Inosine reduces inflammation and improves survival in a
murine model of colitis
J. G.
Mabley1,
P.
Pacher1,
L.
Liaudet2,
F. G.
Soriano2,
G.
Haskó2,
A.
Marton1,
C.
Szabó1,2, and
A. L.
Salzman1
1 Inotek Pharmaceuticals, Beverly, Massachusetts
01915; and 2 Department of Surgery, University of
Medicine and Dentistry - New Jersey Medical School, Newark, New
Jersey 01703
 |
ABSTRACT |
Inosine, a naturally occurring purine formed
from the breakdown of adenosine, has recently been shown to exert
powerful anti-inflammatory effects both in vivo and in vitro. This
study evaluated inosine as a potential therapy for colitis. Colitis was
induced in mice by the administration of dextran sulfate sodium (DSS).
Oral treatment with inosine was begun either before the onset of
colitis or as a posttreatment once colitis was established. Evaluation
of colon damage and inflammation was determined grossly (body wt,
rectal bleeding), histologically, and biochemically (colon levels of MPO, MDA, and cytokines). DSS-induced colitis significantly increased inflammatory cell infiltration into the colon. DSS-induced colitis also
increased colon levels of lipid peroxidation, cytokines, and
chemokines. Inosine protected the colon from DSS-induced inflammatory cell infiltration and lipid peroxidation. Inosine also partially reduced these parameters in an experimental model of established colitis. Thus inosine treatment may be a potential therapy in colitis.
colon; dextran sodium sulfate; cytokines; purine
 |
INTRODUCTION |
IT IS WELL RECOGNIZED
THAT certain naturally occurring purines can exert powerful
modulatory effects on the immune system. Nucleoside adenosine is the
best characterized of these purines and has been shown to affect almost
all aspects of an immune response (2, 8, 19). Adenosine
and its analogs can effect the development of a variety of inflammatory
diseases including endotoxin shock (18), rheumatoid
arthritis (38), plural inflammation (35), or
uveitis (27). Effects of adenosine are partly mediated by the inhibition of deleterious immune-mediated processes, including the
release of proinflammatory cytokines and free radicals
(16). Inosine is a naturally occurring purine, formed from
the breakdown of adenosine by adenosine deaminase (3), and
was widely believed to be without biological actions. However, our
group has recently observed that inosine potently inhibits the release
of proinflammatory cytokines and chemokines by activated murine
macrophages via a posttranscriptional mechanism and that this compound
exerts powerful anti-inflammatory effects in murine endotoxic shock
(14, 17), septic shock (25), and severe lung
inflammation (24). Inosine also has anti-inflammatory
effects in human monocytes, neutrophils, and epithelial cells in vitro
(28), reducing both TNF-
production in response to LPS
treatment as well as inhibiting the ability of human neutrophils
activated with N-formyl-methionyl-leucyl-phenylalanine to
induce cytochrome c reduction (28).
Several murine models of intestinal inflammation resemble human
inflammatory bowel diseases such as Crohn's disease and ulcerative colitis. Both of these diseases are characterized by chronically relapsing inflammation of the bowel of unknown origin. One of the
murine models of inflammatory bowel disease can be induced by the oral
administration of dextran sulfate sodium (DSS). Colitis induced by DSS
exhibits lymphoid hyperplasia, inflammatory cell infiltration, and
focal crypt damage (7, 10, 32). DSS-induced colitis also
causes epithelial injury and ulceration (7, 10, 32). The
underlying mechanism by which colitis is induced involves epithelial
cell damage and phagocytosis of DSS, which leads to stimulation of
lamina propria cells and increased production of proinflammatory
cytokines (10). The cytokine profile of DSS-induced colitis was found to be similar to that found in human inflammatory bowel disease, with an increase in the levels of T helper (Th)1 cytokine mRNA transcripts including IL-1, IL-12, IFN-
, and TNF-
(11). An increased colon IL-12 level appears to be pivotal
in the development of colitis (15), with an anti-IL-12
antibody proving be more effective in preventing experimental colitis
in mice (13) than either anti-IFN-
(13),
anti-IL-1 (22), or anti-TNF-
(33).
