IBD pathogenesis and targeted therapies: How can we improve current management?

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IBD pathogenesis and targeted therapies How can
we improve current management?

• R. Balfour Sartor, M. D.
• CCFA Chief Medical Advisor
• Midget Distinguished Professor of Medicine,
  Microbiology Immunology
• Director, Multidisciplinary IBD Center and
  National Gnotobiotic Rodent Resource
  Center
• University of North Carolina- Chapel Hill

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Inflammatory Bowel Diseases

• Segmental inflammation involving full thickness
  of any part of GI tract
• Immunologic Profile TH1/17 IL-12, 17, 23,
  IFNg activated innate pathways (IL-1b, IL-6,
  TNF)

• Diffuse inflammation limited to the mucosa of the
  colon, involves rectum
• Immunologic Profile TH2 IL-13, activated innate
  pathways (IL-1b, IL-6, TNF, IL-12, IL-23)

Genes HLA
NOD 2 MDR1a
ATG16L1 IL-23R
IL-23R
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2 patients with Crohns disease similar
presentations, different outcomes

• Onset Two 12 y/o boys with failure to grow for
  one year, anemia ? weight loss, abdominal pain,
  nonbloody diarrhea
• Evaluation Ileal Crohns disease
• Treatment Prednisone, 6MP
• Patient A Patient B
• Benign course
  Complications
• Feels well, no flares
  intra-abdominal abscess, . drained,
  resection of 14 ileum
• 
  Post op Infliximab

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How to predict which patient will

• Have an aggressive course?
• Respond to a potential treatment?
• Have complications of disease or therapy?
• Understand mechanisms of disease in an individual
  at time of diagnosis
• Genetic, microbial, immunologic profiles
• and clinical phenotype

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B. Sartor Gastroenter. 2010
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Sartor RB Gastroenterology 2010
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Etiologic Hypothesis of Crohns Disease (2014)

• Chronic intestinal inflammation is due to overly
  aggressive TH1/17 cell responses to a subset of
  luminal bacteria
• Susceptibility is determined by genes that encode
  immune responses, mucosal barrier function or
  bacterial clearance
• Onset/reactivation is triggered by environmental
  stimuli that transiently break the mucosal
  barrier and initiate inflammation

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Crohns disease pathogenesis

• Microbiota
• ? Aggressive
• ? Protective

• Environmental Triggers
• Infections
• NSAIDs
• Diet
• Smoking
• Stress

• Genetic Susceptibility
• Barrier Function
• Bacterial Killing
• Immunoregulation
• 163 genes!

• Immune Response
• ? TH1
• ? TH17
• Defective Innate

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163 confirmed genetic loci in IBD
CD genes
UC genes
110 IBD loci

• Common pathways
• Leprosy
• Mycobacterialsusceptibility
• Other immune-mediated disease

30 CDspecific loci
23 UCspecific loci
NOD2 PTPN22
MHC
Genes in common
Jostins, L. et al. Nature 491, 119124 (01
November 2012)
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163 gene mutations associated with Crohns
disease and ulcerative colitis
Epithelial Barrier

• OCTN 1/2
• organic cation (carnitine) transporter
• DLG5
• Scaffolding protein, epithelium
• MDR1a (UC)
• drug transporter, epithelium
• NOD2/CARD15
• - intracellular bacterial receptor
• XBP1
• - endosomal stress response

Immunoregulation IL-23R (CD and UC) IL-10 and
IL-10R HLA Bacterial killing/processing ATG 16L1-
bacterial autophagy IRGM- bacterial killing,
autophagy NCF4- NADPH- killing bacteria NOD2-
intracellular killing, antimicrobial peptide
secretion
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Crohns disease pathogenesis

• Microbiota
• ? Aggressive
• ? Protective

• Environmental Triggers
• Infections
• NSAIDs
• Diet
• Smoking
• Stress
• Antibiotics

• Genetic Susceptibility
• Barrier Function
• Bacterial Killing
• Immunoregulation

