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ivojin
S.
Jonjev1, andDepartments of 1 Physiology and Biophysics and 2 Surgery, University of Illinois College of Medicine, Chicago, Illinois 60612
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ABSTRACT |
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 TOP
 ABSTRACT
 INTRODUCTION
METHODS
RESULTS
DISCUSSION
REFERENCES
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By pharmacological
manipulation of endogenous adenosine, using chemically distinct
methods, we tested the hypothesis that endogenous adenosine tempers
proinflammatory cytokine responses and oxyradical-mediated tissue
damage during endotoxemia and sepsis. Rats were pretreated with
varying doses of pentostatin (PNT; adenosine deaminase inhibitor) or
8-sulfophenyltheophylline (8-SPT; adenosine receptor antagonist) and
then received either E. coli endotoxin (lipopolysaccharide;
0.01 or 2.0 mg/kg) or a slurry of cecal matter in 5% dextrose in water
(200 mg/kg). Resultant levels of tumor necrosis factor (TNF)-
,
interleukin (IL)-1
, and IL-10 were measured in serum and in liver
and spleen. Untreated, 2 mg/kg lipopolysaccharide elevated serum
TNF-, IL-1, and IL-10. PNT dose dependently attenuated, without
ablating, the elevation in serum TNF- and IL-1 and raised liver
and spleen IL-10. PNT also attenuated elevation of TNF- in serum,
liver, and spleen at 4 and 24 h after sepsis induction, and 8-SPT
resulted in higher proinflammatory cytokines. Modulating endogenous
adenosine was also effective in exacerbated (8-SPT) or diminished (PNT)
tissue peroxidation. Survival from sepsis was also improved when PNT
was used as a posttreatment. These data indicate that endogenous
adenosine is an important modulatory component of systemic inflammatory
response syndromes. These data also indicate that inhibition of
adenosine deaminase may be a novel and viable therapeutic approach to
managing the systemic inflammatory response syndrome without ablating
important physiological functions.
shock; cytokines; oxyradical
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INTRODUCTION |
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TOP
ABSTRACT
INTRODUCTION
METHODS
RESULTS
DISCUSSION
REFERENCES
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OUR LABORATORY HAS DEMONSTRATED that endogenous adenosine is involved in maintaining elevated resting hepatosplanchnic (23, 24) and skeletal muscle perfusion in sepsis (24), in part via stimulation of nitric oxide synthase (34, 36). It is not clear whether adenosine's role as an endogenous modulator of responses to inflammatory processes can be exploited to better manage systemic inflammatory response syndromes (SIRS).
Most of the work describing the immunomodulating abilities of adenosine
have been performed in vitro. Adenosine has been reported to
inhibit -galactosidase secretion (30) and
chemiluminescence (15) from zymosan particle-stimulated
mouse peritoneal macrophages. Adenosine has also been shown to inhibit
tumor necrosis factor (TNF)- produced by monocytes in response to
endotoxin [lipopolysaccharide (LPS)] (11) and reduce
leukocyte accumulation and TNF- production after carrageenan
stimulation (8). However, these in vitro findings cannot
be easily extrapolated to the complex in vivo immune response
associated with sepsis. Firestein et al. (12) explored
this question by using GP-1-515, an adenosine kinase inhibitor, a
proprietary compound that purportedly inhibited adenosine kinase. This
compound was able to inhibit LPS-mediated increases in TNF- and
improve survival, effects that were blocked with adenosine receptor
antagonism. However, effects were only seen in the presence of
GP-1-515, which was structurally similar to adenosine. Thus it is
not clear whether endogenous adenosine is a significant signaling
molecule for SIRS.
The following experiments were designed to test the hypothesis that
endogenous adenosine, produced as a consequence of a septic challenge
in vivo, serves to directly temper proximal cytokine responses and
tissue products of lipid peroxidation, as measured by thiobarbituric
acid-reactive substances (TBARS). Specifically, two chemically distinct
approaches were used to test the hypothesis. First, the adenosine
receptor antagonist 8-sulfophenyltheophylline (8-SPT) was used to
determine whether blockade of adenosine receptors would exacerbate
early proinflammatory cytokine and TBARS concentrations after a septic
challenge. Second, the adenosine deaminase inhibitor 2-deoxycoformycin
was used to determine whether reducing the degradation of endogenous
adenosine would amplify the tempering influences of adenosine on early
proinflammatory cytokine and TBARS concentrations after a septic
challenge. Haskó et al. (13) reported that
adenosine-stimulated release of the anti-inflammatory cytokine
interleukin (IL)-10 is partially responsible for the ability of
adenosine to regulate TNF- release in vitro. Thus we also tested the
hypothesis that endogenous adenosine has effects on IL-10 after a
septic challenge in vivo similar to those reported in vitro.
