Mucus of the human olfactory epithelium contains the insulin-like growth factor-I system which is altered in some neurodegenerative diseases

Growth factors are believed to be involved in the mitotic regulation of the animal olfactory epithelium (OE). We investigated mucus covering the human OE area to see if it contained the insulin-like growth factor-I (TGF-I) an d its binding proteins (IGFBPs) and to examine their behaviour in neurodege nerative diseases. Thirty patients with idiopathic late onset cerebellar at axia (ILOCA), Parkinson's disease, and amyotrophic lateral sclerosis (ALS) and 30 age- and sex-matched healthy subjects were studied. In 10 controls, we also analyzed the mucus of the respiratory mucosa of the nose and tears. We detected IGF-I in the mucus covering the OE and Western ligand blot ana lysis (WLB) showed IGFBPs with an apparent Mr of 41,500/38,500, 34,000 and 24,000, which were immunoprecipitated by specific antisera to IGFBP-3, -2 a nd -4, respectively. Their levels were higher than those observed in the re spiratory mucosa of the nose or in tears. Mucus of the OE of the patients c ontained significantly reduced levels of IGF-I in comparison with those of controls. The intensity of all the IGFBPs-related bands were reduced in the ILOCA, while the remaining patients had a loss in the amounts of IGFBP-3. Plasma IGF-I and IGFBPs levels were similar in patients and controls. in co nclusion, our data show that mucus covering the human OE contains IGF-I and IGFBPs, suggesting that these factors have a role in the activity of the O E. The amounts are reduced in the patients' mucus, possibly reflecting a dy sfunction of the OE itself. (C) 1999 Elsevier Science B.V. All rights reser ved.