| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
-Inducing Factor) Regulates Early Cytokine Production in, and Promotes Resolution of, Bacterial Infection in Mice1
*
Max von Pettenkofer Institut, Ludwig-Maximilians-Universität, Munich, Germany;
Hayashibara Biochemical Laboratories, Inc., Fujisaki Institute, Okayama, Japan; and
Department of Bacteriology, Hyogo College of Medicine, Nishinomiyya, Japan
 |
Abstract |
|---|
 Top Abstract IntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
production is essential for clearance of
Yersinia enterocolitica infection. Similar to IL-12, the
recently described cytokine IL-18 (IFN--inducing factor) is produced
by macrophages and induces IFN- production in spleen cells.
Therefore, we have investigated the role of IL-18 in
Yersinia infection of mice. Heat-killed yersinia-triggered
IL-18-promoted IFN- production of splenocytes was predominantly
dependent on endogenous IL-12 production, whereas IL-12-promoted
IFN- production was not IL-18 dependent. IL-18-induced IFN-
production was to a higher degree dependent on IFN-R-mediated
mechanisms and in synergism with IL-2 resulted in at least fivefold
higher IFN- levels as compared with the combination of IL-12 plus
IL-2. Analysis of the effect of IL-18 on IL-12 production of
LPS-stimulated peritoneal macrophages revealed that IL-18 decreased
LPS-induced IL-12 production, indicating that IL-18 might be involved
in negative regulation of IL-12 production. In vivo studies revealed
that Yersinia-resistant C57BL/6 mice expressed fourfold
higher IL-18 mRNA levels than did susceptible BALB/c mice.
Administration of anti-IL-18 Abs caused a 100- to 1000-fold
increase in bacterial counts in the spleen of infected mice but did not
change IFN- production levels. Taken together, our data demonstrate
that IL-18 is involved in regulation of cytokine production during the
early phase of bacterial infections as well as in clearance of
Yersinia infection. |
Introduction |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
-inducing
factor (IL-18) is a recently described murine and human cytokine. The
murine IL-18 gene encodes a precursor protein of 192 amino acids which
is processed to a mature protein of 157 amino acids (1). Although there
is no apparent similarity to sequences in protein or nucleotide
databases, a structural relationship of IL-18 to the IL-1 family was
described (2). As predicted by Bazan et al. precursor IL-18 is
processed by IL-1ß-converting enzyme
(ICE)3 and cleaved to
mature IL-18 (3). As described for IL-12 (4, 5, 6), IL-18 induces IFN-
production in Th1 clones (1, 7). Likewise, high IFN- levels are
induced by IL-18 in splenic derived CD4 T cells in the presence of B
cells or adherent cells (8). Furthermore, similar to IL-12 (9, 10),
IL-18 stimulates T cell proliferation and NK cell activity (1).
Moreover, IL-18 enhances Fas ligand-mediated cytotoxicity of Th1 T cell
clones (11). Human IL-18 has been found to enhance the production of
IFN- (IFN-) and granulocyte/macrophage CSF in Con A stimulated
PBMC (12). In contrast to IL-12, IL-18 enhances IL-2 and
granulocyte/macrophage CSF production in human T cells (13). Addition
of IL-18 to anti-CD3 mAb-stimulated human T cells enhances
proliferation of these cells. This effect could be completely inhibited
by a neutralizing Ab against IL-2 (13).
Previous studies showed that IL-12-induced IFN- production is
essential for clearance of Yersinia enterocolitica infection
in mice (14). Y. enterocolitica is a Gram-negative,
rod-shaped, mainly extracellularly located pathogen that causes
enteritis and enterocolitis in humans and rodents (15, 16, 17). Systemic
infection including abscesses and granulomatous lesions in spleen and
liver occur, particularly in immunocompromised individuals (18, 19).
Similar to infections with intracellular pathogens T cells,
particularly CD4+ Th1 cells, in cooperation with activated
macrophages are involved in and required for clearance of primary
Yersinia infection (20, 21), since plasmid-encoded virulence
factors such as YadA and Yersinia outer proteins (Yops)
enable Y. enterocolitica to evade innate host defense
mechanisms including complement system and phagocytosis (16, 22, 23).
