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

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

UCUC CDCD

Diffuse inflammation limited to the mucosa of the colon, involves rectum

Immunologic Profile TH2: IL-13, activated innate pathways (IL-1, IL-6, TNF, IL-12, IL-23)

Diffuse inflammation limited to the mucosa of the colon, involves rectum

Immunologic Profile TH2: IL-13, activated innate pathways (IL-1, IL-6, TNF, IL-12, IL-23)

Segmental inflammation involving full thickness of any part of GI tract

Immunologic Profile TH1/17: IL-12, 17, 23, IFNactivated innate pathways (IL-1, IL-6, TNF)

Segmental inflammation involving full thickness of any part of GI tract

Immunologic Profile TH1/17: IL-12, 17, 23, IFNactivated innate pathways (IL-1, IL-6, TNF)

Inflammatory Bowel Diseases

GenesHLA NOD 2MDR1a ATG16L1IL-23R IL-23R

2 patients with Crohn’s 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 Crohn’s diseaseTreatment: Prednisone, 6MP

Patient A Patient B Benign course Complications: Feels well, no flares intra-abdominal abscess,

…………………………. drained, resection of 14” ileum Post op Infliximab

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

Sartor RB Gastroenterology 2010

Fut2B. Sartor

Gastroenter. 2010

Etiologic Hypothesis of Crohn’s 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

Genetic Susceptibility

• Barrier Function• Bacterial Killing• Immunoregulation

• 163 genes!

Environmental Triggers

• Infections• NSAIDs• Diet• Smoking• Stress

Immune Response• ↑ TH1

• ↑ TH17

• Defective Innate

Microbiota• ↑ Aggressive• ↓ Protective

Crohn’s disease pathogenesis

163 confirmed genetic loci in IBD

Common pathways: Leprosy Mycobacterial

susceptibility Other immune-

mediated disease

110 IBD loci

CD genes UC genes

30 CDspecific

loci

23 UCspecific

loci

NOD2PTPN22 MHC

Genes in common

Jostins, L. et al. Nature 491, 119–124 (01 November 2012)

163 gene mutations associated with Crohn’s disease and ulcerative colitis

• OCTN 1/2– organic cation (carnitine)

transporter• DLG5

– Scaffolding protein, epithelium• MDR1UC

– drug transporter, epithelium• NOD2/CARD15 - intracellular bacterial receptor• XBP1 - endosomal stress response

Epithelial Barrier

ImmunoregulationIL-23R (CD and UC)IL-10 and IL-10RHLA

Bacterial killing/processingATG 16L1- bacterial autophagyIRGM- bacterial killing, autophagyNCF4- NADPH- killing bacteria

NOD2- intracellular killing, antimicrobial peptide secretion




• Infections• NSAIDs

• Diet• Smoking• Stress

•Antibiotics


• ↑ TH17




Environmental Triggers of IBD

IBDIBDOnset and Onset and

ReactivationReactivation

AntibioticsAntibiotics

DietDiet

NSAIDsNSAIDs

Acute infections

Acute infections

StressStress

SmokingSmoking

Altered microbiota

Altered mucosal barrier function

and/or immunoregulation

Mode of delivery profoundly affects early colonization of neonates

Dominguez- Bello…R. KnightPNAS 2010

Vaginally- 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

Antibiotic use in childhood is a risk factor for developing Crohn’s disease

(Anders Hviid et al, Gut 60:49-54, 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 Crohn’s disease (RR 3.41), but not UC•Time and dose response: dx within 3 months (RR 4.43) and >7 courses of antibiotics( RR 7.32)

Conclusion: Unknown causal relationship or association with IBD symptoms before diagnosis?

Diet influencesMicrobiota(Wu et al, Science 2011)

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)

Injurious Pro-inflammatory

(Iron, sucrose, fructose, satur. fat)

Bacteroides vulgatus, B. thetaEnterococcus faecalis

E. coli - enteroadherent / invasiveKlebsiella pneumoniaeBilophila wadsworthia

Bifidobacterium animalisFusobacterium varium

Intestinal Helicobacter species

Lactobacillus sp.Bifidobacterium sp.

Non-pathogenic E. coliSaccharomyces boulardii

Bacteroides thetaiotaomicron Faecalibacterium prausnitzii

Clostridium groups IV and XIVA

ProtectiveAnti- inflammatory(Fiber, prebiotics)






• ↑ TH17




Gastrointestinal Bacteria in Normal Humans

Stomach 0-10Stomach 0-1022

LactobacillusLactobacillusCandidaCandidaStreptococcusStreptococcusHelicobacter pyloriHelicobacter pyloriPeptostreptococcusPeptostreptococcus

Colon 10Colon 101111

BacteroidesBacteroidesClostridium coccoidesClostridium coccoidesClostridium leptum/ FusobacteriumClostridium leptum/ FusobacteriumBifidobacteriumBifidobacteriumColiforms (10Coliforms (1088))

