Increased expression of heat-shock protein 27 kDa in Alzheimer disease: a preliminary study

Stress-response (heat shock) proteins (hsps) are induced in living cells under pathological conditions, including diseases of the central nervous system. Increased synthesis of hsps is suggested to play a role in preventing neuronal injury in Alzheimer disease (AD). Using a highly specific antibody we have studied the expression of heat shock protein 27 kDa (hsp 27), in the brains of AD and non-demented, age-matched control patients. Immunoblotting and immunohistochemical methods were used. We report here that in the human brain in the normal condition the expression of hsp 27 is low and limited to the vessels, subpial astrocytes and single astrocytes of the white matter. There is a significant increase in the expression of hsp 27 in the cortex of AD. In AD, the immunoreaction is mainly localized in proliferating astrocytes establishing a pattern of astrocytic gliosis. These findings are the first to show the presence of hsp 27 in human cerebral tissue in normal conditions and its induction in AD.