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 6

CD8+ nasT cells injure neurons in the demyelinated brain.

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CD8+ nasT cells injure neurons in the demyelinated brain. (A) Representa...
(A) Representative images showing APP (red) in cortex 5 days after adoptive transfer of OT-I T cells into AAV.Syn.OVA.GFP-transduced mice fed cuprizone or control chow for 6 weeks. Boxes indicate higher magnification images shown directly beneath each panel. (B) Representative images showing nonphosphorylated neurofilament (npNF; red) and GFP+ axons (green) in the corpus callosum in AAV.Syn.OVA.GFP-transduced B6 or OT-I mice fed cuprizone for 6 weeks. (C) Quantitation of axonal injury parameters following adoptive transfer of B6 (blue) or OT-I (red) T cells into AAV.Syn.OVA.GFP-transduced mice fed cuprizone for 6 weeks. (D) Representative images of RFP+ OT-I T cells (red) in proximity to GFP+ axons (green) in the cortex and corpus callosum 5 days after adoptive transfer into AAV.Syn.OVA.GFP-transduced mice fed cuprizone for 6 weeks. (E) Representative images of the same approach used in D in mice transduced with AAV.Syn.GFP. Boxes in D and E indicate insets (D, i–iv; E, i–ii) shown at higher magnification immediately below the corresponding panel. (F) Optical sections from a z-stack image of a brain-infiltrating RFP+ OT-I T cell (red) in apposition to a GFP+ axon (green) in a mouse transduced with AAV.Syn.OVA.GFP and fed cuprizone for 6 weeks prior to adoptive transfer. (G) 3D renderings of an RFP+ OT-I T cell in contact with a GFP+ axon. (H) Schematic of the multichambered microfluidic device used to introduce T cells to axons. Representative image showing GFP+ axons under attack by RFP+ OT-I T cells; box indicates inset at higher magnification. (I) Axons (green) from cortical neurons transduced with AAV.Syn.OVA.GFP or AAV.Syn.GFP were stimulated for 72 hours with IFN-γ prior to incubation for 1 hour (top row) or 24 hours (bottom row) with RFP+ OT-I T cells isolated from the brain (BILs) 5 days after adoptive transfer into AAV.Syn.OVA.GFP-transduced mice fed cuprizone for 6 weeks. (J) The same approach as in I using blood-derived OT-I T cells. (K) Quantitation of axonal injury from the experiment shown in I after 24 to 72 hours. Low-magnification images in A, B, D, E, and H were acquired with 10× objective. High-magnification insets were acquired with 60× objective (A and D–G) or 40× objective (H). Immunostained tissue sections representative of n = 3–5 mice per condition. In vitro data representative of T cells independently isolated from n = 5 mice. Error bars show the 95% CI. **P < 0.01; ***P < 0.001; ****P < 0.0001 by unpaired, 2-tailed t test (C) or 1-way ANOVA with Dunnett’s multiple-comparison test (K).