| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Opioid Receptors (DOR) on Human Peripheral Blood CD4+ T Cells and DOR-Dependent Suppression of HIV-1 Expression1
*
Department of Pharmacology, Health Science Center, University of Tennessee, Memphis, TN 38120; and
Department of Medicine, Hennepin County Medical Center and University of Minnesota, Minneapolis, MN 55415
 |
Abstract |
|---|
 Top Abstract IntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
opioid receptors (DORs) modulate T cell proliferation, IL-2
production, chemotaxis, and intracellular signaling. Moreover, in
DOR-transfected Jurkat cells, opioids have been shown to suppress
HIV-1 p24 Ag expression. These observations led us to characterize the
expression of DORs by human peripheral blood T cells and to determine
whether a specific DOR agonist,
benzamide,4-{[2,5-dimethyl-4-(2-propenyl)-1-piperazinyl](3-methoxyphenyl)methyl]-N,-,{2S[1(S*),2
,5
]}-(9Cl)
(SNC-80), can suppress p24 Ag expression by HIV-1-infected
CD4+ T cells obtained from normal donors. By
immunofluorescence flow cytometry, PHA stimulated the expression of DOR
from 1.94 ± 0.70 (mean ± SEM) to 20.70 ± 1.88% of
the PBMC population by 48 h (p < 0.0001). DOR
expression was 
40% of both the PHA-stimulated CD4+ and
CD8+ T cell subsets, and virtually all DORs were found on
these subsets. To determine whether activated DORs suppress HIV-1
expression, PBMC were prestimulated with PHA, and then CD4+
T cells were purified, pretreated with SNC-80, and infected with HIV-1.
In a concentration-dependent manner, SNC-80 inhibited production of p24
Ag. SNC-80 10-10 M maximally suppressed (50%) both
lymphocytotropic (HIV-1 MN) and monocytotropic (SF162) strains; higher
concentrations were less effective. Naltrindole, a selective DOR
antagonist, abolished the inhibitory effects of SNC-80. Kinetic studies
indicated that 24-h pre- or postincubation with SNC-80, relative to
infection with HIV-1, eliminated its suppressive effects. Thus,
stimulating the DORs expressed by activated CD4+ T cells
significantly suppressed the expression of HIV-1. These findings
suggest that opioid immunomodulation directed at host T cells may be
adjunctive to standard antiviral approaches to HIV-1
infection. |
Introduction |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
opioid agonists modulate the immune function of lymphocytes located
in solid lymphoid organs and the peripheral circulation. Some of these
effects of synthetic opioids appear to emulate the actions of the
endogenous opioid peptides produced by lymphocytes. Indeed, enkephalin
peptides (e.g., methionine enkephalin) have been identified in splenic
extracts obtained from naive rats, and Con A induced the expression of
preproenkephalin A mRNA by CD4+ murine thymocytes
in vitro (1, 2). Acting through
DORs,3
endogenous enkephalins appear to modulate Con A-stimulated murine
thymocyte proliferation (3). Pharmacological studies also
have shown that synthetic DOR agonists modulate proliferation and IL-2
production by highly purified murine splenic CD4+
and CD8+ T cells stimulated through the TCR
complex in vitro (4).
DOR ligands have been shown to affect lymphocyte intracellular
signaling. Thus, methionine enkephalin exerted biphasic effects on cAMP
levels in human PBL and -endorphin (antagonized by DOR-selective
naltrindole (NTI)), or (D-Ala(2),
D-Leu(5)) enkephalin (DADLE) enhanced the Con
A-induced mobilization of intracellular free calcium by murine splenic
T cells (5, 6). Recent studies also have shown that
DADLE inhibited the anti-CD3-induced phosphorylation of the
mitogen-activated protein kinases, extracellular signal-related kinases
(ERKs) 1 and 2, in murine splenocytes (7).
