Heat-shock protein 70 levels in brain of patients with Down syndrome and Alzheimer's disease.

Heat-shock proteins are proteins serving as molecular chaperones, involved in the protection of cells from various forms of stress. Since the expression of these proteins is closely related to that of amyloid precursor protein (APP), heat-shock protein has been studied in brain of patients with Alzheimer's disease (AD) and furthermore, brain Hsp70 mRNA levels were related to the agonal state. The aim of our study was to demonstrate the presence of Hsp70--immunoreactive protein in brain of controls, patients with AD and Down Syndrome (DS) in individual brain regions. The rationale for the study was to test the hypothesis that expression of Hsp70, a protein involved in apoptosis would be altered in brain of these patients with neurodegenerative disorders where (neuronal) apoptosis is a hallmark of the disease. Brain immunoreactive-Hsp70--protein (Hsp70) was determined by Western blotting using specific monoclonal antibody in five different brain regions (frontal, parietal, occipital, temporal cortex and cerebellum) from controls, DS and AD patients. Hsp70 expression was significantly increased in temporal cortex of patients with AD (arbitrary units: means +/- SD; 0.35 +/- 0.49 for controls, 0.97 +/- 0.70 for DS patients, 1.16 +/- 0.56 for AD patients). In frontal and parietal cortex from DS patients, there was a strong correlation between Hsp70 levels and the length of post-mortem interval (r = 0.95, P < 0.01 and r = 0.82, P < 0.021).