Clearance of Yersinia infection is mediated by various
proinflammatory cytokines. Thus, neutralization of TNF-
, IFN- or
IL-12 abrogates resistance against this pathogen suggesting that T-cell
activated macrophages are important effector cells in the protective
host response to yersiniae (14, 20, 24). Previous studies showed that
C57BL/6 mice are resistant against Y. enterocolitica while
BALB/c mice are susceptible (25). Administration of IFN-, IL-12 or
anti-IL-4 Abs rendered BALB/c mice resistant to yersiniae but did
not significantly affect the course of the infection in
Yersinia-resistant C57BL/6 mice. IL-12 treatment of
Yersinia-infected C57BL/6 mice, however, increased bacterial
numbers in the spleen and toxic effects in the liver were observed
(14). Comparison of Yersinia-resistant C57BL/6 and
Yersinia-susceptible BALB/c mice demonstrated that both
mouse strains differ in their ability to produce IFN- (20, 26).
Hence, BALB/c mice can be characterized as IFN- low producers
and C57BL/6 mice as IFN- high producers. IFN- production of
heat-killed yersiniae (HKY)-stimulated spleen cells derived from
Yersinia-infected mice is predominantly IL-12 dependent.
(15, 16, 17). The reason for the different IL-12-mediated IFN-
production in C57BL/6 and BALB/c mice, however, is not yet clear. Since
there is evidence that IL-18 is involved in IFN- production we
wanted to analyze 1) the principle role of IL-18 in cytokine
regulation, 2) the role of IL-18 in infection with enteropathogenic
Y. enterocolitica, and 3) whether IL-18 might be involved in
the different susceptibility of C57BL/6 and BALB/c mice to Y.
enterocolitica infections.
|
Materials and Methods |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
Female 6- to 8-wk-old C57BL/6 and BALB/c mice were purchased
from Charles River Wiga (Sulzfeld, Germany) and kept under
specific-pathogen-free conditions (positive pressure cabinet). Female
6- to 8-wk-old 129/Sv/Ev IFN-R type II+/+,
129/Sv/Ev IFN-R type II-/- as described by Huang et
al. (27), Ola/129 IL-2+/+ and Ola/129 IL-2-/-
(28), and C57BL/6 TNFR p55-/- (29) were bred under
specific-pathogen-free conditions.
Infection of animals
Freshly thawed, plasmid-harboring Y. enterocolitica strain WA-314 serotype O:8 organisms suspended in 0.1 ml of sterile PBS, pH 7.4, were used for i.v. infection as described previously (20). The actual number of bacteria administered was determined by plating serial dilutions of the inoculum on Mueller-Hinton agar (Merck, Darmstadt, Germany) and counting CFU after an incubation period of 36 h at 26°C. In kinetic studies, four mice per group were killed by carbon dioxide asphyxiation on days 1, 3, and 7 after infection with 5 x 103 bacteria for both C57BL/6 and BALB/c mice if not stated otherwise. The spleens were removed aseptically, and a single-cell suspension was prepared by using 5 ml of PBS containing 0.1% BSA. Then, duplicates of 0.1 ml of serial dilutions of these preparations were plated on Mueller-Hinton agar. The limit of detectable CFU was 25 (log10 25 = 1.4). All animal experiments were reproduced at least three times and revealed comparable results.
Antibodies
The mAbs and polyclonal Abs used in this study were polyclonal
goat anti-mouse IL-12 Abs (kindly provided by M. Gately,
Hoffman-LaRoche Inc., Nutley, NJ), polyclonal rabbit anti-mouse
IL-18 (M. Kurimoto, Hayashibara Biochemical Laboratories, Fujisaki
Institute, Okayama, Japan), monoclonal rat anti-mouse IL-1 receptor
(mu IL1R-M15) (Dr. J. Sims, Immunex Research Inc., Seattle, WA),
anti-murine IL-1 neutralizing Abs (R&D Systems, Wiesbaden,
Germany), anti-murine IL-1ß neutralizing Abs (R&D Systems),
anti-murine IFN- (R4-6A2 and AN 18.17.24), anti-murine IL-12
(C17.8 and C15.6, PharMingen, San Diego, CA), anti-murine TNF-
(G281-2626 and MP6-XT3; PharMingen), and anti-murine IL-2 mAbs
(JES6-1A12 and JES6-5H4; PharMingen).
