Th17 cells in multiple sclerosis express higher levels of JAK2, which increases their surface expression of IFN-γR2

MicroRNAs are dysregulated in peripheral blood mononuclear cells in multiple sclerosis and correlate with T cell mediators

T cell mediators and microRNAs are involved in the pathogenesis of multiple sclerosis (MS), but their interaction largely remains undetermined. We investigated by RT-qPCR the dysregulation of microRNAs in peripheral blood mononuclear cells of MS patients versus healthy controls, according to radiological disease activity or treatment. Several microRNAs correlated positively/negatively with IL21/FOXP3 mRNA expression, but not with serum neurofilament light chain levels. Cytokine expression is conceivably balanced by several regulators, whereas microRNAs possibly target upstream transcription factors rather than directly cytokine mRNAs. Functional studies are needed to investigate their interaction, notably for the predicted targeting of FOXP3 by miR-34c-5p.

Tissue memory relies on stem cell priming in distal undamaged areas

Epithelial cells that participated in wound repair elicit a more efficient response to future injuries, which is believed to be locally restricted. Here we show that cell adaptation resulting from a localized tissue damage has a wide spatial impact at a scale not previously appreciated. We demonstrate that a specific stem cell population, distant from the original injury, originates long-lasting wound memory progenitors residing in their own niche. Notably, these distal memory cells have not taken part in the first healing but become intrinsically pre-activated through priming. This cell state, maintained at the chromatin and transcriptional level, leads to an enhanced wound repair that is partially recapitulated through epigenetic perturbation. Importantly wound memory has long-term harmful consequences, exacerbating tumourigenesis. Overall, we show that sub-organ-scale adaptation to injury relies on spatially organized memory-dedicated progenitors, characterized by an actionable cell state that establishes an epigenetic field cancerization and predisposes to tumour onset.

RGD_PLGA Nanoparticles with Docetaxel: A Route for Improving Drug Efficiency and Reducing Toxicity in Breast Cancer Treatment

Breast cancer is the leading cause of cancer-related death in women. Although many therapeutic approaches are available, systemic chemotherapy remains the primary choice, especially for triple-negative and advanced breast cancers. Unfortunately, systemic chemotherapy causes serious side effects and requires high doses to achieve an effective concentration in the tumor. Thus, the use of nanosystems for drug delivery may overcome these limitations. Herein, we formulated Poly (lactic-co-glycolic acid) nanoparticles (PLGA-NPs) containing Docetaxel, a fluorescent probe, and a magnetic resonance imaging (MRI) probe. The cyclic RGD tripeptide was linked to the PLGA surface to actively target α_vβ₃ integrins, which are overexpressed in breast cancer. PLGA-NPs were characterized using dynamic light scattering, fast field-cycling ¹H-relaxometry, and ¹H-nuclear magnetic resonance. Their therapeutic effects were assessed both in vitro in triple-negative and HER2+ breast cancer cells, and in vivo in murine models. In vivo MRI and inductively coupled plasma mass spectrometry of excised tumors revealed a stronger accumulation of PLGA-NPs in the RGD_PLGA group. Targeted PLGAs have improved therapeutic efficacy and strongly reduced cardiac side effects compared to free Docetaxel. In conclusion, RGD-PLGA is a promising system for breast cancer treatment, with positive outcome in terms of therapeutic efficiency and reduction in side effects.

Toll-like receptor 2 promotes breast cancer progression and resistance to chemotherapy

Cancer stem cells (CSCs) are the main drivers of disease progression and chemotherapy resistance in breast cancer. Tumor progression and chemoresistance might then be prevented by CSC-targeted therapies. We previously demonstrated that Toll-like Receptor (TLR)2 is overexpressed in CSCs and fuels their self-renewal. Here, we show that high TLR2 expression is linked to poor prognosis in breast cancer patients, therefore representing a candidate target for breast cancer treatment. By using a novel mammary cancer-prone TLR2^KO mouse model, we demonstrate that TLR2 is required for CSC pool maintenance and for regulatory T cell induction. Accordingly, cancer-prone TLR2^KO mice display delayed tumor onset and increased survival. Transplantation of TLR2^WT and TLR2^KO cancer cells in either TLR2^WT or TLR2^KO hosts shows that tumor initiation is mostly sustained by TLR2 expression in cancer cells. TLR2 host deficiency partially impairs cancer cell growth, implying a pro-tumorigenic effect of TLR2 expression in immune cells. Finally, we demonstrate that doxorubicin-induced release of HMGB1 activates TLR2 signaling in cancer cells, leading to a chemotherapy-resistant phenotype. Unprecedented use of TLR2 inhibitors in vivo reduces tumor growth and potentiates doxorubicin efficacy with no negative impact on the host immune system, opening new perspectives for the treatment of breast cancer patients.

