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Cutting Edge |
Promotes a Th2 Bias and Enhances Suppression of Autoimmune Encephalomyelitis by Oral Glatiramer Acetate1





* Center for Neurologic Diseases, Brigham and Womens Hospital, Harvard Medical School, Boston, MA 02115;
Department of Neurology, University of California, San Francisco, CA 94143;
Department of Neurology, Stanford Medical School, Stanford, CA 94305; and
Department of Microbiology and Cell Science, University of Florida, Gainesville, FL 32611
| Abstract |
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, a novel type I IFN that possesses immunomodulatory
properties, lacks toxicity normally associated with other type I IFNs.
We examined the effects of oral IFN-
alone and in combination with
oral glatiramer acetate in experimental allergic encephalomyelitis
(EAE). By comparison of oral administration of IFN-
, -
, and -
to myelin basic protein-specific TCR-transgenic mice, we demonstrate
these type I IFNs promote secretion of the Th2 cytokine IL-10 with
similar efficiency. Whereas IFN-
and -
induced IFN-
secretion,
a Th1 cytokine, IFN-
did not. Oral IFN-
alone suppressed EAE.
When suboptimal doses were administered orally in combination to
wild-type mice, IFN-
and glatiramer acetate had a synergistic
beneficial effect in suppression of EAE. This combination was
associated with TGF-
secretion and enhanced IL-10 production. Thus,
IFN-
is a potential candidate for use as a single agent or in
combination therapy for multiple sclerosis. | Introduction |
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(1a and 1b) and glatiramer acetate
(GA4; Copaxone, Cop1)
are currently the only approved medications for treatment of
relapsing-remitting multiple sclerosis (MS) (1, 2). These
two classes of medications have distinct immunoregulatory
characteristics. IFN-
exerts several effects in an Ag-nonspecific
manner (1). Among its activities, IFN-
induces IL-10
secretion (3) and suppresses IFN-
-inducible MHC class
II up-regulation on APC (4). In contrast, GA, a synthetic
basic random copolymer composed of tyrosine (Y), glutamate (E), alanine
(A), and lysine (K), appears to preferentially affect T cells specific
for CNS autoantigens (5), altering their Ag/MHC
recognition not unlike altered peptide ligands (6, 7). GA
also induces populations of GA-reactive Th2 regulatory cells that may
provide bystander suppression in the CNS (8). Despite
approval, IFN-
and GA are only partially effective MS treatments,
and IFN-
, in particular, can be associated with significant side
effects and potential toxicity, underscoring the importance for
developing treatments that are more potent but also possess fewer
potential side effects. Because currently available MS treatments alone
are not entirely satisfactory, there is enthusiasm for testing
medications in combination for enhanced efficacy (9, 10).
In this regard, IFN-
and GA are currently being tested in
combination in relapsing-remitting MS (10).
IFN-
, a type I IFN first identified as a pregnancy recognition
hormone in ruminants (11), possesses antiviral and
immunoregulatory properties (11). Like IFN-
, IFN-
induces T cell secretion of IL-10 and suppresses IFN-
-inducible
class II up-regulation on APC. Similar to other type I IFNs, IFN-
is
acid stable (11). However, in contrast to other type I
IFNs, the biological activities of IFN-
have not been associated
with either significant side effects or toxicities (12, 13). IFN-
was effective in the prevention of both acute and
relapsing (11, 12) experimental allergic encephalomyelitis
(EAE), a model for MS (14). IFN-
also reversed ongoing
relapsing EAE (15). In addition, IFN-
was equally
effective in EAE when given orally as well as parenterally (12, 13). Based upon these observations oral IFN-
was tested in a
phase I MS clinical trial (16). No toxicity was observed.
Thus, because IFN-
lacks toxicity and can be given orally, it is
considered an attractive candidate for further evaluation in MS
therapy.
In the present study, we evaluated the combination of oral IFN-
and
GA in EAE. First, we examined how oral IFN-
alone influences T cell
cytokine secretion in myelin basic protein (MBP)-specific
TCR-transgenic mice. These mice, which contain a homogeneous population
of naive MBP Ac1-11-specific CD4+ (Th0) cells,
serve as a valuable resource to test how immunomodulatory agents
influence T cell activation and differentiation of CNS Ag-specific T
cells. IFN-
administration induced lymphocyte secretion of IL-4,
IL-5, and IL-10 but, in contrast to IFN-
and -
, IFN-
did not
induce IFN-
. Thus, IFN-
supported a Th2 pattern of T cell
differentiation. When administered in combination to wild-type mice at
suboptimal doses, IFN-
and GA had a synergistic beneficial effect in
suppression of EAE. The combination of GA and IFN-
promoted
lymphocyte secretion of TGF-
and enhanced IL-10.
| Materials and Methods |
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PL/J MBP Ac1-11-specific TCR-transgenic female mice (17) were provided by Dr. C. A. Janeway, Jr. (New Haven, CT). PL/J female mice were purchased from The Jackson Laboratory (Bar Harbor, ME). Experimentation was conducted at Brigham and Womens Hospital (Boston, MA) and the University of California (San Francisco, CA) with institutional approval according to the U.S. Public Health Services Policy on Human Care and Use of Laboratory Animals.
