Transcript 9:30 PM Helicobacter - Vanderbilt University Medical Center

Virulence factors of Helicobacter
pylori and host effectors that lead to
gastric cancer
Richard M. Peek Jr.
Vanderbilt University Medical Center
Nashville, TN
Disease outcomes that develop within the
context of H. pylori-induced inflammation
Inflammation
Gastric ulcer, Atrophy, Hypoacidity
Adenocarcinoma of
distal stomach
(OR 2-12)
Hyperacidity
Duodenal ulceration
(OR 3-12)
Determinants which may influence
occurrence of disease in H. pyloricolonized persons
Strain variation
Host genotypes
Environmental co-factors
Age of acquisition
Topography of gastric colonization
Distribution of gastritis and acid secretion in
H. pylori-colonized persons predisposed
towards duodenal ulcer disease
70
60
Acid Output
(mmol/h)
50
40
30
20
10
0
HP -ve
HP +ve
Healthy Healthy
Volunteers Volunteers
HP +ve D.U.
Patients
Distribution of gastritis and acid
secretion in H. pylori-colonized persons
predisposed towards gastric adenocarcinoma
25
20
Acid output
(mmol/h)
15
10
5
0
Preeradication
Posteradication
RAPD PCR profiles of H. pylori isolates
from different patients are distinct
Berg et al., Clin. Inf. Dis.
Comparison of genomic features of
two fully sequenced H. pylori strains
Strain
Feature
26695
J99
Size (kb)
1,668
1,644
% of genome predicted
to be coding
91.0
90.8
Predicted # of ORFs
1590
1495
Strain-specific ORFs
184
89
H. pylori microarray
Probes based on sequences from strain
26695 + sequences unique
to strain J99
Mean size of PCR products is 897 bp
1660 ORFs represented in duplicate
(98.9% of all ORFs)
Salama et al., PNAS
DNA microarray analysis of H. pylori strains
Microarray-based
comparison of 14
independent
H. pylori strains
Gene present
Gene absent
Missing data
Salama et al., PNAS
Goals
To examine the extent and types
of H. pylori genetic diversity that
develop during long-term
colonization within the gastric
niche of a single human host
Events in the history of H. pylori strain J99
Year:
1994
Event:
Original
isolation
1999
Complete
sequence
published
Genetic diversity: RAPD PCR
Sequence analysis
H. pylori whole
genome microarray
2000
New isolates
(n=30) harvested
from source patient
Cardia
Corpus
Antrum
Duodenum
1
12
12
5
1
2
3
4
5
6
7
8
9 10 11 12
J99 A
RAPD profiles of recent and archival H. pylori J99
isolates exhibit subtle differences
Primer
D11344
1254
14307
Israel et al., PNAS
Microarray-generated cluster diagram of
archival J99 and 13 recent J99 isolates
Israel et al., PNAS
Characteristics of cag island
Present in 60 - 70% of U.S. H. pylori isolates
Homology to components of type IV
bacterial secretion systems
CagA is translocated into and phosphorylated
within host epithelial cells following
adherence
Molecular signaling alterations induced by
intracellular delivery of CagA
Redistribution of junctional proteins to
sites of bacterial attachment
7 min
2 hours
4 hours
CagA expressing cells acquire a migratory
and invasive phenotype
Serologic recognition of CagA by H. pylori
infected persons with or without
duodenal ulcer disease
Study
Peptic ulcer
No ulcer
p-value
n
% CagA +
n
% CagA +
Cover 1990
43
95%
74
61%
<0.01
Crabtree 1991
25
100%
51
63%
<0.01
Xiang 1993
22
100%
37
64%
<0.01
Cover 1995
57
83%
39
56%
<0.01
Ching 1996
297
82%
145
37%
<0.01
Weel 1996
76
93%
79
65%
<0.01
Colonization with H. pylori cagA+ strains
and risk for distal gastric cancer
Cases
infected
(%)
Controls
infected
(%)
Odds Ratio
for cancer
(95% CI)
cagA+ vs uninfected
70/82
(85)
48/94
(51)
5.8
(2.6 - 13.0)
cagA- vs uninfected
20/32
(63)
41/87
(47)
2.2
(0.9 - 5.4)
Group Comparison
Parsonnet et. al., Gut
Characteristics of H. pylori vacA
Present in virtually all human isolates
Encodes vacuolating cytotoxin
Possesses regions of sequence diversity
Mosaicism in vacA, the gene that encodes
the vacuolating cytotoxin
vacA
Signal sequence
allelic types
Mid-region
allelic types
s1a
m1
s1b
m2a
s1c
m2b
s2
Stratification of H. pylori strains by
vacA signal sequence alleles and
duodenal ulceration
100
Duodenal
ulcer
disease
(%)
50
0
s1a
s1b
s2
uninfected
vacA signal sequence allele
Atherton et al., Gastroenterology
Association between vacA mid-region
m1 alleles and gastric adenocarcinoma
100
p = 0.025
vacA m1
(%)
50
0
Gastric
adenocarcinoma
(n=27)
Gastritis
alone
(n=35)
Gerhard et al., PNAS
Distribution of H. pylori vacA m-region
genotypes from different parts of the world
Portugal and Spain
100
100
France and Italy
100
m1
50
50
m2a
m2a
m1
50
m2b
0
100
m1
Northern/Eastern
Europe
0
m2a
m2b
m2b
0
North America
100
East Asia
m2a
50
m1
50
m1 m2a
m2b
m2b
0
0
Central/South
America
100
100
Australia
m1
m2a
50
50
m1
m2a
0
m2b
0
m2b
H. pylori strain-specific components are
not absolute determinants of virulence
Most persons colonized with cagA+ vacA toxigenic
strains remain disease free.
