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Gene Expression1
*
Center for Molecular Biology of Oral Diseases, and
Department of Biochemistry and Molecular Biology, University of Illinois, Chicago, IL 60612
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Abstract |
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 Top Abstract IntroductionMaterials and MethodsResultsDiscussionReferences |
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plays a key role in the generation of antitumor CTL
activity in this system, we determined whether NE mediates this
inhibition through inhibition of TNF- production. Here, we show that
NE inhibits the production of TNF- protein and mRNA by
L-PAM TuB spleen cells stimulated in vitro with mitomycin
C-treated tumor cells. Flow cytometric analysis of intracellular
expression of TNF- revealed substantial NE-mediated decreases in the
percentages of TNF-+ cells among CD4+ and
CD8+ T cells and F4/80+ activated macrophages.
NE inhibition of CTL generation was largely overcome by addition of
TNF- to the stimulation cultures. When the ß-adrenergic antagonist
propranolol was added to the stimulation cultures of L-PAM
TuB spleen cells at a concentration that prevented NE-induced cAMP
elevation, the NE-mediated decrease in TNF- mRNA and NE-mediated
inhibition of CTL generation were reversed. Collectively, these results
suggest that NE inhibits antitumor CTL generation, at least in part, by
inhibiting TNF- synthesis through a mechanism(s) involving
ß-adrenergic receptor signaling. |
Introduction |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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Catecholamines can modulate T cell function both by classical
ß-adrenergic receptor
(ß-AR)3 stimulation
(4) and by ß-AR-independent mechanisms (5).
Catecholamine regulation of T cell function is paralleled by
catecholamine regulation of cytokine expression. For example,
stimulation of ß-ARs by catecholamines, such as norepinephrine (NE)
or epinephrine, was reported to be associated with the inhibition of T
cell synthesis of TNF- (6), IL-2 (7, 8),
and IFN-
(7), as well as inhibition of T cell
proliferation (8, 9). Catecholamines also act through
ß-ARs to regulate the expression of cytokine receptors, such as the
IL-2 and TNF- receptors, as well as other surface molecules on
immune cells (10, 11, 12). We have recently reported that NE
acts through ß-AR stimulation and the cAMP/protein kinase A (PKA)
signal transduction pathway to destabilize the mRNA encoding Thy-1 (a
surface glycoprotein implicated in the thymic maturation of T lineage
cells (13)); this observation is consistent with possible
operation of a general lymphocytic catecholamine/cAMP-responsive mRNA
decay system targeting transcripts of genes involved in
immunomodulatory effects of stress (14).
Catecholamines exert complex effects on the generation of CTL. For example, while Hatfield et al. (15) and Felten et al. (3) observed stimulatory catecholamine effects on CTL generation against allogeneic tumor cells, we observed a biphasic effect on the generation of CTL activity against syngeneic tumor cells (16). In our studies, NE stimulated CTL generation by BALB/c spleen cells against the syngeneic MOPC-315 plasmacytoma when added at low concentrations, and inhibited the generation of anti-MOPC-315 CTL activity when added at higher concentrations (16).
Since TNF- was shown to play a key role in the in vitro generation
of CTL activity (17), and since catecholamines have been
reported to decrease TNF- synthesis (6, 18), it is of
interest to determine whether NE inhibition of antitumor CTL generation
occurs as a consequence of an NE-mediated decrease in TNF-
production. As a model in which CTL participate in tumor eradication,
we selected the MOPC-315 plasmacytoma. In this system, TNF- is
important not only for the in vitro generation of splenic antitumor CTL
activity (17), but also for the in vivo acquisition of
potent CD8+ T cell-mediated antitumor cytolytic
activity at the tumor site, following low-dose melphalan
(L-phenylalanine mustard (L-PAM)) therapy of
mice bearing large tumors (19). This CTL activity is
responsible for the eradication of the large tumor burden not
eradicated by the direct antitumor toxicity of the low-dose
L-PAM (20).
