Previous Article | Next Article 
Infection and Immunity, August 1999, p. 4033-4040, Vol. 67, No. 8
0019-9567/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
Trypanosoma cruzi Infects Human
Dendritic Cells and Prevents Their Maturation: Inhibition of Cytokines,
HLA-DR, And Costimulatory Molecules
Laurence
Van
Overtvelt,1
Nathalie
Vanderheyde,1
Valérie
Verhasselt,1
Jamila
Ismaili,1
Louis
De
Vos,2
Michel
Goldman,1
Fabienne
Willems,1 and
Bernard
Vray1,2,*
Laboratoire d'Immunologie
Expérimentale, Faculté de
Médecine,1 and Département
de Biologie Animale, Faculté des
Sciences,2 Université Libre de Bruxelles,
Brussels, Belgium
Received 11 December 1998/Returned for modification 26 January
1999/Accepted 19 May 1999
 |
ABSTRACT |
Trypanosoma cruzi, a parasitic protozoan, is the
etiological agent of Chagas' disease. Despite the many immune system
disorders recognized in this infection and the crucial role played by
dendritic cells (DC) in acquired immune responses, it was not known
whether these cells could be infected by T. cruzi
trypomastigotes and the consequences of such an infection on their
immune functions. We now provide evidence that human monocyte-derived
DC can be infected by T. cruzi and can support its
intracellular multiplication. Interestingly, this infection has
functional consequences on immature DC and on their maturation induced
by lipopolysaccharide (LPS). First, after T. cruzi
infection, the basal synthesis of interleukin-12 (IL-12) and tumor
necrosis factor alpha (TNF-
) was impaired. Furthermore, the process
of maturation of DC induced by LPS was drastically affected by T. cruzi infection. Indeed, secretion of cytokines such as IL-12,
TNF-, and IL-6, which are released normally at high levels by
LPS-activated DC, as well as the up-regulation of HLA-DR and CD40
molecules, was significantly reduced after this infection. The same
effects could be induced by T. cruzi-conditioned medium,
indicating that at least these inhibitory effects were mediated by
soluble factors released by T. cruzi. Taken together, these
results provide new insights into a novel efficient mechanism, directly
involving the alteration of DC function, which might be used by
T. cruzi to escape the host immune responses in Chagas' disease and thus might favor persistent infection.
| |
INTRODUCTION |
Trypanosoma cruzi, the
etiological agent of Chagas' disease, is a hemoflagellate protozoan
parasite that infects humans as well as domestic and wild mammals
(39). This parasite exists in two forms in the vertebrate
host: the trypomastigote, which is the blood form and infects several
cells (macrophages, fibroblasts, nerve cells, and muscle cells), and
the amastigote, which replicates in the host cell cytosol
(9). Cell invasion and intracellular replication are
essential for the induction of the disease and the continuation of the
parasite life cycle. In human infection, most patients survive the
initial acute phase but some develop the chronic manifestations of the
disease, characterized by long-lasting inflammatory lesions and immune
system disorders, years later (14, 39). The use of
experimental murine models has shown that host resistance to T. cruzi depends at least partially on natural killer (NK) cells, T
cells, and macrophages, which produce various cytokines, such as
interleukin-12 (IL-12), gamma interferon (IFN-
), and tumor necrosis
factor alpha (TNF-), involved in the control of the disease (1,
3, 11, 25, 37, 40). However, an efficient protective immunity is
seldom or never achieved so that viable parasites and focal chronic
inflammation can be detected in host tissue for life.
The role of dendritic cells (DC) in T. cruzi infection has
never been investigated, despite their unique and essential function in
the initiation of the acquired immune response (6). Immature DC, which reside in most tissues and organs, actively capture and
process antigens (12). Upon activation by whole bacteria, the microbial cell wall component lipopolysaccharide (LPS), or cytokines such as IL-1
, granulocyte-macrophage colony-stimulating factor (GM-CSF), or TNF-, they migrate to lymph nodes and the spleen, where they activate naive antigen-specific T cells. During this
migration, they undergo a process of maturation, which is a crucial
step in the development of DC into fully potent antigen-presenting cells (APC). During maturation, DC lose their ability to capture and
process antigens, increase their expression of major histocompatibility complex (MHC) class II costimulatory (CD40, CD80, CD86) and adhesion (CD54) molecules, and up-regulate their production of cytokines such as
IL-12. This cytokine plays a key role in the induction of cell-mediated
immunity to intracellular pathogens by triggering the production of
IFN- from NK and T cells (35). In the case of T. cruzi infection, this cytokine is required for both innate and
acquired immunity (1, 24). Indeed, in murine models, the
induction of IL-12 early in infection with T. cruzi
initiates innate resistance which is dependent on IFN- and TNF-
(3, 25) while ensuring the induction of an efficient
adaptive host response.
Accordingly, we investigated the relationship between DC and T. cruzi trypomastigotes by using DC obtained from human blood monocytes incubated with IL-4 and GM-CSF. We first assessed whether DC
could be infected by T. cruzi, as is the case with several viruses (7, 21, 28) and bacteria (15, 22-24, 26,
33) and at least one parasitic protozoan, Leishmania
(32). We next evaluated the influence of DC infection by
T. cruzi on the capacity of these cells to secrete cytokines
(IL-6, IL-8, IL-10, IL-12, and TNF-) and to express MHC class II
costimulatory and adhesion molecules both at the immature stage and
upon maturation induced by LPS.
Finally, we tested whether the observed effects on human DC could be
also attributed to soluble factors released by T. cruzi (termed T. cruzi-conditioned medium [TCM]).
| |
MATERIALS AND METHODS |
Culture medium and reagents.
The culture medium consisted of
RPMI 1640 (Biowhittaker Europe, Verviers, Belgium) supplemented with
L-glutamine (2 mM), gentamicin (20 µg/ml), 2 × 10
5 M 2-mercaptoethanol, 1% nonessential amino acids
(GIBCO, Grand Island, N.Y.), and 10% fetal bovine serum
(Biowhittaker). Recombinant IL-4 was kindly provided by Schering-Plough
(Kenilworth, N.J.). Recombinant GM-CSF was obtained from Novartis
(Basel, Switzerland). LPS (Escherichia coli 0128:B12),
phosphate-buffered saline (PBS), and bovine serum albumin were
purchased from Sigma Chemical Co. (St. Louis, Mo.).