Cytokines
Recombinant IL-18 was supplied by M. Kurimoto, Hayashibara
Biochemical Laboratories, Inc., Fujisaki Institute. IFN- was
supplied by G. R. Adolf, Bender Wien, Austria. IL-12 was supplied
by M. Gately, Hoffman-LaRoche, Nutley, NJ. IL-1 was purchased by R&D
Systems.
Stimulation of spleen cells in vitro
A part of the single-cell suspension described above was used for in vitro culture of splenocytes. Erythrocytes were lysed by a short incubation in 0.15 M NH4Cl, washed three times with HBSS, and resuspended in Click/RPMI 1640 cell culture medium (Biochrom, Berlin, Germany) supplemented with 2 mM L-glutamine (Biochrom), 10 mM HEPES (Biochrom), 5 x 10-5 M 2-ME (Biochrom), 10 µg of streptomycin (Biochrom) per ml, 100 U of penicillin (Biochrom) per ml, and 10% heat-inactivated FCS (Biochrom) at a final cell concentration of 2 x 106 per ml of Click-10% FCS.
For determination of cytokine production, 2 x 106
splenocytes were cultured in 2 ml of cell culture medium in 12-well
macroculture plates (Nunc, Roskilde, Denmark) in the presence of 10
µg/ml HKY). Cytokines were modulated by incubation with polyclonal
goat anti-murine IL-12 Abs at a concentration of 5 to 20 µg/ml,
recombinant IL-12 (10–1,000 pg/ml; kindly provided by M. Gately),
recombinant IL-18 (10–10,000 pg/ml; kindly provided by M. Kurimoto),
polyclonal rabbit anti-mouse IL-18 (5–50 µg/ml; M. Kurimoto),
monoclonal rat anti-mouse IL-1 receptor (3 µg/ml; mu IL1R-M15;
Dr. Sims, Immunex Research Inc.), anti-murine IL-1 neutralizing
Abs (10 µg/ml; R&D Systems, Wiesbaden, Germany), anti-murine IL-1
ß neutralizing Abs (10 µg per ml; R&D Systems). After 48 h,
supernatants were harvested and used in the cytokine assays.
Stimulation of peritoneal macrophages in vitro
Peritoneal exudate cells were obtained from C57BL/6 mice that had received an i.p. injection of 1 ml of 10% proteose peptone (Difco Laboratories, Detroit, MI) 3 days before. Peritoneal exudate cells were washed three times and resuspended in ice-cold RPMI 1640 medium (Biochrom) supplemented with 2 mM L-glutamine (Biochrom), 10 mM HEPES (Biochrom), 100 µg of streptomycin (Biochrom) per ml, 100 U of penicillin (Biochrom) per ml, and 10% heat-inactivated FCS (Biochrom).
These cells (10 x 106 cells/well) were plated in
24-well tissue culture plates (Nunc). The cells were incubated at
37°C for 2 h, and nonadherent cells were removed by repeated
washing with PBS. Macrophage monolayers were incubated with 1 µg of
LPS per ml (Escherichia coli 0127:B8; Sigma,
Deisenhofen, Germany) in addition of IFN- (50 U/ml) and IL-18 (10
ng/ml). Supernatants were collected 4 h later, and levels of IL-12
and TNF- were determined.
Stimulation of EL-4 T lymphoma cells
EL-4 6.1 cells were routinely passaged in RPMI 1640 supplemented with 5% FCS, 2 mM L-glutamine (Biochrom), 5 x 10-5 M 2-ME (Biochrom), 10 µg of streptomycin (Biochrom) per ml, 100 U of penicillin (Biochrom) per ml, and 10% heat-inactivated FCS (Biochrom). EL-4 6.1 cells were washed by centrifugation and resuspended in their respective culture medium at 106 cells/ml to which 10 ng of PMA per ml plus 1 ng of IL-1 or IL-18 per ml with or without anti-IL-1R Abs (3 µg/ml) was added. Supernatants were collected 24 h later, and IL-2 was determined by IL-2 capture ELISA.