Flow Cytometry for Beginners: Hints and Tips for Approaching the Very First Single-Cell Technique

While many single-cell proteomics techniques have been rapidly developed over the past decade, flow cytometry still remains the pillar of single-cell protein analysis, as it allows to rapidly analyze and characterize protein expression in millions of cells.In this chapter, we will describe the main steps to prepare and acquire samples for flow cytometry, with particular focus on the setup of the right controls that are instrumental in analyzing and interpreting the results.

ZEB1 promotes pathogenic Th1 and Th17 cell differentiation in multiple sclerosis

Inappropriate CD4⁺ T helper (Th) differentiation can compromise host immunity or promote autoimmune disease. To identify disease-relevant regulators of T cell fate, we examined mutations that modify risk for multiple sclerosis (MS), a canonical organ-specific autoimmune disease. This analysis identified a role for Zinc finger E-box-binding homeobox (ZEB1). Deletion of ZEB1 protects against experimental autoimmune encephalitis (EAE), a mouse model of multiple sclerosis (MS). Mechanistically, ZEB1 in CD4⁺ T cells is required for pathogenic Th1 and Th17 differentiation. Genomic analyses of paired human and mouse expression data elucidated an unexpected role for ZEB1 in JAK-STAT signaling. ZEB1 inhibits miR-101-3p that represses JAK2 expression, STAT3/STAT4 phosphorylation, and subsequent expression of interleukin-17 (IL-17) and interferon gamma (IFN-γ). Underscoring its clinical relevance, ZEB1 and JAK2 downregulation decreases pathogenic cytokines expression in T cells from MS patients. Moreover, a Food and Drug Administration (FDA)-approved JAK2 inhibitor is effective in EAE. Collectively, these findings identify a conserved, potentially targetable mechanism regulating disease-relevant inflammation.

Qian et al. show that ZEB1 is required for the development of the autoimmune disease multiple sclerosis (MS). ZEB1, a transcription factor, promotes JAK-STAT signaling during Th1/Th17 differentiation by repressing expression of a JAK2-targeting miRNA. ZEB1 and JAK2 are potentially clinically relevant therapeutic targets for MS.

Cytokines and Transgenic Matrix in Autoimmune Diseases: Similarities and Differences

Autoimmune diseases are increasingly recognized as disease entities in which dysregulated cytokines contribute to tissue-specific inflammation. In organ-specific and multiorgan autoimmune diseases, the cytokine profiles show some similarities. Despite these similarities, the cytokines have different roles in the pathogenesis of different diseases. Altered levels or action of cytokines can result from changes in cell signaling. This article describes alterations in the JAK-STAT, TGF-β and NF-κB signaling pathways, which are involved in the pathogenesis of multiple sclerosis and systemic lupus erythematosus. There is a special focus on T cells in preclinical models and in patients afflicted with these chronic inflammatory diseases.

Protective effect of microRNA-134-3p on multiple sclerosis through inhibiting PRSS57 and promotion of CD34+ cell proliferation in rats

MicroRNAs (miRs) have been extensively studied for their involvement in multiple sclerosis (MS). We investigated the involvement of miR-134-3p on MS. The MS rat model was established, and positive expression of interleukin-17 (IL-17) was detected using the immunohistochemical method while the expression of miR-134-3p and serine protease 57 (PRSS57) was determined by means of reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and Western blot analysis. Second, the miR-134-3p overexpression or short hairpin RNA against PRSS57 was introduced into the CD34⁺ cells to investigate the levels of proliferation and apoptosis-related genes by RT-qPCR and Western blot analysis. In addition, analysis of the targeting relations of miR-134-3p and PRSS57 was conducted using online software and dual-luciferase reporter gene assay. Furthermore, neuronal functions, inflammatory response, proliferation, and apoptosis of CD34⁺ cells were assayed by flow cytometry, enzyme-linked immunosorbent assay, and methyl thiazolyl tetrazolium. IL-17 and PRSS57 expression increased while miR-134-3p expression decreased in the spinal cord from MS rats. miR-134-3p could target PRSS57. miR-134-3p overexpression or PRSS57 silencing enhanced mitochondrial activity of neurons, mitochondrial membrane potential content, CD34⁺ cell proliferation, while decreasing Cyt C content, inflammatory response, and cell apoptosis. Collectively, overexpression of miR-134-3p promotes CD34⁺ cell proliferation via inhibition of PRSS57 in MS, which may serve as a promising target for MS intervention.