Our previous studies defined concentrations of NE and incubation
conditions under which NE causes major inhibition of the in vitro
generation of anti-MOPC-315 cytotoxicity by spleen cells from
MOPC-315 tumor-bearer mice, which have been recently treated with
L-PAM and cultured in the presence of inactivated tumor
cells (16). The current studies were designed to determine
whether NE mediates its inhibitory effect for CTL generation by
L-PAM TuB spleen cells through inhibition of TNF-
production. Here, we show that NE leads to inhibition of TNF-
production by stimulation cultures of L-PAM TuB spleen
cells. Moreover, addition of the ß-adrenergic antagonist,
propranolol, to these stimulation cultures reversed both the
NE-mediated inhibition of TNF- production and CTL generation.
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Materials and Methods |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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The MOPC-315 plasmacytoma was maintained in vivo as previously
described (21) as a s.c. tumor in syngeneic 7- to
10-wk-old female BALB/c mice (Charles River Breeding Laboratories,
Wilmington, MA). Routinely, mice were inoculated with 1 x
106 viable tumor cells, a dose that is
300-fold higher than the minimal lethal tumor dose, and leads to the
appearance of a palpable tumor in 4–5 days. Thereafter, the tumors
grow progressively, killing the mice in 16 days.
Chemotherapy
A fresh stock solution of 10 mg/ml L-PAM (Sigma, St.
Louis, MO) was prepared as previously described (22), and
was further diluted with PBS (pH 7.2) to the desired concentration just
before injection. A dose of 2.5 mg L-PAM/kg body weight was
administered i.p. to mice bearing large (20 mm) MOPC-315 tumors,
which resulted from the inoculation of 1 x
106 MOPC-315 tumor cells 10 days earlier
(L-PAM TuB mice). This dose of L-PAM is
curative for 90% of the tumor-bearing mice and leads to the
complete regression of the s.c. tumor nodule within 8–10 days after
L-PAM administration via a CD8+ T
cell-dependent mechanism (22, 23).
Spleen cell suspensions
Single cell suspensions were prepared from the spleens of BALB/c tumor bearer mice that had been treated 3–4 days earlier with 2.5 mg/kg L-PAM. Cell suspensions were prepared by mechanical disruption of the spleens between glass slides. In any individual experiment, pooled spleen cells from three to five mice were used.
Reagents and cytokines
NE and propranolol were purchased from Sigma. NE was freshly
diluted in DMEM (Life Technologies, Grand Island, NY). Recombinant
murine TNF- was obtained from R&D Systems (Minneapolis,
MN).
In vitro stimulation for the generation of CTL
Spleen cells from L-PAM TuB mice were stimulated in
vitro with MOPC-315 tumor cells, according to the method we have
previously described for the in vitro generation of CTL activity
(17). Briefly, 6 x 106 spleen
cells were cultured in the presence or absence of 0.2 x
106 mitomycin C-treated (50 µg/ml for 30 min at
37°C) MOPC-315 tumor cells in 24-well plates in the final volume of 2
ml DMEM supplemented with 2 mM glutamine, 50 µM 2-ME, 50 U/ml
penicillin, 50 µg/ml streptomycin (all from Sigma), and 5%
heat-inactivated FBS (Life Technologies). NE (100 µM) and/or
exogenous TNF- (1 ng/ml) were added at the time of culture
initiation. The cultures were incubated at 37°C in 5%
CO2 for 5 days. In some experiments, cultures
were incubated with NE (100 µM) for 3 h, and then culture media
was replaced with fresh media without NE and the cultures were
incubated for 5 days. Propranolol (1 µM) was added to the cultures 15
min before NE.