Antigens
MBP was prepared from mouse brains and purity was confirmed by gel electrophoresis and amino acid analysis. MBP Ac1-11 (Ac-ASQKRPSQRHG) was synthesized and HPLC purified.
EAE induction
EAE was induced in 10- to 12-wk-old female PL/J mice using 300 µg MBP in CFA containing 8 mg/ml H37Ra (Difco, Detroit, MI). Mice were injected on the flanks and base of the tail. A total of 400 ng of Bordetella pertussis toxin (List Biologicals, Campbell, CA) was administered i.v. on days 0 and 2.
Production and purification of IFN-
Ovine IFN-
gene was expressed in Pichia pastoris
using a synthetic gene construct and purified by sequential
DEAE-cellulose and hydroxyapatite chromatography (12).
Homogeneity was determined by SDS-PAGE and silver staining. Purified
IFN-
had a specific activity of 0.290.44 x
108 U/mg as measured by antiviral activity on
Madin Darby bovine kidney cells. Murine IFN-
and IFN-
were
obtained from Lee Biomolecular (San Diego, CA).
Administration of IFN-
and GA
IFN-
and GA were administered (100 µl each; 200 µl total
volume/day) using 18-gauge feeding needles from Fisher Scientific
(Norcross, GA). A total of 100 µl PBS was administered to mice
treated with IFN-
or GA alone. Mice were treated for 30 days in
experiments testing EAE suppression.
T cells, proliferation, and cytokine measurements
Spleen and lymph node cells were cultured in 96-well plates at
5 x 105 cells/well in X-vivo 20
(BioWhittaker, Walkersville, MD) and appropriate Ag concentrations.
Separate CD4+ and CD8+ T
cells from MBP Ac1-11-specific TCR-transgenic mice were prepared by
high-affinity negative selection using columns containing Ab-coated
glass beads to remove B cells, monocytes, and either
CD4+ or CD8+ cells (R&D
Systems, Minneapolis, MN). CD4+ and
CD8+ T cells were 95 and 8590% pure,
respectively, as measured by flow cytometry. For proliferation, 1
x 104 CD4+ or
CD8+ T cells were cultured in the presence of
5 x 105 irradiated PL/J splenocytes, pulsed
with 1 µCi/well [3H]thymidine at 72 h,
and harvested 16 h later. For cytokine measurements, culture
supernatants were collected at 24 h for IL-2 measurement, 48
h for IFN-
, IL-10, and TNF-
, 72 h for TGF-
, and 120
h for IL-4 and IL-5. Cytokines were measured by ELISA using kits from
BioSource International (Camarillo, CA) as described previously
(18). SE measurements for proliferation and cytokine
measurements were within 10% of the mean.
| Results and Discussion |
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with IFN-
and -
for in vivo induction of IL-10.
Unimmunized MBP Ac1-11-specific TCR-transgenic mice, used as a source
of naive MBP-specific T (Th0) cells, were fed three times with 1
x 105 U of IFN-
, IFN-
, or IFN-
.
Splenocytes, isolated 1 day after the last feeding, were stimulated
with MBP Ac1-11 in vitro. As shown in Fig. 1
was at least as potent as, if not more potent than, IFN-
at
inducing IL-10 secretion.
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(11, 19). In fact, it has been
observed that the frequency of IFN-
-secreting cells increases during
the first 2 mo of IFN-
1b treatment, possibly contributing to the
prominent "flu-like" symptoms that MS patients commonly experience
during initial treatment (19). Thus, we compared IFN-
,
-
, and -
for in vivo induction of IFN-
. IFN-
was
approximately twice as potent as IFN-
(Fig. 1
did not stimulate IFN-
secretion above the level
seen in control (vehicle (PBS)-fed) mice.
