Symposium Mayoly sur le Syndrome de l'Intestin Irritable.
Organisateur: Pr. Boucekkine
ALTERATIONS DE LA BARRIERE MUQUEUSE
ET
SYNDROME DE L'INTESTIN IRRITABLE
L. Buéno
Unité de Neurogastroentérologie INRA
Toulouse, France
Alger, 25 Avril 2010
TRILOGY OF IBS PERIPHERAL PATHOPHYSIOLOGY
Altered gut sensitivity to Distension
• Lower threshold of sensitivity (pain) to distension
evidenced in 60-70% of IBS patients
• Increased perception of pain for a given visceral stimulus
(Whitehead et al.1998, 20-25 ref.)
Colonic mucosal micro-inflammation
• Increased number of mast cells, immune cells (Weston et
al.1993 and 10-12 ref.)
• Presence of pro-inflammatory cytokines (Gwee et al. 2003)
• Release of pro-inflammatory (eicosanoïds)(Jones et
al.1982) and pronociceptive agents (Barbara et al. 2005)
Increased paracellular permeability
• colonic or intestinal level in PI-IBS (Dunlop,2000),
• intestinal in all Rome I (Marschall et al.2004)
• colonic in IBS-D patients (Gesce et al. 2008)
Trimble et al.1995
1995-2009: Evidence (25 articles) of allodynia in 60-70% of IBS patients Trimble et al.1995
but not confirmed for all gut segments
Repetitive Stimulation Sensitizes the
Spinal Cord
Dorsal root
ganglion
Wind-up
Sensitized
spinal
Repeated Mechanosensitive circuits
balloon afferent
distention
HYPERALGESIA IN IRRITABLE BOWEL SYNDROME
(Use of “barostatic” distensions)
45
Baseline
40 Post sigmoid
stimulation
35
Rectal Pain
Threshold 30
(mm Hg)
25
20
0
IBS Controls
Munakata J, Gastroenterology 1997; 112:55
Brain Activation with Noxious Visceral Stimulation
Prefrontal Cortex
Cing Cx included
MCC
pACC
Thalamus
Pf, Re, Cl, Li
Locus coeruleus
Subnucleus
reticularis dorsalis
Spinal cord
IBS Lamina 1
Evidence for colonic mucosal immune alterations and increased
density of mast cell and immunocytes in IBS
Mast cells Lymphocytes T Neutrophils ECC
Patients ICC Ref.
Jejun/ Cecum/ CD3+ CD4+ CD25
ileum colon CD8+
“spastic colon” ++ Hiatt 1962
IBS- D/C ++ Weston et al. 1993
IBS- D/C/A + O’sullivan et al.2000
IBS- D/C/A +PI ++ ++ ++ Thorbloom et al. 2002
IBS-D/C ++ ++ ++ + Chadwick et al. 2002
IBS- D ++ Park et al. 2003
IBS-PI ++ ++ Dunlop et al. 2003
IBS-PI ++ ++ Spiller 2004
IBS- D+SII-C ++ Barbara et al. 2004
IBS- D/ PI ++ Chang et al. 2004
IBS- D ++ ++ Park et al. 2006
ECC: enteric chromaffin cells; ICC : interstitial cell of Cajal; IBS-C: constipated patients;
IBS-D: diarrheoic patients; IBC-A: alternated diarrhea-constipation; PI: post-infectious IBS.
Lymphocytose ganglionnaire dans le SII
Infiltration de lymphocytes dans les ganglions myentériques. La flèche noire indique un
neurone et quelques lymphocytes à la base du neurone.Il ya plus de lymphocytes dans
la zône délimitée par les les flêches bleues. Hématoxiline-éosine, X 380
(d’après Thorbloom et al. 2002)
Activation des lymphocytes T circulants CD4+ et CD8+
et expression de MAdCAM par l’endothélium colique dans l’IBS
Sang
Colon
IBS: D+C+A (Ohman et al.2005)
UCr: RCH en rémission; UCa: RCH active; CTRL: Témoins
COLONIC MAST CELLS IN CLONIC BIOPSIES OF
IBS PATIENTS
CTRL IBS
Increased mast cell tryptase labeling in the sub-mucosa of IBS patients
Proximal colon biopsies in IBS = density of mast cells
amount of tryptase
colocalisation nerve-mast cells
( Barbara et al., 2004)
Facteurs principaux produisant la dégranulation ou l’activation
des mastocytes muqueux du tube digestif
Stress
Mastocyte Degranulation
Allergie Histamine
Leukotrienes
Cytokines*
proteases
Inflammation NGF
Secretion
Infection
Cytokines*
Chemokines
activation
Système S
* Cytokines: TNFa, IL-3, IL-5, IL-4, IL-13, IL-10, GM-CSF
(adapted from Shakoory et al,2004, Penicci et al.2003)
Distribution of nerve terminals close to mast cell
in IBS patients.
PI-IBS CTRL
Mast cell number (mm2)
(ileal mucosa)
MC
MC PI-IBS……… 11.2 ± 2.8*
(n=27)
Non PI-IBS…..10.8 ±1.2*
(n=29)
Control………..6.1±0.5
(n=12)
*: from control at p<0.01
(X1000)
Red: nerve terminals (enolase labeling)
Blue: mast cells (alcian blue)
( Wang et al. Gut 2004 )
RELATIONSHIP BETWEEN MAST CELL-NERVES
CONNECTION AND PAIN IN IBS PATIENTS
4 4
3 3
2 2
1 1
0 0
0 5 10 15 20 0 5 10 15 20
Number of mast cells at a distance < 5µm from nerves
(Barbara et al. Gastro. 2004)
Is increased gut permeability able to initiate mucosal
immune response and visceral hypersensitivity?
