CTSB and neurodegenerative disease: We conducted immunohistochemistry studies of intervertebral discs to analyze interleukin 6 and cathepsin B levels of patients with degenerative disease and spine fracture (Control Group) and to measure hyaluronic acid, interleukin 6 and cathepsin B activity from sera of intervertebral disc degeneration patients, fracture patients, and healthy individuals.