The Presence and Origin of Autoantibodies Against α4 and α7 Nicotinic Acetylcholine Receptors in the Human Blood: Possible Relevance to Alzheimer's Pathology
Affiliations: [a] Palladin Institute of Biochemistry, Kyiv, Ukraine | [b] Gerontology Institute, Kyiv, Ukraine | [c] Institute of Pediatry, Obstetrics and Gynecology, Kyiv, Ukraine | [d] Kavetsky Institute of Experimental Pathology, Oncology and Radiobiology, Kyiv, Ukraine | [e] Hellenic Pasteur Institute, Athens, and Department of Pharmacy, University of Patras, Patras, Greece | [f] Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia
Correspondence:
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Correspondence to: Maryna Skok, Palladin Institute of Biochemistry, 9, Leontovicha Str., 01601 Kyiv, Ukraine. Tel.: +380 44234 33 54; Fax: +380 44279 63 65; E-mail: [email protected].
Abstract: Alzheimer's disease (AD) is characterized by a loss of α4β2 and α7 nicotinic acetylcholine receptors (nAChRs) in the brain and severe memory impairments. Previously, we found that antibodies elicited against extracellular domain of α7 nAChR subunit decreased the number of α7 nAChRs in the brains of mice and impaired episodic memory. Here we show that antibodies capable to bind α7(1-208) are present in the blood of both healthy humans and AD patients. In healthy individuals, their capacity to compete with [125-I]-α-bungarotoxin for the binding to α7(1-208) increased with age. The level of such antibodies was significantly elevated in children with severe form of obstructive bronchitis and in mice injected with Lewis lung carcinoma cells expressing both α4β2 and α7 nAChRs. Elevated antibody levels were accompanied with decreased surface nAChRs on the blood lymphocytes of children and of mice immunized with α7(1-208). Among AD patients, the level of α7 nAChR-specific antibodies was significantly larger in people 62.5 ± 1.5 years old with moderate or severe AD stages (15.2 ± 1.3 MMSE scores) compared to those of 76 ± 1.5 years old with the mild (22.7 ± 0.1 MMSE scores) AD stage. We concluded that α7(1-208) nAChR-specific antibodies found in the human blood are formed as a result of common infections accompanied with the destruction of respiratory epithelium. Elevated blood plasma levels of α7(1-208) nAChR-specific antibodies are characteristic for the early-onset AD and, therefore, are suggested as one of the risk factors for the development of this form of the disease.
