Abstract
The efficacy of B cell depletion therapy in multiple sclerosis indicates their central pathogenic role in disease pathogenesis. The B lymphotropic EBV is a major risk factor in multiple sclerosis, via as yet unclear mechanisms. We reported in a nonhuman primate experimental autoimmune encephalomyelitis model that an EBV-related lymphocryptovirus enables B cells to protect a proteolysis-sensitive immunodominant myelin oligodendrocyte glycoprotein (MOG) epitope (residues 40–48) against destructive processing. This facilitates its cross-presentation to autoaggressive cytotoxic MHC-E–restricted CD8+CD56+ T cells. The present study extends these observations to intact human B cells and identifies a key role of autophagy. EBV infection upregulated APC-related markers on B cells and activated the cross-presentation machinery. Although human MOG protein was degraded less in EBV-infected than in uninfected B cells, induction of cathepsin G activity by EBV led to total degradation of the immunodominant peptides MOG35–55 and MOG1–20. Inhibition of cathepsin G or citrullination of the arginine residue within an LC3-interacting region motif of immunodominant MOG peptides abrogated their degradation. Internalized MOG colocalized with autophagosomes, which can protect from destructive processing. In conclusion, EBV infection switches MOG processing in B cells from destructive to productive and facilitates cross-presentation of disease-relevant epitopes to CD8+ T cells.
Footnotes
This work was supported in part by unrestricted grants to B.G. from Sanofi Genzyme, Biogen, and Novartis. E.M. was supported by a Vice-Chancellor Scholarship for Research Excellence from the University of Nottingham.
The online version of this article contains supplemental material.
- Received February 2, 2017.
- Accepted May 5, 2017.
- Copyright © 2017 by The American Association of Immunologists, Inc.










