eprintid: 10122302
rev_number: 8
eprint_status: archive
userid: 695
dir: disk0/10/12/23/02
datestamp: 2021-02-22 23:15:33
lastmod: 2021-02-22 23:15:33
status_changed: 2021-02-22 23:15:33
type: thesis
metadata_visibility: show
creators_name: Rowland, Ruth Elizabeth Sarah
title: The exploitation of internalina fragments in drug delivery systems.
ispublished: unpub
note: Thesis Digitised by Proquest.
abstract: The objective o f the work reported in this thesis was to investigate the potential of the
protein intemalin when attached to nanoparticles to secure transport across the gut wall.
Intemalin, also called intemalin A or InlA, is a surface protein expressed by the
pathogenic bacteria Listeria monocytogenes in response to temperature and other
environmental cues that indicate the bacterium is in a suitable host. Intemalin has been
shown to interact with E-cadherin, a protein involved in structural maintenance of the
epithelial cells lining the gut wall. Cadherins are found throughout the human body and
the prefix E or N etc. indicates the location where they are most commonly found, E for
epithelial, N for neuronal etc. The interaction between intemalin and E-cadherin causes
a rearrangement of the actin cytoskeleton in the cell and this encourages the membrane
o f the epithelial cells to engulf the bacteria. The bacteria are then intemalised and have
achieved their first step in establishing infection. Once the bacteria are inside the cell
they use a panoply of further pathogenic factors to establish and propagate the infection.
It is the specific interaction between the intemalin (or a fragment of intemalin) and the
E-cadherin that this research addresses as a potential system to deliver dmgs across the
gut wall as a method of targeting vectors containing the dmg.
Many dmgs are still administered by injection, but non-invasive methods, including
oral, pulmonary, buccal, vaginal, rectal and dermal delivery, are preferred. Orally
administered dmgs are the most convenient and practical and have the highest patient
compliance. The gut wall provides a major barrier to the oral delivery of some,
particularly macromolecule pharmaceuticals. It is one o f the major physical barriers that
the immune system employs as a first line of defence against infection. There are many
tools the immune system employs to protect the GI tract; the presence of normal flora to
compete for receptor sites with invaders, mucus that entraps invaders and the propulsion
that moves the mucus and thus the microorganisms and entities entrapped within it out
o f the body. Also the temperature, pH, digestive enzymes and patrolling immune cells
help keep foreign entities out of the body. Pharmaceuticals that are required by the body
need to cross this barrier. Orally administered formulations achieve higher patient
compliance so this work set out to investigate a method o f employing the bacterial
armament to physical carrier systems which have already been exploited experimentally
in these laboratories using invasin (Hussain & Florence 1998) and tomato lectin
(Hussain et al 1997).
15
The effect of the intemalin protein surface adsorbed onto polystyrene nanoparticles
was investigated using the Caco-2 system. The Caco-2 cell system allows for the
evaluation of drug delivery systems that will be orally administered in an isolated and
realistic, but less complex manner. This is due to their ease of cultivation and that they
spontaneously differentiate into enterocyte-like cells, under normal tissue culture
conditions these cell mimic the lining of the gastrointestinal tract. The study was also
expanded to include the transport and effect of incubation of different partial dendrimers
(dendrons) with the Caco-2 system.
The research reported in this thesis establishes that the transport of polystyrene
nanoparticles through Caco-2 cells is modified by the surface adsorption of a
recombinant version of intemalin. Further experiments indicated there was a protein
interaction between the E-cadherin and the synthesised protein.
date: 2005
oa_status: green
full_text_type: other
thesis_class: doctoral_open
thesis_award: Ph.D.
language: eng
primo: open
primo_central: open_green
verified: verified_manual
full_text_status: public
pages: 180
institution: University College London
thesis_type: Doctoral
citation:        Rowland, Ruth Elizabeth Sarah;      (2005)    The exploitation of internalina fragments in drug delivery systems.                   Doctoral thesis  (Ph.D.), University College London.     Green open access   
 
document_url: https://discovery.ucl.ac.uk/id/eprint/10122302/1/The_exploitation_of_internalin.pdf