CD8+ T cells recognizing a neuron-restricted antigen injure axons in a model of multiple sclerosis
Benjamin D.S. Clarkson, … , Liz S. Muschler, Charles L. Howe
Benjamin D.S. Clarkson, … , Liz S. Muschler, Charles L. Howe
Published September 7, 2023
Citation Information: J Clin Invest. 2023;133(21):e162788. https://doi.org/10.1172/JCI162788.
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Research Article Immunology Neuroscience

CD8+ T cells recognizing a neuron-restricted antigen injure axons in a model of multiple sclerosis

Abstract

CD8+ T cells outnumber CD4+ cells in multiple sclerosis (MS) lesions associated with disease progression, but the pathogenic role and antigenic targets of these clonally expanded effectors are unknown. Based on evidence that demyelination is necessary but not sufficient for disease progression in MS, we previously hypothesized that CNS-infiltrating CD8+ T cells specific for neuronal antigens directly drive the axonal and neuronal injury that leads to cumulative neurologic disability in patients with MS. We now show that demyelination induced expression of MHC class I on neurons and axons and resulted in presentation of a neuron-specific neoantigen (synapsin promoter–driven chicken ovalbumin) to antigen-specific CD8+ T cells (anti-ovalbumin OT-I TCR-transgenic T cells). These neuroantigen-specific effectors surveilled the CNS in the absence of demyelination but were not retained. However, upon induction of demyelination via cuprizone intoxication, neuroantigen-specific CD8+ T cells proliferated, accumulated in the CNS, and damaged neoantigen-expressing neurons and axons. We further report elevated neuronal expression of MHC class I and β2-microglobulin transcripts and protein in gray matter and white matter tracts in tissue from patients with MS. These findings support a pathogenic role for autoreactive anti-axonal and anti-neuronal CD8+ T cells in MS progression.

Authors

Benjamin D.S. Clarkson, Ethan M. Grund, Miranda M. Standiford, Kanish Mirchia, Maria S. Westphal, Liz S. Muschler, Charles L. Howe

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Figure 2

Axons present self-antigen on MHC class I in response to inflammation.

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Axons present self-antigen on MHC class I in response to inflammation. (...
(A) Schematic showing elements of the adeno-associated virus (AAV) plasmid encoding synapsin (Syn) promoter–driven expression of cytosolic ovalbumin (OVA) with an axon-targeting motif coupled to EGFP by a T2A autocatalytic sequence (AAV.Syn.OVA.GFP). (B) Representative Western blot of lysates prepared from DIV 12 cortical neurons transduced at plating with 2,000 (2K) or 20,000 (20K) MOI of AAV.Syn.OVA.GFP or AAV.Syn.GFP, probed with anti-OVA. (C) Representative (n = 5 mice) photomicrographs of AAV.Syn.OVA.GFP-transduced mouse cortex showing immunostaining for OVA (red) in GFP-expressing neurons (green). Scale bars: 50 μm. (D and E) Representative images of the OVA peptide SIINFEKL presented on the H2-Kb MHC class I molecule (anti-H2Kb:SIINFEKL; red) colocalized with GFP+ neurons and axons in mice demyelinated by cuprizone (×60 magnification). The absence of staining with no primary antibody and in non–cuprizone-treated AAV.Syn.OVA-GFP–transduced mice is shown on the right. (F and G) H2Kb:SIINFEKL (red) on OVA-GFP+ axons (green) from cortical neurons cultured in microfluidic chambers following axonal stimulation with PBS (F) or 100 ng/mL IFN-γ for 72 hours (G). Yellow puncta in the higher-magnification panels at the bottom indicate expression of SIINFEKL peptide–loaded MHC class I on axons (×40 magnification). (H) Quantification of H2Kb:SIINFEKL labeling on axons in F and G relative to GFP. In vitro data are representative of at least 3 independent experiments. Error bars are SEM. *P < 0.01 by unpaired, 2-tailed t test (H).