptome of peripheral B cells reveals an altered interferon response factor (IRF)-1 pathway in multiple sclerosis patients.

Several evidences emphasize B-cell pathogenic roles in multiple sclerosis (MS). We performed transcriptome analyses on peripheral B cells from therapy-free patients and age/sex-matched controls. Down-regulation of two transcripts (interferon response factor 1-IRF1, and C-X-C motif chemokine 10-CXCL10), belonging to the same pathway, was validated by RT-PCR in 26 patients and 21 controls. IRF1 and CXCL10 transcripts share potential seeding sequences for hsa-miR-424, that resulted up-regulated in MS patients. We confirmed this interaction and its functional effect by transfection experiments. Consistent findings indicate down-regulation of IRF1/CXCL10 axis, that may plausibly contribute to a pro-survival status of B cells in MS.

Author Correction: Transcriptional dysregulation of Interferome in experimental and human Multiple Sclerosis.

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.

Thymosin-α1 expands deficient IL-10-producing regulatory B cell subsets in relapsing-remitting multiple sclerosis patients.

BACKGROUND: B cells are key pathogenic effectors in multiple sclerosis (MS) and several therapies have been designed to restrain B cell abnormalities by directly targeting this lymphocyte population. OBJECTIVES: Moving from our data showing a Toll-like receptor (TLR)7-driven dysregulation of B cell response in relapsing-remitting multiple sclerosis (RRMS) and having found a low serum level of Thymosin-α1 (Tα1) in patients, we investigated whether the addition of this molecule to peripheral blood mononuclear cells (PBMCs) would influence the expansion of regulatory B cell subsets, known to dampen autoimmune inflammation. METHODS: Serum Tα1 level was measured by enzyme immunoassay. Cytokine expression was evaluated by Cytometric Bead Array (CBA), enzyme-linked immunosorbent assay (ELISA), and real-time reverse transcription polymerase chain reaction (RT-PCR). B cell subsets were analyzed by flow cytometry. RESULTS: Tα1 pre-treatment induces an anti-inflammatory status in TLR7-stimulated RRMS PBMC cultures, reducing the secretion of pro-inflammatory interleukin (IL)-6, IL-8, and IL-1ß while significantly increasing the regulatory IL-10 and IL-35. Indeed, Tα1 treatment enhanced expansion of CD19+CD24+CD38hi transitional-immature and CD24low/negCD38hi plasmablast-like regulatory B cell subsets, which likely inhibit both interferon (IFN)-γ and IL-17 production. CONCLUSION: Our study reveals a deficient ability of B cells from MS patients to differentiate into regulatory subsets and unveils a novel anti-inflammatory and repurposing potential for Tα1 in MS targeting B cell response.