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Antimicrobial Agents and Chemotherapy, December 2003, p. 3982-3984, Vol. 47, No. 12
0066-4804/03/$08.00+0 DOI: 10.1128/AAC.47.12.3982-3984.2003
Copyright © 2003, American
Society for
Microbiology. All Rights Reserved.
Efficacy of Sulforaphane in Eradicating Helicobacter pylori in Human Gastric Xenografts Implanted in Nude Mice
Xavier Haristoy,1 Karine Angioi-Duprez,2 Adrien Duprez,3 and Alain Lozniewski1*
Laboratoire
de Bactériologie-Virologie, UMR CNRS
75-65,1
Laboratoire de Microchirurgie
Expérimentale,2
Laboratoire
d'Anatomie Pathologique EMI INSERM 0014,Faculté de Médecine, Université
Henri-Poincaré, Vandæuvre-les-Nancy, France3
Received 15 November 2002/
Returned for modification 24 May 2003/
Accepted 25 August 2003

ABSTRACT
Sulforaphane,
an isothiocyanate abundant in the form of its
glucosinolate precursor
in broccoli sprouts, has shown in vitro
activity against
Helicobacter pylori. We evaluated the effect
of sulforaphane
in vivo against this bacterium by using human
gastric xenografts in
nude mice.
H. pylori was completely eradicated
in 8 of the 11
sulforaphane-treated grafts. This result suggests
that sulforaphane
might be beneficial in the treatment of
H. pylori-infected
individuals.