DOR transcripts have been found in mononuclear cells from several
species. To detect DOR mRNA in simian PBMC, human PBL, and murine
splenocytes, several laboratories have used RT-PCR techniques
(8, 9, 10, 11). DOR transcripts were identified in freshly
obtained simian mononuclear cells and murine splenocytes (8, 11), and expression in murine splenic T cells was enhanced by
cell culture in the absence of mitogens, by Con A, and by cross-linking
the TCR with anti-CD3-
(10, 11, 12). Apparently,
mitogenic stimulation with PHA was required to detect DOR transcripts
in human PBL (9). Thus, low levels of DOR mRNA are present
in lymphocytes found in the systemic circulation of several species,
and substantial induction occurs with lymphocyte stimulation. The
inducible expression of DOR transcripts is consistent with recent
observations on the detection of immunofluorescent DOR protein on
murine splenocytes and T cells obtained after in vivo stimulation with
a single injection of the superantigen, staphylococcal enterotoxin B
(7).
Previous studies have shown that morphine enhanced HIV-1 propagation in
acutely infected PBMC, apparently through µ-like opioid receptors
(13). Several lines of evidence suggest that DORs may
modulate the expression of HIV-1 by normal human
CD4+ T cells. These include the modulatory
effects of DORs on T cell function, the induction of DOR transcripts in
T cells from several species, the recent report of DOR
immunofluorescence on murine T cells, and our previous study showing
that DOR ligands suppressed HIV-1 p24 production by Jurkat cells stably
transfected with a DOR cDNA (DOR-Ju.1 cells) (14, 15). In
the latter study, two DOR agonists, deltorphin and
benzamide,4-{[2,5-dimethyl-4-(2-propenyl)-1-piperazinyl](3-methoxyphenyl)methyl}-N,-,
[2S-[1(S*),2,5]}-(9Cl) (SNC-80),
concentration dependently inhibited the production of p24 Ag, an index
of HIV-1 expression; maximal suppression was observed with
10-13–10-9 M SNC-80
(>60% reduction) or
10-15–10-11 M deltorphin
(>50% reduction).
The objectives of the present study were to characterize the expression
of DOR immunofluorescence by human T cells and to determine whether DOR
agonists suppress p24 Ag production by normal peripheral blood
CD4+ T cells that have been acutely infected with
HIV-1. Immunofluorescence flow cytometry was used to measure DOR
expression by resting and mitogen-stimulated CD4+
vs CD8+ T cells and to determine whether memory
and/or naive cells express DOR. To evaluate whether activated DORs
affect HIV-1 propagation, normal PBMC were PHA stimulated, and
CD4+ T cells were purified and then pretreated
with SNC-80 before infection with either of two strains of HIV-1. Cells
were cultured for 3 days, and p24 Ag production was measured in culture
supernatants. These studies demonstrated that PHA induced the
expression of DORs on 40% of both CD4+ and
CD8+ T cells. Signaling through DORs
substantially reduced the propagation of both lymphocytotropic and
monocytotropic strains of HIV-1 in normal human peripheral blood
CD4+ T cells.
|
Materials and Methods |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
Human PBMC were isolated from units of whole blood randomly obtained from healthy male donors at Life Blood (Memphis, TN). Whole blood was diluted 1/2 with PBS, layered onto lymphocyte separation medium (ICN, Aurora, OH), and centrifuged (400 x g) for 25 min at 24°C. The middle layer was removed and again spun, the pellet was resuspended, and the RBC were lysed with alkaline lysis buffer (0.15 M ammonium chloride, 0.01 M potassium carbonate, 1 mM Na EDTA). After centrifugation, the pellet was resuspended at 2 x 106 cells/ml in culture media within small flasks (RPMI 1640, 5% FBS with penicillin, streptomycin, and glutamine), and either vehicle or PHA, 5 µg/ml (Sigma, St. Louis, MO), was added for 48 or 96 h of culture.
Immunofluorescence flow cytometry
After cell culture, human PBMC were fixed with 4%
paraformaldehyde for 10 min at 4°C, washed three times with TBS
containing 1% donkey serum (50 mM Tris-HCl, 150 mM NaCl, pH 7.4), and
then incubated overnight at 4°C with blocking buffer (5% donkey
serum in TBS). Cells were incubated with both rabbit anti-DOR
antisera (1/400 dilution; raised against the N-terminal peptide of DOR
(aa 3–17 of the murine receptor); Chemicon International, Temecula,
CA) and mouse anti-human-CD4 or anti-human-CD8 (BD PharMingen,
San Diego, CA) for 2 h at 22°C, and then washed and incubated
with biotinylated donkey anti-rabbit IgG for 60 min at 22°C.