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METHODS |
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TOP
ABSTRACT
INTRODUCTION
METHODS
RESULTS
DISCUSSION
REFERENCES
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Materials
8-SPT. 8-SPT (Research Biochemicals International, Nattuck, MA), a nonselective (A1/A2/A3) but highly specific (no phosphodiesterase inhibition) adenosine receptor antagonist (3, 9, 14), was solubilized in sterile water to obtain an injectate volume of 1 ml/kg at a dose of 20 mg/kg every 8 h. The dose was determined based on pilot studies, which obtained and maintained complete blockade of hemodynamic effects of an exogenously administered adenosine (1 mmol/kg) bolus.
2-Deoxycoformycin.
2-Deoxycoformycin (pentostatin, Supergen, Dublin, CA), a potent
inhibitor of adenosine deaminase, was solubilized in sterile water to
concentrations ranging from 10
6 to 1.0 mg/ml at final
injection volumes of 1 ml/kg.
Animals
The experiments reported herein were approved by the Animal Care and Use Committee of the University of Illinois and were conducted according to the principles set forth in the Guide for the Care and Use of Laboratory Animals, revised in 1996. Male Sprague-Dawley rats (Harlan, IN), weighing 300-350 g, were housed at constant temperature with 10- and 14-h periods of light and dark exposure, respectively. Animals were allowed access to standard rat chow and water ad libitum during an acclimation period of at least 7 days before use in these experiments.Protocol 1: Pentostatin Dose Response After LPS
To determine the optimal attenuating dose of pentostatin, we used a fixed septic challenge with Escherichia coli LPS (2 mg/kg; serotype 0127:B8, lot 10692.2JA; Difco Labs, Detroit, MI). After weighing, rats received an intraperitoneal (IP) injection of one of five doses of pentostatin or sterile water (treatment control). One hour later, rats were challenged with 2 mg/kg LPS or saline IP (challenge control). Two hours after LPS injection, rats were lightly anesthetized with isoflurane. The chest and abdomen were immediately opened, and blood was withdrawn via cardiac puncture. Blood was allowed to clot, and, after centrifugation, serum was removed and frozen at
80°C for later assay. Our laboratory has used this dose of
endotoxin in previous work to create an acute, hypodynamic shock
syndrome within 2 h of the endotoxin challenge (10,
17).
Protocol 2: Cecal Soilage Model of Sepsis
Protocol subgroup A. Rats were randomized to treatment (pentostatin, 8-SPT, or sterile water) and challenge groups (septic and nonseptic) before surgery. Rats were weighed and anesthetized with an IP injection of pentobarbital sodium (50 mg/kg; Abbott). Adequate anesthesia was confirmed by the absence of an interdigital pinch reflex. Rats then received either 8-SPT (20 mg/kg) or pentostatin (1 mg/kg) IP. The dose of pentostatin used was based on results from protocol 1 (above). A polyethylene catheter (Intramedic PE-50, Baxter) was inserted into the right carotid artery for blood collection. The catheter was secured, tunneled subcutaneously to exit in the interscapular region, and flushed with heparinized saline (5 U/ml of 0.9% saline).
After catheterization, a 0.25-cm vertical midline abdominal incision was made, and a cecal slurry or 5% dextrose in water (nonseptic control) was injected in a volume of 5 ml/kg under direct vision. The cecal slurry was prepared by mixing cecal contents obtained from donor rats (euthanized with IP pentobarbital sodium; 100 mg/kg) with 5% dextrose in water to yield a concentration of 200 mg cecal material in 5 ml. The slurry was prepared fresh each day, and material from one donor rat was used within 2 h for three to five experimental animals. The incision was closed with interrupted silk sutures, and the abdomen was gently massaged to distribute the injectate. All rats were returned to individual cages with free access to food and water. Blood samples were obtained from conscious, unrestrained rats at 4 and 24 h after sepsis induction. Animals were then euthanized with an overdose of pentobarbital sodium (80 mg/kg iv) and examined for gross pathological changes. After this, the spleen and liver were removed and immediately frozen at80°C for later assays. Blood was allowed to
clot, and, after centrifugation, serum was removed and frozen at
80°C for later assay.
Our laboratory has previously shown that this model produces a
hyperdynamic, normotensive, septic state by 24 h
(34). In the septic groups, one rat treated with water and
two treated with 8-SPT died before 24 h postinduction.
Protocol subgroup B. To determine the efficacy of pentostatin as a postinsult treatment, a more lethal challenge of cecal slurry was required to consistently obtain a significant number of deaths within 24-72 h after the insult. After insertion of jugular catheters under general pentobarbital sodium anesthesia, rats were made septic, as described above in Protocol subgroup A, with the exception that rats received 400 mg/kg cecal slurry IP. Two hours after sepsis induction, when rats begin displaying overt signs of illness (piloerection, lethargy, tachycardia, and leukopenia), each animal received either 1 ml water (vehicle; n = 13) or 1 mg/kg pentostatin (in 1 ml; n = 13) over 5 min intravenously, followed by 50 ml/kg of 0.9% normal saline for resuscitation over 20 min. The number of animals alive at 24-144 h was recorded.