Human DC.
Human DC were generated from peripheral blood
mononuclear cells as previously described (36). Briefly,
peripheral blood mononuclear cells from healthy volunteers were
isolated by density centrifugation of heparinized blood on Lymphoprep
(Nycomed, Oslo, Norway), resuspended in culture medium, and allowed to
adhere to culture flasks. After 2 h at 37°C, nonadherent cells
were removed and adherent cells were cultured in medium containing
GM-CSF (800 U/ml) and IL-4 (500 U/ml). Every 2 days, GM-CSF and IL-4
were added. After 7 days of culture, nonadherent cells corresponding, to the DC-enriched fraction, were harvested, washed, and used for
subsequent experiments. As previously reported (8), the DC-enriched fraction obtained by this method routinely contains more
than 95% DC as assessed by morphology and flow cytometry analysis.
T. cruzi trypomastigotes and TCM.
T. cruzi
trypomastigotes (Tehuantepec strain, Mexico) were maintained by weekly
intraperitoneal inoculations to BALB/c mice. To obtain large quantities
of parasites, trypomastigotes (2.5 × 105
parasites/rat) were inoculated into F344 Fischer rats (Iffa Credo, Brussels, Belgium) irradiated with X rays (700 rads). Trypomastigotes were obtained from the blood (containing 10 U of heparin/ml) of infected rats by ion-exchange chromatography on DEAE-cellulose (Whatman
DE 52) equilibrated with phosphate saline glucose buffer at pH 7.4 (30, 34). Trypomastigotes were centrifuged (15 min at
1,800 × g and 4°C) and resuspended in endotoxin-free PBS.
TCM was prepared by the method described by Kierszenbaum et al.
(27) to obtain trypanosomal immunosuppressive factor.
Briefly, suspensions of T. cruzi (2 × 107
trypomastigotes/ml in RPMI 1640 medium) were incubated at 37°C and
5% CO2 for 24 h. The parasites were then removed by
filtration through a sterile 0.22-µm-pore-size filter (Millipore
Corp., Bedford, Mass.). This TCM was aliquoted and stored at 
20°C
until used. When necessary, it was diluted in culture medium to obtain
a final concentration of 12.5, 25, 50, or 75%.
Effects of T. cruzi infection and TCM on DC.
To
assess whether T. cruzi infects human DC, 5 × 105 DC/ml were cultured in 24-well plates with
trypomastigotes at parasite-to-cell ratios of 0.1:1, 0.5:1, 1:1, 2:1,
5:1, 10:1, and 20:1. After 24 h, the DC were washed to remove free
parasites, fixed with methanol, and then stained with Giemsa stain. In
some experiments, DC were not fixed but were further incubated for a
total of 48 or 72 h to assess the intracellular multiplication of
amastigotes. The percentage of infected DC and the mean number of
amastigotes per infected DC were recorded after microscopic examination
of at least 300 cells (34).
The effects of T. cruzi on cytokine production and surface
molecule expression of DC were investigated by using DC incubated either with trypomastigotes (parasite-to-cell ratios of 5:1, 10:1, and
20:1) or with TCM (12.5 to 50% [vol/vol] of the culture medium) for
24 h. In some experiments, DC were cultured in the bottom of wells
and separated by a cell-impermeable filter from trypomastigotes placed
in a transwell (clear, 6.5-mm diameter, 0.4-µm pore size, 24-well
size [Corning Costar Corp., Cambridge, Mass.]). Similar experiments
were performed with DC incubated in medium containing 10 ng of LPS per
ml together with trypomastigotes (parasite-to-cell ratios, 0.1:1,
0.5:1, 1:1, 2:1, 5:1, 10:1, 20:1, and 30:1) or TCM (3, 6.25, 12.5, 25, 50, and 75%).
Cytokine assays.
Culture supernatants of DC were harvested,
and TNF-, IL-6, IL-8, IL-10, and IL-12 (p40) levels were assayed
with enzyme-linked immunosorbent assay (ELISA) kits from Biosource
Europe (Nivelles, Belgium). The IL-12 (p40) assay detects both the
heterodimeric (p70) and homodimeric (p40-p40) forms of human IL-12.
IL-12 (p70) production was measured with an ELISA kit provided by
Genzyme (Leuven, Belgium). The absorbances were measured in a
microplate ELISA reader (Spectracount Microplate Photometer; Packard,
Meriden, Conn.).
Flow cytometry analysis.
For immunophenotyping,
105 DC were harvested and washed in PBS supplemented with
0.5% bovine serum albumin and 10 mM NaN3 and incubated for
30 min at 4°C with one of the following phycoerythrin- or fluorescein
isothiocyanate (FITC)-conjugated murine monoclonal antibodies (MAb):
anti-HLA-DR immunoglobulin G2a (IgG2a) MAb (Becton Dickinson, San Jose,
Calif.), anti-CD80 (B7-1) IgG1 MAb (Becton Dickinson), anti-CD54
(ICAM-1) IgG2b MAb (Becton Dickinson), anti-CD14 IgG2b MAb (Becton
Dickinson), anti-CD86 (B7-2) IgG2b MAb (PharMingen, San Diego, Calif.),
and anti-CD40 IgG1 MAb (Biosource Europe). As controls, DC were stained
with corresponding isotype-matched MAbs. The DC were fixed with 1%
paraformaldehyde before being subjected to flow cytometry analysis
(FACSCalibur; Becton Dickinson).
Analysis of cell viability.
Double staining for annexin
V-FITC and propidium iodide (PI) was performed for analysis of cell
viability, as described elsewhere (5). An annexin V kit
(Bender Medsystems, Vienna, Austria) was used. Briefly, DC
(105) were washed with PBS and resuspended in 200 µl of
annexin V binding buffer (10 mM HEPES-NaOH [pH 7.4], 140 mM NaCl, 2.5 mM CaCl2) containing 5 µl of annexin V-FITC. After 10 min
of incubation at 0°C, the cells were washed before the addition of 1 µg of PI per ml and analyzed by flow cytometry.
TEM.