Although the murine DSS model of inflammatory bowel disease differs
from the human disease, it has been recommended and is a widely used
preclinical model for testing the efficacy of treatments for
inflammatory bowel disease (5, 7, 12). In this study, we
investigate the therapeutic efficacy of inosine in an animal model of
inflammatory bowel disease.
 |
MATERIALS AND METHODS |
Reagents were obtained from the following sources: DSS (MW
40,000) was from ICN Pharmaceuticals; inosine, human MPO,
1,1,3,3-tetramethoxypropane, thiobarbituric acid, sodium dodecyl
sulfate, tetramethylbenzidine, hexadecyltrimethylammonium bromide,
and hydrogen peroxide were from Sigma (St. Louis, MO); BALB/c mice were
from Taconic Farms (Germantown, NY); and specific cytokine ELISA kits
were from R&D Systems (Minneapolis, MN).
Induction of colitis and treatment.
Male BALB/c mice, 8 wk of age, weighing 20-23 g were used for
these studies. Animals are housed in rooms at a controlled temperature and light-dark cycle for 48 h before starting experimental
protocols. All animal experiments were carried out in accordance with
"Guide for the Care and Use of Laboratory Animals" [DHEW
Publication No. (NIH) 85-23, Revised 1985, Office of Science and
Health Reports, DRR/NIH, Bethesda, MD 20205] and with the approval of
Inotek's Institutional Animal Care and Use Committee.
Mice were fed 5% DSS, molecular mass 30-40 kDa dissolved in
distilled water ad libitum throughout the experiment (31).
Inosine was administered either orally by gavage or intraperitoneally twice a day. Control mice were treated with vehicle, which was either
water for the oral inosine experimental protocol or saline for the
intraperitoneal inosine experimental protocol. For the delayed inosine
treatment experiments, mice were given vehicle up to the day inosine
treatment was started. Inosine was given at doses ranging from 25 to
200 mg · kg
1 · day
1
and was based on recent studies testing inosine in rodent models of
inflammation (14, 18, 25). Intake of the DSS solution was
monitored throughout the experiments and was found to be unchanged among experimental groups (data not shown).
Evaluation of colitis severity and drug effects.
Parameters recorded in the experiments were body weight, colon length,
mortality, and bleeding from the rectum as determined by ocular
inspection. Mice were weighed on days 1 and 10 with the subsequent colitis-induced weight change expressed as a
percentage of the original weight. Mice were killed by cervical
dislocation, and the colon was resected between the ileocecal junction
and the proximal rectum, close to its passage under the pelvisternum. The colon was placed on a nonabsorbent surface and measured with a
ruler. Colonic biopsies were taken for histological and biochemical analysis. One biopsy was fixed in 15% formaldehyde, embedded in paraffin, and sectioned (4-µm slices). The sections were then stained
with hematoxylin and eosin and viewed by an investigator (blinded) and
scored for inflammation severity (0 = none, 1 = mild, 2 = moderate, and 3 = severe) and extent (0 = none, 1 = mucosal, 2 = mucosal and submucosal, and 3 = transmural) as
well as crypt damage (0 = none, 1 = basal 1/3, 2 = basal
2/3, 3 = crypts lost epithelium present, and 4 = crypts and
surface epithelium lost), with representative sections being shown here.
MPO activity.
Colon biopsies were homogenized (50 mg/ml) in 0.5%
hexadecyltrimethylammonium bromide in 10 mM MOPS and centrifuged at
15,000 g for 40 min. Suspension was then sonicated three
times for 30 s. An aliquot of supernatant (20 µl) was mixed with
a solution of 1.6 mM tetramethylbenzidine and 1 mM hydrogen peroxide.
Activity was measured spectrophotometrically as the change in
absorbance at 650 nm at 37°C, using a Spectramax microplate reader
(Molecular Devices, Sunnyvale, CA). Results are expressed as milliunits
of MPO activity per milligram of protein, which were determined with the Bradford assay.
Malondialdehyde assay.
Malondialdehyde formation was used to quantify the lipid peroxidation
in the colon and was measured as thiobarbituric acid-reactive material.
Tissues were homogenized (100 mg/ml) in 1.15% KCl buffer. Two hundred
microliters of the homogenates were then added to a reaction mixture
consisting of 1.5 ml 0.8% thiobarbituric acid, 200 µl 8.1% sodium
dodecyl sulfate, 1.5 ml 20% acetic acid (pH 3.5), and 600 µl
distilled H2O. The mixture was then heated at 90°C for 45 min. After cooling to room temperature, the samples were cleared by
centrifugation (10,000 g, 10 min) and their absorbance was
measured at 532 nm using 1,1,3,3-tetramethoxypropane as an external
standard. The level of lipid peroxides was expressed as nanomoles MDA
per milligram of protein (Bradford assay).
Colon cytokine levels.
