Degeneration specific NF-L immunoreactivity in spinal cord and brainstem 10 days post-cervical spinal cord contusion

Abstract

We recently described a panel of novel antibodies to epitopes on the neurofilament light chain (NF-L) which are hidden in healthy neurons and their processes but specifically exposed during neurodegeneration ( doi.org/10.1101/2022.08.27.504533 ). We saw widespread immunopositivity for such antibodies in degenerating and degenerated processes in the rat spinal cord 1-5 days following cervical spinal cord injury (cSCI). Here we aimed to determine if such immunopositivity would persist at 10 days following cSCI. Male Sprague Dawley rats received laminectomy (n=3) or right unilateral contusion at C4 (n=3; 150kdyn; Infinite Horizon Impactor). Tissue was harvested 10 days post-SCI and stained with either Cresyl Violet for routine histology or for immunohistochemistry using mouse monoclonal antibody MCA-6H63, one of several novel antibodies binding to degeneration specific NF-L epitopes (EnCor Biotechnology Inc.). Spinal cord MCA-6H63 immunopositivity was not detected in spinal cords from the laminectomy group. Contusion produced the expected histopathology with ipsilateral grey and white matter disruption and some damage to the contralateral dorsal columns. Punctate labeling for MCA-6H63 was prominent at the lesion epicenter, as well as in the ipsilateral cord rostral and caudal to the injury, consistent with axonal degeneration. Sparse, punctate MCA-6H63 positivity was observed in the contralateral cervical white matter. Qualitatively, MCA-6H63 staining was most robust in the ventral and lateral white matter ipsilateral and caudal to the lesion. This location was consistent with ongoing Wallerian degeneration in prominent spinal tracts including spinothalamic, spinocerebellar, reticulospinal, vestibulospinal and raphespinal. Bilateral MCA-6H63 staining in the dorsal columns was present mostly rostral to the injury. Some MCA-6H63 staining was noted in the medulla, most prominently ipsilateral to the lesion. We conclude that at 10 days post-cSCI this novel NF-L antibody specifically identifies degenerating and degenerated axonal profiles. This is a promising technique in assessing neurodegeneration following SCI and other neurodegenerative diseases. R01HL139708-01A1 (DDF), R01 HL153140-01 (DDF), and EnCor Biotechnology Inc. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.