• Immune Response
• ? TH1
• ? TH17
• Defective Innate

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Environmental Triggers of IBD
Altered mucosal barrier function and/or
immunoregulation
Altered microbiota
Acute infections
Antibiotics
NSAIDs
IBDOnset and Reactivation
Smoking
Diet
Stress
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Mode of delivery profoundly affects early
colonization of neonatesDominguez- BelloR.
KnightPNAS 2010Vaginally- delivered babies
microbiotacontains vaginal dominant organisms
(lactobacillus species), while C. section babies
have predominant skin organisms (Staphlococcus
species)C. section associated with risk of
celiac disease, IBD, NEC, asthma, atopic
dermatitis
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Antibiotic use in childhood is a risk factor for
developing Crohns disease (Anders Hviid et al,
Gut 6049-54, 2011)

• Prospective, nationwide cohort study of children
  born between 1995 2003 in Denmark (N 577,622)
• Findings
• Relative risk increased for IBD (1.84), and
  selectively for Crohns disease (RR 3.41), but
  not UC
• Time and dose response dx within 3 months (RR
  4.43) and gt7 courses of antibiotics( RR 7.32)
• Conclusion Unknown causal relationship or
  association with IBD symptoms before diagnosis?

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Diet influences Microbiota (Wu et al, Science
2011)
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Diet determines the composition of gut bacteria
Growth and function of aggressive species by
refined sugars and iron protective bacteria by
complex carbohydrates (fiber, prebiotics)
Protective Anti- inflammatory (Fiber, prebiotics)
Injurious Pro-inflammatory (Iron, sucrose,
fructose, satur. fat)
Bacteroides vulgatus, B. theta Enterococcus
faecalis E. coli - enteroadherent /
invasive Klebsiella pneumoniae Bilophila
wadsworthia Bifidobacterium animalis Fusobacterium
varium Intestinal Helicobacter species
Lactobacillus sp. Bifidobacterium
sp. Non-pathogenic E. coli Saccharomyces
boulardii Bacteroides thetaiotaomicron
Faecalibacterium prausnitzii Clostridium
groups IV and XIVA
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Crohns disease pathogenesis

• Microbiota
• ? Aggressive
• ? Protective

• Environmental Triggers
• Infections
• NSAIDs
• Diet
• Smoking
• Stress

• Genetic Susceptibility
• Barrier Function
• Bacterial Killing
• Immunoregulation

• Immune Response
• ? TH1
• ? TH17
• Defective Innate

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Gastrointestinal Bacteria in Normal Humans
Stomach 0-102 Lactobacillus Candida Streptococcus
Helicobacter pylori Peptostreptococcus
Duodenum 102 Streptococcus Lactobacillus
Distal Ileum 107-108 Clostridium Bacteroides sp
Coliforms
Jejunum 102 Streptococcus Lactobacillus
Colon 1011 Bacteroides Clostridium
coccoides Clostridium leptum/ Fusobacterium Bifido
bacterium Coliforms (108)
Proximal Ileum 103 Streptococcus Lactobacillus
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Metabolism in the colonic ecosystem
Oligosaccharides
Polysaccharides
Mucins
Proteins
Bacteroides
clostridia peptostreptococci peptococci
Succinate
Bifidobacterium Lactobacillus
Clostridium IV
Clostridium IX
SO4--
Clostridium XIVa E. halli R. hominis
Sulfate Reducing Bacteria
H2S
CO2
Lactate
Acetogens
H2
Ethnogeny
Phenols NH4 Amines
Acetate
Butyrate
Propionate
Methane
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Clinical evidence (mostly correlative)that
enteric bacteria, viruses or fungi can induce
Crohns disease

• Disease located in areas of highest bacterial
  populations
• Increased mucosal association and translocation
• Abnormal composition commensals- dysbiosis
• Certain CD- associated genes alter gut microbiota
  and bacterial killing
• Infections can induce flares of IBD (C. diff
  toxin, CMV)
• Fecal stream diversion prevents CD relapse,
  disease recurs upon restoration of fecal flow
• Manipulating bacterial populations treats certain
  subsets
• Microbe-specific serologic and T cell responses