A third colon biopsy was removed and snap frozen in liquid nitrogen,
the sample was then homogenized in 700 µl of a
Tris · HCl buffer containing protease inhibitors.
Samples were centrifuged for 30 min, and the supernatant was frozen at
80°C until assay. Cytokine levels were determined using ELISA.
Statistical analysis.
Results are presented as means ± SE; statistical analysis was
preformed using either one-way ANOVA followed by Student-Newman-Keuls multiple comparisons post hoc analysis, Fisher's exact test,
Mann-Whitney U-test, or Kaplan-Meier survival analysis as
appropriate, with a P value of <0.05 considered significant.
 |
RESULTS |
Inosine treatment protects against DSS-induced colitis.
Treatment of BALB/c mice with 5% DSS in their drinking water for 10 days resulted in clinical, gross, and histological signs of colitis.
DSS-treated mice had a marked weight loss, shortened colon length, and
gross rectal bleeding (Table 1) compared
with mice receiving regular drinking water. Inosine treatment starting on day 1 dose-dependently reversed these effects (Table 1).
Colon biopsies from DSS-treated mice had significantly increased levels of both MPO (Fig. 1A),
indicative of inflammatory cell tissue infiltration, and MDA (Fig.
1B), indicative of lipid peroxidation damage. Inosine again
dose-dependently protected against the DSS-induced increases in these
parameters (Fig. 1, A and B). Histological analysis of colon biopsies showed an accumulation of lymphocytes and
marked crypt destruction with some surface mucosal layer disruption in
the mice treated with DSS (Fig.
2B) compared with control mice (Fig. 2A and Table 2). Inosine
protected against both the infiltration of neutrophils and against the
mucosal damage (Fig. 2C and Table 2). Similar results were
obtained when inosine was administered intraperitoneally. The colon
length in vehicle-treated animals was reduced to 4.5 ± 0.2 cm,
and this was significantly increased to 5.5 ± 0.2 and 5.7 ± 0.2 cm with 100 or 200 mg · kg
1 · day
1
inosine intraperitoneally, respectively. Similarly, rectal bleeding was
significantly reduced from 60 to 10 and 0%. We also examined colon
levels of MPO and MDA; in both cases, inosine significantly reduced the
levels compared with vehicle-treated animals. MPO levels were reduced
from 337 ± 60 to 101 ± 21 and 69 ± 16 mU/mg protein
with 100 or 200 mg · kg
1 · day
1
inosine treatment. Similarly, MDA levels were reduced from 3.5 ± 0.5 to 1.9 ± 0.3 nmol/mg protein with 200 mg · kg
1 · day
1
inosine. The level of MDA in the colon after 100 mg · kg
1 · day
1
ip inosine was 2.5 ± 0.4 nmol/mg protein, which was not
significantly different statistically from the vehicle-treated
colon.

View larger version (24K):
[in this window]
[in a new window]
|
Fig. 1.
Inosine dose-dependently reduces the levels of MPO
(A) and malondialdehyde (MDA) (B) in the colons
of mice with an acute colon inflammation induced by dextran sulfate
sodium (DSS). Mice were exposed to DSS ad libitum for 10 days,
treatment with inosine (25, 50, 100, or 200 mg · kg 1 · day 1,
twice a day) started on day l. Results are expressed as
means ± SE from 8-20 animals, statistical analysis was
conducted by one-way ANOVA followed by Student-Newman-Keuls multiple
comparisons post hoc analysis where P < 0.05 was
considered significant. *P < 0.05, **P < 0.01 vs. untreated animals and P < 0.05,  P < 0.01 vs. DSS-treated animals.
|
|

View larger version (111K):
[in this window]
[in a new window]
|
Fig. 2.
Effect of inosine (200 mg · kg 1 · day 1)
on the morphological changes observed in the colon of mice treated with
DSS for 10 days. Inosine was administered orally starting on
day 1. On day 10, mice were killed and
colon biopsies were taken and fixed in 10% formalin solution. Samples
were embedded in paraffin and sectioned (3-µm sections). Sections
were stained with hematoxylin and eosin and were viewed at either ×100
or ×400 magnification. Sections presented are representative of
sections from 10 mice. Magnification of the first two columns is ×100
and the third column, ×400.
|
|
Inosine partially attenuates disease symptoms in established
colitis. Mice treated with 200 mg · kg
1 · day
1
inosine starting on day 4 or 7 after
commencement of DSS had an increased colon length but had no effect on
either the colitis-mediated loss of body weight or the incidence of
rectal bleeding (Table 3). Treatment of
mice on day 4 with inosine also had lower colon levels of
both MPO and MDA (Table 3). In long-term survival experiments, mice
treated with 5% DSS for 30 days exhibited a 100% mortality rate by 20 days (Fig. 3). In contrast, mice treated
with inosine (200 mg · kg
1 · day
1)
starting on day 1, 4, or 7 showed a
marked increase in survival with 100, 70, and 30%, respectively, of
mice alive on day 20, and even on day
30, 60, 20, and 10% of mice were still alive (Fig. 3).