Distal Ileum 10Distal Ileum 1077-10-1088

ClostridiumClostridiumBacteroides Bacteroides sp sp ColiformsColiforms

Duodenum 10Duodenum 1022

StreptococcusStreptococcusLactobacillusLactobacillus

Jejunum 10Jejunum 1022


Proximal Ileum 10Proximal Ileum 1033


Acetate Butyrate PropionateMethane

PhenolsNH4

+

Amines

H2SClostridium XIVaE. halli R. hominis

Metabolism in the colonic ecosystem

Ethnogeny

Sulfate Reducing Bacteria

Clostridium IX

Clostridium IV

Lactate

Oligosaccharides

BifidobacteriumLactobacillus

Polysaccharides

BacteroidesSuccinate

Mucins Proteins

clostridiapeptostreptococci

peptococci

SO4--

CO2

Acetogens H2

Clinical evidence (mostly correlative)that enteric bacteria, viruses or fungi can induce

Crohn’s 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

0

20

40

60

80

100F

req

ue

ncy

of

Dis

ea

se B

eh

av

ior

%

Number of Immune Responses

Anti-microbial Antibody Sum and Disease BehaviorInflammatoryIP (internal penetrating)

S (stenosing)

* Odds Ratio

0N=199

1N=262

2N=194

3N=57

Surgery

P trend < 0.0001

*2.2

*1.0

*5.0

*9.5

*1.7

*1.0

*4.2

*6.1

P trend < 0.0001

Dubinsky MC et al CGH 2008;6:1105

IBD: Patient Stratification by Dysbiosis (abnormal composition)

Peterson et al, 2008. Cell Host Microbe. 3:417-427Frank et al., 2007. PNAS. 104(34):13780-13785

No

rma

l Ab

norm

al

AbnormalNormal

IBD-dysbiosis subset is characterized by contraction of Firmicutes and Bacteroidetes

and expansion of Proteobacteria

Frank DN, et al. PNAS 2007;104(34):13780–13785

0

20

40

60

80

100

% o

f clo

ne li

brar

ies

No

Lachnospiraceae(Clostridia XIVa/IV)

YesIBD-Subset

Bacillus

Other

Bacteroidetes

Proteobacteria

Actinobacteria

Firmicutes

Faecalibacterium prausnitzii is a putative protective commensal bacterium:

Low mucosal concentrations at surgery predict post- operative recurrence in 20 CD Patients

Sokol H et al. Proc Natl Acad Sci U S A. 2008;105:16731.

10

8

6

4

2

0

F. p

rau

snit

zii (

%)

At surgery At 6 months

No endoscopic recurrenceEndoscopic recurrence

*

Insights from gnotobiotic rodentsInsights from gnotobiotic rodentsNational Gnotobiotic Rodent Resource Center (NIH, CCFA)National Gnotobiotic Rodent Resource Center (NIH, CCFA)

Germ-free Selectively SPF/ CONV-R CONV-D conventionalizedcolonized

conventionally

The stage:A gnotobioticisolator

The actors:

(monoassociated) SPF raisedAdapted from Jeff Gordon

No immune activation

No immune activation

Macrophage and TH1/TH17

immune activation

Macrophage and TH1/TH17

immune activation

No colitisNo colitis ColitisColitis

Resident bacteriaResident bacteriaNo bacteriaNo bacteria

Essential Role of Commensal Enteric Bacteria in the Essential Role of Commensal Enteric Bacteria in the Pathogenesis of Experimental Chronic Intestinal Pathogenesis of Experimental Chronic Intestinal

InflammationInflammation

Mice

IL-2KO () IL-10KO

TCRKO

CD326TGMDR1KO

SAMP1/Yit () CD45RBhi SCID

RatsHLA-B27 TG

Indomethacin

Guinea pigsCarrageenan

Non-human primateCotton top tamarin

Differential ability of various bacterial speciesto induce or prevent experimental colitis

All bacterial species are not equal!

Cecal bacteriaHLA B27

transgenic rat

HLA B27

transgenic rat

Bacteroides vulgatus

E. coli

Cecal bacteria + Lactobacillus GG

Aggressive colitisAggressive colitis

ProtectionProtection

No colitisNo colitis

Moderate colitisModerate colitis

Rath et al., J Clin Invest 1996;98:945Rath et al., Infect Immunity 1999; 67:2969 Dieleman et.al., Gut 2003; 52:370

Germ free, no colitis

Functionally altered E. coli are present in ileal Crohn’s disease

Adherent/invasive E. coli

•Adhere to/invade epithelial cells•Persist within EC, macrophages•Increased in ileal Crohn’s disease (Darfeuille- Michaud, et al.Baumgart, Simpson, ISME J. 2007)

•Bind to CEACAM 6 on ileal epithelial cells Barnich et al, JCI 2007)

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

Injurious Pro-inflammatory

Bacteroides vulgatus, B. thetaEnterococcus faecalis

E. coli - adherent / invasiveKlebsiella pneumoniaeRuminococcus gnavus

Segmented filamentous bacteriumFusobacterium varium

Intestinal Helicobacter species

Lactobacillus sp.Bifidobacterium sp.

Faecalibacterium prausnitziiRoseburia species

Non-pathogenic E. coliSaccharomyces boulardii

Bacteroides thetaiotaomicron

ProtectiveProbiotic



• 163 genes!




• ↑ TH17




Sartor RB Gastroenterology 2010

Fut2B. Sartor

Gastroenter. 2010

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