Antibodies Against the Coil2 Region of Neurofilament Light Chain Identify Neurodegeneration in Human Pompe Spinal Cord and Injured Rat Spinal Cord.

Introduction: Neurodegeneration is common in neurologic injury but methods to specifically identify degenerating axons in histological sections are limited. An antibody against the Coil2 region of neurofilament light chain (NF-L), which is uniquely exposed during degeneration, was recently developed (PMID:37091583). We used this antibody to A) map axonal degeneration during sub-acute SCI in a rat model, a period of continued neurodegeneration relevant to potential neuroprotective interventions and B) conduct a proof-of-concept experiment to determine if the antibody could identify apparent neurodegeneration in human spinal cord tissues.

Methods: Adult Sprague Dawley rats received either a right unilateral C4 contusion (150kdyn; Infinite Horizons Impactor; n=6) or C4 laminectomy (n=5). Ten days post-injury, spinal cord and brainstem were collected, paraformaldehyde-fixed, cryosectioned and stained with anti-NF-L-Coil2 antibody (MCA-6H63; EnCor Biotechnology). Spinal cord tissue from an adult male human with late-onset Pompe disease was obtained at autopsy, paraffin-embedded, sectioned and stained with the same anti-NF-L-Coil2 antibody.

Results: Following SCI, immunopositive fibers were prominent and had a dysmorphic punctate appearance expected of a pathological axon in cross-section and a location consistent with axon tracts disrupted by the lesion. Staining was absent in laminectomy tissue and spinally injured tissue incubated with isotype and concentration matched control Ig. In the Pompe spinal cord, anti-NF-L-Coil2 immunopositive axons and soma were readily identified in the ventral gray matter throughout spinal neuraxis, suggestive of motoneuron degeneration. Robust immunopositive axons were also visualized in white matter tracts and ventral roots. Staining was absent in tissues that were incubated isotype concentration matched control Ig.

Conclusion : The anti-NFL-Coil2 antibody enables identification of apparent Wallerian degeneration and axonal dieback in both rodent and human spinal cord. Positive staining in the human Pompe spinal cord is consistent with the emerging concept that effective Pompe disease treatment must target the central nervous system and neurodegeneration.