T. cruzi-infected DC were pelleted and fixed in
2.5% glutaraldehyde for 1 h, washed twice in PBS and then fixed
in 0.1 M sodium cacodylate buffer (pH 7.4) for 24 h, and postfixed
in a 4% aqueous solution of osmium tetroxide for 1 h. The DC were
then dehydrated in a graded series of ethanol and embedded in Epon 812. Thin sections were stained with uranyl acetate and lead citrate for
examination by transmission electron microscopy (TEM).
Statistical analysis.
Data were compared by using the
nonparametric Wilcoxon's paired one-tailed test.
| |
RESULTS |
T. cruzi infects human DC.
In a first set of
experiments, we investigated whether T. cruzi infects human
DC. For this purpose, we evaluated by light microscopy the infection
rate of human DC cocultured with T. cruzi trypomastigotes
for 24 h. The percentage of infected cells increased with
increasing parasite-to-cell ratios (Fig.
1A) as well as the mean number of
amastigotes per infected DC (Fig. 1B). To assess the intracellular
multiplication of amastigotes, DC were infected with T. cruzi trypomastigotes (parasite-to-cell ratio, 5:1) for 24 h
and then excess parasites were removed by extensive washing. Cultures
of DC were incubated for an additional 24 or 48 h, fixed, and
stained with Giemsa stain. The mean number of amastigotes per cell
increased five- to eightfold between 24 and 72 h of culture (Fig.
1C).
View larger version (15K):
[in this window]
[in a new window]
|
FIG. 1.
T. cruzi-infected human DC. (A and B) DC were
incubated with T. cruzi trypomastigotes at different
parasite-to-cell ratios (0.1:1 to 20:1). After 24 h, the cultures
were washed to remove free parasites and DC were fixed with methanol
and stained with Giemsa stain. The percentages of infected DC (A) and
mean numbers of amastigotes per infected DC (B) were recorded after
microscopy examination of at least 300 cells. Data are from four
independent experiments with four different blood donors. (C) In
another set of experiments, DC were first incubated with T. cruzi trypomastigotes at a parasite-to-cell ratio of 5:1 for
24 h and then excess parasites were removed by extensive washing.
Cultures of DC were continued for an additional incubation time of 24 or 48 h before the cells were fixed and stained with Giemsa stain.
Mean numbers of amastigotes per infected DC were recorded after
microscopy examination of at least 300 cells. Data are from three
independent experiments with three different blood donors.
|
|
The intracellular location of the parasites was determined by using
both light microscopy and TEM. At the beginning of the
infection,
parasites were seen in the parasitophorous vacuole
(Fig.
2A), from which they escaped into the
cytosol (Fig.
2B).
We also observed that DC viability was over 95%, as
assessed by
the trypan blue test, and was not affected by
T. cruzi infection
(data not shown).
View larger version (71K):
[in this window]
[in a new window]
|
FIG. 2.
Light microscopy and TEM of T. cruzi-infected
human DC. (A) DC were incubated with T. cruzi
trypomastigotes (parasite-to-cell ratio, 20:1) for 24 h, fixed
with methanol, and stained with Giemsa stain. T, trypomastigote;
arrows, parasite inside a parasitophorous vacuole; arrowheads, parasite
in the cytosol. Bar, 2.5 µm. (B) DC were incubated with T. cruzi trypomastigotes (parasite-to-cell ratio, 5:1) for 24 h
and treated for TEM. T, trypomastigote; arrow, parasite in the cytosol;
N, DC nucleus. Bar, 1.5 µm.
|
|
Taken together, these data indicated that
T. cruzi
trypomastigotes invade, survive, and multiply in the
DC.
Effects of T. cruzi infection and TCM medium on
cytokine production and surface molecule expression by immature human
DC.
We next investigated whether T. cruzi would affect
the production of cytokines by human DC. IL-12 (p40) and TNF-
secretion by DC was significantly decreased after infection with
trypomastigotes at almost all parasite-to-cell ratios (5:1, 10:1, and
20:1) tested. In contrast, IL-8 production was not modified (Table
1). IL-6 and IL-10 levels were below the
detection limits of the assays in the presence and absence of
trypomastigotes (data not shown). To establish whether this inhibitory
effect required DC infection, we used a culture system in which DC and
trypomastigotes were separated by the presence of a cell-impermeable
filter. Inhibition of IL-12 (p40) and TNF- synthesis was also
observed under these conditions, indicating the production of
filterable inhibitory soluble factors by T. cruzi (Fig.
3).
View larger version (12K):
[in this window]
[in a new window]
|
FIG. 3.
Filterable soluble factors released by T. cruzi inhibit the basal production of IL-12 (p40) and TNF-. DC
were cultured in the bottom of wells and separated by a
cell-impermeable filter from trypomastigotes placed in a transwell. The
parasite-to-cell ratios were 5:1 and 10:1. After 24 h,
supernatants were collected to determine the cytokine production by
ELISA. Results of one representative experiment of three are shown.
|
|
To assess whether this production of inhibitory factors was spontaneous
or was induced by the presence of DC or DC products,
we used TCM
prepared as described by Kierszenbaum et al. (
27).
A
comparable dose-dependent impairment of IL-12 (p40) and TNF-
production was observed when DC were incubated with increasing
concentrations of TCM (12.5, 25, and 50%; Table
1). To exclude
a
cytotoxic effect of TCM on DC, the viability of the DC was evaluated
by
using annexin V and PI staining. Treatment of DC with TCM at
all the
concentrations used did not alter cell viability as assessed
by annexin
V and PI staining (Table
2).
Effects of
T. cruzi infection or TCM treatment on the
expression of HLA-DR, CD40, CD54, CD80, and CD86 molecules, which are
involved in the APC function of DC, were also tested.
T. cruzi infection or TCM treatment of DC had no effect on the basal
expression
of these molecules (data not shown and Table
3).
Effects of T. cruzi infection and TCM on DC maturation
induced by LPS stimulation.
Since DC maturation is an essential
process during which DC acquire optimal immunostimulatory properties,
we examined the influence of T. cruzi infection on the
response of DC to LPS, which has been previously described to be a
major stimulus for cytokine production and up-regulation of surface
molecule expression (8, 43). Therefore, we performed the
same experiments as those described above in the presence of LPS (10 ng/ml). We first observed that DC were infected to the same extent in
the presence and in the absence of LPS (data not shown). Furthermore,
as shown in Fig. 4, the enhanced
secretion of IL-12 (p40), TNF-, and IL-6 normally induced by LPS was
decreased by both T. cruzi infection and TCM in a
dose-dependent manner. A maximal inhibitory effect was reached at a
parasite-to-cell ratio of 30:1 or when TCM was used instead of 75% of
the culture medium. The heterodimeric bioactive p70 form of IL-12 was
also inhibited by T. cruzi infection and TCM (Fig.