Identification of Monotonically Differentially Expressed Genes for IFN-β-Treated Multiple Sclerosis Patients

Multiple sclerosis (MS) is a common neurological disability of the central nervous system. Immune-modulatory therapy with interferon-β (IFN-β) has been used as a first-line treatment to prevent relapses in MS patients. While the therapeutic mechanism of IFN-β has not been fully elucidated, the data of microarray experiments that collected longitudinal gene expression profiles to evaluate the long-term response of IFN-β treatment have been analyzed using statistical methods that were incapable of dealing with such data. In this study, the GeneRank method was applied to generate weighted gene expression values and the monotonically expressed genes (MEGs) for both IFN-β treatment responders and nonresponders were identified. The proposed procedure identified 13 MEGs for the responders and 2 MEGs for the nonresponders, most of which are biologically relevant to MS. Our work here provides some useful insight into the mechanism of IFN-β treatment for MS patients. A full understanding of the therapeutic mechanism will enable a more personalized treatment strategy possible.

V617F-independent upregulation of JAK2 gene expression in patients with inflammatory bowel disease

BACKGROUND

Inflammatory bowel disease (IBD) is one of the most important immune-mediated disorders of the gastrointestinal tract. Besides, IBD is associated with numerous extraintestinal complications such as venous thromboembolism (VTE), an important risk factor for vascular complications, which results in the increased morbidity and mortality. The JAK2 (Janus kinase 2) V617F mutation is a well-known point mutation which is involved in the pathogenesis of IBD, and VTE. Therefore, the aims of this study were to evaluate expression of JAK2 and association of V617F mutation in JAK2 of Iranian patients with IBD.

METHODS

Two hundred and forty-six patients with IBD (209 UC and 37 CD) and 206 healthy controls were enrolled in this study. The genomic DNA and total RNA were extracted from peripheral blood mononuclear cells (PBMCs). Then, the JAK2 V617F mutation detection was performed using the restriction fragment length polymorphism (RFLP) method. In addition, the JAK2 mRNA expression was evaluated using a quantitative polymerase chain reaction (q-PCR) using the SYBR Green assay.

RESULTS

There was no association of V61F mutation in patients with IBD with or without thrombosis compared with healthy control. However, the relative mRNA expression of JAK2 was significantly upregulated in patients with IBD in comparison with healthy control (P < 0.0001). In addition, the JAK2 mRNA expression was significantly decreased in patients with IBD having thrombosis compared with those without thrombosis ( P < 0.0001).

CONCLUSIONS

Taken together our findings suggested that JAK2 V61F-independent upregulation of JAK2 mRNA expression in patients with IBD. Moreover, despite the absence of JAK2 V617F mutation in patients with IBD, the increased gene expression of JAK2 can be explained by another molecular mechanism such as regulation of gene expression at the transcriptional level which may play crucial roles in the pathogenesis of IBD.

Bovine herpesvirus 4-based vector delivering the full length xCT DNA efficiently protects mice from mammary cancer metastases by targeting cancer stem cells

Despite marked advancements in its treatment, breast cancer is still the second leading cause of cancer death in women, due to relapses and distal metastases. Breast cancer stem cells (CSCs), are a cellular reservoir for recurrence, metastatic evolution and disease progression, making the development of novel therapeutics that target CSCs, and thereby inhibit metastases, an urgent need. We have previously demonstrated that the cystine-glutamate antiporter xCT (SLC7A11), a protein that was shown to be overexpressed in mammary CSCs and that plays a key role in the maintenance of their redox balance, self-renewal and resistance to chemotherapy, is a potential target for mammary cancer immunotherapy. This paper reports on the development of an anti-xCT viral vaccine that is based on the bovine herpesvirus 4 (BoHV-4) vector, which we have previously showed to be a safe vaccine that can transduce cells in vivo and confer immunogenicity to tumor antigens. We show that the vaccination of BALB/c mice with BoHV-4 expressing xCT (BoHV-4-mxCT), impaired lung metastases induced by syngeneic mammary CSCs both in preventive and therapeutic settings. Vaccination induced T lymphocyte activation and the production of anti-xCT antibodies that can mediate antibody-dependent cell cytotoxicity (ADCC), and directly impair CSC phenotype, self-renewal and redox balance. Our findings pave the way for the potential future use of BoHV-4-based vector targeting xCT in metastatic breast cancer treatment.

