S-100 beta 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 characte rized by progressive motor neuron loss and astrogliosis. We studied the imm unohistochemical expression of S-100 beta, a calcium-binding protein with b oth neurotrophic and neurotoxic activities, in the spinal cord of patients with ALS. Adjacent sections were processed with an in situ end-labeling tec hnique for the demonstration of apoptosis-related DNA fragmentation. In con trols, low expression of S-100 beta was found in astrocytes but not motor n eurons. Compared to controls, S-100 beta was overexpressed in ALS. Most sta ined cells were reactive astrocytes, but a minority of motor neurons was al so labeled. Neuronal labeling was unrelated to the presence of signs of atr ophy/degeneration. S-100 beta expression was also unrelated to neuronal or glial apoptosis. S-100 beta upregulation in ALS spinal cord suggests that t he protein might be involved in cellular defense mechanisms against oxidati ve stress. (C) 1999 Published by Elsevier Science Ireland Ltd. All rights r eserved.