Thereafter, cells were washed extensively, incubated for 10 min at
4°C with fluorescein avidin defined calf serum (Vector Labs,
Burlingame, CA), again washed, and then resuspended in TBS. To evaluate
the expression of DORs by naive vs memory cells, CyChrome
anti-human CD45RA or CyChrome anti-human CD45RO
(PharMingen, San Diago, CA) and their isotype (CyChrome mouse IgG1,
) were used. Cytofluorometric analyses (104
cells per run) were performed using an EPICS XL flow cytometer
(Coulter, Palo Alto, CA) equipped with an argon laser, and filtered for
excitation at 488 nm and emission at 526 and 682 nm. For background
control, normal rabbit serum (NRS) substituted for the primary antisera
against DOR, CyChrome mouse IgG1, (isotype) for anti-CD4,
anti-CD8, anti-CD45RA, or anti-CD45RO. Mean background
immunofluorescence levels at 48 and 96 h ranged from 1.1 to 2.1%
(NRS) or 1.7 to 2% (isotype) in unstimulated cells, and from 6.1 to
4.5% (NRS) or 2 to 3.7% (isotype) in PHA-stimulated cells. The
background cytofluorometric signal, determined for each quadrant in
each experiment, was subtracted from the total signal in that quadrant.
Immunoneutralization with the N-terminal DOR Ag reduced PHA-stimulated
anti-DOR immunofluorescence from 20.5 ± 1.5% of total PBMC
to 3.3 ± 0.4% of the population.
Lymphocyte activation and purification before HIV-1 infection
Four healthy, HIV-1-seronegative laboratory personnel served as
donors of venous blood. From heparinized blood, PBMC were obtained by
Ficoll-Hypaque centrifugation using lymphocyte separation medium. PBMC
were then activated for 3 days with 4 µg/ml PHA in RPMI supplemented
with 10% heat-inactivated FBS, 5 U/ml IL-2, 2
mM-L-glutamine, 100 U/ml penicillin, and 100 µg/ml
streptomycin. CD4+ lymphocytes were then isolated
from the activated PBMC using Dynabeads (Dynal, Lake Success, NY),
according to directions supplied by the manufacturer. Briefly, magnetic
polystyrene beads coated with primary mAb to CD4 were incubated with
PBMC for 45 min at 4°C on an orbital rotator at cell-bead ratio of
1:4. The lymphocytes bound to the beads were separated using a magnet
(Dynal MPC) and washed four times with PBS containing 2% FBS. After
isolation, DETACHaBEAD was used to remove the isolated
CD4+ cells from Dynabeads (1 µm/100-µl cell
suspension was used to detach positively selected lymphocytes from the
magnetic beads using a Dynal-MPC magnet). Isolated
CD4+ lymphocytes were 
98% pure by FACScan
analysis and were 98% viable by trypan blue dye exclusion
criteria.
Human immunodeficiency virus-1
The HIV-1 MN isolate used in this study was originally recovered from the peripheral blood of an asymptomatic HIV-1-infected patient and prepared as previously described (13). This viral isolate has characteristics most suggestive of a T-tropic strain, i.e., it replicates readily in the T cell line H9 and in primary activated CD4+ lymphocytes, but is not expressed in cultures of human microglial cells, which are primary brain macrophages that are productively infected by M-tropic, but not by T-tropic HIV-1 strains. In addition, a monocytotropic HIV-1 isolate, SF162, was tested. This was provided by the National Institutes of Health AIDS Research and Reference Reagent Program (National Institute of Allergy and Infectious Diseases, Rockville, MD).
Drug treatment and HIV-1 infection of CD4 lymphocytes
Purified activated CD4+ lymphocytes were incubated with SNC-80, a DOR-specific agonist, and/or NTI, a DOR-specific antagonist, at varying concentrations for indicated time periods before or postinfection with either strain of HIV-1 at a multiplicity of infection of 0.02. NTI and SNC-80 were provided by Drs. P. Portoghese (University of Minnesota) and K. Rice (National Institutes of Health), respectively. After 2 h of incubation with HIV-1 at 37°C, CD4+ lymphocytes were washed three times with PBS and resuspended in culture medium (RPMI 1640, 10% FBS, penicillin/streptomycin, 2 µg/ml PHA, and 5 U/ml IL-2) containing SNC-80. Three days postinfection, culture supernatants were collected in duplicate for HIV-1 p24 Ag assay.
