The enteric nervous system
and gut homeostasis
Pr. Michel Neunlist ● Directeur de recherche INSERM
1
The enteric nervous system
and gut homeostasis
UMR Inserm U913
Institut des Maladies de l’Appareil Digestif
Nantes
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2
The gastrointestinal tract :
oldest organ in evolution
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36
Overview of the presentation
I.Gut central actors of human health and disease
II. The enteric nervous system in control of gut
homeostasis
III.Nutritional modulation of gut homeostasis : the
ENS as a target and effector
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The gastrointestinal tract : an organ
complex and essential for our survival
30 tons
food
50 tons of liquids
1- Motility
2- Absorption nutrients/electrolytes
3- Intestinal barrier functions
macrophages,lymphocytes…
microbiota
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Gut homeostasis:
definition
Capacity to maintain the
organ/system at equilibrium
in response to constrains
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Gut local homeostasis:
a complex cellular system
• Smooth muscle cells
• Fibroblasts
• Intestinal epithelial cells
• Immune cells
• Endothelial cells
• Neurons and astrocytes,.....
Need coordination between cells ‘locally’ but also globally along ‘organs’
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The gut systemic homeostasis : integrating
complex environmental signals
Inner signals
Outer signals
• Brain
• Liver
• Heart
• Lung
• Muscle....
• Microbiota,
• Nutrition
• Pathogens,....
Signals changes during time (min, hours, days) and during age
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Intestinal epithelial barrier microenvironement :
key actors of gut homeostasis
Microbiota
Nutrients
Myofibroblasts
Immune cells
Neurons/glial cells
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Adapted Renz, Brandzaeg and Hornef, Nat Rev Immunol, 2012
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What cells are key cellular regulators
of gut homeostatic functions ?
Homeostasis : Capacity to maintain a
system/organ at equilibrium in
response to constrains
• Intestinal epithelial cells :
• First target and integrators of environmental challenges
• The enteric nervous system :
• Detect, initiate, coordinate and terminate the response
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Intestinal epithelial barrier function
in health
Electrolytes
Nutriments
Virus Bacteria
 Monolayer of proliferating and differentiating epithelial cells
 Passage of nutrients and electrolytes / Control passage of pathogens
 Extrinsic barrier (secretion of electrolytes / mucus / anti microbial peptides)
 Intrinsic barrier (control of paracellular / transcellular permeability)
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The gastrointestinal tract (intestinal
epithelial barrier) and chronic
diseases
●
Central role in multi-factorial
and multi-organ diseases
–
Genetical factors of susceptibility
and environmental triggers
(toxic; pathogens; nutritional)
Inflammatory diseases
• IBD; IBS
Perinatal
Childhood
Autism
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Adult
Metabolic syndrome
Obesity
Cancers
Ageing
Neuro-degenerative
•Parkinson’s diseases
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Intestinal epithelial barrier dysfunctions in
chronic diseases
Creutzfeldt-Jakob D;
Parkinson’s D
Autism; ....
‘Leaky gut’
Virus Bacteria
Metabolic syndrome ;
Obesity
Type I diabetes
LPS; antigen; virus; toxin
  para/transcellular permeability
 Altered barrier repair
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Inflammatory bowel diseases;
Irritable bowel syndrome;....
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Intestinal barrier dysfunction predicts ageonset mortality
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Rera M et al., PNAS 2012
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Preventing barrier dysfunction delays onset
of age dependent mortality
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Rera M et al., Aging, 2013
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Intestinal epithelial barrier microenvironement :
key actors of gut homeostasis
Microbiota
Nutrients
Myofibroblasts
Immune cells
Neurons/glial cells
Breizh Algae Tour - Sept. 15th, 2014
Adapted Renz, Brandzaeg and Hornef, Nat Rev Immunol, 2012
49
Overview of the presentation
I.Gut central actors of human health and disease
II. The enteric nervous system in control of gut
homeostasis
III.Nutritional modulation of gut homeostasis : the
ENS as a target and effector
Breizh Algae Tour - Sept. 15th, 2014
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The Digestive Neuro-Glio Epithelial Unit alike the
Neuro-Glio Endothelial Unit of the brain?
Epithelial cells
Human colonic mucosa
0,5µm
S100ß
Nerve fiber
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Neunlist et al., Nat Rev Hepatol Gastroenterol , 2013
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The digestive tract :
an neurological organ
ChAT: choline acetyl transferase
NOS: Nitric oxide synthase
VIP: Vasoactive intestinal peptide
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Components of the enteric nervous system
: neurons and glial cells
Neurons
Glial cells
200 millions neurons; 1 billion glial cells;
50 000 vagal fibers (80% afferent toward the brain)
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Enteric nervous system : central actor of
gut homeostasis
Enteric neuron loss
(Hirschsprung D)
Enteric glial cells loss
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Bush et al., 1998; Cornet et al., 2001
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It can do it without the brain…..