L-Ferritin targets breast cancer stem cells and delivers therapeutic and imaging agents

A growing body of evidence suggests that cancer stem cells (CSC) have the unique biological properties necessary for tumor maintenance and spreading, and function as a reservoir for the relapse and metastatic evolution of the disease by virtue of their resistance to radio- and chemo-therapies. Thus, the efficacy of a therapeutic approach relies on its ability to effectively target and deplete CSC. In this study, we show that CSC-enriched tumorspheres from breast cancer cell lines display an increased L-Ferritin uptake capability compared to their monolayer counterparts as a consequence of the upregulation of the L-Ferritin receptor SCARA5. L-Ferritin internalization was exploited for the simultaneous delivery of Curcumin, a natural therapeutic molecule endowed with antineoplastic action, and the MRI contrast agent Gd-HPDO3A, both entrapped in the L-Ferritin cavity. This theranostic system was able to impair viability and self-renewal of tumorspheres in vitro and to induce the regression of established tumors in mice. In conclusion, here we show that Curcumin-loaded L-Ferritin has a strong therapeutic potential due to the specific targeting of CSC and the improved Curcumin bioavailability, opening up the possibility of its use in a clinical setting.

NK cells control breast cancer and related cancer stem cell hematological spread

The growth and recurrence of a number of cancers is driven by a scarce population of cancer stem cells (CSCs), which are resistant to most current therapies. It has been shown previously that natural killer (NK) cells recognize human glioma, melanoma, colon and prostate CSCs in vitro. We herein show that human and mouse breast CSCs are also susceptible to NK cytotoxic activity in vitro. Moreover, CSC induced autologous NK cell activation and expansion in vivo, which correlate with the inhibition of CSC metastatic spread. These data suggest that NK cells control CSC metastatic spread in vivo and that their use in breast cancer therapy may well be fruitful.

Heterogeneous Network Edge Prediction: A Data Integration Approach to Prioritize Disease-Associated Genes

The first decade of Genome Wide Association Studies (GWAS) has uncovered a wealth of disease-associated variants. Two important derivations will be the translation of this information into a multiscale understanding of pathogenic variants and leveraging existing data to increase the power of existing and future studies through prioritization. We explore edge prediction on heterogeneous networks—graphs with multiple node and edge types—for accomplishing both tasks. First we constructed a network with 18 node types—genes, diseases, tissues, pathophysiologies, and 14 MSigDB (molecular signatures database) collections—and 19 edge types from high-throughput publicly-available resources. From this network composed of 40,343 nodes and 1,608,168 edges, we extracted features that describe the topology between specific genes and diseases. Next, we trained a model from GWAS associations and predicted the probability of association between each protein-coding gene and each of 29 well-studied complex diseases. The model, which achieved 132-fold enrichment in precision at 10% recall, outperformed any individual domain, highlighting the benefit of integrative approaches. We identified pleiotropy, transcriptional signatures of perturbations, pathways, and protein interactions as influential mechanisms explaining pathogenesis. Our method successfully predicted the results (with AUROC = 0.79) from a withheld multiple sclerosis (MS) GWAS despite starting with only 13 previously associated genes. Finally, we combined our network predictions with statistical evidence of association to propose four novel MS genes, three of which (JAK2, REL, RUNX3) validated on the masked GWAS. Furthermore, our predictions provide biological support highlighting REL as the causal gene within its gene-rich locus. Users can browse all predictions online (http://het.io). Heterogeneous network edge prediction effectively prioritized genetic associations and provides a powerful new approach for data integration across multiple domains.