Cytokine Assays
Cytokines were measured from serum or tissue by using commercially available ELISA assays with the use of rat antibodies to each specific cytokine (R&D Systems, Minneapolis, MN). Serum was assayed directly after dilution. Tissue samples were pulverized under liquid nitrogen with homogenizing buffer [10 mM Trizma · HCl, 1 mM EGTA, 350 mM sucrose, 5 mM sodium azide (NaN3), 10 mM-mercaptoethanol, 0.02 mM phenylmethylsulfonyl fluoride, 50 mM sodium fluoride (NaF), 1 mg/ml pepstatin, 1 mg/ml leupeptin, pH 7.5, at
4°C]. A total of 10× volume of homogenization buffer was added to
the tissue sample and homogenized with an Omni Polytron homogenizer
with small size tip for 3 × 10 s bursts while on ice. The
homogenate was centrifuged at 100,000 g for 60 min at 4°C, and the supernatant was assayed after dilution.
TBARS Assay
TBARS were determined according to the methods of Ohkawa et al. (26) by using malondialdehyde to generate a standard curve. Samples of liver and spleen were homogenized on ice in 1:10 wt/vol of 1.15% KCl buffer containing 0.01% butylated hydroxytoluene. Samples were centrifuged at 21,000 g for 10 min at 4°C. Sample was added to 0.8% aqueous solution of thiobarbituric acid with 8.1% sodium dodecyl sulfate and 20% acetic acid and heated at 90°C for 60 min. After cooling to room temperature with tap water, the reaction mixture was centrifuged for 10 min at 1,500 g, and absorbance of the supernatant was read at 532 nm. Protein concentrations were measured by the bicinchoninic acid method (Pierce, Rockford, IL).Statistics
Data were assumed to be distributed normally. After we tested for and ensured homogeneity of variances by Bartlett's test, data were analyzed by two-way ANOVA (treatments vs. groups) followed by Student-Newman-Keuls test to identify differences. Data are expressed as means ± SE. The was set at 0.05 and at 0.2 to reject
the null hypothesis.
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RESULTS |
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TOP
ABSTRACT
INTRODUCTION
METHODS
RESULTS
DISCUSSION
REFERENCES
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Two hours after endotoxin administration, rats displayed signs of
acute endotoxemia, including piloerection and lethargy. Gross
examination revealed hemorrhagic bowel; sanguine fluid in the lumen of
the small intestine, cecum, and colon; and a granular appearance to the
liver. These signs were absent in animals that received the optimal
dose of pentostatin. Serum TNF- was significantly elevated at 2 h post-LPS (Fig. 1). Pretreatment with
pentostatin attenuated TNF- concentrations in a dose-dependent
manner, reaching a maximum attenuating effect at 0.1-0.5 mg/kg.
This is 5- to 10-fold lower than a single-infusion pentostatin dose
when used as an antineoplastic agent (4). It is important
to note that pentostatin attenuated the concentrations of this proximal
cytokine but was unable to ablate the response. LPS administration also
resulted in significant elevation of serum IL-1 (Table
1). Pentostatin was able to attenuate
IL-1 concentrations, similar to its effects on TNF-. Both TNF-
and IL-1 were not detectable in serum from saline-challenged
(non-LPS) rats, regardless of the presence or absence of pentostatin.
Low concentrations of IL-10 were found in saline-challenged rats
(82 ± 31 pg/ml). Significantly higher concentrations of IL-10
were measured 2 h after LPS administration (Table 1). Pentostatin
had no effect on the IL-10 response to LPS at the doses that caused
maximal attenuation of TNF- and IL-1, suggesting that the
suppression of proinflammatory cytokines by pentostatin was not
secondary to stimulation of this anti-inflammatory cytokine. However,
examination of IL-10 concentrations in the liver and spleen revealed
some further elevation in LPS-induced IL-10 after treatment with
pentostatin. Gross appearance in pentostatin-treated LPS rats was
indistinguishable from that of saline-challenged rats. Serum TNF-
and IL-1 were below detection of the assays in saline-challenged
rats.
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The effects of pentostatin on serum TNF- in response to a much lower
dose of LPS were investigated as well. The results are shown in Fig.