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Anti-microbial Antibody Sum and Disease Behavior
Inflammatory
IP (internal penetrating)
S (stenosing)
Surgery
Frequency of Disease Behavior
0 N199
1 N262
2 N194
3 N57
Odds Ratio
Number of Immune Responses
Dubinsky MC et al CGH 200861105
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IBD Patient Stratification by Dysbiosis
(abnormal composition)
Abnormal
Normal
Normal
Abnormal
Frank et al., 2007. PNAS. 104(34)13780-13785
Peterson et al, 2008. Cell Host Microbe.
3417-427
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IBD-dysbiosis subset is characterized by
contraction of Firmicutes and Bacteroidetes and
expansion of Proteobacteria
IBD-Subset
No
Yes
100
Actinobacteria
80
Proteobacteria
Bacteroidetes
60
of clone libraries
Other
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Bacillus
Firmicutes
Lachnospiraceae(Clostridia XIVa/IV)
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0
Frank DN, et al. PNAS 2007104(34)1378013785
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Faecalibacterium prausnitzii is a putative
protective commensal bacteriumLow mucosal
concentrations at surgery predict post- operative
recurrence in 20 CD Patients
No endoscopic recurrence Endoscopic recurrence
10
8

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F. prausnitzii ()
4
2
0
At surgery
At 6 months
Sokol H et al. Proc Natl Acad Sci U S A.
200810516731.
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Insights from gnotobiotic rodentsNational
Gnotobiotic Rodent Resource Center (NIH, CCFA)
The stage A gnotobiotic isolator
The actors
Germ-free Selectively SPF/ CONV-R
CONV-D
conventionalized
colonized conventionally
(monoassociated) SPF raised
Adapted from Jeff Gordon
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Essential Role of Commensal Enteric Bacteria in
the Pathogenesis of Experimental Chronic
Intestinal Inflammation
No bacteria
Resident bacteria
Mice IL-2KO (?) IL-10KO TCRa KO CD3e26TG MDR1KO S
AMP1/Yit (?) CD45RBhi SCID Rats HLA-B27
TG Indomethacin Guinea pigs Carrageenan Non-huma
n primate Cotton top tamarin
Macrophage and TH1/TH17 immune activation
No immune activation
No colitis
Colitis
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Differential ability of various bacterial
species to induce or prevent experimental
colitis All bacterial species are not equal!
Aggressive colitis
Cecal bacteria
HLA B27 transgenic rat
Moderate colitis
Bacteroides vulgatus
Germ free, no colitis
No colitis
E. coli
Cecal bacteria Lactobacillus GG
Protection
Rath et al., J Clin Invest 199698945 Rath et
al., Infect Immunity 1999 672969 Dieleman
et.al., Gut 2003 52370
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Functionally altered E. coli are present in ileal
Crohns disease

• Adherent/invasive E. coli
• Adhere to/invade epithelial cells
• Persist within EC, macrophages
• Increased in ileal Crohns disease
• (Darfeuille- Michaud, et al.
• Baumgart, Simpson, ISME J. 2007)
• Bind to CEACAM 6 on ileal
• epithelial cells
• Barnich et al, JCI 2007)

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Intestinal inflammation vs. homeostasis depends
on the relative balance of beneficial vs.
detrimental bacteria This balance is unique in
each individual and each individual responds
differently to various bacterial species
Protective Probiotic
Injurious Pro-inflammatory
Lactobacillus sp. Bifidobacterium
sp. Faecalibacterium prausnitzii Roseburia
species Non-pathogenic E. coli Saccharomyces
boulardii Bacteroides thetaiotaomicron
Bacteroides vulgatus, B. theta Enterococcus
faecalis E. coli - adherent / invasive Klebsiella
pneumoniae Ruminococcus gnavus Segmented
filamentous bacterium Fusobacterium
varium Intestinal Helicobacter species
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Crohns disease pathogenesis

• Microbiota
• ? Aggressive
• ? Protective

• Environmental Triggers
• Infections
• NSAIDs
• Diet
• Smoking
• Stress

• Genetic Susceptibility
• Barrier Function
• Bacterial Killing
• Immunoregulation
• 163 genes!

• Immune Response
• ? TH1
• ? TH17
• Defective Innate

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B. Sartor Gastroenter. 2010
Fut2
Sartor RB Gastroenterology 2010