TEXT
The recommended treatment of
Helicobacter pylori-associated
diseases
today includes a combination of two or more
antibiotics with
an inhibitor of acid secretion. However, even with
these treatments,
some bacteria may persist, in a nongrowing, tolerant
form or
possibly intracellularly
(
5,
7,
10). This may lead to
eradication
failure, which is defined as the persistence of
H.
pylori at
least 1 month after the end of antimicrobial therapy
(
9). Moreover,
development
of resistance of
H. pylori strains to one or more
of the
antibiotics commonly used has been demonstrated previously
(
28).
Thus, a need for
new therapeutic agents that are effective against
extracellular and
potentially intracellular forms of
H. pylori exists. We
recently showed that sulforaphane, an isothiocyanate
abundant in the
form of its glucosinolate precursor in broccoli
and broccoli sprouts,
is a potent bactericidal agent against
both extra- and intracellular
H. pylori in vitro
(
11). Substantial
quantities
of isothiocyanates (up to 100 mg daily) and even greater
quantities
of their glucosinolate precursors are widely consumed by
humans
(
12,
13,
29). They may act locally
within the gastrointestinal
tract or may distribute systemically after
conversion to their
cognate isothiocyanates
(
12,
15,
34). In this study, we
investigated
the efficacy of sulforaphane in vivo against
H.
pylori by using
a recently developed model which uses human
gastric xenografts
in nude mice
(
22).
Sulforaphane,
i.e.,
[(-)-1-isothiocyanato-(4R)-(methylsulfinyl)butane]
was kindly provided by J. W. Fahey (Johns Hopkins University
School of Medicine, Baltimore, Md.). Stock solutions were prepared in
acetonitrile, and further dilutions were made in sterile water. H.
pylori strain 26695, which was previously adapted for use in the
gastric xenograft model
(23), was used for graft
inoculation. The strain was grown on Columbia agar supplemented with
10% horse blood under microaerobic conditions as previously
described (22). For this
isolate, the MIC of sulforaphane was 4 µg/ml, as determined by
using the agar dilution method (pH 7.4) as recommended by the National
Committee for Clinical Laboratory Standard (NCCLS)
(30).
Xenografts
exhibiting human mature gastric epithelium and acidic secretion were
obtained in nude mice as previously described
(22) and with the
approval of the French National Consultative Ethical Committee.
Bacterial inoculation was performed by using a catheter that was
implanted in the xenograft lumen
(22). Two weeks after
inoculation, each graft was microsurgically opened. Mucus was sampled
for qualitative culture onto blood agar, and three biopsies were taken
from antrum-adjacent sites for quantitative culture and histology. The
levels of colonization and the concentrations of intracellular bacteria
were determined by quantitative culture as previously described
(23). For histological
studies, specimens were processed by standard methods and stained with
hematoxylin-eosin to assess the intensity of gastritis and with a
modified Giemsa stain for detection of H. pylori
(22).
The grafted
animals were then randomly divided into two groups of 11. In the first
group, 0.5 ml of sterile water with 0.5% acetonitrile containing
7.5 µmol of sulforaphane (approximately 1.33 mg) was
administered via catheter once a day for 5 days. The same solution
without sulforaphane was administered in the same way for 5 days in the
other 11 infected grafts (control group). The effect of sulforaphane on
H. pylori eradication was evaluated 4 weeks after treatment
per the previous recommendation for human subjects
(9). At that time, the
animals were euthanized and the grafts were removed and opened. Three
biopsy specimens were then taken from adjacent sites in the
antrum for histological examination and determination of the level of
mucosal colonization as well as the concentration of intracellular
bacteria concentrations as described above. Eradication was defined by
the absence of H. pylori detection by both histology and
culture methods. Personnel performing this evaluation were masked
(blinded) with regard to the treatment status. The MIC of sulforaphane
was determined for all recovered isolates obtained from each
culture-positive graft.
Before treatment, all 22 inoculated
grafts were equally infected by H. pylori 26695, with no
significant differences in numbers of CFU between the grafts that were
destined to receive sulforaphane and the controls (P =
0.34, Mann-Whitney U test) (Table
1). No organism other than H. pylori was recovered from either
mucus or mucosal samples. Viable intracellular bacteria were also
isolated in all the grafts and represented 0.04 to 2.5% (mean,
0.9%) of all the viable bacteria detected in the gastric mucosa.
At that time, rare limited erythematous areas associated with
hemorrhagic points or ulcerations were observed at the surface of the
antrum in all inoculated grafts. Histological examination of antral
biopsies confirmed the presence of H. pylori and showed mild
inflammation and mild or moderate activity associated with diffuse
interstitial edema. During the administration of sulforaphane or
placebo (diluent vehicle control) and throughout the posttherapy
period, no adverse reaction or change in weight or behavior was
observed in the mice. Moreover, we did not observe any macroscopic or
histopathological changes in internal organs at the end of the
experiments. One month after the end of treatment, eradication was
observed in 8 of the 11 sulforaphane-treated grafts (Table
1). Neither macroscopic
abnormalities nor antral gastritis were observed in these
culture-negative grafts. For the control group, there was no
significant difference between the mucosal bacterial concentrations