While the experiments described above demonstrated that IFN-
promoted IL-10 secretion and did not induce IFN-
, they did not
establish whether IFN-
treatment promoted secretion of other Th2
cytokines. Thus, we examined for secretion of IL-4 and IL-5 (Fig. 1
B). Splenocytes from IFN-
-fed MBP Ac1-11 TCR-transgenic
mice secreted IL-4, IL-5, and IL-10 when stimulated with MBP Ac1-11
(Fig. 1
B, insets), but reduced levels of IL-2 and IFN-
(data not shown). Similarly, lymphocytes from IFN-
-fed
wild-type PL/J mice immunized with MBP Ac1-11 or SJL/J
miceimmunized with encephalitogenic proteolipoprotein
peptidep139151 also secreted Th2 cytokines IL-4, IL-5, and
IL-10 and reduced levels of IL-2 and IFN-
(data not shown). To
examine whether CD4+ or
CD8+ cells were responsible for Th2 cytokine
secretion, CD4+ and CD8+
cells were purified from IFN-
-fed MBP Ac1-11-specific TCR-transgenic
mice and restimulated in the presence of fresh APC and MBP Ac1-11. As
shown in Fig. 1
B, these Th2 cytokines were produced in
cultures containing CD4+ T cells. In contrast, a
lower amount of IL-5 and only minimal levels of IL-4 or IL-10 were
detected in cultures containing CD8+ T cells.
Similarly, Th2 cytokine secretion was observed in cultures containing
CD4+, but not CD8+, T cells
from IFN-
-fed proteolipoprotein p139151-immunized SJL/J mice (data
not shown). Monocytes from IFN-
-treated MS patients can produce
IL-10 (3, 20). Interestingly, the level of IL-10
production in cultures containing total spleen cells from
IFN-
-treated mice was similar to that observed when purified
CD4+ T cells from IFN-
-treated mice were
restimulated with fresh APC (Fig. 1
B). While our results did
not negate the possibility that monocytes may have contributed to the
secretion of IL-10, they indicate that IFN-
-induced IL-10 secretion
was driven by CD4+ T cells.
In a previous study, it was observed that when IFN-
was applied in
vitro at 100 or 1000 U/ml it inhibited Ag-induced proliferation by 40
or 61%, respectively (12). In contrast, while Th2
deviation was observed when IFN-
was administered orally at 1
x 105 U and examined in vitro without additional
IFN-
, no significant inhibition of proliferation was observed in
total spleen cells or in cultures containing separated
CD4+ or CD8+ cells (Fig. 1
B). In addition, we did not observe inhibition of
proliferation in other experiments using 1 x
105 U IFN-
or less. However, when mice were
administered 1 x 106 U or higher doses in
separate experiments >50% inhibition of proliferation was observed
(O. Stuve, J. M. Soos, and S. S. Zamvil, unpublished
observations).
To examine how IFN-
modulates Th1 and Th2 cytokine responses in EAE,
mice were immunized for EAE induction with MBP and treated with either
IFN-
or vehicle (PBS). While MBP-specific TCR-transgenic mice are
quite useful for examining regulation of Th cell differentiation
(17), it can be preferable to test treatment effects on
EAE induced in wild-type mice, which contain a normal T cell
repertoire. Cytokine production by MBP-reactive lymphocytes was
examined 20 days after immunization of PL/J mice. At this time
PBS-treated mice reached an average paralysis grade of 2.5 while mice
treated with IFN-
mice did not develop EAE (see Fig. 2
). Control (PBS-treated) mice that
developed EAE exhibited a classic Th1 response with production of
IFN-
and TNF-
(Fig. 2
). These mice also produced robust levels of
IL-2 but did not produce any detectable IL-10. In contrast,
MBP-stimulated lymph node cells or splenocytes from IFN-
-treated
mice secreted substantial IL-10. Lymph node cells and splenocytes from
these same mice secreted less IFN-
, TNF-
, and IL-2. Thus, IFN-
prevention of EAE correlated with induction of IL-10 and a concomitant
reduction of the Th1 cytokines, IFN-
, TNF-
, and IL-2.
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and GA have distinct modes of action (2, 8, 11) and oral administration of either one can ameliorate EAE
(13, 21), we investigated whether they could complement
each other when administered in combination. In preliminary experiments
various doses (1 x 105, 5 x
104, and 1 x 104 U)
of IFN-
were tested alone. Whereas 1 x
105 U IFN-
protected mice from EAE, below this
amount there was a dose-dependent loss in efficacy. One hundred
micrograms of GA alone was also suboptimal. However, as shown in Table I
and GA were administered
in combination at suboptimal doses, mice were protected. In comparison
with IFN-
(5 x 104 U) treatment alone,
there was a significant reduction (Z = 4.4;
p < 0.001) in EAE incidence when mice were given
combination therapy. In comparison with GA alone, combination therapy
was also associated with a significant reduction (Z =
2.6; p < 0.005) in EAE incidence. These in vivo
results indicated that these two immunomodulatory agents could function
in an additive or synergistic manner.
