Monday, 27 October 2014

More Epitopes to induce EAE and MS?

Novel pathogenic epitopes of myelin oligodendrocyte glycoprotein induce experimental autoimmune encephalomyelitis in C57BL/6 mice. Delarasse C, Smith P, Baker D, Amor S. Immunology. 2013 Dec;140(4):456-64. doi: 10.1111/imm.12155.
Myelin oligodendrocyte glycoprotein (MOG), a minor protein of the central nervous system myelin, is recognized as a potential target in multiple sclerosis and neuromyelitis optica. The extracellular domain of MOG is commonly used in a wide range of mouse strains and other animals to induce experimental autoimmune encephalomyelitis (EAE), an autoimmune animal model of multiple sclerosis, because it is a target for antibody-mediated attack. Previous studies, using selected peptides, have indicated that MOG(35-55) peptide is an encephalitogenic epitope in C57BL/6 (H-2(b)) mice. A more systematic analysis of both T-cell and B-cell responses following immunization of C57BL/6 mice with either recombinant extracellular mouse MOG protein (1-116) or with overlapping peptides spanning the whole sequence of MOG, before assessment of responses to 15 mer and 23 mer peptides was undertaken. The studies identified T-cell responses within the MOG(35-55) (extracellular domain) but also two new immunogenic and encephalitogenic T-cell epitopes within residues MOG(113-127), MOG(120-134) (localized in the transmembrane region) and MOG(183-197) (in the second hydrophobic MOG domain). In addition, residue MOG(113-127) was found to be a B-cell epitope, suggesting that this may be a useful adjunct for the induction of EAE as well as for immunological studies in C57BL/6 mice, which are increasingly being used to study immune function through the use of transgenic and gene knockout technology.

Immunodominant T-cell epitopes of MOG reside in its transmembrane and cytoplasmic domains inEAE.Shetty A, Gupta SG, Varrin-Doyer M, Weber MS, Prod'homme T, Molnarfi N, Ji N, Nelson PA, Patarroyo JC, Schulze-Topphoff U, Fogal SE, Forsthuber T, Sobel RA, Bernard CC, Slavin AJ, Zamvil SS. Neurol Neuroimmunol Neuroinflamm. 2014 Aug 14;1(2):e22. doi: 10.1212/NXI.0000000000000022. eCollection 2014 Aug.

OBJECTIVE:Studies evaluating T-cell recognition of myelin oligodendrocyte glycoprotein (MOG) in multiple sclerosis (MS) and its model, experimental autoimmune encephalomyelitis (EAE), have focused mostly on its 117 amino acid (aa) extracellular domain, especially peptide (p) 35-55. We characterized T-cell responses to the entire 218 aa MOG sequence, including its transmembrane and cytoplasmic domains.
METHODS:T-cell recognition in mice was examined using overlapping peptides and intact full-length mouse MOG. EAE was evaluated by peptide immunization and by adoptive transfer of MOG epitope-specific T cells. Frequency of epitope-specific T cells was examined by ELISPOT.
RESULTS:Three T-cell determinants of MOG were discovered in its transmembrane and cytoplasmic domains, p119-132, p181-195, and p186-200. Transmembrane MOG p119-132 induced clinical EAE, CNS inflammation, and demyelination as potently as p35-55 in C57BL/6 mice and other H-2(b) strains. p119-128 contained its minimal encephalitogenic epitope. p119-132 did not cause disease in EAE-susceptible non-H-2(b) strains, including Biozzi, NOD, and PL/J. MOG p119-132-specific T cells produced Th1 and Th17 cytokines and transferred EAE to wild-type recipient mice. After immunization with full-length MOG, a significantly higher frequency of MOG-reactive T cells responded to p119-132 than to p35-55, demonstrating that p119-132 is an immunodominant encephalitogenic epitope. MOG p181-195 did not cause EAE, and MOG p181-195-specific T cells could not transfer EAE into wild-type or highly susceptible T- and B-cell-deficient mice.
CONCLUSIONS:Transmembrane and cytoplasmic domains of MOG contain immunodominant T-cell epitopes in EAE. A CNS autoantigen can also contain nonpathogenic stimulatory T-cell epitopes. Recognition that a myelin antigen contains multiple encephalitogenic and nonencephalitogenic determinants may have implications for therapeutic development in MS.

Always good to see that people can repeat our work.

This paper demonstrates that there are many epitopes (bits of the protein) in myelin that can induce T cell proliferation but they don't necessarily induce disease in animals, as we have shown numerous times for myelin and non-myelin antigens. 

Therefore studies based on simple proliferation assays of T cell responses in humans, as a prelude to doing trials may pick the wrong candidates and indeed many of the pathogenic epitopes in animals that we have found don't give good proliferative responses, so this is probably the wrong way to select candidates peptides for antigen-specific treatment studies.

The epitopes that are recognised by the Mice can also be recognised by some MSers. Does this mean it causes disease? 
Varrin-Doyer M, Shetty A, Spencer CM, Schulze-Topphoff U, Weber MS, Bernard CC, Forsthuber T, Cree BA, Slavin AJ, Zamvil SS.MOG transmembrane and cytoplasmic domains contain highly stimulatory T-cell epitopes in MS. Neurol Neuroimmunol Neuroinflamm. 2014;1(2):e20. doi: 10.1212/NXI.0000000000000020. eCollection 2014 Aug.

OBJECTIVE: Recently, we reported that the 218 amino acid murine full-length myelin oligodendrocyte glycoprotein (MOG) contains novel T-cell epitopes p119-132, p181-195, and p186-200, located within its transmembrane and cytoplasmic domains, and that p119-132 is its immunodominant encephalitogenic T-cell epitope in mice. Here, we investigated whether the corresponding human MOG sequences contain T-cell epitopes in patients with multiple sclerosis (MS) and healthy controls (HC).
METHODS: Peripheral blood T cells from patients with MS and HC were examined for proliferation to MOG p119-130, p181-195, p186-200, and p35-55 by fluorescence-activated cell sorting analysis using carboxylfluorescein diacetate succinimidyl ester dilution assay. Intracellular production of proinflammatory cytokines was analyzed by flow cytometry.
RESULTS: MOG p119-130, p181-195, and p186-200 elicited significantly greater T-cell responses than p35-55 in patients with MS. T cells from patients with MS proliferated significantly more strongly to MOG p119-130 and p186-200 than did T cells from HC. Further, MOG p119-130-specific T cells exhibited Th17 polarization, suggesting this T-cell epitope may be relevant to MS pathogenesis.
CONCLUSIONS: Transmembrane and cytoplasmic MOG domains contain potent T-cell epitopes in MS. Recognition of these determinants is important when evaluating T-cell responses to MOG in MS and may have implications for development of myelin antigen-based therapeutics.

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