5). The stimulation of IL-8 and IL-10
production was not modified (data not shown). Finally, we observed that
LPS-induced HLA-DR and CD40 up-regulation was significantly inhibited
by both trypomastigotes (parasite-to-cell ratio 30:1) and TCM (75%),
while no effect was found on CD54, CD80, and CD86 (Fig.
6 and Table 3). DC remained CD14 negative
in the presence of trypomastigotes or TCM. This inhibitory effect on
LPS-induced IL-12 (p40) production as well as costimulatory-molecule
expression (HLA-DR and CD40) was also observed at lower
parasite-to-cell ratios (0.1:1, 0.5:1, 1:1, and 2:1) and lower
concentrations of TCM (3 and 6.25%) (data not shown).
View larger version (32K):
[in this window]
[in a new window]
|
FIG. 4.
T. cruzi infection and TCM inhibit
LPS-induced cytokine release from DC. A total of 5 × 105 DC were incubated with LPS (10 ng/ml) with or without
trypomastigotes or TCM for 24 h, and cytokine levels were measured
in culture supernatants. (A) Levels of cytokines produced in the
absence (NI) or presence of trypomastigotes at different
parasite-to-cell ratios. (B) Levels of cytokines produced in the
absence (NI) or presence of TCM at different graded concentrations.
Data represent the mean and standard error of the mean of five
independent experiments performed with five different blood donors.
*, P  0.03 by nonparametric Wilcoxon's paired
one-tailed test, compared to cytokine levels in the absence of T. cruzi trypomastigotes or TCM.
|
|
View larger version (11K):
[in this window]
[in a new window]
|
FIG. 5.
T. cruzi infection and TCM inhibit
LPS-induced IL-12 (p70) release from DC. DC were stimulated with LPS
(10 ng/ml) in the presence of trypomastigotes at different
parasite-to-cell ratios (A) or in the presence of increasing
concentrations of TCM (B). After 24 h, supernatants were collected
for determination of IL-12 (p70) levels by ELISA. Results of one
representative experiment of two are shown.
|
|
View larger version (26K):
[in this window]
[in a new window]
|
FIG. 6.
T. cruzi infection and TCM inhibit
LPS-induced HLA-DR and CD40 up-regulation. DC were incubated with LPS
(10 ng/ml) with or without trypomastigotes (parasite-to-cell ratio,
30:1) (A) or TCM (75%) (B). DC incubated in the presence of medium
alone were used as control. After 24 h, DC were harvested and
washed, and the expression of HLA-DR (left) and CD40 (right) was
determined by flow cytometry. Thin lines represent FACS profiles
obtained for DC incubated with medium alone. Thick lines represent FACS
profiles obtained for DC incubated with LPS alone. Dotted lines
represent FACS profiles obtained for DC incubated with LPS in the
presence of trypomastigotes (A) or TCM (B). The solid histograms
represent FACS profiles after staining with the corresponding
isotype-matched control MAb. Results of one representative experiment
of six are shown.
|
|
| |
DISCUSSION |
In the present report, we demonstrate for the first time that
human DC, the only APC with the ability to initiate a primary immune
response, could be infected by T. cruzi and support its intracellular multiplication. T. cruzi is first internalized
in a parasitophorous vacuole, from which it escapes into the cytosol. Our observations on human DC infection are in line with those obtained
in experiments with human and murine macrophages infected by T. cruzi (4).
Interestingly, T. cruzi infection of human monocytes-derived
DC has functional consequences for immature DC and their maturation induced by LPS. Indeed, no increase in the basal production of cytokines is induced by this infection, in contrast to infection by
other pathogens, which induce DC maturation (15, 19, 24, 26, 33,
38, 44). Instead, an inhibition of basal production of IL-12 and
TNF- is induced after this infection. The decreased basal production
of IL-12 by human DC was also observed with Leishmania donovani promastigotes, Histoplasma capsulatum,
Mycobacterium kansasii (2), and viruses
(influenza virus, measles virus, and human immunodeficiency virus)
(7, 16, 17). Most interestingly, LPS-induced DC maturation
was profoundly impaired by T. cruzi infection. Indeed,
IL-12, TNF-, and IL-6 were inhibited in DC activated by LPS in the
presence of T. cruzi. Studies performed with mouse models,
both in vitro and in vivo, suggested that T. cruzi is a
potent stimulator of IL-12 and TNF- synthesis by macrophages (3, 10, 31). In contrast, and consistent with our results on
human DC, LPS-induced IL-12 and TNF- production was inhibited when
human macrophages were infected in vitro with T. cruzi or treated with a mucin-like protein derived from the parasite
(13).
Furthermore, in addition to their major IL-12 production upon microbial
infection in vivo, the importance of DC in the initiation of acquired
immunity is well established (19, 38). Thus, by altering the
ability of the DC to secrete IL-12, TNF-, and IL-6 (cytokines
involved in the control of intracellular infection [35,
41]), T. cruzi may use a new mechanism to evade the
immune response.
The activity of T. cruzi on DC could be also mediated
through transwells, suggesting the production of filterable inhibitory soluble factors by the parasite. Indeed, supernatants derived from
suspensions of T. cruzi or TCM have the same inhibitory
effect on cytokine release. These results indicate that a close contact between DC and T. cruzi, leading to infection, is not a
prerequisite for inhibition of cytokine synthesis. Parasite-derived
molecules released into the culture medium seem to be responsible for
this inhibition. Moreover, the presence of DC is not required for the spontaneous release of the inhibitory active principle of TCM by the
parasite. Preliminary data suggest that the biological activity of TCM
on monocyte-derived human DC could be attributed at least to a small
(<3,000-Da), heat-stable molecule(s) (data not shown). The effect of
TCM on cytokine production is related to trypanosomal immunosuppressive
factor, which inhibits lymphoproliferation and IL-2 receptor expression
on human T lymphocytes (27). Similarly, in a mouse
experimental model, down-regulation of T lymphocyte activation has been
demonstrated by using trypomastigotes and parasite-derived
glycoinositol-phospholipid (18, 42). These results are also
reminiscent of similar disturbances observed in T. cruzi-infected mouse macrophages, such as impairment of APC
function (29, 34). These data and our own observations suggest that T. cruzi affects many functions of the host
cells, probably by releasing several biologically active molecules,
indicating that the infection by itself is not necessary.