For complex human diseases, identifying the genes harboring susceptibility variants has taken on medical importance. Disease-associated genes provide clues for elucidating disease etiology, predicting disease risk, and highlighting therapeutic targets. Here, we develop a method to predict whether a given gene and disease are associated. To capture the multitude of biological entities underlying pathogenesis, we constructed a heterogeneous network, containing multiple node and edge types. We built on a technique developed for social network analysis, which embraces disparate sources of data to make predictions from heterogeneous networks. Using the compendium of associations from genome-wide studies, we learned the influential mechanisms underlying pathogenesis. Our findings provide a novel perspective about the existence of pervasive pleiotropy across complex diseases. Furthermore, we suggest transcriptional signatures of perturbations are an underutilized resource amongst prioritization approaches. For multiple sclerosis, we demonstrated our ability to prioritize future studies and discover novel susceptibility genes. Researchers can use these predictions to increase the statistical power of their studies, to suggest the causal genes from a set of candidates, or to generate evidence-based experimental hypothesis.

Expression of Interferon-γ Receptor Genes in Peripheral Blood Mononuclear Cells Is Associated With Rheumatoid Arthritis and Its Radiographic Severity in African Americans

OBJECTIVE

The factors responsible for radiographic severity in African American patients with rheumatoid arthritis (RA) are poorly understood. We sought to identify genes whose expression in peripheral blood mononuclear cells is associated with radiographic severity in RA.

METHODS

In the first phase of the study, we performed real-time quantitative polymerase chain reaction to analyze the expression of 182 candidate genes in 40 African American RA patients with extremes of radiographic damage (low versus high radiographic scores) and disease duration (≤2 years versus >2 years) and 20 healthy African American control subjects; the genes were selected based on plausible immune pathways. In the second phase, we analyzed the expression of the genes that were shown to be significantly associated with radiographic scores in 576 African American patients with RA and 51 African American control subjects who had not been studied previously, accounting for autoantibody status and disease duration.

RESULTS

We observed significant differences in IFNGR1 expression between patients with RA and control subjects (adjusted P [P(adj)] = 6 × 10(-14)) and in IFNGR2 expression between RA patients with erosions and those with no erosions (P(adj) = 0.01 by Wilcoxon's rank sum test). We also observed significant correlations between IFNGR2 expression and radiographic scores (P(adj) = 0.03 for erosions, P(adj) = 0.04 for joint space narrowing, and P(adj) = 0.03 for total radiographic score [zero-inflated negative binomial regression model]) and annualized progression rate (P(adj) = 0.0024 by Spearman's correlation analysis).

CONCLUSION

These findings have important implications with respect to the role of interferon-γ (IFNγ) in the pathogenesis of RA and may lead to identification of a biomarker for radiographic damage. Additional studies are needed to define the cell subsets responsible for the association of IFNγ receptor gene expression with radiographic findings, which downstream mechanisms are involved, and generalizability to other RA populations.

Interaction of astrocytes and T cells in physiological and pathological conditions

The central nervous system (CNS) has long been recognized as a site of 'immune privilege' because of the existence of the blood brain barrier (BBB) which presumably isolates CNS from the peripheral immunosurveillance. Different from the peripheral organs, CNS is unique in response to all forms of CNS injury and disease which is mainly mediated by resident microglia and astrocyte. There is increasing evidence that immune cells are not only involved in neuroinflammation process but also the maintenance of CNS homeostasis. T cells, an important immune cell population, are involved in the pathogenesis of some neurological diseases by inducing either innate or adaptive immune responses. Astrocytes, which are the most abundant cell type in the CNS, maintain the integrity of BBB and actively participate in the initiation and progression of neurological diseases. Surprisingly, how astrocytes and T cells interact and the consequences of their interaction are not clear. In this review we briefly summarized T cells diversity and astrocyte function. Then, we examined the evidence for the astrocytes and T cells interaction under physiological and pathological conditions including ischemic stroke, multiple sclerosis, viral infection, and Alzheimer's disease. This article is part of a Special Issue entitled SI: Cell Interactions In Stroke.

Th22 cells are expanded in multiple sclerosis and are resistant to IFN-β

Th1 and Th17 cells have been considered as effectors in mouse EAE and in the human counterpart, MS. Recently, IL-22, a Th17-related, proinflammatory cytokine, has been associated with a new Th cell subset, defined as Th22, involved in chronic inflammatory conditions, such as psoriasis; the role of IL-22 in MS has not yet been elucidated. Here, we report that similar to Th17 cells, the number of Th22 cells increased in the PB and the CSF of RR MS patients, especially during the active phases of the disease. However, as opposed to Th17 cells, the expansion of Th22 cells occurred before the active phases of the disease. Th22 cells were found to be specific for the autoantigen MBP and also expressed high levels of CCR6 and T-bet, as for Th17 cells, indicating that Th22 self-reactive cells could have CNS-homing properties and be pathogenic in active RRMS patients. Conversely to Th17 cells, Th22 cells displayed lower levels of IFNAR1 and were insensitive to IFN-β inhibition. These data suggest that expansion of Th22 cells in MS could be one of the factors that critically influence resistance to IFN-β therapy.