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secretion by CNS autoantigen-specific T cells
(2, 21). Because previous studies attributed the
beneficial affects of IFN-
to production of IL-10 (11, 12, 15) and we observed that IFN-
induced substantial quantities
of IL-10, we evaluated whether the combination of suboptimal doses of
oral IFN-
and oral GA, which was effective in EAE protection,
facilitated MBP-specific T cells to secrete TGF-
and IL-10. As shown
in Fig. 3
alone produced a moderate
level of IL-10. However, mice treated with suboptimal doses of oral
IFN-
and oral GA produced approximately two times the sum of the
IL-10 produced by lymphocytes from mice treated with either agent
alone. In contrast to oral GA, oral IFN-
did not induce TGF-
, and
the amount of TGF-
produced by MBP-specific T cells from
TCR-transgenic mice treated with the combination of oral GA and oral
IFN-
was similar to that of mice treated with GA alone (see Fig. 3
and oral GA were administered in
combination (Table I
secretion.
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could either prevent or reverse relapsing
EAE (12, 15). IFN-
also prevented superantigen-induced
EAE relapses (12). Furthermore, we have observed that oral
IFN-
could suppress murine collagen-induced arthritis (J. M.
Soos, H. L. Weiner, and S. S. Zamvil, unpublished
observation). Thus, the beneficial anti-inflammatory properties of
IFN-
are not restricted to immune responses to CNS autoantigens but
may be applicable to other organ-specific autoimmune conditions. Like
other type I IFNs, IFN-
induces IL-10 when given as monotherapy
(11, 12, 15). The results from previous studies (12, 15) and this investigation demonstrated that the beneficial
clinical effects of IFN-
in EAE were dose dependent. Larger in vivo
doses of IFN-
induced higher levels of IL-10 by Ag-reactive T cells
examined in vitro. However, IL-10 may not be solely responsible for the
clinical efficacy of IFN-
. For example, it is also known that
IFN-
suppresses IFN-
-inducible MHC class II up-regulation
(11) and, as we have shown, IFN-
also promotes
secretion of IL-4 and IL-5. Thus, it is possible that these other
immunoregulatory characteristics of IFN-
may also contribute to its
beneficial effects.
Previously, it was reported that administration of oral or parenteral
IFN-
in combination with GA did not improve clinical EAE
(22), raising concern for the safety of using GA in
combination with a type I IFN. The mechanism(s) responsible for their
observation was not clearly elucidated. Interestingly, an initial
clinical MS trial designed to test the safety of IFN-
1a and GA
concluded that combination was safe (10). In our study we
have clearly shown that the combination of oral IFN-
and GA is
beneficial in EAE. Among other differences between the earlier EAE
study and this investigation is that GA was administered parenterally
in their study and not orally. Most importantly, we have also
demonstrated that IFN-
, in contrast to IFN-
or IFN-
, does not
promote secretion of IFN-
, an attractive feature of this type I IFN,
which could also contribute to the different clinical observations made
in these two studies. This key pharmacodynamic difference between
IFN-
and IFN-
should be considered in view of the results from a
recent pilot MS trial using oral IFN-
that suggested that oral
IFN-
may not be effective in treatment of relapsing-remitting MS
(23). In addition, patients in that trial received either
10,000 or 30,000 U of IFN-
. In contrast, in the phase I oral IFN-
trial (16), patients were given from 4 x
107 to 3.6 x 108
antiviral units daily, without significant toxicity.
The goal of combination therapy in MS is to improve efficacy without
increasing side effects (9). Thus, medications chosen for
combination therapy should not have overlapping toxicities.
Theoretically, these medications should produce an additive or
synergistic effect. Thus, MS medications that have different modes of
action, possibly acting on different parts of the pathogenic cascade,
may be preferred. In this regard, IFN-
, like IFN-
, exerts effects
in an Ag-independent manner (1), whereas GA appears to
affect primarily T cells specific for CNS autoantigens (6, 8). In this report, we have demonstrated for the first time that
combination of a type I IFN and GA can suppress EAE. Because oral or
parenteral administration of IFN-
is effective in EAE and is not
associated with significant side effects or toxicities, IFN-
is an
excellent candidate for use as a single agent or in combination in
MS.
| Acknowledgments |
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| Footnotes |
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2 Current address: Immunologic Toxicology, GlaxoSmithKline Pharmaceuticals, King of Prussia, PA 19406. ![]()
3 Address correspondence and reprint requests to Dr. Scott S. Zamvil, Department of Neurology, University of California, 521 Parnassus Avenue, C-440, San Francisco, CA 94143. E-mail address: zamvil{at}itsa.ucsf.edu ![]()
4 Abbreviations used in this paper: GA, glatiramer acetate; MS, multiple sclerosis; EAE, experimental allergic encephalomyelitis; MBP, myelin basic protein. ![]()
Received for publication December 31, 2001. Accepted for publication June 28, 2002.
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