Antitumor cytotoxicity assay
The cytolytic activity of the cultured spleen cells was
determined by the 51Cr-release assay, as
previously described (21). Briefly, 1 x
104 51Cr-labeled tumor cells were incubated with
cultured spleen cells at three different E:T ratios in 96-well plates
in a total volume of 200 µl of RPMI 1640 supplemented with 10% FBS
(Life Technologies). After a 3.5-h incubation at 37°C, 100 µl of
supernatant was aspirated and analyzed on an Auto Scintillation
Counter (Packard Instruments, Downers Grove, IL). The percentage of
specific 51Cr release was calculated with the
following formula: [(Ecpm -
Scpm)/(Mcpm -
Scpm)] x 100%, where
Ecpm represents the 51Cr
release by target cells incubated with effector cells,
Scpm represents the spontaneous release, and
Mcpm represents the maximal release obtained by
the addition of 100 µl of 2% Nonidet P-40 detergent solution to the
target cells. Each experiment was performed at least three times, and
the results of a representative experiment are provided as the mean
percentages of specific 51Cr release of
triplicate samples ± SEM. In addition, to illustrate the
reproducibility of our observations, the data from all experiments
addressing the same question were converted to lytic units (LU) per
1 x 106 effector cells with the aid of the
computer program developed for the Clinical Immunology Service, Program
Resources Inc. (Frederick Cancer Research and Development
Center/National Cancer Institute, Frederick, MD), where 1 LU is defined
as the number of effector cells producing 20% lysis of 1 x
104 target cells. The cumulative data from all
experiments are presented as the mean percentage ± SEM of the LU
of the control group.
Measurements of IL-2, TNF-, and IFN- concentrations
Spleen cells admixed with mitomycin C-treated MOPC-315 tumor
cells were cultured for 24–72 h at 37°C. The supernatants were
removed and assayed for IL-2, TNF-, and IFN- using a sandwich
ELISA as previously described (24). Rat anti-mouse
IL-2 mAb JES6-1A12, rat anti-mouse TNF- mAb G281-2626, and rat
anti-mouse IFN- mAb R4-6A2 were used as capture Abs. Rat
anti-mouse IL-2 mAb JES6-5H4, rat anti-mouse TNF- mAb
MP6-XT3, and rat anti-mouse IFN- mAb XMG1.2 were used as
detection Abs. All anti-cytokine mAbs were purchased from
PharMingen (San Diego, CA). The sensitivity of the ELISAs was 15–20
pg/ml for all cytokines.
Flow cytometry analysis
Splenocytes admixed with mitomycin C-treated MOPC-315 tumor
cells were cultured for 72 h in 24-well plates with 3 µM of
monensin (Sigma) present for the last 5 h of the incubation
period. Subsequently, the splenocytes were stained with FITC-conjugated
anti-mouse CD3, CD4, CD8 (all from PharMingen), or F4/80 (Caltag
Laboratories, Burlingame, CA) mAbs. The cells were then fixed,
permeabilized by saponin (0.1% in PBS; Sigma), and stained with
PE-conjugated rat anti-mouse TNF- (MP6-XT22) mAbs (PharMingen).
PE-conjugated rat IgG1 (PharMingen) was used as a negative control for
intracellular cytokine staining. To demonstrate specificity of
staining, the binding of PE-labeled anti-TNF- mAbs was blocked
by preincubating cells with 10-fold excess of the unlabeled
anti-TNF- (MP6-XT22) mAbs.
RNase protection assay
Spleen cells were admixed with tumor cells and cultured in
24-well plates for 4 h with or without NE (100 µM). Aliquots of
total RNA from the cultures were analyzed for TNF- and GAPDH mRNAs
by RNase protection assay (14) utilizing the mCK-3 probe
template set from PharMingen.
