Abstract
Campylobacter
JeJum
IS
the
leading
cause
of
foodborne
gastroenteritis
worldwide,
yet
despite
the
organism's
prevalence,
relatively
little
is
known
about
the
mechanisms
of
pathogenesis.
This
is
mainly
due
to
the
lack
of
a
convenient
small
animal
model
of
infection
combined
with
certain
inherent
weaknesses
with
widely
used
in
vitro
models.
The
aim
was
to
develop
two
improved
models
to
study
C.
jejuni
interactions
with
intestinal
epithelial
cells.
The
Ex
Vivo
Organ
Culture
(EVOC)
model
involves
co-culturing
C.
jejuni
with
human
intestinal
biopsies.
C.
jejuni
11168H
and
81-176
wild-type
strains
were
demonstrated
to
induce
the
secretion
of
human
beta-defensins
2
and
3
(hBD-2
and
hBD-3).
Furthermore,
the
supernatants
of
infected
biopsies
were
demonstrated
to
contain
significantly
higher
levels
of
IL-l~,
IL-6,
IL-12
and
IL-23
compared
to
uninfected
controls.
Experiments
using
11168H
flaA
and
neuBl
mutants
demonstrated
that
the
induced
defensin
response
was
not
due
to
host
recognition
of
either
flagellin
or
the
terminal
sialic
acid
residue
of
C.
jejuni
illS.
The
Vertical
Diffusion
Chamber
(VDC) model
involves
co-culturing
C.
jejuni
with
polarised
human
intestinal
epithelial
cells
(lECs)
with
micro
aerobic
conditions
at
the
apical
surface
and
aerobic
conditions
at
the
basolateral
surface.
Survival
and
integrity
of
the
IECs
under
these
conditions
over
24
hours
was
demonstrated.
Co-
culture
experiments
under
these
conditions
resulted
in
an
increase
in
both
C.
jejuni
interaction
with
and
invasion
of
IECs.
This
was
mirrored
by
an
increased,
polarised
host
innate immune
response.
Transcriptional
analysis
of
aerobically
and
microaerobically
co-cultured
C.
jejuni
11168H
identified
several
genes
that
may
playa
role
in
these
increased
interactions.
The
levels
of
interaction
and
invasion
of
defined
C.
jejuni
11168H
mutants
with
Caco-2
cells
were
analysed
to
identify
bacterial
factors
that
contribute
to
these
increased
interactions.
Both
11168HflaA
and
rpoN
mutants
exhibited
lower
levels
of
interaction
and
invasion
than
the
wild-type
strain,
suggesting
the
involvement
of
bacterial
motility
in
the
increased
interactions
under
micro
aerobic
conditions.
The
reduction
in
this
increased
interaction
phenotype
was
more
pronounced
at
shorter
co-incubation
times,
suggesting
that
motility
is
particularly
important
during
the
early
phases
of
interaction.
The
development
of
these
two
model systems
should
allow·
future
3
experiments
to
more
accurately
investigate
host-pathogen
interactions
during
C.
jejuni
infection
of
the
human
intestinal
trac