Besides their ability to produce large amounts of cytokines while
maturing, DC up-regulate their MHC and costimulatory molecules, leading
to an efficient stimulation of naive T cells. Our results indicate that
T. cruzi infection did not drive any up-regulation of
HLA-DR, costimulatory, or adhesion molecules and that parasite-derived molecules had no effect on the basal expression of these molecules. In
contrast, both T. cruzi and TCM prevented an optimal
maturation of DC by LPS, since a reduced expression of HLA-DR and CD40
molecules was observed. Because of the central roles of HLA-DR
molecules and CD40-CD40L pathway in the induction and effector phase of immune system responses (20), the inhibition of these
surface molecules by T. cruzi is another strategy to escape
specific immune system surveillance and to persist in the host.
Taken together, these data indicate that by altering the maturation of
DC, which is a crucial step in induction of a potent cellular immune
response, T. cruzi, probably by releasing soluble immunosuppressive factors, may unbalance the immune response to its
benefit. If so, this inhibition might be added to the long list of
escape mechanisms used by T. cruzi to reduce the
effectiveness of the host immune response and could explain the
persistence of the parasites together with a long-lasting inflammation process.
| |
ACKNOWLEDGMENTS |
We thank V. Vercruysse for valuable technical assistance and I. Mazza for help in preparing the manuscript.
This work was supported by grants from Action de Recherche
Concertée de la Communauté Française de Belgique,
ULB, 1991 and 1994, and Fondation Emile Defay. L.V.O. is the recipient
of a grant from the Fonds pour la Formation à la Recherche dans l'Industrie et dans l'Agriculture (FRIA).
| |
FOOTNOTES |
*
Corresponding author. Mailing address:
Laboratoire d'Immunologie Expérimentale (CP 615),
Faculté de Médecine, Université Libre de Bruxelles,
808 route de Lennik, B-1070 Brussels, Belgium. Phone: 32-2-555.62.60. Fax: 32-2-555.63.60. E-mail: bvray{at}med.ulb.ac.be.
Editor:
J. M. Mansfield
| |
REFERENCES |
| 1.
|
Abrahamsohn, I. A.
1998.
Cytokines in innate and acquired immunity to Trypanosoma cruzi infection.
Braz. J. Med. Biol. Res.
31:117-121[Medline].
|
| 2.
|
Ahuja, S. S.,
S. Mummidi,
H. L. Malech, and S. K. Ajuha.
1998.
Human dendritic cell (DC)-based anti-infective therapy: engineering DCs to secrete functional IFN-gamma and IL-12.
J. Immunol.
16:868-876.
|
| 3.
|
Aliberti, J. C. S.,
M. A. G. Cardoso,
G. A. Martins,
R. T. Gazzinelli,
L. Q. Vieira, and J. S. Silva.
1996.
Interleukin-12 mediates resistance to Trypanosoma cruzi in mice and is produced by murine macrophages in response to live trypomastigotes.
Infect. Immun.
64:1961-1967[Abstract].
|
| 4.
|
Araujo-Jorge, T. C.
1989.
The biology of Trypanosoma cruzi-macrophage interaction.
Mem. Inst. Oswaldo Cruz
84:441-462[Medline].
|
| 5.
|
Auphan, N.,
J. A. DiDonato,
C. Rosette,
A. Helmberg, and M. Karin.
1995.
Immunosuppression by glucocorticoids: inhibition of NF- B activity through induction of IB synthesis.
Science
270:286-290[Abstract/Free Full Text].
|
| 6.
|
Banchereau, J., and J. Steinman.
1998.
Dendritic cells and the control of immunity.
Nature
392:245-252[Medline].
|
| 7.
|
Bender, A.,
M. Albert,
A. Reddy,
M. Feldman,
B. Sauter,
G. Kaplan,
W. Hellman, and N. Bhardwaj.
1998.
The distinctive features of influenza virus infection of dendritic cells.
Immunobiology
198:552-567[Medline].
|
| 8.
|
Buelens, C.,
V. Verhasselt,
D. De Groote,
K. Thielemans,
M. Goldman, and F. Willems.
1997.
Human dendritic cell responses to lipopolysaccharide and CD40 ligation are differentially regulated by interleukin-10.
Eur. J. Immunol.
27:1848-1852[Medline].
|
| 9.
|
Burleigh, B. A., and N. W. Andrews.
1995.
The mechanisms of Trypanosoma cruzi invasion of mammalian cells.
Annu. Rev. Microbiol.
49:175-200[Medline].
|
| 10.
|
Camargo, M. M.,
I. C. Almeida,
M. E. S. Pereira,
M. A. J. Feguson,
L. R. Travassos, and R. T. Gazzinelli.
1997.
Glycosylphosphatidylinositol-anchored mucin-like glycoproteins isolated from Trypanosoma cruzi trypomastigotes initiate the synthesis of proinflammatory cytokines by macrophages.
J. Immunol.
158:5890-5901[Abstract].
|
| 11.
|
Cardillo, F.,
J. C. Voltarelli,
S. G. Reed, and J. S. Silva.
1996.
Regulation of Trypanosoma cruzi infection in mice by gamma interferon and interleukin-10: role of NK cells.
Infect. Immun.
64:128-134[Abstract].
|
| 12.
|
Cella, M.,
F. Sallusto, and A. Lanzavecchia.
1997.
Origin, maturation and antigen presenting function of dendritic cells.
Curr. Opin. Immunol.
9:10-16[Medline].
|
| 13.
|
de Diego, J.,
C. Punzon,
M. Duarte, and M. Fresno.
1997.
Alteration of macrophage function by a Trypanosoma cruzi membrane mucin.
J. Immunol.
159:4983-4989[Abstract].
|
| 14.
|
DosReis, G. A.
1997.
Cell-mediated immunity in experimental Trypanosoma cruzi infection.