Measurement of cAMP concentration
Spleen cells (5 x 106) were suspended in 1 ml PBS supplemented with 5% heat-inactivated FBS. After a 15-min incubation at room temperature, adenylyl cyclase was activated by the addition of NE (100 µM) or forskolin (100 µM). The incubation continued for an additional 15 min at 37°C, and then cAMP was isolated by liquid phase extraction. Ice-cold ethanol was added to the cell suspension (final concentration of 65% v/v ethanol), and the tubes were centrifuged at 2000 x g for 3 min at 4°C. Supernatants were collected, and the precipitate was washed a second time with ice-cold 65% (v/v) ethanol. Supernatants were combined and centrifuged (2000 x g, 15 min, 4°C). The extracts were dried in a vacuum oven at 50°C, then dissolved in 0.05 M sodium acetate buffer (pH 5.8) containing 0.02% BSA. cAMP concentration was measured by an enzyme immunoassay system (Amersham, Arlington Heights, IL; no. RPN 225).
Statistical analysis
The Student’s t test was employed to determine the significance of the differences between groups. A p value < 0.05 was considered significant.
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Results |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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Spleen cells taken from tumor-bearing mice 3 days after treatment
with low-dose L-PAM (L-PAM TuB spleen cells)
were cultured in vitro with mitomycin C-treated MOPC-315 tumor cells in
the presence or absence of NE. After 3 days, the culture supernatants
were assayed by ELISA for TNF-, IL-2, and IFN- concentrations. In
addition, on day 5 after culture initiation, the L-PAM TuB
spleen cells were evaluated for their lytic activity against MOPC-315
tumor cells to confirm the inhibitory activity of NE in this system. As
seen in Fig. 1
, and in confirmation of
our previous observations (16), addition of 10–100 µM
NE caused a concentration-dependent inhibition of anti-MOPC-315
cytotoxicity, leading to a 7-fold decrease in
LU20/106 spleen cells at
the highest concentration of NE used (100 µM). The overall
viability of the spleen cells was not affected by NE at any
concentration employed (data not shown). As seen in Fig. 2, addition of 10–100 µM NE also
caused a concentration-dependent decrease of TNF-, IL-2, and IFN-
levels in conditioned medium collected on day 3 after culture
initiation.
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was previously shown to be crucial for the generation of
CTL activity by spleen cells from low-dose L-PAM treated
mice, and since TNF- had to be present within the first 48 h of
the 5-day stimulation culture to fully realize its potentiation effect
for CTL generation in the MOPC-315 system (17),
experiments were performed to determine whether NE-mediated inhibition
of TNF- production was evident at earlier times after culture
initiation. Time course studies revealed that, within 48 h, the
presence of NE (100 µM) was associated with >50% reduction in the
concentration of TNF- in supernatants from stimulation cultures of
L-PAM TuB spleen cells (Fig. 3). Similar kinetics for NE-mediated
inhibition were observed for IL-2 and IFN- production by spleen
cells (data not shown).
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cytokine expression
by CD3+ and CD3- populations in stimulation
cultures of L-PAM TuB spleen cells
Given the fact that TNF- can be produced by different cell
types, experiments were conducted to determine which cell types
produced less TNF- as a result of exposure to NE. Accordingly,
spleen cells from L-PAM TuB mice were cultured with
mitomycin C-treated tumor cells in the presence or absence of NE (100
µM). After 3 days, cells were stained with FITC-conjugated
anti-CD3 mAbs, then permeabilized and stained with PE-conjugated
anti-TNF- mAbs to demonstrate the presence of
intracellular cytokine. As seen in Fig. 4A, NE treatment did not
affect the total percentage of CD3+ cells in the
cultures, which was 30% in the presence or absence of NE. However,
a substantial decrease was noted in the percents of
TNF-+/CD3+ as well as
TNF-+/CD3- populations
as a consequence of NE addition to the stimulation cultures. This
translates into a decrease from 6.6 ± 0.4 to 0.1 ± 0.8 in
the TNF-+ cells among the
CD3+ cells (p < 0.05)
and a decrease from 7.6 ± 0.8 to 0.4 ± 0.4 in the
TNF-+ cells among the
CD3- cells (p < 0.05)
(Fig. 4B). Finally, the NE-mediated decrease in
cell-associated TNF- detected in these assays reflected changes in
the levels of cytokine within cells, rather than on their external
surfaces, since we did not detect binding of PE-conjugated
anti-TNF- Abs to NE-treated or NE-untreated cells in the absence
of permeabilization (data not shown).