HIV-1 p24 Ag assay
HIV-1 p24 Ag levels were measured using an enzyme-linked immunoassay (Abbott Laboratories, Abbott Park, IL), as previously described. A standard dilution curve derived from known amounts of p24 Ag was used to quantify the Ag levels in culture supernatants. The sensitivity of this assay is 30 pg/ml.
Statistical analysis
Data are expressed as means ± SEM. For comparisons of multiple group means, analysis of variance was performed and, except where noted, posthoc testing utilized Scheffé’s test. As indicated, other comparisons were performed with t tests.
|
Results |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
A is a representative experiment in which the distribution of
cells expressing either DOR and/or CD4 or DOR and/or CD8 is shown. By
48 h, PHA increased the fraction of
DOR+/CD4+ and
DOR+/CD8+ T cells. Both
groups were composed of subsets expressing higher and lower levels of
CD4+ or CD8+. To determine
whether this was related to differences in cell size, the T cell
subsets were gated to measure the fraction of small cells. In both the
CD4+ and CD8+ populations,
similar percentages of small cells were found in the subsets expressing
higher or lower levels of these surface markers (fraction of small
cells in the lower CD4+ subset, 79% ± 1.4 vs
higher CD4+, 81.8% ± 1.9; and lower
CD8+, 86.5% ± 0.6 vs higher
CD8+, 87.2% ± 0.8). Therefore, regardless of
the level of CD4+ or CD8+
expression, DOR was predominantly detected on small cells.
|
B represents the quantitative data (mean ± SEM)
from four experiments in which PBMC were stimulated with PHA for 48 or
96 h, and the background cytofluorometric signal (NRS or isotypes)
was subtracted. Considering the total PBMC population, 2–3% was DOR
positive after 48 or 96 h of cell culture in the absence of
mitogen; PHA increased the DOR-positive fraction by 10-fold at 48
h (p < 0.001). By 96 h, DOR expression
remained elevated in PHA-stimulated cells (p <
0.001 compared with saline control), but the fraction of
DOR+ cells was less than at 48 h
(p < 0.01). The fluorescence intensity per
cell was determined at 48 h in the PHA vs vehicle-treated cells. A
3.3-fold increase in DOR fluorescence intensity per cell was observed
(mean channel fluorescence: 0.119 ± 0.023 for vehicle and
0.373 ± 0.067 for PHA, n = 4 per group;
p = 0.012).
The fraction of CD4+ or
CD8+ T cells was slightly increased by PHA (data
not shown). However, Fig. 1B shows that PHA greatly
increased the percentage of these subsets that expressed DOR at both
time intervals (p < 0.001). By 48 h,
40% of both the CD4+ and the
CD8+ subsets were DOR positive, an increase from
6% in the respective vehicle-treated cultures. The fraction of
cells expressing DOR in the PHA-stimulated CD4+
and CD8+ subsets declined significantly by
96 h (p < 0.05). In PHA-stimulated cell
cultures, calculations showed that DOR-positive cells were either
CD4+ or CD8+ cells.
In three separate experiments, CD45RA and CD45RO were used to determine
whether DOR is expressed by naive or memory T cells. These studies were
performed 48 h after stimulation by PHA, a time when the fraction
of CD45RA+ and CD45RO+
cells was unaffected by PHA (Fig. 2). In contrast, additional experiments showed that between 2 and 6 days
of PHA diminished the CD45RA+ fraction (45
± 2% to 24 ± 2%, respectively; p < 0.0001,
n = 6) and elevated the CD45RO+
fraction during this time interval (51 ± 1% to 61 ± 1%,
respectively; p < 0.0001, n = 6). The
experiments in Fig. 2 showed that PHA significantly increased the
fraction of cells positive for both DOR and CD45RA from 2% (vehicle
treated) to 15% of the total PBMC. Since all
DOR+ cells were T cells and 40% of total PBMC
were T cells, calculations demonstrated that 37% of T cells were
positive for both DOR and CD45RA. Similarly, PHA significantly
increased the fraction of
DOR+/CD45RO+ in total PBMC
from 4% in the vehicle-treated group to 16%; 41% of T cells were
positive for both Ags. Thus, PHA stimulated similar fractions of both
CD45RA- and CD45RO-positive T cells to express DOR.
|
shows that SNC-80, a DOR-specific agonist, dose dependently inhibited
50% of the p24 Ag accumulated in the supernatant from
CD4+ T cells that were cultured for 3 days after
infection with HIV-1. SNC-80 was effective when cells were pretreated
for 1 h before infection, but not 24 h pre- or postinfection.