2. Administration of 0.01 mg/kg
ip LPS resulted in elevated serum TNF-, but this was significantly
lower than that seen in response to 2 mg/kg LPS. Neither 0.5 nor 1.0 mg/kg pentostatin administration reduced serum TNF any lower than it had when the higher dose of endotoxin was used (P = 0.94 and 0.901, respectively), suggesting a lower limit to the ability
of pentostatin to attenuate this TNF response. Relative to untreated
endotoxic rats, pentostatin resulted in a diminished response that did
not achieve -criteria for significance (P = 0.21)
but had a power equal to 0.14, suggesting some true diminution of a
much smaller magnitude.
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Chronic Sepsis
We used a model of sepsis previously employed by our laboratory to study the role of endogenous adenosine in modulating the cytokine response to a more clinically relevant challenge. This model results in a hyperdynamic state within 24 h of sepsis induction (34, 36) and a progressive sepsis beyond day 3, with progressive leukocytosis and lactacidemia through day 7 (25). As shown in Table 2, serum TNF- was elevated as early as 30 min after sepsis induction
and remained elevated up to 72 h after sepsis induction. In liver and spleen, soluble TNF- was also elevated at 24 h
after sepsis induction (84.2 ± 10.8 and 63.8 ± 21.2 ng/g
tissue, respectively). The surgical procedure (nonseptic controls) used
to induce sepsis also resulted in a transient elevation of TNF- in
both liver (18.4 ± 5.3 ng/g) and spleen (9.3 ± 3.8 ng/g) at
24 h, but these were significantly lower than that in the septic
rats.
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The influence of endogenous adenosine on the 4- and 24-h serum TNF-
response to the septic challenge was determined in response to either
pentostatin or 8-SPT. In the water-treated septic group, serum TNF-
was elevated at 4 and 24 h (Fig. 3),
similar to that seen in Table 2. Pentostatin attenuated this
response at both 4 and 24 h after sepsis induction. 8-SPT
treatment resulted in significantly higher serum TNF- at 24 h;
at 4 h, the power of the comparison was too low to definitively
state a difference, or lack thereof, but the direction of change was
consistent with the 24-h effect. Similar results were found in liver
and spleen total TNF- at 24 h after sepsis induction (Fig.
4). These results indicate that
preventing endogenous adenosine degradation with pentostatin diminishes
the in vivo TNF- response to sepsis, whereas blockade of adenosine
receptors alone amplifies this response. These data are consistent with
the hypothesis that endogenous adenosine is an important endogenous
modulator of the proximal cytokine response to a septic challenge.
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As a consequence of these effects of adenosine, we also postulated a
modulation of oxyradical-mediated damage. Samples of liver and spleen
were tested for evidence of TBARS resulting from the peritonitis. Liver
and spleen TBARS in each group are shown in Fig.
5. In septic rats treated with 8-SPT, the
concentration of tissue TBARS was increased in the spleen relative to
that in the water-treated septic rat group. Liver values were also
consistently elevated, albeit not to a statistically significant level.
Pretreatment with pentostatin significantly reduced the tissue
concentrations of TBARS relative to that in the water control-treated
septic rats and 8-SPT-treated septic rats. These data indicate that
endogenous adenosine is also an important modulator of oxyradical
damage after a septic challenge.
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Whereas the previous protocol was designed to assess effects of
pentostatin on blood and tissue parameters while minimizing the
confounding influence of examining only survivors, a more lethal
challenge was used to study mortality per se. The survival data
presented in Table 3 demonstrate the effectiveness of pentostatin in
reducing mortality, even when it is administered 2 h after a more
lethal septic challenge. One and six days after sepsis induction, 4 of
13 and 7 of 13 rats, respectively, had died in the vehicle-treated
group. In contrast, only 1 of 13 rats in the pentostatin-treated group
died (significantly different by Fishers exact test: P = 0.03 at 6 days).
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DISCUSSION |
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TOP
ABSTRACT
INTRODUCTION
METHODS
RESULTS
DISCUSSION
REFERENCES
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The data from these experiments compliment previous work from our
laboratory (23, 24, 34, 36) and demonstrate a significant role for endogenous adenosine as a modulating component in SIRS. The
results demonstrate that prevention of adenosine degradation attenuates
proinflammatory cytokine responses after either LPS or a septic
challenge, but a robust response remains intact. Blockade of adenosine
receptors had the opposite effect, amplifying the elevation in TNF-.
As such, this modulation of proinflammatory cytokines can be directly
associated with adenosine receptor-mediated actions and indicates that
endogenously produced adenosine is modulating the response intermediate
to either 8-SPT or pentostatin that was seen in the untreated LPS or
septic rats. Importantly, beneficial effects of pentostatin use were
not limited to pretreatment. Septic rats treated with 1 mg/kg
pentostatin 2 h after sepsis induction were very well protected up
to 6 days after the insult. These data indicate that endogenous
adenosine is an important modulator of the responses to inflammatory
processes. Furthermore, these data suggest that endogenous adenosine
should not be considered an anticytokine molecule. Pentostatin had no
significant effect on the TNF- response to a milder LPS challenge of
0.01 mg/kg, and it appeared that there was a lower limit to which
manipulation of endogenous adenosine could be used to influence
TNF-. This may make this a novel therapeutic approach in that a
significant proinflammatory response is left intact.