Assays for IFN-, IL-12, TNF-, and IL-2
IFN-.
IFN- levels were determined by using a capture ELISA as described
recently (30). Briefly, ELISA microtiter plates (Greiner, Solingen,
Germany) were coated with anti-IFN- mAb (AN-18.17.24). After
blocking of nonspecific binding sites, supernatants were added to the
wells and incubated overnight. After several wash steps, biotin-labeled
anti-IFN- mAb (R4-6A2) was added. Finally, an
avidin-biotin-alkaline phosphatase complex (Strept ABC-AP kit; DAKO,
Glostrup, Denmark) was added. For signal development the wells were
incubated with p-nitrophenyl phosphate disodium (Sigma), and
the optical density was determined at wavelengths of 405 and 490 nm
with an ELISA reader. The levels of IFN- from spleen cell culture
were determined from the straight-line portion of the standard curve by
using recombinant murine IFN- (20).
TNF-.
TNF- levels were determined by a capture ELISA using rat
anti-mouse TNF- mAb (G281-2626) and biotin-labeled
anti-TNF- mAb (MP6XT3) as described above for IFN- ELISA.
IL-12.
IL-12 (p40 and p70) levels were determined by a capture ELISA using
anti-IL-12 mAb (C17.8) and biotin-labeled anti-IL-12 mAb
(C15.6) as described for IFN- ELISA.
IL-2.
IL-2 levels were determined by a capture ELISA using rat anti-mouse
IL-2 mAb (JES6-1A12) and biotin-labeled anti-IL-2 mAb (JES6-5H4) as
described for IFN- ELISA.
In vivo administration of Abs and cytokines
In various experiments, the course of infection was modulated by i.p. administration of 1) recombinant murine IL-18 (20–4000 ng) and 2) recombinant murine IL-12 (2 ng) on day -1, 0, 1, 2, 3 postinfection (p.i.), and 3) 300 µg of polyclonal rabbit anti-mouse IL-18 Abs on day -1 p.i. Control animals were injected i.p. with the appropriate volume of PBS.
RT-PCR
As described previously, mice were killed and the liver was infused with 10 to 20 ml of PBS, pH 7.4 (4°C), removed, and homogenized in 5 ml of buffer consisting of 5 M guanidine isothiocyanate (Sigma), 25 mM sodium citrate (Serva, Heidelberg, Germany), 0.5% N-lauroylsarcosine (Sigma), and 100 mM 2-ME (Fluka, Buchs, Switzerland). The homogenates were processed for RNA isolation, as described previously (26). Briefly reverse transcription was performed by mixing 20 µg of RNA in 10 µl of diethylpyrocarbonate (Sigma)-treated distilled H2O with 2 µg of oligo(dT) (United States Biochemical Corp., Cleveland, OH). This solution was incubated for 10 min at 65°C. Then 10 µl of a solution containing 2x reverse transcriptase buffer ((100 mM Tris-HCl (pH 8.3), 150 mM KCl, 6 mM MgCl2 (Life Technologies), 40 U of RNasin (Promega Biotec, Madison, WI), 20 mM DTT (Life Technologies), and 2 mM deoxynucleoside triphosphates)) was added, and tubes were incubated for 60 min at 37°C. Finally, tubes were heated to 90°C for 5 min, and 180 µl of distilled H2O were added to the reaction mixture. Samples were stored at -20°C until further use (Life Technologies). Primer pairs specific for ß-actin (sense 5'-TGG AAT CCT GTG GCA TCC ATG AAA C-3'; antisense 5'-TAA AAC GCA GCT CAG TAA CAG TCC G-3'; PCR product, 348 bp), IL-18 (sense 5'-ACT GTA CAA CCG CAG TAA TAC GG-3'; antisense 5'-AGT GAA CAT TAC AGA TTT ATC CC-3'; PCR product, 434 bp) were designed and purchased from Roth (Karlsruhe, Germany).
