S-100β protein is upregulated in astrocytes and motor neurons in the spinal cord of patients with amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by progressive motor neuron loss and astrogliosis. We studied the immunohistochemical expression of S-100 beta, a calcium-binding protein with both neurotrophic and neurotoxic activities, in the spinal cord of patients with ALS. Adjacent sections were processed with an in situ end-labeling technique for the demonstration of apoptosis-related DNA fragmentation. In controls, low expression of S-100 beta was found in astrocytes but not motor neurons. Compared to controls, S-100 beta was overexpressed in ALS. Most stained cells were reactive astrocytes, but a minority of motor neurons was also labeled. Neuronal labeling was unrelated to the presence of signs of atrophy/degeneration. S-100 beta expression was also unrelated to neuronal or glial apoptosis. S-100 beta upregulation in ALS spinal cord suggests that the protein might be involved in cellular defense mechanisms against oxidative stress. (C) 1999 Published by Elsevier Science Ireland Ltd. All rights reserved.