View larger version (17K):
[in this window]
[in a new window]
|
Fig. 3.
Inosine treatment significantly improves survival of mice
with an acute colon inflammation. Mice were exposed to DSS ad libitum
for 30 days, treatment with inosine (200 mg · kg 1 · day 1
twice a day) commenced on days l, 4, and
7. The number of mice surviving each day was recorded.
Results are expressed as %survival from 20 animals. Statistical
analysis was conducted using a Kaplan-Meier survival analysis, where
P < 0.05 was considered significant. Survival of the
mice was improved by inosine, where P < 0.0001 for
inosine treatment starting on day 1 or
4 and P = 0.0003 for inosine treatment
starting on day 7.
|
|
Effect of inosine on the colon cytokine profile.
DSS-treated mice had greatly increased colon levels of inflammatory
chemokines and cytokines (Fig. 4, A and
B). Untreated mice had
undetectable colon levels of chemokines or cytokines (data not shown).
Inosine (200 mg · kg
1 · day
1)
significantly reduced the colon levels of chemokines (Fig.
4A) major intrinsic protein (MIP)-1 and -2 and
proinflammatory cytokines (Fig. 4B) IL-1, IL-6, and IL-12.
Inosine was also able to attenuate the colon levels of TNF (Fig.
4B).

View larger version (12K):
[in this window]
[in a new window]
|
Fig. 4.
Effect of inosine on colon chemokine (A) and
cytokine (B) levels after colitis. Cytokine levels were
determined in colon biopsies from mice treated for 10 days with
DSS ± inosine (200 mg · kg 1 · day 1).
Results are expressed as means ± SE from 10 animals. Statistical
analysis was conducted by one-way ANOVA followed by
Student-Newman-Keuls multiple comparisons post hoc analysis, where
P < 0.05 was considered significant.
 P < 0.01 vs. DSS-treated animals. MIP, major
intrinsic protein.
|
|
 |
DISCUSSION |
We have demonstrated here that inosine effectively suppresses the
development of experimental colitis in vivo. Inosine exerted anti-inflammatory effects when treatment began simultaneously with the
application of DSS and was able to attenuate disease parameters in
established colitis. Inosine also dramatically increased survival in a
long-term disease model of colitis. Inosine markedly changed the
colitis-induced cytokine profile of the colon. Inosine reduces colon
levels of chemokines MIP-1
and -2, which are involved in the innate
and adaptive immune response because of their ability to recruit,
activate, and costimulate T cells and monocytes (42). Interestingly, the reduction of levels of MIP-1
by inosine appears to be a common observation seen not only in colitis but also in LPS-induced shock (14), septic shock (25),
and lung inflammation (24), suggesting that increased
chemokine levels are pivotal in the inflammatory process. Inhibiting
their production/expression may explain why inosine is protective in a
wide variety of inflammatory conditions. Inosine-induced reduction of
colon IL-12 levels, a cytokine pivotal in colitis (15), is
also striking, mimicking the effectivness of an anti-IL-12 antibody in
protecting against colitis (13). These observations
coupled with the reduction in colon levels of other Th1 cytokines such
as IL-1, IL-6, and TNF-
may account for inosine's mechanism of
action in attenuating colitis.
Interestingly, we observed similar protection against colitis when
inosine was administered intraperitoneally, suggesting a systemic
effect of insoine as well as a possible local protective effect after
oral treatment. It is conceivable that inosine may cause osmotic
purging of the colonic lumen, thereby reducing the effective dose of
DSS acting on the colon. Observation of inosine intraperitoneal
treatment protecting against colitis demonstrates that this possible
osmotic effect would not account for all of inosine's mechanism of
protection. Indeed, we have given rats an oral dose of inosine and
killed them at various time intervals so the inosine content of various
sections of the digestive tract could be determined. After a single
dose of 200 mg/kg inosine, we were able to detect inosine down to the
jejunum and a small amount in the ileum, but we were unable to detect
inosine in either the contents of the cecum or colon (unpublished
observations). It therefore appears that inosine is being absorbed
and/or broken down before it reaches the colon and its protective
effect in colitis is likely due to a systemic action rather than local. A systemic effect of inosine is supported by data we have obtained in
other animal models of inflammation, where oral inosine treatment protected against diabetes (26) and arthritis (unpublished
observations) and intraperitoneal administration protected against
endotoxic shock (14), septic shock (25), and
acute respiratory distress syndrome (24).
