Increased Efflux of Amyloid-β Peptides through the Blood-Brain Barrier by Muscarinic Acetylcholine Receptor Inhibition Reduces Pathological Phenotypes in Mouse Models of Brain Amyloidosis

Article type: Research Article

Authors: Paganetti, Paolo^a | Antoniello, Katia^{a; 1} | Devraj, Kavi^{b; 1} | Toni, Nicolas^{a; 2} | Kieran, Dairin^{a; 3} | Madani, Rime^a | Pihlgren, Maria^a | Adolfsson, Oskar^a | Froestl, Wolfgang^a | Schrattenholz, André^c | Liebner, Stefan^b | Havas, Daniel^d | Windisch, Manfred^d | Cirrito, John R.^e | Pfeifer, Andrea^a | Muhs, Andreas^{a; *}

Affiliations: [a] AC Immune SA, Lausanne, Switzerland | [b] Institute of Neurology, Medical School Goethe University, Frankfurt am Main, Germany | [c] ProteoSys AG, Mainz, Germany | [d] QPS Austria, Grambach, Austria | [e] Department of Neurology, Knight AD Research Center, and Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO, USA

Correspondence: [*] Correspondence to: Dr. Andreas Muhs, CSO, AC Immune SA, EPLF Building PSE-B, CH-1015 Lausanne, Switzerland. Tel.: +41 21 693 9124; E-mail: andreas.muhs@acimmune.com.

Note: [1] These authors contributed equally to this work.

Note: [2] Current address: Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland.

Note: [3] Current address: Quintiles Outcome, St-Prex, Switzerland.

Abstract: The formation and accumulation of toxic amyloid-β peptides (Aβ) in the brain may drive the pathogenesis of Alzheimer's disease. Accordingly, disease-modifying therapies for Alzheimer's disease and related disorders could result from treatments regulating Aβ homeostasis. Examples are the inhibition of production, misfolding, and accumulation of Aβ or the enhancement of its clearance. Here we show that oral treatment with ACI-91 (Pirenzepine) dose-dependently reduced brain Aβ burden in AβPPPS1, hAβPPSL, and AβPP/PS1 transgenic mice. A possible mechanism of action of ACI-91 may occur through selective inhibition of muscarinic acetylcholine receptors (AChR) on endothelial cells of brain microvessels and enhanced Aβ peptide clearance across the blood-brain barrier. One month treatment with ACI-91 increased the clearance of intrathecally-injected Aβ in plaque-bearing mice. ACI-91 also accelerated the clearance of brain-injected Aβ in blood and peripheral tissues by favoring its urinal excretion. A single oral dose of ACI-91 reduced the half-life of interstitial Aβ peptide in pre-plaque mhAβPP/PS1d mice. By extending our studies to an in vitro model, we showed that muscarinic AChR inhibition by ACI-91 and Darifenacin augmented the capacity of differentiated endothelial monolayers for active transport of Aβ peptide. Finally, ACI-91 was found to consistently affect, in vitro and in vivo, the expression of endothelial cell genes involved in Aβ transport across the Blood Brain Barrier (BBB). Thus increased Aβ clearance through the BBB may contribute to reduced Aβ burden and associated phenotypes. Inhibition of muscarinic AChR restricted to the periphery may present a therapeutic advantage as it avoids adverse central cholinergic effects.

Keywords: Aβ brain efflux, Aβ clearance, Aβ homeostasis, AβPP transgenic mice, amyloid-β peptides, drug treatment, muscarinic receptors, plaque deposition

DOI: 10.3233/JAD-131091

Journal: Journal of Alzheimer's Disease, vol. 38, no. 4, pp. 767-786, 2014