Earlier attempts to explore this question left unresolved problems.
Firestein et al. (12) reported the ability of
GP-1-515 to inhibit the TNF- response to LPS and that this
could be blocked by adenosine receptor antagonism. However, the
adenosine receptor antagonist had no effect on the LPS response in the
absence of GP-1-515, which seemed to suggest that naturally
evolved endogenous adenosine was playing no role. However, some
important differences between those studies and ours should be pointed
out. First, GP-1-515 is structurally similar to adenosine, leaving
open the possibility of direct receptor-mediated influences of the
compound. Their data also differ from ours in that adenosine receptor
antagonism, in the absence or presence of GP-1-515, had no effect
on IL-1 responses to LPS. Our data extended beyond LPS responses
into a clinically relevant model of sepsis. In this setting, our data clearly demonstrate the capability to amplify or diminish influences of
endogenous adenosine on multiple responses to a septic challenge. We
also demonstrate a lower limit to the influences of endogenous adenosine, which may also explain the mixed results seen by Firestein et al. (12). In a recent report, Martin et al.
(20) demonstrated that plasma adenosine concentrations
were elevated in patients with sepsis and that the increased
concentrations correlated with the severity of the patients'
condition. Earlier work from our laboratory demonstrated that
endogenous adenosine is also a significant modulator of resting
vascular tone in sepsis. Combined with the findings from the
experiments reported herein, the evidence indicates that adenosine is a
modulator of multiple physiological responses to inflammatory
processes, strongly influencing, but not mediating, the clinical
picture of SIRS. A summary hypothesis diagram of the proposed multiple
modulatory functions of endogenous adenosine in SIRS is shown in Fig.
6.
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Manipulation of adenosine's metabolic pathways has been a therapeutic
approach in the treatment of diseases such as myocardial ischemia and hairy cell leukemia (4). With the
findings from our experiments and others, there is considerable
evidence that manipulation of adenosine metabolism could be beneficial
in sepsis. Our manipulation of adenosine activity to affect the
pathophysiology of septic insults reveals a self-limiting modulatory
effect. The inability to suppress serum TNF- below a limit,
regardless of the severity of the challenge (Fig. 2), suggests that
endogenous adenosine becomes an important modulator only when
stimulation of the inflammatory response exceeds a minimum level. These
responses are similar to in vitro effects. Adenosine is capable of
suppressing macrophage activation and limiting cytokine release
(11, 21, 32, 33), which is a likely source of the effects
we are reporting herein. Adenosine also attenuates neutrophil adherence
and production of reactive oxygen radical moieties by neutrophils
(7, 8).
One of the most intriguing potentials in manipulating the adenosine pathway is that it would only dampen these responses, rather than resulting in total blockade or inhibition of these immune responses. This would allow for a more tempered response, which appears to be critical for survival (29). This is reminiscent of endogenous adenosine's role as a negative feedback inhibitor of cardiac inotropic responses to stimulators of adenylate cyclase (16). Adenosine is also a potent vasodilator, active only at sites of its production, where decreases in the oxygen supply-to-demand ratio prevail or where excessive adenylate cyclase activity occurs. Even in this regard, manipulation of the adenosine metabolic pathway would only affect regions wherein endogenous adenosine is being produced in significant quantities and would have no effect in other regions. Such an approach is worth investigating for the treatment and management of sepsis. The fundamental premise for such an approach is that there are sufficient increases in endogenous adenosine production in relevant physiological systems during sepsis to render manipulation of adenosine's metabolism effective for the treatment of clinical sepsis. The results presented herein attest to the validity of that premise.
We focused our attention primarily on changes in tissue and plasma
TNF- concentrations as a marker of the proximal cytokine response.
TNF- is the most thoroughly studied cytokine with regard to
modulation by adenosine (2, 8, 11-13, 19, 27, 32). In
addition, TNF- is a proximal cytokine, initiating inflammatory responses to infection. However, the results of our studies in LPS-challenged rats indicate that endogenous adenosine can also play a
role as modulator of other proximal proinflammatory cytokines, such as
IL-1. Pentostatin treatment also resulted in elevated liver and
spleen IL-10 after LPS in vivo, which supports a role for this
anti-inflammatory cytokine in these responses as well. Haskó et
al. (13) reported that adenosine-mediated attenuation of
macrophage proinflammatory responses could be explained, in part, by
adenosine-mediated stimulation of IL-10. Such a cytokine interaction
may be at work in the setting of SIRS. Further work is needed to
determine how manipulation of endogenous adenosine pathways affects the
mechanisms underlying inflammatory processes and cytokine interactions
in SIRS responses.