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Enteric neuronal circuits responsible
for peristaltism
Longitudinal muscle
Sensory
Neurons
Excitatory
Motoneurons
Ach
Inhibitory
Motoneurons
NO
ATP
Myenteric Plexus
VIP
Circular muscle
5-HT
CCK
Ach
Bolus activates
Mechano / Chemosensors
Epithelium with EC cells
Lumen
Circular muscle
oral
anal
Myenteric plexus
Longitudinal muscle
Building a brain in the gut: development
of the enteric nervous system
Nyshiyama et al., Nat Neuroscience, 2012
•
•
•
Goldstein and Burns, Clinical Genetics, 2012
Heanue TA, Pachnis V, Nat. Rev. Neurosci. 2007
Colonization of gut by neural crest cells (E9-15 in mice; Week 4-7 in humans)
Time dependent proliferation and differentiation of different subclasses of neurons
Enteric glial cells differentiate only in late embryonic stages
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The perinatal period : a highly plastic period
of gut and ENS functions
Birth
Conception
No
motility
Spontaneous activity not
generated by neurons
Neuronal circuitry in place
Mature motility
but not mature
Burns et al., Seminars in Pediatric Surgery, 2009
Robberts et al., Am J Physiol., 2007; Guo et al., Neurogastro Mot 2009
Hu
ChAT
P1
P1
Weaning
P21
P36
P21
de Vries et al., Am J Physiol., 2010
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Post natal period is associated with major
neuroplastic and functional changes
P21
P36
Weaning
Colonic contractile activity
J7
J14
J36
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Flux sulfonic acid
P1
de Vries et al., Am J Phys, 2010
Paracellular permeability
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Neurally mediated maintenance of barrier integrity :
role of vasoactive intestinal peptide
% flux / control
- Neurostim
125
100
75
*
50
+ Neurostim
25
Electrode
Stim
Neunlist et al., Am J Physiol 2003
0
NS
S
ZO-1
Protéine ZO-1 (%)
Coculture ENS/ IEC
125
100
*
75
50
25
0
S
S+VIP-ra
In vivo barrier protective effects of VIP (C rodentium)
VIP
ZO-1
Conlin et al., Am J Physiol 2009
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Glial cells mediated maintenance of
barrier integrity
- EGC
S. flexneri
- EGC
+ EGC
S. flexneri
+EGC
Enteric
glia
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Flamant et al., Gut, 2011
61
Activity dependent protection of intestinal barrier:
in vivo sacral nerve stimulation
N=12 pigs
Controls (6); Bilateral(6)
T0
B
C
SNS
Control
A
T3h
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Bregeon et al., unpublished
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Overview of the presentation
I.Gut central actors of human health and disease
II. The enteric nervous system in control of gut
homeostasis
III.Nutritional modulation of gut homeostasis : the
ENS as a target and effector
Breizh Algae Tour - Sept. 15th, 2014
63
Impact of the luminal microenvironment upon ENS
phenotype and functions:
exemple of the microbiota
Microbiota
1) Can microbiota modulate
gut and ENS functions ?
2) What mechanisms
are involved ?
Neurons/glial cells
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The microbiota modulate gut motility
Germ free ± strains
Transit time
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Husebye et al., Am J Physiol 2001
65
Regional differences of Lactobacillus reuteri et
rhamnosus strains upon gut motility
Lactobacillus reuteri
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Lactobacillus rhamnosus
Wu et al., Neurogastroenterol Mot, 2013
66
Impact of the luminal microenvironment upon ENS
phenotype and functions:
exemple of
the microbiota
Microbiota
1) Can microbiota modulate
gut and ENS functions ?
2) What mechanisms
are involved ?
Neurons/glial cells
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Bacteriodes fragilis activates enteric neurons
via membrane derived Polysaccharide A
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Mao et al., Nat Comm, 2013
68
Impact of the luminal microenvironment
upon ENS phenotype and functions:
exemple of the microbiota
Microbiota
Bacterial metabolites
(AGCC;AGPI)
1) Can microbiota modulate
gut and ENS functions ?
2) What mechanisms
are involved ?