Inosine is considered an inactive metabolite in most biological
systems, but recently, evidence from our group and others has shown
that this is not the case. For example, it prevents glial cell death
during glucose deprivation (21), decreases the release of
intracellular enzymes from hypoxic lymphocytes (6),
improves renal function during ischemia (9), and
removes the harmful effects of total hepatic ischemia. More
recently, our group has demonstrated that inosine has anti-inflammatory effects in vitro (17) and in vivo in animals models of
endotoxic shock, septic shock, and lung inflammation (14, 17, 24, 25). Inosine's effects have been shown to be direct and not due
to its degradation product, hypoxanthine (17). However, inosine's anti-inflammatory effects are partially but not completely mediated by activation of adenosine receptors (17). It is
possible that inosine produces its inhibitory effects on cytokine
production via binding to A3 receptors, a receptor shown to
be present on monocytes and macrophages (30, 34). It has
also been shown that the effect of inosine on cytokine release is
posttranscriptional and does not involve interference with the
activation of p38, p42/44, JNK, degradation of inhibitor
B,
or elevation of intracellular cAMP levels (17). Inosine
treatment was particularly effective in attenuating the rises in colon
cytokine and chemokine levels observed in colitis. The marked reduction
of both MIP-1
and MIP-2 may explain why there is less colon
infiltration by inflammatory cells.
Inosine has also been shown to inhibit the enzyme poly(ADP-ribose)
synthetase (PARS), albeit at high concentrations (41). Inhibition of PARS has been shown to be beneficial in many inflammatory diseases (37), including experimental colitis in the mouse
(44) and rat (29). Inosine may also enhance
endogenous antioxidant systems because the breakdown of inosine yields
urate, a scavenger of oxyradicals and peroxynitrite (1, 4, 20,
39), both of which have been implicated in the pathogenesis of
colitis (36, 43). We have also examined the effectiveness
of a specific peroxynitrite decomposition catalyst in colitis and found
it to be protective (23). However, the effects of a
peroxynitrite scavenger on immune cell infiltration and
cytokine/chemokine levels in the colon of colitic mice was minimal and
do not compare with what we observed with inosine treatment, further
evidence of a systemic anti-inflammatory mechanism of action of inosine
in colitis.
The posttranscriptional nature of inosine's action both on cytokine
release, inhibition of PARS, and urate production may be considered
preferable, because one would expect an increased window of therapeutic
opportunity, i.e., inosine may remain effective in a posttreatment
paradigm. Indeed, our data suggest that inosine is able to attenuate
established colitis. Purines have also been shown to promote healing of
small bowel ulcers in experimental enterocolitis (40), and
this, too, may play a role in inosine's posttreatment protective
effects in colitis. Promotion of repair of damaged mucosa by inosine
may explain the decrease in inflammatory cells infiltrating the colon.
In conclusion, we have demonstrated the effectiveness of inosine as a
protective therapy in an experimental model of murine colitis. Inosine
was not only able to prevent colitis development but also had a
beneficial effect on the established disease. The current data, coupled
with inosine's excellent safety record, suggest that the concept of
testing and developing inosine as a colitis therapy in humans may be justified.
 |
ACKNOWLEDGEMENTS |
This study was supported by National Institutes of Health Grants
R43-DK-57379 (to A. L. Salzman) and RO1-GM-66189-01 (to G. Hasko).
 |
FOOTNOTES |
Drs. J. G. Mabley, P. Pacher, and A. Marton are employees of
Inotek Pharmaceuticals; Drs. C. Szabó and A. L. Salzman are employees, owners, and stockholders of Inotek Pharmaceuticals.
Address for reprint requests and other correspondence:
J. G. Mabley, Inotek Pharmaceuticals, Suite 419E, 100 Cummings Center, Beverly, MA 01915 (E-mail:
jmabley{at}inotekcorp.com).
The costs of publication of this
article were defrayed in part by the
payment of page charges. The article
must therefore be hereby marked
"advertisement"
in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
August 28, 2002;10.1152/ajpgi.00060.2002
Received 13 February 2002; accepted in final form 23 August 2002.
 |
REFERENCES |
1.