Parasitol. Today
13:335-342.
[Medline] |
| 15.
|
Filgueira, L.,
F. O. Nestlé,
M. Rittig,
H. I. Joller, and P. Groscurth.
1996.
Human dendritic cells phagocytose and process Borrelia burgdorferi.
J. Immunol.
157:2998-3005[Abstract].
|
| 16.
|
Fugier-Vivier, I.,
C. Servet-Delprat,
P. Rivailler,
M.-C. Rissoan,
Y.-J. Liu, and C. Rabourdin-Combe.
1997.
Measles virus suppresses cell-mediated immunity by interfering with the survival and functions of dendritic and T cells.
J. Exp. Med.
186:813-823[Abstract/Free Full Text].
|
| 17.
|
Ghanekar, S.,
L. Zheng,
A. Logar,
J. Navratil,
L. Borowski,
P. Gupta, and C. Rinaldo.
1996.
Cytokine expression by human peripheral blood dendritic cells stimulated in vitro with HIV-1 and herpes simplex virus.
J. Immunol.
157:4028-4036[Abstract].
|
| 18.
|
Gomes, N. A.,
J. O. Previato,
B. Zingales,
L. Mendonça-Previato, and G. A. DosReis.
1996.
Down-regulation of T lymphocyte activation in vitro and in vivo induced by glycoinositolphospholipids from Trypanosoma cruzi.
J. Immunol.
156:628-635[Abstract].
|
| 19.
|
Gorak, P. M. A.,
C. R. Engwerda, and P. M. Kaye.
1998.
Dendritic cells, but not macrophages, produce IL-12 immediately following Leishmania donovani infection.
Eur. J. Immunol.
28:687-695[Medline].
|
| 20.
|
Grewal, I. S.,
P. Borow,
E. G. Pamer,
M. B. A. Oldstone, and R. A. Flavell.
1997.
The CD40-CD154 system in anti-infective host defense.
Curr. Opin. Immunol.
9:491-497[Medline].
|
| 21.
|
Grosjean, I.,
C. Caux,
C. Bella,
I. Berger,
F. Wild,
J. Banchereau, and D. Kaiserlian.
1997.
Measles virus infects human dendritic cells and blocks their allostimulatory properties for CD4+ T cells.
J. Exp. Med.
186:801-812[Abstract/Free Full Text].
|
| 22.
|
Guzman, C. A.,
M. Rohde, and K. N. Timmis.
1994.
Mechanisms involved in uptake of Bordetella bronchiseptica by mouse dendritic cells.
Infect. Immun.
62:5538-5544[Abstract/Free Full Text].
|
| 23.
|
Guzman, C. A.,
M. Rohde,
T. Chakraborty,
E. Domann,
M. Hudel,
J. Wehland, and K. N. Timmis.
1995.
Interaction of Listeria monocytogenes with mouse dendritic cells.
Infect. Immun.
63:3665-3673[Abstract].
|
| 24.
|
Henderson, R. A.,
S. C. Watkins, and J. L. Flynn.
1997.
Activation of human dendritic cells following infection with Mycobacterium tuberculosis.
J. Immunol.
159:635-643[Abstract].
|
| 25.
|
Hunter, C. A.,
T. Slifer, and F. Araujo.
1996.
Interleukin-12-mediated resistance to Trypanosoma cruzi is dependent on tumor necrosis factor alpha and gamma interferon.
Infect. Immun.
64:2381-2386[Abstract].
|
| 26.
|
Inaba, K.,
M. Inaba,
M. Naito, and R. M. Steinman.
1993.
Dendritic cell progenitors phagocytose particulates, including bacillus Calmette-Guerin organisms, and sensitize mice to mycobacterial antigens in vivo.
J. Exp. Med.
178:479-488[Abstract/Free Full Text].
|
| 27.
|
Kierszenbaum, F.,
S. Majumder,
P. Paredes,
M. K. Tanner, and M. B. Sztein.
1998.
The Trypanosoma cruzi immunosuppressive factor (TIF) targets a lymphocyte activation event subsequent to increased intracellular calcium ion concentration and translocation of protein kinase C but previous to cyclin D2 and cdk4 mRNA accumulation.
Mol. Biochem. Parasitol.
92:133-145[Medline].
|
| 28.
|
Knight, S. C., and S. Patterson.
1997.
Bone marrow-derived dendritic cells, infection with human immunodeficiency virus, and immunopathology.
Annu. Rev. Immunol.
15:593-615[Medline].
|
| 29.
|
La Flamme, A. C.,
S. J. Kahn,
A. Y. Rudensky, and W. C. Van Voorhis.
1997.
Trypanosoma cruzi-infected macrophages are defective in major histocompatibility complex class II antigen presentation.
Eur. J. Immunol.
27:3085-3094[Medline].
|
| 30.
|
Lanham, S. M., and D. G. Godfrey.
1970.
Isolation of salivarian trypanosomes from man and other mammals using DEAE-cellulose.
Exp. Parasitol.
28:521-534[Medline].
|
| 31.
|
Meyer zum Büschenfelde, C.,
S. Cramer,
C. Trumpfheller,
B. Fleischer, and S. Frosch.
1997.
Trypanosoma cruzi induces strong IL-12 and IL-18 gene expression in vivo: correlation with interferon-gamma (IFN-) production.
Clin. Exp. Immunol.
110:378-385[Medline].
|
| 32.
|
Moll, H.,
S. Flohé, and M. Röllinghoff.
1995.
Dendritic cells in Leishmania major-immune mice harbor persistent parasites and mediate an antigen-specific T cell immune response.
Eur. J. Immunol.
25:693-699[Medline].
|
| 33.
|
Ojcius, D. M.,
Y. Bravo de Alba,
J. M. Kanellopulos,
R. A. Hawkins,
K. A. Kelly,
R. G. Rank, and A. Dautry-Varsat.
1998.
Internalization of Chlamydia by dendritic cells and stimulation of Chlamydia-specific T cells.
J. Immunol.
160:1297-1303[Abstract/Free Full Text].
|
| 34.
|
Plasman, N.,
J.-G. Guillet, and B. Vray.
1995.
Impaired protein catabolism in Trypanosoma cruzi-infected macrophages: possible involvement in antigen presentation.