Neurons/glial cells
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Resistant starch diet induces neuroplastic
changes in the ENS via butyrate
Standard diet (SD)
Resistant starch diet
(RSD)
15 days
- Expression of ChAT / NOS in
myenteric neurons
- Transit
Resistant starch increases specifically butyrate production (46±8 and 20±5 μmol/g)
Standard diet
Hu
Resistant starch diet
Transit time (min)
50
40
30
ChAT
*
20
10
0
0,5
1,5
SD
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Soret et al., Gastroenterology, 2010
2,5
RSD
70
Butyrate enhances post natal maturation of
the ENS and colonic motility
Birth
Butyrate
Saline
P7
Plasticity of ENS
and motility
P17
Enemas
P21
Transit time (s)
% ChAT-IR/Hu-IR
Butyrate enemas
Neotrans clinical
trial (Pr JC Rozé)
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Suply et al., Am J Physiol, 2012
71
Bacteria modulated fatty acid composition
of the host
Bifidobacterium breve
NCIMB 702258 (+/linoleic acid (w6))
8-12 weeks
Adipose tissue
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Wall et al., Am J Clin Nutr 2009
72
Polyunsaturated fatty acid (PUFAs) induced
neuroplastic and functional changes
Analysis of fatty acid
composition (jejunum)
Gestation + 28 d post natal
Control diet (lard based)
n-3PUFA diet (linseed oil based;
linolenic acids (18:3n-3))
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de Quelen et al., J Physiol., 2011
73
Polyunsaturated fatty acid (PUFAs) induced
neuroplastic and functional changes
n3-PUFA
Control
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de Quelen et al., J Physiol., 2011
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Conclusions and perspectives
●
The enteric nervous system : a central regulator of gut
homeostasis (barrier function; motility) but still much
remains to be known
–
Neuro-glial control of intestinal epithelial stem cells, immune cells….
–
How environnemental factors (in utero, post-natal and later in life) affect gut
and ENS phenotype/functions ?
●
●
The enteric nervous system : a mediator of
nutrients/microbiota effects upon gut function
Modulation of ENS / gut functions by microflora :
it‘s all in the strain and/or their metabolites
–
Need to identify target specific strains/nutrients (enhance/reduce
motility/barrier)
–
Need better phenotyping of enteric neuropathies in human diseases in
order to define subgroups of patients for specific personalized nutritional
intervention
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Acknowledgments
Paris
Nantes
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Acknowledgments
UMR 1280 Phan
UMR Senah
Financement
J.P. Segain
G. Boudry
Harvard Medical School
G. Tearney
A. Goldstein
P. Sansonetti
G. Barbara
R. de Giorgio
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Thanks for your
attention!
4
Impact of the luminal microenvironment
upon ENS phenotype and functions :
exemple of high fat diet
Régime obésogène
Dysbiose
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Neuropathies entériques provoquées par
un régime obésogéne
High fat diet
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6 months
Voss et al., PlosOne, 2013
Impact on neuronal cell death
80
Effets neuroprotecteurs d’un régime
obésogène
12w
High fat Low fiber diet
Control diet
C57BL/6J Rj
- Expression of ChAT / NOS in
myenteric neurons
- Gastric emptying
juvenile mice
(4weeks)
Hu C/D
Neurones
Hu-IR
/ggl
100 µm
T0
ND
WD
12 semaines
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Baudry et al., J Physiol, 2012
81
Effets neuroprotecteurs d’un régime
obésogène
12w
High fat Low fiber diet
Control diet
C57BL/6J Rj
- Expression of ChAT / NOS in
myenteric neurons
- Gastric emptying
juvenile mice
(4weeks)
Hu C/D
Neurones
Hu-IR
/ggl
100 µm
T0
ND
WD
12 semaines
Breizh Algae Tour - Sept. 15th, 2014
Baudry et al., J Physiol, 2012
82
Effets neuroprotecteurs d’un régime
obésogène
Neurones
Hu-IR
Hu C/D
/ggl
100 µm
T0
ND
WD
12 semaines
Neuronesn
NOS-IR
Neurones
ChAT-IR
T0
ND
WD
12 semaines
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T0
ND
WD
12 semaines
83
Les effets neuroprotecteurs d’un régime
obésogène induisent une accélération
de la vidange gastrique
Vidange gastrique (%)
*
ND
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Baudry et al., J Physiol, 2012
*
WD
84
Les effets neuroprotecteurs d’un régime
obésogène induisent une accélération
de la vidange gastrique
Vidange gastrique (%)
*
ND
Saline
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L-NAME
Baudry et al., J Physiol, 2012
*
*
WD
Saline
L-NAME
85
Composition en graisses (acides gras saturés vs
insaturés) determine les effets du régime sur le
SNE?
Palmitic Acid Acid oleic
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Voss et al., PlosOne, 2013
86