A more comprehensive dose-response study was performed with
CD4+ cells from four healthy donors (Fig. 4). In the upper panel of Fig. 4, p24 Ag production by cells
infected with HIV-1 MN was maximally suppressed by SNC-80
10-10 M; an inverted U-shaped dose-response
relationship was observed. Using blood obtained from the same donors,
the lower panel of Fig. 4 shows that SNC-80 had a similar
effect on p24 Ag production by cells infected with the SF162 strain of
HIV-1.
|
|
shows that the specific DOR antagonist, NTI, markedly reduced the
suppressive effects of SNC-80 on p24 Ag accumulation. As expected, in
the absence of NTI, SNC-80 10-10 M reduced p24
Ag expression by 50% when supernatant from cells infected with
either the MN (Fig. 5, upper panel) or SF162 strain (Fig. 5, lower panel) was assayed. At 10-9 and
10-10 M, NTI effectively blocked the suppressive
effects of SNC-80, whereas NTI alone had no effect.
|
|
Discussion |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
40% of these subsets. After PHA stimulation, the DOR-positive cells
appeared in the T cell fraction, and similar fractions of both
CD45RA+ and CD45RO+ cells
had become DOR+. Subnanomolar concentrations of
the DOR agonist, SNC-80, were shown to suppress the production of p24
Ag by lymphocytotropic and monocytotropic strains of HIV-1. The
specificity of this suppression was evident in its concentration
dependence and reversal by the DOR antagonist, NTI.
In several species, mononuclear cells contain DOR transcripts, although
very few studies have provided substantial evidence for the detection
of DOR itself (19, 20). DOR transcript levels are
uniformly low in freshly obtained mononuclear cells, requiring reverse
transcription with PCR and a relatively large number of amplification
cycles for detection in simian and human PBMC and in murine splenocytes
(8, 9, 10, 11). In murine splenocytes, recent studies have shown
that stimulation in vivo or in vitro significantly increased the level
of DOR transcripts. This was evident after in vivo treatment with a
single injection of staphylococcal enterotoxin B, which produced a
2-fold increase by 8 h (7). In vitro, Con A and
anti-CD3- had similar effects, stimulating transcript expression
by T cells, including CD4+ and
CD8+ subsets (10, 11, 12). T cell DOR
transcripts increased from <1 copy/cell to 22 and 42 copies/cell after
24 and 48 h of anti-CD3- (12). Moreover,
experiments with actinomycin D implied that transcriptional activation
mediates the anti-CD3--driven increase (12).
By 48 h in culture, PHA stimulated a 5- to 7-fold increase in DOR
immunoreactivity in the CD4+ and
CD8+ T cell subsets, respectively. Accounting for
40% of these T cell subsets, this level of DOR expression declined
by 96 h in both T cell subsets. After PHA stimulation, these
DOR+ T cells represented virtually all of the
DOR+ cells. Since the fraction of
CD45RA+ and CD45RO+ cells
was unaffected by PHA at 48 h (in contrast to 6 days), it is
likely that individual T cells had not changed their status with
respect to the expression of these Ags at this time interval. This
suggests that similar percentages of T cells positive for CD45RA or
CD45RO were induced to express DOR by PHA. Thus, these studies provide
evidence for the activation-associated expression of DOR on both naive
and memory T cells in response to PHA (16, 17, 18).
