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2016-02-17 - Colloque/Présentation - poster - Anglais - 1 page(s)

Andre Séverine , Verteneuil Sébastien, Delcroix Marie, Muller Robert , Vander Elst Luce , Laurent Sophie , Burtea Carmen , "Peptide-mediated modulation of a phospholipase isoform and blood-brain barrier transcytosis in the context of Alzheimer’s disease therapy" in Belgian Peptide Group Meeting, Bruxelles, Belgique, 2016

  • Codes CREF : Sciences biomédicales (DI3200)
  • Unités de recherche UMONS : Chimie générale, organique et biomédicale (M108)
  • Instituts UMONS : Institut des Sciences et Technologies de la Santé (Santé), Institut des Biosciences (Biosciences)
  • Centres UMONS : Centre de Recherche en Microscopie et Imagerie Médicale (CMMI)

Abstract(s) :

(Anglais) Introduction The neurodegenerative disorder known as Alzheimer’s disease (AD) is one of the main causes of dementia in the elderly. Many studies suggest the involvement of some phospholipase (PL) isoforms in memory impairment and neurodegeneration [1] and their modulation was already assessed in the treatment of neurological disorders [2]. However, most of the tested molecules are non-specific or irreversible. We have therefore targeted one of the main phospholipase isoforms (PLA2) with phage display-derived peptides aiming to specifically modulate its activity and develop in this way a new therapeutic strategy for the AD patients. On the other hand, the blood-brain barrier (BBB) protects the brain against xenobiotics and limits the access of most molecules, including the therapeutic agents. The development of non-invasive BBB crossing strategies is thus crucial for the treatment of the central nervous system (CNS) pathologies without BBB disruption. Being based on natural shuttling pathways, LDL receptor (LDLR)-mediated transcytosis across the BBB is a promising target for drug delivery to the CNS [3]. Several LDLR-targeted peptides were identified by phage display in order to facilitate the access to the brain of our therapeutic peptides and their mechanism of transcytosis was investigated. Methods A randomized linear peptide library fused to the p3 coat proteins of the M13 bacteriophage was used to identify PLA2- and LDLR-specific peptides. Phage clones were selected based on their dissociation (Kd) and inhibition constants 50% (IC50). The amino acid sequence of the expressed peptides was deciphered after DNA sequencing, and peptides were synthesized. The binding to the brain of PLA2-specific peptides was evaluated by immunocytochemistry. The endocytosis of LDLR-targeted peptides as well as the elucidation of their endocytosis mechanism were assessed by immunofluorescence. Results and Prospects Three PLA2-targeted clones were selected based on their Kd that ranged from 10-13M to 10-12M and their IC50 of around 10-11 M, showing thus a good affinity and ability to inhibit PLA2 binding to its substrate. Corresponding peptides were synthesised and immunocytochemistry studies confirmed the binding of two of them to PLA2 expressed by mouse brain. Concerning the BBB crossing strategy, two clones were selected (Kd between 10-11 M and 10-12 M) based on their aptitude to compete with natural ligands and to dissociate from LDLR at acidic pH and in the absence of calcium. The corresponding peptides were synthesized and their endocytosis was confirmed on human brain endothelial cells, while their colocalization with LDLR was very good on brain slices. The endocytosis studies confirmed their co-localisation with caveolae, whereas the lysosome degradation is bypassed. These peptides will be used to design multi-functional pharmaceutical molecules able to cross the BBB and modulate PLA2 activity, paving the way toward a more effective therapy of AD. 1. Schaeffer EL et al. Prog Neuropsychopharmacol Biol Psychiatry. 2010;34: 1381–1389. 2. Kudo I et al. Prostaglandins Other Lipid Mediat. 2002;68-69: 3–58. 3. Dehouck B et al. J Cell Biol. 1997;138: 877–889.