The τ protein of oral epithelium increases in Alzheimer’s disease

Abstract

Background. Alzheimer's disease (AD) is an important problem that should be solved in the 21st century. Prior to treatment, a simple and easy diagnostic method using biological markers should be available. As a method to attain this goal, we detected and determined τ protein in oral mucosal epithelium. Methods. Oral epithelium was exfoliated from 34 patients with AD or 29 patients with vascular dementia, and 33 young and 34 age-matched controls. Western blot was performed for determining the molecular weight of oral τ protein. The τ protein level was determined with an enzyme-linked immunosorbent assay (ELISA) kit for cerebrospinal fluid (CSF). CSF τ was also measured and compared with oral τ. Results. Western blot analysis using an anti-non-phosphorylated τ-protein antibody showed two bands, one at 65 Kd and the other at 110 Kd. The τ-protein level in oral epithelia showed a significant positive correlation with those in the CSF (p < .05). The patients with AD had significantly higher levels of τ protein than the patients with vascular dementia and the controls (p < .01). AD patients with a younger age at onset of the study showed a higher level of the τ protein than the patients with later age at onset (p < .05). Conclusions. Like other nonneural tissues, oral epithelium contains small τ and big τ. The τ protein in oral epithelium reflects the pathological changes, as does the CSF τ. Individuals who develop AD may have had high levels of the τ protein in oral mucosal epithelium since early childhood. The τ-protein level in oral epithelia could be helpful in diagnosing AD.