Adenosine has also been shown to inhibit a variety of neutrophil functions, including adherence (7), TNF-stimulated lactoferrin secretion (31), and, importantly, H2O2 production (7). Oxyradical injury can also be a result of adenosine accumulation (1, 5, 6, 18, 22, 28, 37-39). Via either of these pathways, manipulation of endogenous adenosine pathways can influence net oxyradical-mediated damage. Our results support this, but the data cannot be used to determine the relative contribution of the pathways involved. The blockade of adenosine receptors could exacerbate oxyradical-mediated damage by preventing adenosine-mediated inhibition of neutrophil activity (7) or by reducing perfusion (23, 24, 34, 36). Reduction of oxyradical damage by preventing the degradation of endogenous adenosine could occur via increased inhibition of neutrophil activity and by preventing adenosine's entry into the xanthine oxidase pathway. More work is needed to identify the relative contributions of each pathway that could be involved in these responses. Still, the data indicate that inhibition of the adenosine deaminase enzymes is also beneficial in the setting of sepsis in decreasing lipid peroxidation.
Therapeutic implications of these results are being explored. Endogenous adenosine's immunomodulating actions behave as a physiological negative feedback system. As such, manipulation of adenosine pathways and receptor-mediated actions act via amplification or attenuation of complex physiological effector systems rather than the more conventional approaches that served to intervene directly on specific effector mediators. Thus physiological regulatory systems remain intact and active; inhibition of adenosine deaminase enzymes still allows for a robust immune response. Because sepsis is associated with an exaggerated immune response, tissue perfusion maldistribution, oxyradical-mediated tissue damage, and manipulation of adenosine deaminase hold therapeutic promise via modulation of all of these pathways in which endogenous adenosine serves as a physiological feedback mechanism.
Perspectives
Significant advances in our understanding of SIRS reveal a complex, multisystem pathology. SIRS have eluded significant advances in treatment, in part, as a result of its influences on diverse, yet integrated, physiological systems. The approach to managing SIRS reported herein, manipulating endogenous adenosine, is novel from two perspectives. First, the goal is to amplify normal physiological responses, those that occur via endogenously produced adenosine, to regain homeostasis. This differs from past approaches that target a single inflammatory molecule or second-messenger system in an attempt to directly influence outcome. Second, the approach influences diverse, yet integrated, physiological systems. Specifically, endogenous adenosine modulates local tissue perfusion, responses to inflammatory agents and inflammatory molecule interactions, oxyradical production via multiple pathways, and neurohumoral function, to name a few. These functions are accomplished through the various signaling pathways coupled to adenosine receptors in each cell type.| |
ACKNOWLEDGEMENTS |
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The authors thank Drs. James L. Ferguson and H. Bruce Bosmann for discussion of results and review of this manuscript.
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FOOTNOTES |
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This work was funded by the University of Illinois at Chicago College of Medicine and Supergen. Pentostatin was a generous gift from Supergen.
Address for reprint requests and other correspondence: W. R. Law, Univ. of Illinois College of Medicine, Dept. of Physiology and Biophysics, and Surgery, 835 S. Wolcott St., Chicago, IL 60612 (E-mail: wrlaw{at}uic.edu).
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.
10.1152/ajpregu.00373.2001
Received 3 July 2001; accepted in final form 9 January 2002.
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REFERENCES |
|---|
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TOP
ABSTRACT
INTRODUCTION
METHODS
RESULTS
DISCUSSION
REFERENCES
|
|---|
1.
Arvidsson, S,
Fält K,
and
Haglund U.
Feline E. coli bacteremia-effects of misoprostol/scavengers of methylprednisolone on hemodynamic reactions and gastrointestinal mucosal injury.
Acta Chir Scand
156:
215-221,
1990[ISI][Medline].
2.
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].
3.
Brackett, LE,
Shamim MT,
and
Daly JW.
Activities of caffeine, theophylline, and enprofylline analogs as tracheal relaxants.
Biochem Pharmacol
39:
1897-1904,
1990[ISI][Medline].
4.
Brogden, RN,
and
Sorkin EM.
Pentostatin: a review of its pharmacodynamic and pharmacokinetic properties, and therapeutic potential in lymphoproliferative disorders.
Drugs
46:
652-677,
1993[ISI][Medline].
5.
Broner, CW,
Shenep JL,
Stidham GL,
Stokes DC,
Fairclough D,
Schonbaum GR,
Rehg JE,
and
Hildner WK.
Effect of antioxidants in experimental Escherichia coli septicemia.
Circ Shock
29:
77-92,
1989[ISI][Medline].
6.
Castillo, M,
Toledo-Pereyra LH,
Gutierrez R,
Prough D,
and
Shapiro E.