Five microliters of cDNA prepared as described above were added to 20 µl of a solution consisting of 1 U of Taq DNA polymerase (Amersham, Buckinghamshire, United Kingdom), 200 µM concentrations each of deoxynucleoside triphosphates, 200 to 500 nM 5' and 3' primers and Taq polymerase buffer (50 mM KCl, 10 mM Tris-HCl (pH 8.3), and 1.5 mM MgCl2; Amersham). PCR was performed in a DNA thermal cycler (Biometra, Göttingen, Germany) with 22 to 35 cycles. The PCR products were visualized by electrophoresis of 20 µl of the reaction product. Data shown are representative of at least three experiments including three to five animals per group and time point.
To assess IL-18 mRNA expression semiquantitatively, RT-PCR was performed as described above. The PCR product was run on an agarose gel and then transferred on nylon membrane by Southern blotting as described elsewhere (30). For hybridization, ß-actin and IL-18 probes generated by RT-PCR including the primer described above were purified by Prep-A-Gene-Kit (Bio-Rad, Munich, Germany) and labeled by digoxigenin-11-dUTP (Boehringer Mannheim, Mannheim, Germany). Then the probes were purified by QIA quick-spin PCR purification kit (Qiagen, Hilden, Germany). Prehybridization and hybridization procedures were conducted according to the instructions of the manufacturer (Boehringer Mannheim). Finally, the reaction was visualized by incubation with a polyclonal sheep anti-digoxigenin Fab fragment conjugated to alkaline phosphatase followed by the addition of the chemiluminescent alkaline substrate Lumigen PPD (Boehringer Mannheim). The signal was detected by exposing the membrane to an x-ray film as well as by counting the light emission with a chemiluminometer (Hamamatsu Photonics, Herrsching, Germany).
Statistics
Differences between mean values were analyzed with Student’s t test. p < 0.05 was considered statistically significant.
|
Results |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
production in C57BL/6 and BALB/c
mice
To compare the efficiency of IL-12- and IL-18-induced IFN-
production, naive spleen cells from C57BL/6 or BALB/c mice were
stimulated with HKY in addition to various concentrations of IL-12 or
IL-18, and IFN- production was determined in cell culture
supernatants. Both IL-12 and IL-18 induced significant IFN-
production in a dose-dependent manner (Fig. 1
). However, 
10 pg of IL-12 were
sufficient to induce a significant IFN- production in splenocytes,
while at least 10-fold higher concentrations of IL-18 were required to
achieve comparable levels (Fig. 1). Comparison of C57BL/6 and BALB/c
splenocytes revealed that both IL-12 and IL-18 induced IFN-
production at 10-fold lower levels in C57BL/6 splenocytes, indicating
that IL-18- and IL-12-mediated IFN- production is more efficient in
C57BL/6 than in BALB/c spleen cells.
|
Previous studies showed a higher Yersinia-triggered
IFN- mRNA expression in the liver and a higher IFN- production in
splenocytes of C57BL/6 compared with BALB/c mice, although both strains
of mice produce comparable quantities of IL-12 after exposure to
Y. enterocolitica (14, 26). This could be due to different
IL-18 production in C57BL/6 and BALB/c mice. Therefore, possible
synergistic effects of IL-12 and IL-18 were studied. For this purpose,
submaximal concentrations of IL-18 plus various amounts of IL-12, and
vice versa, were added to HKY-stimulated spleen cells, and IFN-
production was determined after 48 h. The results depicted in
Figure 2 indicate that there is a
synergistic dose-dependent effect of IL-12 on IL-18 and vice versa for
Yersinia-triggered IFN- production.
|
production of spleen cells is IL-12 but not
IL-1 dependent
To investigate whether IL-12 is IL-18 dependent or vice versa in
its ability to induce IFN- production, spleen cells from naive or
Yersinia-infected mice were stimulated with HKY in addition
to anti-IL-18 Abs plus IL-12 or anti-IL-12 Abs plus IL-18.
