Human endogenous retroviruses (HERVs) have been associated with multiple sclerosis (MS) pathogenesis. Several related HERV-W sequences have been implicated in disease occurrence and progression; the MS retrovirus (MSRV) is one such element whose envelope protein has been recently demonstrated to be involved in innate immune pathogenesis. To distinguish MSRV from other HERV-W sequences we analyzed the relative abundance of individual HERV-W env sequences by employing a real-time PCR approach using specific oligonucleotide primers and tissue samples from MS and non-MS patients. Our analyses reveal that ERVWE1 env-encoding DNA and RNA exhibited increased detection (p < 0.05) and expression (p < 0.01) in the brains of MS patients. Similarly, ERVWE1 env transcripts were inducible in glial cells (p < 0.05), while comparable changes in MSRV abundance were not observed. These results indicate that individual HERVs might have distinct roles in MS pathogenesis.

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Although human endogenous retroviruses (HERVs) constitute 8% of the human genome, their role(s) in health and disease remain uncertain. Nonetheless, increased HERV gene activity has been reported in neuroinflammatory diseases such as multiple sclerosis (MS). The human endogenous retrovirus (HERV)-W7q envelope gene encodes a glycosylated envelope protein, syncytin-1, which is expressed in many tissues. Analysis of HERV envelopes (env) revealed a selectively increased abundance of syncytin-1 encoding RNA in brains from patients with MS (p<0.01) relative to non-MS patients. However, HERV env expression from blood-derived leukocytes did not differ between groups. A quantitative PCR-based assay for syncytin-1 RNA showed that median viral RNA levels were higher in brains of MS patients (5.0 log10 copies/microg RNA) relative to non-MS patients (4.6 log10 copies/microg RNA) (p<0.05). Median syncytin-1 DNA levels in MS brains (9.8 log10/microg DNA) were higher than non-MS brain tissue (7.9 log10/microg DNA) (p<0.001) without evidence of new integration events. In contrast, there were no differences in syncytin-1 RNA copy numbers between groups in both CSF (non-MS: 5.0 log10/ml versus MS: 3.8 log10/ml) and plasma (non-MS: 5.033 log10/ml versus MS: 2.9 log10/ml). These observations emphasize the selective induction of syncytin-1 in brain tissue of MS patients but also illustrate the complex dynamics of this retroelement in neuroinflammatory processes.

Multiple roles have been indicated for reactive oxygen species (ROS) in the immune system in recent years. ROS have been extensively studied due to their ability to damage DNA and other subcellular structures. Noticeably, they have been identified as a pivotal second messenger for T-cell receptor signaling and T-cell activation and participate in antigen cross-presentation and chemotaxis. As an agent with direct toxic effects on cells, ROS lead to the initiation of the autoimmune response. Moreover, ROS levels are regulated by antioxidant systems, which include enzymatic and nonenzymatic antioxidants. Enzymatic antioxidants include superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase. Nonenzymatic antioxidants contain vitamins C, A, and E, glutathione, and thioredoxin. Particularly, cellular antioxidant systems have important functions in maintaining the redox system homeostasis. This review will discuss the significant roles of ROS generation and antioxidant systems under normal conditions, in the immune system, and pathogenesis of multiple sclerosis.

With the development of novel treatments for autoimmune disorders, it has become a popular research focus which mesenchymal stem cells (MSCs) have the capacity to counteract with autoimmune diseases progression. One of the underlying mechanisms behind their activities is the release of extracellular vesicles especially exosomes. MSC-derived exosomes are hypoimmunogenic nanocarriers which contain numerous immunoregulatory factors and similar to other exosomes, are able to pass through boundaries like the blood-brain barrier (BBB). Accumulating evidence provided by animal studies has demonstrated that MSC-derived exosomes, as a novel therapy, can re-induce self-tolerance, without subsequent complications reported for other treatments. Therefore, therapeutic applications of MSC-derived exosomes are contributing to core advances in the field of autoimmune diseases. Here, we briefly describe the biological characteristics of MSC-derived exosomes and review the experimentally verified outcomes for autoimmune disease therapy purposes.

Nod‐like receptor protein 3 (NLRP3) inflammasome is a multi‐protein complex that controls the production of pro‐inflammatory cytokines, IL‐18 and IL‐1β, through caspase‐1 activation. These inflammatory cytokines play an important role in the development of multiple sclerosis (MS). The inflammasome NLRP3 gene variations and expression level have been suggested to affect the immune system activity. This case–control study was performed to determine the association of NLRP3 genetic variants and differential expression with MS. We analysed four common single nucleotide polymorphisms (SNPs) of NLRP3 (rs‐10754558, rs‐35829419, rs‐3806265, rs‐4612666) in a group of 150 Iranian patients with relapsing–remitting MS (RRMS) in comparison with 100 healthy controls. The genotyping was performed using the TaqMan method. For the analysis of NLRP3 gene expression level, we studied a group of 37 RRMS patients (18 patients at relapse phase and 19 at remission phase, treated with IFN‐β) in comparison with 22 healthy controls using real‐time PCR. In this study, we found that NLRP3 rs3806265 C allele and CC genotype were significantly more frequent in the RRMS patients (p value = 0.03 OR = 1.66, 95% CI = 1.14–2.43) and p value = 0.04, OR = 3.26, 95% CI = 1.19–8.93, respectively), while the frequency of T allele significantly decreased in controls (p value = 0.03, OR = 0.6, 95% CI = 0.41–0.87). The frequency of CG genotype at position rs10754558 was also significantly higher in the controls compared with patients (p value = 0.03, OR = 0.5, 95% CI = 0.30–0.80). Moreover, expression level of the NLRP3 in patients at remission phase was significantly reduced in comparison with patients at relapse phase and also healthy controls (p = 0.01 and p = 0.04, respectively). The association of NLRP3 polymorphisms with the susceptibility of MS and its reduced expression after IFN‐β therapy, support the idea that NLRP3 inflammasome could have a critical role in inflammatory responses in MS.

Invasion of auto-reactive CD4+ T cells especially Th17 into central nervous system (CNS) is an underlying pathogenic mechanism in multiple sclerosis (MS). CD4+ T cells release exosomes which are enriched in microRNAs, reflective of cell’s physiological or pathological condition. Thus exosomes could be potent agents to provide quantitative and qualitative information about involved cells in MS. We investigated the expression of pathogenic microRNAs in T cells-derived exosomes of MS patients or healthy controls. Conventional T cells (Tconv) derived from relapsing-remitting (RR) MS patients (n=10) and healthy controls (n=10) were purified and cultured for 3 days by soluble anti-CD3/CD28. Exosomes were purified from cultured-T cells supernatants. The expression levels of exosomal miR-146a, miR-29a, miR-155, and miR-326 were quantified by real-time PCR. A statistically significant increased expression of miR-326 in Tconv-derived exosomes was observed in RRMS patients as compared with controls (7.5±1.88vs 2.51±0.9 p=0.03), On the contrary, no differences were found in the expression levels of miR-155, miR-146a, and miR-29a, in Tconv-derived exosomes of  patients as compared with controls (p>0.05).  Our results point to altered expression in exosome-derived microRNAs. MiR-326 was previously shown to play a role in the immunopathogenesis of MS by inducing TH17 differentiation and maturation. Therefore, miR-326 containing exosomes might also be a potential clinical target in course of MS. Moreover, the deregulation of this miRNA in exosomes may serve as a diagnostic and prognostic biomarker.

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