A Study Of Microtubule, Tubulin And Tau Protein In Skin Basal Cells From Alzheimer's Disease Patients

Objectives: To quest a convenient and practical extraneuronal biological marker that is reliable for diagnosing Alzheimer's disease.Methods: According to the clinical diagnostic standards, we selected 17 subjects, including 7 Alzheimer's diseases patients, 5 vascular dementia patients and 5 normal controls to study the constructive changes of microtubules and make the qualitative and quantitive analyses of microtubules, tubulin and tau protein by using immunocytochemistry, immunoelectron microscopy and stereology technique. Results: (1) Immunocytochemical results manifest that the immunopositive stain of a -tubulin is mainly located in epidermis. In dermis the stain is light. The stain in Alzheimer's disease patients is the strongest among three groups, and the stain in vascular dementia patients is lighter than in the normal controls. Tau protein immunopositive stain is distributed in all layers of epidermis, and there are scattering immunopositive cells in dermis. The stain subsequence is similar to that of a -tubulin. The quantitive analyses show that the difference of AOD and VIOD scale is striking in skin basal cells among three groups(P<0.01). (2) The results of immunoelectron microscope display that some microtubules can be seen clearly in skin basal cells of three groups. The quantity of microtubules in skin basal cells from Alzheimer's disease patients is significantly fewer than from vascular dementia patients and normal controls, and the quantity of microtubules in skin basal cells from vascular dementia patients is obviously more than from normal controls(P<0.01). The granules of colloidal gold labeled by a -tubulin and tau protein antibodies are mainly distributed in cytoplasm of skin basal cells, and the number of colloidal golds in Alzheimer's disease patients is significantly more than in vascular dementia patients and normal controls, and the number of colloidal golds in normal controls is more than in vascular dementia patients(P<0.01).Conclusions: In skin basal cells of Alzheimer's disease patients, the changes of microtubule network mainly manifest depolymerization and diminution of microtubules, then levels of free tubulin and tau protein increase in cytoplasm. Thesechanges of microtubule network in basal cells could reflect those of nervous tissue indirectly and would be regarded as an extraneuronal biological marker for diagnosing Alzheimer's disease at early stage.