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protein by
CD4+ T cells, CD8+ T cells, and the
F4/80+ subset of splenic macrophages
Since NE reduced the percentage of TNF--positive cells among
the CD3+ spleen cell population, experiments were
performed to determine which subset(s) of T cells was affected by NE.
As seen in Fig. 5A, NE
treatment did not affect the total percentages of
CD8+ or CD4+ cells in the
cultures. However, addition of NE did lead to a profound decrease in
the percentages of TNF-+ cells among the
CD8+ and the CD4+ cell
populations (Fig. 5B).
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+
cells among the CD3- subpopulation of
L-PAM TuB spleen cells stimulated in culture with MOPC-315
cells (Fig. 4
), and since activated macrophages have also been reported
in other systems to be a major source of TNF- production
(24), we assessed whether NE affected intracellular
TNF- expression by cells expressing F4/80+, a
specific marker for activated macrophages. As seen in Fig. 5A, NE treatment did not affect the total percentage of
F4/80+ cells in the stimulation cultures, but
addition of NE significantly reduced the percentage of
TNF-+ cells contained within the
F4/80+ cell population (Fig. 5B).
Effect of NE on TNF- mRNA expression by spleen cells
To elucidate the molecular mechanism(s) underlying the NE-mediated
inhibition of TNF- production, we investigated the effect of NE on
TNF- gene expression in L-PAM TuB spleen cells
stimulated in vitro with MOPC-315 tumor cells. For this purpose, the
spleen cells were admixed with mitomycin C-treated tumor cells and
cultured in the presence or absence of NE (100 µM). After 3 h,
the cells were harvested, total RNA was prepared, and concentrations of
TNF- mRNA, as well as GAPDH mRNA, were determined by an RNase
protection assay. As part of these studies, we established that no
detectable level of TNF- mRNA was expressed by MOPC-315 tumor cells
(data not shown). As shown in Fig. 6, NE
caused a dramatic decrease in the level of spleen cell TNF- mRNA,
while not affecting the level of GAPDH mRNA.
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mRNA
expression and CTL generation by stimulation cultures of
L-PAM TuB spleen cells
Experiments were performed to determine whether signaling through
ß-ARs is involved in NE-mediated inhibition of TNF- mRNA
expression. For this purpose, L-PAM TuB spleen cells were
admixed with tumor cells and incubated in the presence of NE (100 µM)
with or without prior addition of propranolol (15 min earlier than NE),
at a concentration (1 µM) that antagonized NE-induced cAMP elevation
in the L-PAM TuB spleen cells (Fig. 7A). Three hours after NE
addition, total RNA was prepared and evaluated by the RNase protection
assay for TNF- and GAPDH mRNA levels. Under these culture
conditions, propranolol completely overcame the NE inhibitory effect,
restoring TNF- mRNA expression to control levels (Fig. 7B).
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mRNA expression was evident after 3 h
of exposure to NE, and since propranolol completely overcame this
inhibition, experiments were performed to determine whether 3 h of
exposure to NE also led to inhibition of antitumor CTL generation by
L-PAM TuB spleen cells, and, if so, whether propranolol
could overcome the NE inhibitory effect for CTL generation. For this
purpose, parallel cultures were incubated in the presence of NE with or
without propranolol for 3 h, followed by culture for 5 days in the
absence of NE or propranolol. As shown in Fig. 7C, exposure
of L-PAM TuB spleen cells to NE for 3 h led
to a substantial inhibition of CTL generation during the subsequent
5-day culture period. This NE-mediated inhibition was largely
(40–70%) antagonized by propranolol.