DORs are seven-transmembrane G protein-coupled receptors that were
originally cloned from neural cells and have been studied extensively
in the nervous system (21). In the immune system, DORs
have been shown to modulate Con A-stimulated calcium mobilization and
anti-CD3--induced phosphorylation of the extracellular-regulated
kinases, ERK1, 2, in splenocytes (6, 7). From a functional
perspective, DOR agonists, produced endogenously, are known to suppress
Con A-stimulated thymocyte proliferation (3). In addition,
synthetic DOR agonists suppressed the anti-CD3--driven
proliferation of highly purified CD4+ and
CD8+ splenic T cells, and the production of IL-2
(4). Our previous experiments demonstrated that DOR
ligands suppressed HIV-1 p24 Ag production by Jurkat cells stably
transfected with a DOR cDNA (DOR-Ju.1 cells) (14, 15). Two
DOR agonists, deltorphin and SNC-80, concentration dependently
inhibited the production of p24 Ag, and maximal suppression was
observed with 10-13–10-9
M SNC-80 (>60% reduction) or
10-15–10-11 M deltorphin
(>50% reduction). At higher concentrations, neither agonist was
effective. Although not well understood, this U-shaped dose-response
function may reflect the interaction of intracellular signaling
cascades, which varies with agonist concentration.
In the present investigations, we observed a similar concentration
dependence and degree of suppression of p24 Ag production by activated
human peripheral blood T cells inoculated with HIV-1 MN or SF162. At a
concentration of 10-10 M, SNC-80 was maximally
effective, whereas at 10-7 M, suppression was no
longer evident. In both strains of HIV-1, maximal suppression was
50%. This degree of suppression coheres with our finding that
40% of CD4+ T cells express DOR within the
time interval (48 h) used to activate the PBMC before inoculation with
HIV-1. If these observations are causally related, it would suggest
that DOR agonists are able to suppress p24 Ag expression to a much
greater degree in the CD4+ T cell subpopulation
that are DOR+.
These investigations indicate that a relatively brief preincubation
with SNC-80 was required; in contrast, a 24-h pre- or posttreatment
with SNC-80 was ineffective. Preincubation is required for the effects
of DOR agonists on other immune functions. For example, suppression of
the anti-CD3--stimulated proliferation of highly purified murine
splenic T cell subsets and IL-2 production was optimal when lymphocytes
were treated with DOR agonists for 1 h before culture with
anti-CD3- (4). In addition, for the suppressive
effect of DOR agonists on anti-CD3--induced ERK phosphorylation,
pretreatment was necessary (7). These observations suggest
that preincubation with a DOR agonist modulates the activity of
intracellular pathways involved in TCR-dependent signaling. This may
reflect the effects of DORs on the tyrosine phosphorylation of
intracellular signals known to regulate cell growth and proliferation
(22). Somatostatin, a ubiquitous extracellular signal
peptide that activates Gi protein-coupled receptors, also has been
shown to inhibit the growth and proliferation of a variety of cell
lineages (23). Indeed, somatostatin-enhanced
phosphotyrosine phosphatase activity, which inactivates growth factor
receptor kinases, has been implicated in its action
(23, 24, 25). Thus, phosphotyrosine phosphatases may be
involved in mediating the intracellular action of DORs, which, like
somatostatin receptors, are commonly coupled to Gi proteins.
In previous studies, preincubation was also required for the effects of
morphine on HIV-1 p24 Ag expression by human PBMC cocultures
(13). In these studies, normal donor PBMC were incubated
with morphine sulfate and then activated with PHA before the addition
of HIV-1-infected PBMC. The morphine-enhanced expression of HIV-1 p24
Ag was both stereoselective and reversible by µ opioid
receptor-specific antagonists (13). Although this report
contrasts with the present observations and with our report on the
inhibitory effects of DOR agonists on HIV-1-infected DOR-Ju.1 cells,
there are important differences in experimental design. The
ligand-receptor interactions of morphine and SNC-80 depend on two
different opioid receptor subtypes that can couple to different
intracellular effectors, depending on cell type. In addition, the
design of the present studies suggests that the effects of DOR ligands
were directly on T cells, whereas it is not possible to precisely
identify the cellular target in the previous experiments with PBMC
cocultures. Thus, the contrasting effects of µ vs opioids on
HIV-1 p24 Ag expression are likely to reflect differences in the
receptor-specific intracellular effectors that are modulated by these
compounds.
