IS EBV part of MS pathogenesis?
The new study presented at ECTRIMS by Dr. Schneider-Hohendorf offered evidence that MS patients have excess CD8-positive T cells that recognize EBV antigens typically shed during active viral infection. The results suggest “that the immune system is responding to that chronic infection,” said Dr. Cree.
The findings have some implications for a clinical study now in progress, called EMBOLD, which is looking at whether a heterologous infusion of T cells that have been primed to attack EBV could improve symptoms of progressive MS. “The hypothesis there is that chronically infected cells within the body are causing progressive MS and that if we could eradicate those cells, both within the central nervous system and within the periphery, perhaps we could see improvement in MS functional outcomes,” said Dr. Cree, who is a co-investigator for the EMBOLD study. The trial is using T cells from donors that are matched for the human leukocyte antigen complex, which is hoped will target and kill EBV-infected cells.
The study presented by Dr. Schneider-Hohendorf supports the approach. “There is an implication from this study that the trial that that’s currently being conducted might actually possibly have a benefit in the sense that there’s now another piece of evidence to indicate that EBV is not only a risk factor for MS, but may actually participate during the course of the disease as part of the pathogenesis,” said Dr. Cree.
In the new study, the researchers sequenced the T-cell receptor variable beta-chain (TRBV) peripheral repertoire among three cohorts of MS patients: A discovery cohort with 1,336 patients with MS and 229 controls; a validation cohort with 59 patients with MS and 51 controls; and 35 monozygotic twins who were discordant for MS. They identified sequences known to bind to EBV, SARS-CoV-2, cytomegalovirus, and influenza A, and used the latter three viruses as a proof of concept to demonstrate the validity of the approach. EBV-specific MHC-1 restricted CD8 TRBV in the serum of MS patients, with large effect sizes in the discovery (+2.2), validation (+2.1), and MS twin (+1.6) populations. The findings in the twin population rule out a genetic or environmental explanation for the findings in the discovery and validation cohorts, according to Dr. Schneider-Hohendorf.
The researchers also sequenced CSF among six healthy donors and five patients with MS and found significant differences. The T-cell populations had more lytic properties that suggested ongoing immune surveillance. “We can conclude that we found a broader response that could indicate an aberrant immune response. This could be a remnant of disease triggering an event or it could indicate an ongoing immune response to EBV. Is this EBV activity? We really don’t know. To find out, we would expand our pathogen-specific sequences, we would assess CNS tissue and lesions, and we would define the primary response in pediatric cohorts to better understand what might go wrong,” Dr. Schneider-Hohendorf concluded.
Dr. Cree has a financial relationship with Biogen and is a co-investigator for the EMBOLD trial. Dr. Schneider-Hohendorf has financial relationships with Biogen, Novartis, and Roche.