Acute-phase protein hemopexin is a negative regulator of Th17 response and experimental autoimmune encephalomyelitis development

Hemopexin (Hx) is an acute-phase protein synthesized by hepatocytes in response to the proinflammatory cytokines IL-6, IL-1β, and TNF-α. Hx is the plasma protein with the highest binding affinity to heme and controls heme-iron availability in tissues and also in T lymphocytes, where it modulates their responsiveness to IFN-γ. Recent data have questioned regarding an anti-inflammatory role of Hx, a role that may be both heme-binding dependent and independent. The aim of this study was to investigate the role of Hx in the development of a T cell-mediated inflammatory autoimmune response. During experimental autoimmune encephalomyelitis (EAE), the mouse model of multiple sclerosis, Hx content in serum increased and remained high. When EAE was induced in Hx knockout (Hx(-/-)) mice, they developed a clinically earlier and exacerbated EAE compared with wild-type mice, associated to a higher amount of CD4(+)-infiltrating T cells. The severe EAE developed by Hx(-/-) mice could be ascribed to an enhanced expansion of Th17 cells accounting for both a higher disposition of naive T cells to differentiate toward the Th17 lineage and a higher production of Th17 differentiating cytokines IL-6 and IL-23 by APCs. When purified human Hx was injected in Hx(-/-) mice before EAE induction, Th17 expansion, as well as disease severity, were comparable with those of wild-type mice. Taken together, these data indicate that Hx has a negative regulatory role in Th17-mediated inflammation and prospect its pharmacological use to limit the expansion of this cell subset in inflammatory and autoimmune disease.

Multiple sclerosis: the role of cytokines in pathogenesis and in therapies

Multiple sclerosis, the clinical features and pathological correlate for which were first described by Charcot, is a chronic neuroinflammatory disease with unknown etiology and variable clinical evolution. Although neuroinflammation is a descriptive denominator in multiple sclerosis based on histopathological observations, namely the penetration of leukocytes into the central nervous system, the clinical symptoms of relapses, remissions and progressive paralysis are the result of losses of myelin and neurons. In the absence of etiological factors as targets for prevention and therapy, the definition of molecular mechanisms that form the basis of inflammation, demyelination and toxicity for neurons have led to a number of treatments that slow down disease progression in specific patient cohorts, but that do not cure the disease. Current therapies are directed to block the immune processes, both innate and adaptive, that are associated with multiple sclerosis. In this review, we analyze the role of cytokines in the multiple sclerosis pathogenesis and current/future use of them in treatments of multiple sclerosis.

Citrullination of histone H3 interferes with HP1-mediated transcriptional repression

Multiple Sclerosis (MS) is an autoimmune disease associated with abnormal expression of a subset of cytokines, resulting in inappropriate T-lymphocyte activation and uncontrolled immune response. A key issue in the field is the need to understand why these cytokines are transcriptionally activated in the patients. Here, we have examined several transcription units subject to pathological reactivation in MS, including the TNFα and IL8 cytokine genes and also several Human Endogenous RetroViruses (HERVs). We find that both the immune genes and the HERVs require the heterochromatin protein HP1α for their transcriptional repression. We further show that the Peptidylarginine Deiminase 4 (PADI4), an enzyme with a suspected role in MS, weakens the binding of HP1α to tri-methylated histone H3 lysine 9 by citrullinating histone H3 arginine 8. The resulting de-repression of both cytokines and HERVs can be reversed with the PADI-inhibitor Cl-amidine. Finally, we show that in peripheral blood mononuclear cells (PBMCs) from MS patients, the promoters of TNFα, and several HERVs share a deficit in HP1α recruitment and an augmented accumulation of histone H3 with a double citrulline 8 tri-methyl lysine 9 modifications. Thus, our study provides compelling evidence that HP1α and PADI4 are regulators of both immune genes and HERVs, and that multiple events of transcriptional reactivation in MS patients can be explained by the deficiency of a single mechanism of gene silencing.