Immunology
86:636-645[Medline].
|
| 35.
|
Romani, L.,
P. Puccetti, and F. Bistoni.
1997.
Interleukin-12 in infectious diseases.
Clin. Microbiol. Rev.
10:611-636[Abstract].
|
| 36.
|
Romani, N.,
S. Gruner,
D. Brang,
E. Kämpgen,
A. Lenz,
B. Trockenbacher,
G. Konwalinka,
P. O. Fritsch,
R. Steinman, and G. Schuler.
1994.
Proliferating dendritic cell progenitors in human blood.
J. Exp. Med.
180:83-93[Abstract/Free Full Text].
|
| 37.
|
Silva, J. S.,
J. C. Aliberti,
G. A. Martins,
M. A. Souza,
J. T. Souto, and M. A. Padua.
1998.
The role of IL-12 in experimental Trypanosoma cruzi infection.
Braz. J. Med. Biol. Res.
31:111-115[Medline].
|
| 38.
|
Sousa, C. R.,
S. Hieny,
T. Scharton-Kersten,
D. Jankovic,
H. Charest,
R. N. Germain, and A. Sher.
1997.
In vivo microbial stimulation induces rapid CD40 ligand-independent production of interleukin-12 by dendritic cells and their redistribution in the T cell areas.
J. Exp. Med.
186:1819-1829[Abstract/Free Full Text].
|
| 39.
|
Tanowitz, H. B.,
D. Simon,
S. A. Morris,
L. M. Weiss, and M. Wittner.
1992.
Chagas' disease.
Clin. Microbiol. Rev.
5:404-419.
|
| 40.
|
Tarleton, R. L.
1995.
The role of T cells in Trypanosoma cruzi infections.
Parasitol. Today
11:7-9.
[Medline] |
| 41.
|
Truyens, C.,
A. Angelo-Barrios,
F. Torrico,
J. Van Damme,
H. Heremans, and Y. Carlier.
1994.
Interleukin-6 (IL-6) production in mice infected with Trypanosoma cruzi: effect of its paradoxical increase by anti-IL-6 monoclonal antibody treatment on infection and acute-phase and humoral immune responses.
Infect. Immun.
62:692-696[Abstract/Free Full Text].
|
| 42.
|
Vandekerckhove, F.,
A. Darij,
M. T. Rivera,
Y. Carlier,
B. Vray,
A. Billiau, and P. de Baetselier.
1994.
Modulation of T-cell responsiveness during Trypanosoma cruzi infection: analysis in different lymphoid compartments.
Parasite Immunol.
16:77-85[Medline].
|
| 43.
|
Verhasselt, V.,
C. Buelens,
F. Willems,
D. De Groote,
N. Haeffner Cavaillon, and M. Goldman.
1997.
Bacterial lipopolysaccharide stimulates the production of cytokines and the expression of costimulatory molecules by human peripheral blood dendritic cells: evidence for a soluble CD14-dependent pathway.
J. Immunol.
158:2919-2925[Abstract].
|
| 44.
|
von Stebut, E.,
Y. Belkaid,
T. Jakob,
D. L. Sacks, and M. C. Udey.
1998.
Uptake of Leishmania major amastigotes results in activation and interleukin-12 release from murine skin-derived dendritic cells: implications for the initiation of anti-Leishmania immunity.
J. Exp. Med.
188:1547-1552[Abstract/Free Full Text].
|
Infection and Immunity, August 1999, p. 4033-4040, Vol. 67, No. 8
0019-9567/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
This article has been cited by other articles:
-
Kamda, J. D., Singer, S. M.
(2009). Phosphoinositide 3-Kinase-Dependent Inhibition of Dendritic Cell Interleukin-12 Production by Giardia lamblia. Infect. Immun.
77: 685-693
[Abstract]
[Full Text]
-
Poncini, C. V., Soto, C. D. A., Batalla, E., Solana, M. E., Gonzalez Cappa, S. M.
(2008). Trypanosoma cruzi Induces Regulatory Dendritic Cells In Vitro. Infect. Immun.
76: 2633-2641
[Abstract]
[Full Text]
-
Banks, K. E., Humphreys, T. L., Li, W., Katz, B. P., Wilkes, D. S., Spinola, S. M.
(2007). Haemophilus ducreyi Partially Activates Human Myeloid Dendritic Cells. Infect. Immun.
75: 5678-5685
[Abstract]
[Full Text]
-
Ben Nasr, A., Haithcoat, J., Masterson, J. E., Gunn, J. S., Eaves-Pyles, T., Klimpel, G. R.
(2006). Critical role for serum opsonins and complement receptors CR3 (CD11b/CD18) and CR4 (CD11c/CD18) in phagocytosis of Francisella tularensis by human dendritic cells (DC): uptake of Francisella leads to activation of immature DC and intracellular survival of the bacteria. J. Leukoc. Biol.
80: 774-786
[Abstract]
[Full Text]
-
Chamekh, M., Vercruysse, V., Habib, M., Lorent, M., Goldman, M., Allaoui, A., Vray, B.
(2005). Transfection of Trypanosoma cruzi with Host CD40 Ligand Results in Improved Control of Parasite Infection. Infect. Immun.
73: 6552-6561
[Abstract]
[Full Text]
-
Vray, B., Camby, I., Vercruysse, V., Mijatovic, T., Bovin, N. V., Ricciardi-Castagnoli, P., Kaltner, H., Salmon, I., Gabius, H.-J., Kiss, R.
(2004). Up-regulation of galectin-3 and its ligands by Trypanosoma cruzi infection with modulation of adhesion and migration of murine dendritic cells. Glycobiology
14: 647-657
[Abstract]
[Full Text]
-
Alba Soto, C. D., Mirkin, G. A., Solana, M. E., Gonzalez Cappa, S. M.
(2003). Trypanosoma cruzi Infection Modulates In Vivo Expression of Major Histocompatibility Complex Class II Molecules on Antigen-Presenting Cells and T-Cell Stimulatory Activity of Dendritic Cells in a Strain-Dependent Manner. Infect. Immun.
71: 1194-1199
[Abstract]
[Full Text]
-
Overtvelt, L. V., Andrieu, M., Verhasselt, V., Connan, F., Choppin, J., Vercruysse, V., Goldman, M., Hosmalin, A., Vray, B.