Peritonitis after cecal ligation perforation. An experimental model to study the therapeutic role of antibiotics associated with allopurinol and catalase.
Am Surg
57:
313-316,
1991[ISI][Medline].
7.
Cronstein, BN,
Levin RI,
Philips M,
Hirschhorn R,
Abramson SB,
and
Weissmann G.
Neutrophil adherence to endothelium is enhanced via adenosine A1 receptors and inhibited via adenosine A2 receptors.
J Immunol
148:
2201-2206,
1992[Abstract].
8.
Cronstein, BN,
Naime D,
and
Firestein G.
The antiinflammatory effects of an adenosine kinase inhibitor are mediated by adenosine.
Arthritis Rheum
38:
1040-1045,
1995[ISI][Medline].
9.
Daly, JW,
Padgett W,
Shamim MT,
Butts LP,
and
Waters J.
1,3-Dialkyl-8-(p-sulfophenyl)xanthines: potent water-soluble antagonists for A1- and A2-adenosine receptors.
J Med Chem
28:
487-492,
1985[ISI][Medline].
10.
Dziki, AJ,
Lynch WH,
Ramsey CB,
and
Law WR.
Beta-adrenergic-dependent and -independent actions of naloxone on perfusion during endotoxin shock.
Circ Shock
39:
29-38,
1993[ISI][Medline].
11.
Eigler, A,
Greten TF,
Sinha B,
Haslberger C,
Sullivan GW,
and
Endres S.
Endogenous adenosine curtails lipopolysaccharide-stimulated tumour necrosis factor synthesis.
Scand J Immunol
45:
132-139,
1997[ISI][Medline].
12.
Firestein, GS,
Boyle D,
Bullough DA,
Gruber HE,
Sajjadi FG,
Montag A,
Sambol B,
and
Mullane KM.
Protective effect of an adenosine kinase inhibitor in septic shock.
J Immunol
152:
5853-5859,
1994[Abstract].
13.
Haskó, G,
Czabó C,
Németh ZH,
Kvetan V,
Pastores SM,
and
Vizi ES.
Adenosine receptor agonists differentially regulate IL-10, TNF-, and nitric oxide production in RAW 264.7 macrophages and in endotoxemic mice.
J Immunol
157:
4634-4640,
1996[Abstract].
14.
Haynes, JJ,
Killilea DW,
Peterson PD,
and
Thompson WJ.
Erythro-9-(2-hydroxy-3-nonyl)adenine inhibits cyclic-3',5'-guanosine monophosphate-stimulated phosphodiesterase to reverse hypoxic pulmonary vasoconstriction in the perfused rat lung.
J Pharmacol Exp Ther
276:
752-757,
1996
15.
Itoh, K,
Majima T,
Edo K,
Mizugaki M,
and
Ishida N.
Suppressive effect of 1-methyladenosine on the generation of chemiluminescence by mouse peritoneal macrophages stimulated with opsonized zymosan.
Tohoku J Exp Med
157:
205-214,
1989[ISI][Medline].
15a.
Law WR (Inventor). Use of adenosine deaminase inhibitors to
treat systemic inflammatory response syndrome. US Patent
6,103,702. 15 Aug. 2000. Int. Cl. A61K 031/70.
16.
Law, WR,
Carney PJ,
and
McLane MP.
Influence of adenosine on the stimulatory effect of isoprenaline and insulin on myocardial contractility in vivo.
Cardiovasc Res
25:
151-157,
1991
17.
Law, WR,
Mourelatos MG,
Krahmer R,
Dziki AJ,
Lynch WH,
and
Ferguson JL.
Effects of phentolamine or yohimbine on naloxone's actions during endotoxin shock in rats.
Shock
3:
217-224,
1997.
18.
Leff, JA,
Parsons PE,
Day CE,
Taniguchi N,
Jochum M,
Fritz H,
Moore FA,
Moore EE,
McCord JM,
and
Repine JE.
Serum antioxidants as predictors of adult respiratory distress syndrome in patients with sepsis.
Lancet
341:
777-780,
1993[ISI][Medline].
19.
LeMoine, O,
Stordeur P,
Schandené L,
Marchant A,
de Groote D,
Goldman M,
and
Devière J.
Adenosine enhances IL-10 secretion by human monocytes.
J Immunol
156:
4408-4414,
1996[Abstract].
20.
Martin, C,
Leone M,
Viviand X,
Ayem M,
and
Guieu R.
High adenosine plasma concentration as a prognostic index for outcome in patients with septic shock.
Crit Care Med
28:
3198-3202,
2001.
21.
McWhinney, CD,
Dudley MW,
Bowlin TL,
Peet NP,
Schook L,
Bradshaw M,
De M,
Borcherding DR,
and
Edwards CK, III.