IL-18 induced IFN- levels were strongly reduced by the addition of
anti-IL-12 Abs in spleen cell cultures, indicating that
IL-18-induced IFN- production strongly depends on IL-12 (Fig. 3). In contrast, IL-12-induced IFN-
levels were only slightly reduced by anti-IL-18 Abs. Comparable
results were obtained for spleen cell cultures from
Yersinia-infected mice (data not shown).
|
production is IL-1R dependent. The data
depicted in Figure 3
show that the addition of anti-IL-1 Abs or
anti-IL-1R Abs had no impact on IL-12- or IL-18-induced IFN-
levels, indicating 1) that IL-12 or IL-18-induced IFN- production is
not IL-1 dependent and 2) that IL-18-induced effects are not mediated
by IL-1R. In addition, EL-4 T cell lymphoma cells stimulated with PMA
in combination with IL-1 , but not with IL-18, produced significant
IL-1R-dependent levels of IL-2 (data not shown), providing further
evidence that IL-18 does not signal through IL-1R. Regulatory effect of IL-18 on activated peritoneal macrophages
To study whether IL-18 induces IL-12 production, inflammatory
peritoneal macrophages were stimulated with LPS in combination with
IL-18 or IFN-, and the production of TNF- and IL-12 was
determined in cell culture supernatants 4 h later. As depicted in
Figure 4, IL-18 did not influence
LPS-triggered TNF- production. However, IL-18 reduced and
anti-IL-18 Abs increased LPS-triggered IL-12 production in the
absence of IFN- (Fig. 4). The addition of IFN--enhanced
LPS-mediated IL-12 production significantly. However, the addition of
neither IL-18 nor anti-IL-18 Abs changed IL-12 production in the
presence of IFN- (Fig. 4). These results led to the hypothesis that
after LPS stimulation IL-18 is produced and down-modulates IL-12
production by peritoneal macrophages in the absence of IFN- while
pretreatment with IFN- bypasses this negative regulatory effect.
|
production in cytokine-deficient
mice
To study whether IL-2-, TNFR-, and IFN-R-mediated mechanisms
influence IL-12- or IL-18-induced IFN- production, spleen cells from
IFN-R-, TNFR p55-, or IL-2-deficient mice were stimulated with HKY
in the presence of IL-12 or IL-18. HKY-stimulated spleen cells from
IFN-R-/- mice produced lower amounts of IL-18-
(90% reduction) or IL-12- (50% reduction) induced IFN-
compared with IFN-R+/+ spleen cells (Fig. 5A). In line with the
data that IL-18- induced IFN- is IL-12 dependent, these results
suggest that IFN-R-mediated IL-12 induction seems to synergize with
IL-18 for high amounts of IFN- produced by spleen cells.
|
than did IL-2+/+ spleen cells. Furthermore, the
addition of 10 U of IL-2 per ml increased IL-12- and IL-18-induced
IFN- levels significantly in both IL-2+/+ and
IL-2-/- mice (Fig. 5B), indicating that
IL-2 synergizes with IL-12 and IL-18 in IFN- production. The
synergistic effect on IFN- levels of IL-2 with IL-18 seems to be
much more efficient than the combination of IL-2 plus IL-12.
HKY-stimulated spleen cells from TNFR-/- and
TNFR+/+ mice produced comparable IL-12- or IL-18-induced
amounts of IFN- (Fig. 5C).
IFN- production is IL-12 and IL-18 dependent in yersiniosis
To assess whether IFN- production is IL-18 dependent, spleen
cells from Yersinia-infected C57BL/6 mice were stimulated
with HKY in the presence of anti-IL-18 or anti-IL-12 Abs and
IFN- levels were determined in cell culture supernatants. IFN-
levels were significantly reduced by anti-IL-12 Abs (70%;
p < 0.001) and anti-IL-18-Abs (30%;
p < 0.01) (Fig. 6).