Effect of exogenous TNF- on NE-mediated inhibition of CTL
generation
The close correlation between inhibition of NE-mediated CTL
generation and inhibition of TNF- production suggests that exogenous
TNF- could overcome the NE-mediated inhibition of antitumor CTL
generation. To test this hypothesis, L-PAM TuB spleen cells
admixed with inactivated tumor cells were exposed to NE (100 µM) in
the presence or absence of exogenous recombinant mouse TNF- at a
concentration (1ng/ml) not affecting the generation of antitumor CTL
activity in the absence of NE. Fig. 8
shows that exogenous TNF- substantially offset the inhibitory effect
of NE for antitumor CTL generation (50–70%).
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Discussion |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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has been shown to be of crucial
importance for CTL generation in this system (17), we
hypothesized that the inhibitory effect of NE for anti-MOPC-315 CTL
generation is associated with NE-induced suppression of TNF-
production. Here, we show that, indeed, concentrations of NE inhibitory
to anti-MOPC-315 CTL generation caused a decrease in the
concentration of TNF- in spleen culture supernatants and a decrease
in the percentages of TNF-+ cells among
various splenic subpopulations having potential importance for the
generation of a CTL response. Moreover, the addition of TNF- to the
spleen cell cultures largely overcame the NE-mediated inhibition of the
generation of the anti-MOPC-315 CTL response, further suggesting
that NE down-regulation of TNF- may be responsible for the decreased
antitumor response.
The decrease in TNF- level upon exposure of the spleen cell cultures
to NE was evident at both mRNA and protein levels. The inhibitory
effect of NE on TNF- mRNA levels indicates that mechanisms relating
to transcription and/or mRNA stability are involved. However, the
possibility that NE also exerts translational or posttranslational
effects on the generation or localization of TNF- protein has not
been ruled out by the experiments described in this report.
Our flow cytometric analysis showed that NE caused decreases in
intracellular levels of TNF- protein in at least three spleen cell
subpopulations: CD8+ T cells,
CD4+ T cells, and F4/80+
activated macrophages. Since all of these cell types can serve as
physiologically significant sources of TNF-, it is reasonable to
hypothesize that any or all of them could be key targets for NE
inhibition that interrupts a paracrine or an autocrine TNF-
signaling pathway critical for CTL generation. However, despite the
importance of CD4+ T cell-mediated "help" to
many cellular immune responses, our previous finding that depletion of
CD4+ T cells from spleen cell preparations just
before initiation of stimulation cultures does not affect
anti-MOPC-315 CTL generation (25), suggests that the
production of TNF- by CD4+ cells may not be
essential for the generation of anti-MOPC-315 cytotoxicity. Thus,
the NE-mediated decreases in expression of intracellular TNF- by
CD8+ T cells and/or by
F4/80+ activated macrophages are considered to be
more likely to have a role in CTL down-regulation in the MOPC-315
system.
We show here that the NE inhibitory effect for CTL generation can be
substantially overcome by the addition of exogenous TNF-. Our
finding that TNF- does not completely overcome the inhibitory effect
of NE for CTL generation may be due to the fact that NE also decreases
production by the tumor-stimulated spleen cell cultures, of two
additional "type 1" cytokines (IL-2 and IFN-) that have been
reported to promote cell-mediated immunity in a number of systems
(4, 26, 27). While the experiments presented in this
communication provide support for the idea that TNF- is important
for the generation of antitumor spleen cell CTL activity, possible
roles for the observed NE inhibitory effects on IL-2 and IFN- also
merit consideration. Indeed, results of a preliminary study (V.
Kalinichenko, unpublished observations) indicate that addition of
exogenous IL-2 also partially restores the generation of antitumor CTL
activity in L-PAM TuB spleen cell cultures in the presence
of NE, and addition of TNF- and IL-2 together totally overcame NE
inhibition of CTL generation.