found before administration of the diluent and those found 5 weeks
later (P = 0.10, Mann-Whitney U test) (Table
1). In
sulforaphane-treated grafts that were not eradicated and in control
grafts, both macroscopic and histological features were similar to
those observed before treatment. Intracellular bacteria were detected
in all control grafts (1 to 2.7% of all the viable bacteria
detected) and in two of the three sulforaphane-treated grafts that were
not eradicated (0.04 and 0.3% of all the viable bacteria
detected). For isolates obtained from control grafts, no change in the
MIC of sulforaphane was observed, whereas a fourfold increase of the
MIC (to 16 µg/ml) was observed for all the isolates obtained
from the three sulforaphane-treated grafts from which H.
pylori was not eradicated. Such organisms were not detected after
plating of the initial inoculum onto sulforaphane-containing
agar.
A wide variety of plant extracts, i.e., individual plant
components
such as phytochemicals and phytochemical mixtures, have been
shown
to be active in vitro against
H. pylori
(
1,
3,
4,
6,
8,
17-
21,
24-
26,
32,
33,
35,
36).
A few of these
phytochemicals have been tested in vivo
(
2,
14,
16,
20,
24,
27,
31),
but clearance of
H. pylori was observed only in two cases: after
administration
of tea catechins to
H. pylori-infected gerbils
(
24)
and after
administration of goshuyu-to, a medicinal preparation
which contains
various plant extracts, including ginseng, to
humans
(
16). It is therefore
critical to subject all plant compounds
that are active against
H.
pylori in vitro to in vivo studies
to determine their
effectiveness in whole-organism systems,
since most plant-derived
compounds have not proven efficacious
in such testing. Thus, having
recently shown that sulforaphane
was active against
H. pylori
in vitro and that it prevented
the formation of
benzo[a]pyrene-induced stomach tumors in ICR
mice
following an estimated daily intake of 7.5 µmol for
5 weeks
(
11), we next evaluated
its potency in eradicating
H. pylori, using the same dose for
5 days, in human gastric xenografts
that were implanted in nude mice.
In the present work, we have
shown that sulforaphane has a significant
effect against
H. pylori in vivo, since we observed an
eradication rate of 73%
for the treated group and noted no
eradication in the control
group. Previous studies have demonstrated
that sulforaphane,
which has a concentration-dependent bactericidal
activity against
H. pylori, may accumulate in
H.
pylori-infected cells and reach
intracellular levels at least
fivefold higher than the administered
concentration, suggesting that a
reason for its bactericidal
activity against intracellular bacteria may
be related to its
accumulation in mammalian cells
(
11). Whether
intracellular
accumulation of sulforaphane occurs in vivo is not yet
known,
but this may be one reason that the effectiveness of
sulforaphane
was not influenced in our study by the presence of
intracellular
bacteria. A failure of complete eradication was observed
in
only 3 of the 11 sulforaphane-treated grafts (due to the nature
of
the experiment, it was impossible to know whether there was
a transient
effect on
H. pylori colonization), and such failure
was always
associated with the presence of isolates for which
the MIC of
sulforaphane was fourfold higher than that during
the initial
inoculation of an isolate. This apparent reduction
in susceptibility
may explain, at least partially, the failure
of sulforaphane to
completely eradicate
H. pylori in these three
xenografts.
Other reasons, such as the existence of subtherapeutic
antibiotic
concentrations or poor stability of the drug at the
site of infection,
cannot be excluded.
We showed that H. pylori can be
eradicated from human gastric xenografts after short-term
administration of sulforaphane at a dose (1.33 mg/day in each xenograft
[volume,
7 ml]; 0.19 mg/ml) that can be achieved in
the human diet (100 mg/day [stomach volume, 0.5 to 1 liter];
0.1 to 0.2 mg/liter) (12,
13,
29). Thus, the
administration of sulforaphane that can be safely delivered in the
diet, particularly from broccoli sprouts, could be beneficial for the
treatment of H. pylori-associated gastric diseases. A
sulforaphane-enriched diet might also be of value for prophylaxis
against H. pylori infection and should be further evaluated.
Xenografts represent the only in vivo model that permits the study of
the effect of a compound on H. pylori interacting with fully
differentiated human gastric mucosa. Since this model does not
completely mimic the microenvironment of the infected human stomach,
which is subject to the action of food, digestive physiology, and the
potential coexistence of other bacterial species, further studies in
humans are necessary to confirm the in vivo activity of sulforaphane
against H. pylori.

ACKNOWLEDGMENTS
We thank
Jed W. Fahey, Katherine K. Stephenson, and Paul Talalay
(Department of
Pharmacology and Molecular Sciences, The Johns
Hopkins University
School of Medicine, Baltimore, Md.) for their
gift of sulforaphane and
for their expert editorial
advice.

FOOTNOTES
* Corresponding
author. Mailing address: Laboratoire de Bactériologie,
Hôpital Central, 29 Avenue du Maréchal de Lattre de
Tassigny, 54035 Nancy Cedex, France. Phone: (33) 3 83 85 21 96. Fax:
(33) 3 83 85 26 73. E-mail:
a.lozniewski{at}chu-nancy.fr.


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Antimicrobial Agents and Chemotherapy, December 2003, p. 3982-3984, Vol. 47, No. 12
0066-4804/03/$08.00+0 DOI: 10.1128/AAC.47.12.3982-3984.2003
Copyright © 2003, American
Society for
Microbiology. All Rights Reserved.
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