Ames, BN,
Cathcart R,
Schwiers E,
and
Hochstein P.
Uric acid provides an antioxidant defense in humans against oxidant- and radical-caused aging and cancer: a hypothesis.
Proc Natl Acad Sci USA
78:
6858-6862,
1981[Abstract].
2.
Apasov, S,
Koshiba M,
Redegeld F,
and
Sitkovsky MV.
Role of extracellular ATP and P1 and P2 classes of purinergic receptors in T-cell development and cytotoxic T lymphocyte effector functions.
Immunol Rev
146:
5-19,
1995[ISI][Medline].
3.
Barankiewicz, J,
and
Cohen A.
Purine nucleotide metabolism in resident and activated rat macrophages in vitro.
Eur J Immunol
15:
627-631,
1985[ISI][Medline].
4.
Becker, BF,
Reinholz N,
Ozcelik T,
Leipert B,
and
Gerlach E.
Uric acid as radical scavenger and antioxidant in the heart.
Pflügers Arch
415:
127-135,
1989[ISI][Medline].
5.
Bennett, CF,
Kornbrust D,
Henry S,
Stecker K,
Howard R,
Cooper S,
Dutson S,
Hall W,
and
Jacoby HI.
An ICAM-1 antisense oligonucleotide prevents and reverses dextran sulfate sodium-induced colitis in mice.
J Pharmacol Exp Ther
280:
988-1000,
1997[Abstract/Free Full Text].
6.
Cole, AW,
and
Palmer TN.
Action of purine nucleosides on the release of intracellular enzymes from rat lymphocytes.
Clin Chim Acta
92:
93-100,
1979[ISI][Medline].
7.
Cooper, HS,
Murthy SN,
Shah RS,
and
Sedergran DJ.
Clinicopathologic study of dextran sulfate sodium experimental murine colitis.
Lab Invest
69:
238-249,
1993[ISI][Medline].
8.
Cronstein, BN.
Adenosine, an endogenous anti-inflammatory agent.
J Appl Physiol
76:
5-13,
1994[Abstract/Free Full Text].
9.
De Rougemont, D,
Brunner FP,
Torhorst J,
Wunderlich PF,
and
Thiel G.
Superficial nephron obstruction and medullary congestion after ischemic injury: effect of protective treatments.
Nephron
31:
310-320,
1982[ISI][Medline].
10.
Dieleman, LA,
Palmen MJ,
Akol H,
Bloemena E,
Pena AS,
Meuwissen SG,
and
Van Rees EP.
Chronic experimental colitis induced by dextran sulphate sodium (DSS) is characterized by Th1 and Th2 cytokines.
Clin Exp Immunol
114:
385-391,
1998[ISI][Medline].
11.
Egger, B,
Bajaj-Elliott M,
MacDonald TT,
Inglin R,
Eysselein VE,
and
Buchler MW.
Characterisation of acute murine dextran sodium sulphate colitis: cytokine profile and dose dependency.
Digestion
62:
240-248,
2000[ISI][Medline].
12.
Elson, CO,
Sartor RB,
Tennyson GS,
and
Riddell RH.
Experimental models of inflammatory bowel disease.
Gastroenterology
109:
1344-1367,
1995[ISI][Medline].
13.
Fuss, IJ,
Marth T,
Neurath MF,
Pearlstein GR,
Jain A,
and
Strober W.
Anti-interleukin 12 treatment regulates apoptosis of Th1 T cells in experimental colitis in mice.
Gastroenterology
117:
1078-1088,
1999[ISI][Medline].
14.
Garcia Soriano, F,
Liaudet L,
Marton A,
Hasko G,
Batista Lorigados C,
Deitch EA,
and
Szabo C.
Inosine improves gut permeability and vascular reactivity in endotoxic shock.
Crit Care Med
29:
703-708,
2001[ISI][Medline].
15.
Hans, W,
Scholmerich J,
Gross V,
and
Falk W.
Interleukin-12 induced interferon-gamma increases inflammation in acute dextran sulfate sodium induced colitis in mice.
Eur Cytokine Netw
11:
67-74,
2000[ISI][Medline].
16.
Hasko, G,
Kuhel DG,
Chen JF,
Schwarzschild MA,
Deitch EA,
Mabley JG,
Marton A,
and
Szabo C.
Adenosine inhibits IL-12 and TNF-
production via adenosine A2a receptor-dependent and independent mechanisms.
FASEB J
14:
2065-2074,
2000[Abstract/Free Full Text].