In view of previous results suggesting a possible negative role for
IFN- in the generation of antitumor CTL activity in the
L-PAM TuB spleen culture system (19), it does
not seem likely that the NE inhibition of IFN- production observed
in the current studies plays a major role in the inhibitory
activity of NE for CTL generation. However, IFN- does enhance many
cellular immune responses (27, 28). Thus, NE-mediated
down-regulation of IFN- expression, such as that described here, is
likely to have an important role in stress-associated inhibition of
host immunity against a variety of infectious agents, parasites, and
tumors.
The ß-AR antagonist propranolol was found, in our studies, to
completely reverse NE-mediated decreases in the amount of TNF- mRNA
in total spleen cell RNAs. In previous studies of cytolytic activity,
propranolol was unable to antagonize the inhibitory effects of
long-term (5-day) incubation with NE on the generation of antitumor CTL
activity (16). In contrast, in the current studies, NE
potently inhibited antitumor CTL generation when the spleen cells were
exposed transiently (3 h) to NE, and then cultured for 5 days in its
absence, and this inhibition was largely antagonized by propranolol
(18). These findings indicate that NE-mediated activation
of the ß-AR/cAMP/PKA pathway can be an effective mechanism for the
NE-mediated inhibition of antitumor CTL generation. The potent
CTL-inhibitory effects of cAMP/PKA stimulation is further supported by
earlier results in our laboratory, wherein cholera toxin, a stimulator
of endogenous cAMP production, and dibutyryl-cAMP, a
membrane-penetrating analogue of cAMP, also potently inhibited the
generation of anti-MOPC-315 cytotoxicity (16).
However, the current findings that the propranolol reversal of
short-term NE-mediated inhibition of antitumor CTL generation is only
partial (40–70%) is consistent with our earlier findings that
NE is capable of directing major ß-AR-independent inhibitory effects
on the generation of tumor-directed CTL immunity (16).
Taken together, these findings suggest that the ß-AR-independent
actions of NE cause only partial, albeit significant, inhibition of
antitumor CTL generation if NE exposure is of short duration, but that
the ß-AR-independent inhibition becomes increasingly prominent as
time of exposure of the L-PAM TuB spleen cell cultures to
NE is increased. Within 5 days of NE exposure, the ß-AR-independent
(propranolol-insensitive) component of NE inhibition of CTL generation
becomes dominant and obscures the ß-AR-dependent
(propranolol-sensitive) component.
The ability of NE to suppress the generation of anti-MOPC-315
cytotoxicity by L-PAM TuB spleen cells by down-regulating
TNF- production suggests that stress-induced elevation of NE levels
may also down-regulate the in vivo acquisition of CTL activity against
tumor cells by down-regulating TNF- production. Our current studies
illustrate that the inhibitory effect of NE upon CTL generation can be
largely overcome by addition of exogenous TNF-. These results
suggest that elevation of TNF- levels in vivo could help to overcome
the inhibitory effect of stress-induced NE elevation for the
development of CTL activity. Enhanced understanding of these mechanisms
may facilitate the therapeutic effectiveness of modalities that depend
on the development of antitumor CTL activity for tumor eradication.
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Footnotes |
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2 Address correspondence and reprint requests to Dr. Donald A. Chambers, Department of Biochemistry and Molecular Biology, University of Illinois, 1819 West Polk Street, Chicago, IL 60612. E-mail address:
3 Abbreviations used in this paper: ß-AR, ß-adrenergic receptor; NE, norepinephrine; L-PAM, L-phenylalanine mustard; L-PAM TuB mice, mice treated with a low dose of L-PAM when they bore a large tumor; PKA, protein kinase A.
Received for publication March 18, 1999. Accepted for publication June 14, 1999.
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References |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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-interferon-induced major histocompatibility class II (Ia) antigen expression on cultured astrocytes via ß-2-adrenergic signal transduction mechanisms. Proc. Natl. Acad. Sci. USA 85:1292. on the activation of human lymphocytes. Cell. Immunol. 111:461.[Medline]
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, Indicate statistically significant decreases in the
concentrations of TNF-