(2002). Trypanosoma cruzi down-regulates lipopolysaccharide-induced MHC class I on human dendritic cells and impairs antigen presentation to specific CD8+ T lymphocytes. Int Immunol
14: 1135-1144
[Abstract]
[Full Text]
-
Brodskyn, C., Patricio, J., Oliveira, R., Lobo, L., Arnholdt, A., Mendonca-Previato, L., Barral, A., Barral-Netto, M.
(2002). Glycoinositolphospholipids from Trypanosoma cruzi Interfere with Macrophages and Dendritic Cell Responses. Infect. Immun.
70: 3736-3743
[Abstract]
[Full Text]
-
Ouaissi, A., Guilvard, E., Delneste, Y., Caron, G., Magistrelli, G., Herbault, N., Thieblemont, N., Jeannin, P.
(2002). The Trypanosoma cruzi Tc52-Released Protein Induces Human Dendritic Cell Maturation, Signals Via Toll-Like Receptor 2, and Confers Protection Against Lethal Infection. J. Immunol.
168: 6366-6374
[Abstract]
[Full Text]
-
Zimmer, M. I., Larregina, A. T., Castillo, C. M., Capuano, S. III, Falo, L. D. Jr, Murphey-Corb, M., Reinhart, T. A., Barratt-Boyes, S. M.
(2002). Disrupted homeostasis of Langerhans cells and interdigitating dendritic cells in monkeys with AIDS. Blood
99: 2859-2868
[Abstract]
[Full Text]
-
Wei, S., Marches, F., Borvak, J., Zou, W., Channon, J., White, M., Radke, J., Cesbron-Delauw, M.-F., Curiel, T. J.
(2002). Toxoplasma gondii-Infected Human Myeloid Dendritic Cells Induce T-Lymphocyte Dysfunction and Contact-Dependent Apoptosis. Infect. Immun.
70: 1750-1760
[Abstract]
[Full Text]
-
Newman, S. L., Holly, A.
(2001). Candida albicans Is Phagocytosed, Killed, and Processed for Antigen Presentation by Human Dendritic Cells. Infect. Immun.
69: 6813-6822
[Abstract]
[Full Text]
-
Qi, H., Popov, V., Soong, L.
(2001). Leishmania amazonensis-Dendritic Cell Interactions In Vitro and the Priming of Parasite-Specific CD4+ T Cells In Vivo. J. Immunol.
167: 4534-4542
[Abstract]
[Full Text]
-
Semnani, R. T., Sabzevari, H., Iyer, R., Nutman, T. B.
(2001). Filarial Antigens Impair the Function of Human Dendritic Cells during Differentiation. Infect. Immun.
69: 5813-5822
[Abstract]
[Full Text]
-
Cutler, C. W., Jotwani, R., Pulendran, B.
(2001). Dendritic Cells: Immune Saviors or Achilles' Heel?. Infect. Immun.
69: 4703-4708
[Full Text]
-
Angeli, V., Faveeuw, C., Roye, O., Fontaine, J., Teissier, E., Capron, A., Wolowczuk, I., Capron, M., Trottein, F.
(2001). Role of the Parasite-derived Prostaglandin D2 in the Inhibition of Epidermal Langerhans Cell Migration during Schistosomiasis Infection. JEM
193: 1135-1148
[Abstract]
[Full Text]
-
Bonini, C., Lee, S. P., Riddell, S. R., Greenberg, P. D.
(2001). Targeting Antigen in Mature Dendritic Cells for Simultaneous Stimulation of CD4+ and CD8+ T Cells. J. Immunol.
166: 5250-5257
[Abstract]
[Full Text]
-
Bodnar, K. A., Serbina, N. V., Flynn, J. L.
(2001). Fate of Mycobacterium tuberculosis within Murine Dendritic Cells. Infect. Immun.
69: 800-809
[Abstract]
[Full Text]
-
Ho, L.-J., Wang, J.-J., Shaio, M.-F., Kao, C.-L., Chang, D.-M., Han, S.-W., Lai, J.-H.
(2001). Infection of Human Dendritic Cells by Dengue Virus Causes Cell Maturation and Cytokine Production. J. Immunol.
166: 1499-1506
[Abstract]
[Full Text]
-
Gildea, L. A., Morris, R. E., Newman, S. L.
(2001). Histoplasma capsulatum Yeasts Are Phagocytosed Via Very Late Antigen-5, Killed, and Processed for Antigen Presentation by Human Dendritic Cells. J. Immunol.
166: 1049-1056
[Abstract]
[Full Text]
-
Svensson, M., Johansson, C., Wick, M. J.
(2000). Salmonella enterica Serovar Typhimurium-Induced Maturation of Bone Marrow-Derived Dendritic Cells. Infect. Immun.
68: 6311-6320
[Abstract]
[Full Text]
-
Subauste, C. S., Wessendarp, M.
(2000). Human Dendritic Cells Discriminate Between Viable and Killed Toxoplasma gondii Tachyzoites: Dendritic Cell Activation After Infection with Viable Parasites Results in CD28 and CD40 Ligand Signaling That Controls IL-12-Dependent and -Independent T Cell Production of IFN-{gamma}. J. Immunol.
165: 1498-1505
[Abstract]
[Full Text]
-
Fortsch, D., Rollinghoff, M., Stenger, S.
(2000). IL-10 Converts Human Dendritic Cells into Macrophage-Like Cells with Increased Antibacterial Activity Against Virulent Mycobacterium tuberculosis. J. Immunol.
165: 978-987
[Abstract]
[Full Text]
-
Whelan, M., Harnett, M. M., Houston, K. M., Patel, V., Harnett, W., Rigley, K. P.
(2000). A Filarial Nematode-Secreted Product Signals Dendritic Cells to Acquire a Phenotype That Drives Development of Th2 Cells. J. Immunol.
164: 6453-6460
[Abstract]
[Full Text]
-
Engelmayer, J., Larsson, M., Subklewe, M., Chahroudi, A., Cox, W. I., Steinman, R. M., Bhardwaj, N.
(1999). Vaccinia Virus Inhibits the Maturation of Human Dendritic Cells: A Novel Mechanism of Immune Evasion. J. Immunol.
163: 6762-6768
[Abstract]
[Full Text]
Top
Abstract
Introduction
