P1-356: S100B, but not NSE, serum levels differentiate mild from severe Alzheimer's disease patients

Abstract

S100β is a calcium binding protein mostly produced and released by astrocytes in the central nervous system. The neuron-specific enolase (NSE) is a cytoplasmatic glycolytic enzyme, whose isoform γγ is found in neurons, as well as in cells with neuroendocrine differentiation. Taken together, NSE and S100β protein could be considered, respectively, neuronal and glial peripheral markers of CNS pathologies. We evaluated S100β and neuron-specific enolase (NSE) serum levels in mild, moderate and severe Alzheimer's disease (AD) patients and community healthy elderly. A cross-sectional study with 36 Alzheimer's disease patients (probable NINCDS-ADRDA criteria) and 66 community-dwelling healthy elderly was carried out. Severity was assigned by the Clinical Dementia Rating (CDR) scale. The inclusion criteria for the normal elderly were age greater than 60 years and CDR=0. Blood samples (3 ml) were collected without anticoagulants by venipuncture. Serum was obtained by centrifugation at 3000g for 5 min and, soon thereafter, was frozen at -70 °C until analysis. In AD, S100β levels were significantly different between mild and severe dementia (P=0.02). There was a tendency for a difference between mild and moderate AD patients (P=0.06; Mann-Whitney U=26.00). NSE did not show significant difference among dementia severity. S100β levels marginally correlated with MMSE scores (Spearman r=-0.33; P=0.05), but not with age (Spearman r=-0.05; P=0.76). There was no statistically significant difference between S100β and NSE serum levels of AD and normal elderly. In healthy elderly, S100β (r=−0.02; P=0.90) and NSE levels did not vary with age (r=0.18; P=0.21). NSE levels were higher among men than women (P=0.049), and S100β was similar. Among the healthy elderly, the levels of S100β and NSE were not different between the eldest (80) and the youngest group. NSE and S100B may not have a diagnostic role as peripheral markers in AD, but serum S100B may have a potential role as a biomarker of the degree of severity of this disease.