17.
Hasko, G,
Kuhel DG,
Nemeth ZH,
Mabley JG,
Stachlewitz RF,
Virag L,
Lohinai Z,
Southan GJ,
Salzman AL,
and
Szabo C.
Inosine inhibits inflammatory cytokine production by a posttranscriptional mechanism and protects against endotoxin-induced shock.
J Immunol
164:
1013-1019,
2000[Abstract/Free Full Text].
18.
Hasko, G,
Nemeth ZH,
Vizi ES,
Salzman AL,
and
Szabo C.
An agonist of adenosine A3 receptors decreases interleukin-12 and interferon-gamma production and prevents lethality in endotoxemic mice.
Eur J Pharmacol
358:
261-268,
1998[ISI][Medline].
19.
Hasko, G,
and
Szabo C.
Regulation of cytokine and chemokine production by transmitters and co-transmitters of the autonomic nervous system.
Biochem Pharmacol
56:
1079-1087,
1998[ISI][Medline].
20.
Hooper, DC,
Bagasra O,
Marini JC,
Zborek A,
Ohnishi ST,
Kean R,
Champion JM,
Sarker AB,
Bobroski L,
Farber JL,
Akaike T,
Maeda H,
and
Koprowski H.
Prevention of experimental allergic encephalomyelitis by targeting nitric oxide and peroxynitrite: implications for the treatment of multiple sclerosis.
Proc Natl Acad Sci USA
94:
2528-2533,
1997[Abstract/Free Full Text].
21.
Jurkowitz, MS,
Litsky ML,
Browning MJ,
and
Hohl CM.
Adenosine, inosine, and guanosine protect glial cells during glucose deprivation and mitochondrial inhibition: correlation between protection and ATP preservation.
J Neurochem
71:
535-548,
1998[ISI][Medline].
22.
Kojouharoff, G,
Hans W,
Obermeier F,
Mannel DN,
Andus T,
Scholmerich J,
Gross V,
and
Falk W.
Neutralization of tumour necrosis factor (TNF) but not of IL-1 reduces inflammation in chronic dextran sulphate sodium-induced colitis in mice.
Clin Exp Immunol
107:
353-358,
1997[ISI][Medline].
23.
Liaudet, L,
Mabley JG,
Pacher P,
Szabo C,
and
Salzman AL.
The novel and potent peroxynitrite scavenger, FP 15, protects against development of colitis in mice (Abstract).
FASEB J
16:
A599,
2002.
24.
Liaudet, L,
Mabley JG,
Pacher P,
Virag L,
Soriano FG,
Marton A,
Hasko G,
Deitch EA,
and
Szabo C.
Inosine exerts a broad range of anti-inflammatory effects in a murine model of acute lung injury.
Ann Surg
235:
568-578,
2002[ISI][Medline].
25.
Liaudet, L,
Mabley JG,
Soriano FG,
Pacher P,
Marton A,
Hasko G,
and
Szabo C.
Inosine reduces systemic inflammation and improves survival in septic shock induced by cecal ligation and puncture.
Am J Respir Crit Care Med
164:
1213-1220,
2001[Abstract/Free Full Text].
26.
Mabley, JG,
Suarez-Pinzon WL,
Pacher P,
Hasko G,
Rabinovitch A,
and
Szabo C.
Inosine protects against both the primary disease and rejection of syngeneic islet grafts in NOD mice (Abstract).
FASEB J
16:
A985,
2002.
27.
Marak, GE, Jr,
de Kozak Y,
Faure JP,
Rao NA,
Romero JL,
Ward PA,
and
Till GO.
Pharmacologic modulation of acute ocular inflammation. I. Adenosine.
Ophthalmic Res
20:
220-226,
1988[ISI][Medline].
28.
Marton, A,
Pacher P,
Murthy KG,
Nemeth ZH,
Hasko G,
and
Szabo C.
Anti-inflammatory effects of inosine in human monocytes, neutrophils and epithelial cells in vitro.
Int J Mol Med
8:
617-621,
2001[ISI][Medline].
29.
Mazzon, E,
Dugo L,
Li JH,
Di Paola R,
Genovese T,
Caputi AP,
Zhang J,
and
Cuzzocrea S.
GPI 6150, a PARP inhibitor, reduces the colon injury caused by dinitrobenzene sulfonic acid in the rat.
Biochem Pharmacol
64:
327-337,
2002[ISI][Medline].
30.
McWhinney, CD,
Dudley MW,
Bowlin TL,
Peet NP,
Schook L,
Bradshaw M,
De M,
Borcherding DR,
and
Edwards CK, 3rd.