Increased paracellular permeability
=
Entry of pathogens, toxins, antigens, bacteria
Epithelial cells
- activation of immunocytes
- cytokines release
- inflammatory mediators
Motility ENS Nociceptive
disorders hypersensitivity PAIN
disorders
(LPS, DNA,peptidoglycans,…etc.)
Tight junction
Intestinal or colonic mucosa Pathogens Allergens
Epithelial
cells
Mast
T-cell cell
B-cell
Sensory nerves
Granulocyte
(nociceptive fibers)
( from Perdue et al. 2000 )
INFLUENCE OF FECAL SUPERNATANT FROM IBS PATIENTS INFUSED
ON PARACELLULAR PERMEABILITY OF MICE COLONIC STRIPS
Fecal supernatants (n=6) IBS-D fecal supernatants (n=3)
300
200
*
100
IBS-D fecal supernatants (n=4) 0
WT PAR-2-/-
Increase in permeability triggered by
apical application of IBS-D fecal
supernatant is reduced by ser-protease
inhibitor and is absent in PAR-2 -/- KO
mice
(Gecse et al. 2008)
INFLUENCE OF FECAL SUPERNATANT FROM IBS-D PATIENTS INFUSED
INTRACOLONICALLY IN MICE ON COLONIC SENSITIVITY TO DISTENSION
(Gecse et al.
2008)
INFLUENCE OF FECAL SUPERNATANT FROM IBS-D PATIENTS ON
COLONIC EPITHELIAL TJ INTEGRITY IN MICE
P-MLC (green) P-MLC in colonic mucosa
ZO-1 (green)
P-MLC is over expressed in colonic mucosa
infused with IBS-D supernatant reflecting a
EC cytoskeleton contractionC
Resulting opening of TJs is associated with
a reduced apical expression of ZO-1
(Gecse et al. 2008)
Mechanisms involved in long-term sensitization of mucosal
sensory nerves in IBS-D patients
Luminal ser- proteases
PAR-2 activation
Increased
permeability
(mins to hours)
IFNg tryptase
Mucosal
micro-inflammation T-cell Mast cell
(hours to weeks)
Inflammatory tryptase
mediators
SP
Nerve terminal
sensitization Afferent neurons
(weeks to months)
Long-term
hypersensitivity
( Bueno et al. 2008)
Factors able to alter gut permeability/sensitivity in FGID
Inflammation
stress (gastroenteritis) sepsis
enzymes Allergens, parasites
Biliary salts bacteria (proteases?)
Bacterial secetion or lysis (acetaldehyde, LPS…etc)
IN VITRO MEASUREMENT OF PARACELLULAR PERMEABILITY OF
COLONIC BIOPSIES (Ussing chambers)
The degree of porosity of biopsies
from IBS patients is higher than
that of healthy subjects
independently of bowel habit
alterations.
This altered permeability is associated
with a decrease in the expression of
ZO-1, a protein linking the
actinomyosin apical ring to the proteins
of the TJs
Piche et al. Gut 2009
EFFECTS OF COLONIC BIOPSY SUPERNATANT ON CaCo2 CELL
PERMEABILITY AND CORRELATIONS WITH SYMPTOM SCORES
Increase of permeability of CaCo2
cells, 48h after mucosal exposure
with supernatant of biopsies from
IBS patients
Changes in permeability of CaCo2
cells is correlated with the pain
score of explored IBS patients
Piche et al. Gut 2009
RELATIONSHIPS BETWEEN GUT PERMEABILITY AND PAINFUL SENSATIONS
TO DISTENSION MEASURED IN VIVO
INTESTINAL PERMEABILITY VISCERAL PAIN*
0.30
10.0
0.25
Lactulose/ Mannitol
VAS score (visceral)
7.5
0.20
0.15 5.0
0.10
2.5
0.05
0.00 0.0
Normal IBS Normal IBS
Pain measurement after repeated (2) 35mm Hg rectal distension performed during 30 sec.
* at 2 min. interval. Zhou et al. Pain 2009
RELATIONSHIPS BETWEEN GUT PERMEABILITY AND SOMATIC* SENSITIVITY
IN IBS PATIENTS
120
100
Patients with
altered
80
FBDSI score
permeability
60
40
20
0
CONTROL IBS
*skin thermal stimulus (Pelletier probe 3x3 cms) at 47°C applied to the left hand during 10 sec.
Zhou et al. Pain 2009
CONCLUSIONS
La douleur abdominale associée au SII à le plus souvent comme
origine une hypersensibilité intestinale ou colique à la distension.
Cette hypersensibilité est associée à une micro-inflammation de la
paroi pouvant être considérée comme résultant d'une augmentation de
la “porosité“ de la muqueuse colique associée au passage de bactéries
et toxines.
Cette augmentation de perméabilité à été montrée, in vivo et in vitro,
être corrélée aux symptômes
Certains facteurs luminaux dont les protéases agissent sur les
récepteurs des cellules épithéliales pour augmenter cette perméabilité