Important geographic differences in prevalence of H.
pylori cagA+ strains exist between Western (~60%)
and Eastern (~95%) populations.
H. pylori cagA+ vacA toxigenic strains are related to
both duodenal ulceration and gastric cancer, two
mutually exclusive disease outcomes.
Host factors and H. pylori-induced
carcinogenesis
H. pylori
Gastric
acidity
Inflammation
IL-1b and H. pylori-induced carcinogenesis
H. pylori
IL-1b
Gastric
acidity
Inflammation
Relationship between IL-1
polymorphisms and IL-1b production
IL-1b
-31 C
IL-1b
-511 T
IL-1RN
2/2
IL-1b
-31 T
IL-1b
-511 C
IL-1RN
IL-1b production
1/1
IL-1b production
IL-1 genotype frequencies in H. pyloriinfected gastric cancer patients and controls
Locus
IL-1b –31
Genotype
T/T
C/T
C/C
Odds Ratio
1.0
1.8 (1.3-2.4)
2.5 (1.6-3.8)
IL-1b -511
C/C
C/T
T/T
1.0
1.8 (1.3-2.4)
2.6 (1.7-3.9)
IL-1RN
1/1
1/2
2/2
1.0
1.2 (0.9-1.6)
3.7 (2.4-5.7)
El-Omar et al., Nature
Multivariate odds ratios for the association
of pro-inflammatory genotypes with
different upper GI malignancies
Genotype
Esophageal
Noncardia
adenocarcinoma gastric cancer
(n=108)
(n=188)
IL-1b 511T
1.0 (0.6-1.7)
2.3 (1.4-3.8)*
IL-1RN 2/2
1.0 (0.4-2.8)
3.6 (1.7-7.6)*
IL-10 ATA/ATA
1.5 (0.5-4.4)
2.5 (1.1-5.7)*
TNF -308
1.0 (0.6-1.8)
2.2 (1.4-3.7)*
El-Omar et al., Gastroenterology
Association of H. pylori virulence and host
IL-1b genotypes with gastric cancer
H. pylori and
IL-1b –511
genotyp es
cagA-/CC
cagA-/T
cagA+/CC
cagA+/T
Gastritis
alone
(n)
35
46
26
28
vacA s2/CC
vacA s2/T
vacA s1/CC
vacA s1/T
27
35
17
22
Gastric
cancer
(n)
4
8
38
80
Odds ratio
(95% CI)
1 (referent)
1.5 (0.4-5.5)
13 (4.1-40)*
25 (8.2-77)*
1
1.0 (referent)
8
6.2 (0.7-52)
27
43 (5.3-345 )*
71
87 (11-679)*
Figueiredo et al., JNCI
Analysis of Gastric Cancer Development
with Respect to Treatment
Log-Rank P=.33
Placebo
Active Treatment
Cumulative
incidence (%)
Follow-up, months
Wong et al., JAMA
Analysis of Gastric Cancer Development
with Respect to Treatment in Patients without
Premalignant Lesions
Log-Rank P=.02
Placebo
Active Treatment
Cumulative
incidence (%)
Follow-up, months
Wong et al., JAMA
Long-term follow-up of persons
treated for H. pylori infection
Mera et al., Gut, 2005
Markers for gastric
adenocarcinoma
Gastric cancer risk represents the
summation of the polymorphic nature of
the bacterial population in a particular
host, the host genotype, and environmental
exposures, each affecting the equilibrium
of long-term interactions between H.
pylori and humans.
Markers for gastric
adenocarcinoma
Identification of novel polymorphisms in
microbial and human host response genes
will provide new opportunities to better
define disease risk and to develop better
targeted
therapeutics
for
high-risk
individuals.