Expression of a mucociliary-specific epitope in human olfactory epithelium

Increased density of olfactory receptor neurons immunoreactive for apolipoprotein E in patients with Alzheimer's disease

Immunolocalization of apolipoprotein E (apoE) was investigated in human olfactory mucosa in which olfactory receptor neurons (ORNs) were identified with antiserum to protein gene product (PGP) 9.5. Tissue was obtained at autopsy from 10 nondemented middle-aged or elderly subjects and 9 patients with Alzheimer's disease (AD). Double-labeling immunofluorescence established that apoE immunoreactivity was colocalized in a subpopulation of PGP 9.5-immunoreactive ORNs. The mean number of apoE-immunoreactive ORNs per unit epithelial length in AD patients was about 3.5 times greater than that in nondemented patients, although the mean number of PGP 9.5-immunoreactive ORNs was similar. The apoE-immunopositive Schwann cells in olfactory nerve bundles were the probable source of apoE in the ORNs. The increased numbers of apoE-immunoreactive ORNs in AD patients compared to nondemented subjects demonstrates another manifestation of AD-related neuropathology, in addition to cytoskeletal changes, beta-amyloid deposition, and changes in immunoreactivity for other neuroproteins, that parallels changes in neurons in the AD brain.

Age- and gender-related trends in the expression of glutathione S-transferases in human nasal mucosa

The cellular expression of alpha, mu, and pi classes of glutathione S-transferases (GSTs) was investigated in human nasal mucosa by means of immunocytochemical techniques. In the olfactory mucosa, immunoreactivity for GST-alpha was most intense in the acinar cells of the Bowman's glands, with weak immunoreactivity in the supranuclear region of sustentacular cells. Whereas GST-pi was localized only in the sustentacular cells, no GST-mu was detected. In the respiratory mucosa, GST-alpha and GST-pi were detected at the brush borders of ciliated columnar epithelial cells. There were age- and gender-related trends in the expression of GST-alpha, but not GST-pi, in the olfactory mucosa. The intensity of immunoreactivity in the olfactory mucosa was decreased in older subjects. The expression of GST-alpha in the olfactory mucosa of females consistently exhibited greater intensity than that of males at all the ages studied. These differences were not observed in the respiratory mucosa. These results indicate that acinar cells of the Bowman's glands and sustentacular cells are the major sites of phase II biotransformation in the human nasal mucosa.

Human olfactory receptor neurons express heat shock protein 70: age-related trends

Immunocytochemical methods were used to investigate the cellular distribution and age-related trends in the expression of constitutive and/or inducible forms of heat shock protein (hsp) 70 in the human nasal mucosa of 22 subjects who ranged in age from 16 weeks prenatal to 90 years, including 3 subjects with Alzheimer's disease. The olfactory mucosa was characterized by the presence of olfactory marker protein-immunoreactive olfactory receptor neurons. The hsp 70 immunoreactivity was localized in olfactory receptor neurons and the supranuclear region of sustentacular cells in the olfactory epithelium, and in the acinar cells of the Bowman's glands in the lamina propria. A systematic age-related decrement in the expression of hsp 70 immunoreactivity was observed in the olfactory receptor neurons. This trend was not apparent in sustentacular cells and Bowman's glands. A marked decrement in hsp 70 immunoreactivity was also noted in the olfactory receptor neurons of subjects with Alzheimer's disease when compared to age-matched controls. These results suggest that the age-dependent decrease in hsp 70 in olfactory receptor neurons of older subjects and those with Alzheimer's disease may be attributable to their greater susceptibility to stress.