Probing the association between Multiple Sclerosis and Epstein Barr Virus from a therapeutic perspective

EBV infected cells in the multiple sclerosis brain express PD-L1: How the virus and its niche may escape immune surveillance

The presence of EBV infected B cells in postmortem multiple sclerosis (MS) brain tissue suggests immune evasion strategies. Using immunohistochemical techniques we analysed the expression of the immune checkpoint molecule PD-L1 and its receptor PD-1 in MS brains containing B cell-enriched perivascular infiltrates and meningeal follicles, a major EBV reservoir. PD-1 and PD-L1 immunoreactivities were restricted to CNS-infiltrating immune cells. PD-L1 was expressed on B cells, including EBV infected B cells, while PD-1 was expressed on many CD8+ T cells, including EBV-specific CD8+ T-cells, and fewer CD4+ T cells. PD-L1+ cells and EBV infected cells were in close contact with PD-1+ T cells. PD-L1 expressed by EBV infected B cells could favour local immune evasion leading to EBV persistence and immunopathology in the MS brain.

Adult-onset neurodegeneration in XMEN disease

BACKGROUND

XMEN (X-linked immunodeficiency with magnesium defect, Epstein-Barr virus (EBV), and N-linked glycosylation defect) disease results from loss-of-function mutations in MAGT1, a protein that serves as a magnesium transporter and a subunit of the oligosaccharyltransferase (OST) complex. MAGT1 deficiency disrupts N-linked glycosylation, a critical regulator of immune function. XMEN results in recurrent EBV infections and a propensity for EBV-driven malignancies. Although XMEN is recognized as a systemic congenital disorder of glycosylation (CDG), its neurological involvement is rare and poorly characterized.

CASES

Two young men, ages 32 and 33, are described here with truncating mutations in MAGT1, progressive behavioral changes, and neurodegenerative symptoms. These features manifested well into adulthood. Both patients still presented with many of the molecular and clinical hallmarks of the typical XMEN patient, including chronic EBV viremia and decreased expression of NKG2D.

CONCLUSION

While previously unrecognized, XMEN may include prominent and disabling CNS manifestations. How MAGT1 deficiency directly or indirectly contributes to neurodegeneration remains unclear. Elucidating this mechanism may contribute to the understanding of neurodegeneration more broadly.

Toll-like receptor 10 is down-regulated in serum of patients with relapsing-remitting multiple sclerosis but not associated with Epstein-Barr virus

In this study, toll-like receptor 10 (TLR10) and Epstein-Barr virus (EBV) were determined in the peripheral blood of 43 patients with relapsing-remitting multiple sclerosis and 41 age- and gender-matched controls. Serum TLR10 levels were assessed using an enzyme-linked immunosorbent assay kit. EBV DNA and viral load were detected using a real-time polymerase chain reaction assay kit. Results revealed that median TLR10 levels were significantly lower in patients than in controls (318 vs. 574 pg/mL; p < 0.001). Most patients were classified as low producers of TLR10 (≤ median of controls) compared to controls (84.0 vs. 51.0%; p < 0.001). Logistic regression analysis revealed that participants with low TLR10 production had an odds ratio of 4.52. Receiver operating characteristic curve analysis indicated that TLR10 is a good predictor of multiple sclerosis (area under the curve = 0.778; p < 0.001). Prevalence of EBV was less frequent in patients than in controls but the difference was not significant (23.3 vs. 41.5%; p = 0.102), while median EBV load was significantly higher in patients compared to controls (8.55 vs. 1.29 DNA copy/100 cells). When TLR10 levels were stratified according to age group, gender, EBV positivity, Expanded Disability Status Scale (EDSS), or therapy, no significant differences were found in each stratum. Further, no significant correlation was found between TLR10 levels and EDSS or EBV load. In conclusions, TLR10 was down-regulated in serum of multiple sclerosis patients, and this down-regulation was not affected by age, gender, EBV load, EDSS, or therapy.