Activation of adenosine A3 receptors on macrophages inhibits tumor necrosis factor-
.
Eur J Pharmacol
310:
209-216,
1996[ISI][Medline].
31.
Nemeth, ZH,
Deitch EA,
Szabo C,
Mabley JG,
Pacher P,
Fekete Z,
Hauser CJ,
and
Hasko G.
Na+/H+ exchanger blockade inhibits enterocyte inflammatory response and protects against colitis.
Am J Physiol Gastrointest Liver Physiol
283:
G122-G132,
2002[Abstract/Free Full Text].
32.
Okayasu, I,
Hatakeyama S,
Yamada M,
Ohkusa T,
Inagaki Y,
and
Nakaya R.
A novel method in the induction of reliable experimental acute and chronic ulcerative colitis in mice.
Gastroenterology
98:
694-702,
1990[ISI][Medline].
33.
Olson, AD,
DelBuono EA,
Bitar KN,
and
Remick DG.
Antiserum to tumor necrosis factor and failure to prevent murine colitis.
J Pediatr Gastroenterol Nutr
21:
410-418,
1995[ISI][Medline].
34.
Sajjadi, FG,
Takabayashi K,
Foster AC,
Domingo RC,
and
Firestein GS.
Inhibition of TNF-
expression by adenosine: role of A3 adenosine receptors.
J Immunol
156:
3435-3442,
1996[Abstract].
35.
Schrier, DJ,
Lesch ME,
Wright CD,
and
Gilbertsen RB.
The antiinflammatory effects of adenosine receptor agonists on the carrageenan-induced pleural inflammatory response in rats.
J Immunol
145:
1874-1879,
1990[Abstract/Free Full Text].
36.
Singer, II,
Kawka DW,
Scott S,
Weidner JR,
Mumford RA,
Riehl TE,
and
Stenson WF.
Expression of inducible nitric oxide synthase and nitrotyrosine in colonic epithelium in inflammatory bowel disease.
Gastroenterology
111:
871-885,
1996[ISI][Medline].
37.
Szabo, C,
and
Dawson VL.
Role of poly(ADP-ribose) synthetase in inflammation and ischaemia-reperfusion.
Trends Pharmacol Sci
19:
287-298,
1998[ISI][Medline].
38.
Szabo, C,
Scott GS,
Virag L,
Egnaczyk G,
Salzman AL,
Shanley TP,
and
Hasko G.
Suppression of macrophage inflammatory protein (MIP)-1
production and collagen-induced arthritis by adenosine receptor agonists.
Br J Pharmacol
125:
379-387,
1998[Abstract].
39.
Szabo, C,
Zingarelli B,
and
Salzman AL.
Role of poly-ADP ribosyltransferase activation in the vascular contractile and energetic failure elicited by exogenous and endogenous nitric oxide and peroxynitrite.
Circ Res
78:
1051-1063,
1996[Abstract/Free Full Text].
40.
Veerabagu, MP,
Meguid MM,
Oler A,
and
Levine RA.
Intravenous nucleosides and a nucleotide promote healing of small bowel ulcers in experimental enterocolitis.
Dig Dis Sci
41:
1452-1457,
1996[ISI][Medline].
41.
Virag, L,
and
Szabo C.
Purines inhibit poly(ADP-ribose) polymerase activation and modulate oxidant-induced cell death.
FASEB J
15:
99-107,
2001[Abstract/Free Full Text].
42.
Ward, SG,
Bacon K,
and
Westwick J.
Chemokines and T lymphocytes: more than an attraction.
Immunity
9:
1-11,
1998[ISI][Medline].
43.
Zingarelli, B,
Cuzzocrea S,
Szabo C,
and
Salzman AL.
Mercaptoethylguanidine, a combined inhibitor of nitric oxide synthase and peroxynitrite scavenger, reduces trinitrobenzene sulfonic acid-induced colonic damage in rats.
J Pharmacol Exp Ther
287:
1048-1055,
1998[Abstract/Free Full Text].
44.
Zingarelli, B,
Szabo C,
and
Salzman AL.
Blockade of poly(ADP-ribose) synthetase inhibits neutrophil recruitment, oxidant generation, and mucosal injury in murine colitis.
Gastroenterology
116:
335-345,
1999[ISI][Medline].
Am J Physiol Gastrointest Liver Physiol 284(1):G138-G144
0193-1857/03 $5.00
Copyright © 2003 the American Physiological Society