Both the requirement for preincubation with SNC-80 and the suppressive effects of DOR agonists on lymphocytotropic and monocytotropic strains of HIV-1 suggest that early cellular events involved in viral replication may be affected by activating DORs. Viral entry is a good candidate since HIV-1 gains access to CD4+ T cells by interacting with both CD4 molecules and chemokine coreceptors (26). In support of this, a recent study reported that DOR agonists inhibited chemokine-induced chemotaxis by inducing the phosphorylation and desensitization of the chemokine receptor (27).
In summary, these studies have shown that a large fraction of
CD4+ and CD8+ T cells can
be induced to express DORs by mechanisms dependent on activation
through the TCR. DORs, which modulate intracellular signaling pathways
affecting T cell function, can suppress the expression of p24 Ag by
HIV-1-infected CD4+ T cells. These findings
suggest that adjunctive opioid immunotherapy may augment the
antiviral therapy of HIV-1 infection.
|
Footnotes |
|---|
2 Address correspondence and reprint requests to Dr. Burt M. Sharp, Department of Pharmacology, Health Science Center, University of Tennessee, 874 Union Avenue, Memphis, TN 38163. E-mail address: bsharp{at}utmem.edu
3 Abbreviations used in this paper: DOR, opioid receptor; ERK, extracellular signal-related kinase; NRS, normal rabbit serum; NTI, naltrindole; SNC-80, benzamide,4-{[2,5-dimethyl-4-(2-propenyl)-1-piperazinyl](3-methoxyphenyl)methyl}-N,-,{2S[1(S*),2,5]}-(9Cl).
Received for publication November 10, 2000. Accepted for publication May 3, 2001.
|
References |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
opioids on highly purified CD4+ and CD8+ murine T-cells. J. Pharmacol. Exp. Ther. 273:1105.-Endorphin enhances concanavalin A-stimulated calcium mobilization by murine splenic T-cells. Endocrinology 137:3386.[Abstract]
opioid receptors by splenocytes from SEB-treated mice and effects on phosphorylation of MAP kinase. Cell. Immunol. 205:84.[Medline]
opioid receptor mRNA in murine splenocytes. J. Neuroimmunol. 78:198.[Medline]
opioid receptor expression by anti-CD3-, PMA, and ionomycin in murine splenocytes and T cells. J. Leukocyte Biol. 65:707.[Abstract]
opioid receptors in a transfected human T-cell line. Proc. Natl. Acad. Sci. USA 93:8294.
production. J. Immunol. 140:1401.[Abstract]
- and -classes. J. Endocrinol. 122:161. opioid receptor by functional expression. Science 258:1952. and µ opiate receptor-mediated heterologous desensitization. J. Exp. Med. 188:317.This article has been cited by other articles:
|
|
 |
|
  S. A Mousa, R. H Straub, M. Schafer, and C. Stein {beta}-Endorphin, Met-enkephalin and corresponding opioid receptors within synovium of patients with joint trauma, osteoarthritis and rheumatoid arthritis Ann Rheum Dis, July 1, 2007; 66(7): 871 - 879. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 N. A. Shahabi, K. McAllen, and B. M. Sharp {delta} Opioid Receptors Stimulate Akt-Dependent Phosphorylation of c-jun in T Cells J. Pharmacol. Exp. Ther., February 1, 2006; 316(2): 933 - 939. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 I. Tegeder and G. Geisslinger Opioids As Modulators of Cell Death and Survival--Unraveling Mechanisms and Revealing New Indications Pharmacol. Rev., September 1, 2004; 56(3): 351 - 369. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 E. Stener-Victorin and C. Lindholm Immunity and {beta}-Endorphin Concentrations in Hypothalamus and Plasma in Rats with Steroid-Induced Polycystic Ovaries: Effect of Low-Frequency Electroacupuncture Biol Reprod, February 1, 2004; 70(2): 329 - 333. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 I. Szabo, M. A. Wetzel, N. Zhang, A. D. Steele, D. E. Kaminsky, C. Chen, L.-Y. Liu-Chen, F. Bednar, E. E. Henderson, O. M. Z. Howard, et al. Selective inactivation of CCR5 and decreased infectivity of R5 HIV-1 strains mediated by opioid-induced heterologous desensitization J. Leukoc. Biol., December 1, 2003; 74(6): 1074 - 1082. [Abstract] [Full Text]
|
|
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