Activation of adenosine A3 receptors on macrophages inhibits tumor necrosis factor-.
Eur J Pharmacol
310:
209-216,
1996[ISI][Medline].
22.
Morgan, RA,
Manning PB,
Coran AG,
Drongowaski RA,
Till GO,
Ward PD,
and
Oldham KT.
Oxygen free radical activity during live E. coli septic shock in the dog.
Circ Shock
25:
319-323,
1988[ISI][Medline].
23.
Motew, SJ,
Mourelatos MG,
Miller RN,
Ferguson JL,
and
Law WR.
Evidence that adenosine contributes to maintenance of hepatosplanchnic blood flow during peritoneal sepsis in rats.
Shock
7:
439-446,
1997[ISI][Medline].
24.
Motew, SJ,
Sam AD, II,
Mourelatos MG,
Sharma AC,
Alden KJ,
Ferguson JL,
and
Law WR.
Adenosine receptor antagonism affects regional resting vascular resistance during rat peritoneal sepsis.
J Surg Res
80:
326-332,
1998[ISI][Medline].
25.
Mourelatos, MG,
Enzer N,
Ferguson JL,
Rypins EB,
Burhop KE,
and
Law WR.
The effects of diaspirin cross-linked hemoglobin in sepsis.
Shock
5:
141-148,
1996[ISI][Medline].
26.
Ohkawa, H,
Ohishi N,
and
Yagi K.
Assay for lipid peroxides in animal tissues by thiobarbituric acid reaction.
Anal Biochem
95:
351-358,
1979[ISI][Medline].
27.
Parmely, MJ,
Zhou WW,
Edwards CK, III,
Borcherding DR,
Silverstein R,
and
Morrison DC.
Adenosine and a related carbocyclic nucleoside analogue selectively inhibit tumor necrosis factor- production and protect mice against endotoxin challenge.
J Immunol
151:
389-396,
1993[Abstract].
28.
Peralta, JG,
Llesuy S,
Evelson P,
Carreras MC,
Flecha BG,
and
Poderoso JJ.
Oxidative stress in skeletal muscle during sepsis in rats.
Circ Shock
39:
153-159,
1993[ISI][Medline].
29.
Read, RC.
Experimental therapies for sepsis directed against tumour necrosis factor.
J Antimicrob Chemother
41:
65-69,
1998
30.
Riches, DWH,
Watkins JL,
Hensen PM,
and
Stanworth DR.
Regulation of macrophage lysosomal secretion by adenosine, adenosine phosphate esters, and related structural analogues of adenosine.
J Leukoc Biol
37:
545-557,
1985[Abstract].
31.
Richter, J.
Effect of adenosine analogues and cAMP-raising agents on TNF-, GM-CSF-, and chemotactic peptide-induced degranulation in single adherent neutrophils.
J Leukoc Biol
51:
270-275,
1992[Abstract].
32.
Ritchie, PK,
Spangelo BL,
Krzymowski DK,
Rossiter TB,
Kurth E,
and
Judd AM.
Adenosine increases interleukin-6 release and decreases tumour necrosis factor release from rat adrenal zona glomerulosa cells, ovarian cells, anterior pituitary cells, and peritoneal macrophages.
Cytokine
9:
187-198,
1997[ISI][Medline].
33.
Sajjadi, FG,
Takabayashi K,
Foster AC,
Domingo RC,
and
Firestein GS.
Inhibition of TNF- expression by adenosine.
J Immunol
156:
3435-3442,
1996[Abstract].
34.
Sam, AD, II,
Sharma AC,
Rice AN,
Ferguson JL,
and
Law WR.
Adenosine and nitric oxide regulate regional vascular resistance via interdependent and independent mechanisms during sepsis.
Crit Care Med
28:
1931-1939,
2000[ISI][Medline].
36.
Sam, AD, II,
Sharma AC,
Rice AN,
Ferguson JL,
and
Law WR.
Interdependence of adenosine and nitric oxide in hepato-splanchnic circulation during sepsis.
J Surg Res
94:
61-67,
2000[ISI][Medline].
37.
Schiller, HJ,
Reilly PM,
and
Bulkley GB.
Antioxidant therapy.
Crit Care Med
21:
S92-S102,
1993[ISI][Medline].
38.
Xu, D,
Qi L,
Guillory D,
Cruz N,
Berg R,
and
Deitch EA.
Mechanisms of endotoxin-induced intestinal injury in a hyperdynamic model of sepsis.
J Trauma
34:
676-683,
1993[ISI][Medline].
39.
Zager, RA.
Adenine nucleotide changes in kidney, liver, and small intestine during different forms of ischemic injury.
Circ Res
68:
185-196,
1991
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Significantly different relative to LPS alone, P 
0.05.
2 mg/kg LPS: P 
