Howe, Charles

Abstract MR imaging suggests an anatomic correspondence between WM and GM lesions in progressing MS patients, suggesting an underlying neuronal-signaling or neurodegenerative element to the progressive disease state. While retrograde signals evolving from stressed axons that alter soma gene expression have been previously described in models of axonal transection or crush injury, those resulting from inflammation and demyelination are unknown. Using microfluidic chambers that segregate neuronal soma and axons, we have previously demonstrated increased axonal MHC I following treatment with IFNg, a cytokine prominent in demyelinating MS lesions. Furthermore, expression of antigen-loaded MHC I predisposed axons to injury by antigen-specific CD8+ T cells in vitro. Here we report that neurons also upregulate expression of MHC class Ib mRNAs in response to axonal stimulation with IFNg. Genes most highly upregulated following cytokine treatment included H2-M3, H2-Q5, H2-Q6, H2-Q7, H2-Q8, H2-T10 , and H2-T23. We further report the development of an in vivo model system for measuring axonal vulnerability to antigen-specific immune attack following demyelination using an AAV vector to induce neuron-specific expression of axonally-targeted neoantigen (ovalbumin) tagged with cleavable eGFP. We also present optimized methods using AAV vectors in mice for infecting retinal, motor cortex, and hippocampal neurons to induce target gene expression in axons projecting to optic nerve and corpus collosum.