EBV as the 'gluten of MS' hypothesis: Bypassing autoimmunity

The EBV as the 'gluten of MS' hypothesis discussed by Drosu et al. in a recent Editorial envisages the existence of similar mechanisms leading to celiac disease and multiple sclerosis, such as induction of immunity against an ubiquitous exogenous antigen - gluten and EBV, respectively - and subsequent development of autoimmunity that is maintained by persistence of the initial trigger. While this hypothesis provides the rationale for treating MS with antivirals to lower EBV load, it can be misleading when trying to translate concepts of T cell-B cell interaction and autoimmunity development in celiac disease to multiple sclerosis. Here, we propose that EBV might act as the driver of multiple sclerosis without involving autoimmunity.

Toll-like receptor 10 gene polymorphism and risk of multiple sclerosis among Iraqi patients

Background

Toll-like receptors (TLRs) are a family of 10 pattern recognition receptors (TLR1–TLR10) involved in the regulation of inflammatory and immune responses besides their role in the pathogenesis of autoimmune diseases including multiple sclerosis (MS). TLR10 is the least studied TLR in MS, and data for single nucleotide polymorphisms (SNPs) of the TLR10 gene are limited. Therefore, a case–control study was performed on 85 patients with relapsing–remitting MS and 86 healthy controls (HC) to explore SNPs in the promoter region of TLR10 gene. A 927-bp region was amplified, and Sanger sequencing identified 10 SNPs with a minor allele frequency ≥ 10% (rs200395112 T/A, rs201802754 A/T, rs201228097 T/A, rs113588825 G/A, rs10004195 T/A, rs10034903 C/G, rs10012016 G/A/C, rs10012017 G/T, rs33994884 T/Deletion [Del] and rs28393318 A/G).

Results

Del allele and T/Del genotype of rs33994884, as well as AG genotype of rs28393318, showed significantly lower frequencies in MS patients compared to HC. Allele and genotype frequencies of the 10 SNPs showed no significant differences between MS patients classified according to the Expanded Disability Status Scale. Haplotype analysis revealed that haplotype A-T-A-G-A-G-G-T-A showed a significantly increased frequency in MS patients compared to HC (odds ratio [OR] = 9.70; 95% confidence interval [CI] = 1.28–73.31; corrected probability [pc] = 0.03), while frequency of A-T-A-G-T-C-A-T-G haplotype was significantly decreased (OR = 0.10; 95% CI = 0.01–0.85; pc = 0.05).

Conclusions

The study indicated that two SNPs may influence susceptibility to MS (rs33994884 and rs28393318), but haplotype analysis of TLR10 gene SNPs was more informative.

Epstein-Barr Virus and Neurological Diseases

Epstein-Barr virus (EBV), also known as human herpesvirus 4, is a double-stranded DNA virus that is ubiquitous in 90–95% of the population as a gamma herpesvirus. It exists in two main states, latent infection and lytic replication, each encoding viral proteins with different functions. Human B-lymphocytes and epithelial cells are EBV-susceptible host cells. EBV latently infects B cells and nasopharyngeal epithelial cells throughout life in most immunologically active individuals. EBV-infected cells, free viruses, their gene products, and abnormally elevated EBV titers are observed in the cerebrospinal fluid. Studies have shown that EBV can infect neurons directly or indirectly via infected B-lymphocytes, induce neuroinflammation and demyelination, promote the proliferation, degeneration, and necrosis of glial cells, promote proliferative disorders of B- and T-lymphocytes, and contribute to the occurrence and development of nervous system diseases, such as Alzheimer’s disease, Parkinson’s disease, multiple sclerosis, acute cerebellar ataxia, meningitis, acute disseminated encephalomyelitis, and brain tumors. However, the specific underlying molecular mechanisms are unclear. In this paper, we review the mechanisms underlying the role of EBV in the development of central nervous system diseases, which could bebeneficial in providing new research ideas and potential clinical therapeutic targets for neurological diseases.