These results indicate that HKY-induced IFN- production is
predominantly IL-12- but also partially IL-18-dependent.
|
To assess whether different IL-18 levels might account for
different IFN- production of Yersinia-resistant C57BL/6
and Yersinia-susceptible BALB/c mice, IL-18 mRNA levels in
liver tissue were determined before and after Y.
enterocolitica infection. Semiquantitative analysis of IL-18 mRNA
expression levels revealed that IL-18 mRNA is constitutively expressed
in liver tissue. However, a fourfold higher mRNA expression level was
found in C57BL/6 than in BALB/c mice (Fig. 7). These data led to the hypothesis that
the higher IL-18 mRNA levels could be responsible for different IFN-
levels and possibly different suceptibility of BALB/c and C57BL/6 mice
for Y. enterocolitica infection.
|
The role of IL-18 in protective host responses against Y.
enterocolitica was investigated in C57BL/6 and BALB/c mice. For
this purpose, mice were injected i.p. with neutralizing anti-IL-18
Abs before Y. enterocolitica infection. The data presented
in Figure 8 indicate that administration
of anti-IL-18 Abs increased susceptibility against yersiniae in
C57BL/6 as well as in BALB/c mice. Thus, bacterial numbers were more
than 100-fold increased in anti-IL-18-Ab treated mice compared with
control mice. From these data, we can conclude that IL-18 is an
important mediator of the protective host response against yersiniae.
In parallel experiments, spleen cells from both mouse strains were
isolated and exposed to HKY in vitro, and IFN- production was
determined in the cell culture supernatants (Fig. 8). In line with
previous studies, only spleen cells from C57BL/6 mice but not those
from BALB/c mice produced significant IFN- levels. Moreover, no
significant differences in IFN- production were observed in
HKY-stimulated splenocytes derived from anti-IL-18-treated C57BL/6
mice compared with control mice. These data suggest that IL-18 mediates
resistance by an IFN--independent mechanism.
|
To evaluate whether exogenous IL-18 can mediate protection against
Yersinia infection, mice were infected i.v. with yersiniae
and additionally treated with various amounts of IL-18 1 day before and
after infection. Bacterial numbers in spleens were determined on day
6 p.i. Administration of 1 to 4 µg of IL-18 per day did not
change bacterial numbers in spleens of Yersinia-infected
C57BL/6 or BALB/c mice (Fig. 9). The same
results were obtained when 20 to 100 ng of IL-18 per day or only one
dose of IL-18 (3 to 16 µg) was administered 1 day before the
infection (data not shown).
|
).
|
|
Discussion |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
by Yersinia-resistant C57BL/6 mice and low levels of IFN-
by Yersinia-susceptible BALB/c mice is associated with
Yersinia susceptibility (20, 26). Moreover, we have
demonstrated that IFN- production is mostly IL-12 dependent in
spleen cells derived from Yersinia-infected mice (14). In
vivo administration of anti-IL-12 Abs or recombinant IL-12 raised
the evidence that IL-12 is essential for clearance of Y.
enterocolitica infection (14) and depends on IFN-R-mediated
mechanisms.4 However,
although resistant C57BL/6 mice produce comparable quantities of IL-12
compared with susceptible BALB/c mice, the latter produce less IFN-
(14). The basis of the different responsiveness of both strains of mice
for IL-12-induced IFN- production in Yersinia infection
is not clear. Therefore, we hypothesized that other cytokines than
IL-12, e.g., IL-10 or TGF-ß, might account for the different IFN-
production of resistant and susceptible mice. However, the different
IFN- production levels in Yersinia-infected C57BL/6 and
BALB/c mice can only partially be explained by immunoregulating
cytokines such as IL-10 that suppress IFN- production, because,
e.g., suppression of IFN- production by IL-10 in HKY-stimulated
spleen cells derived from Yersinia-infected mice was
observed only during the late phase of infection (14). Moreover, no
significant differences in TGF-ß levels were observed in C57BL/6 and
BALB/c mice, although in vivo studies indicate that a relative lack of
TGF-ß is associated with a strong IFN- production by C57BL/6
mice.4 On the other hand, the different responsiveness of
both strains of mice for IL-12-induced IFN- production in
Yersinia infection could be due to a different regulation
and expression of IL-12R ß2 chain (31). Thus, the molecular basis for
the loss of the IL-12 responsiveness in T cells from
Leishmania-susceptible BALB/c and maintenance of IL-12
responsiveness in T cells from Leishmania-resistant B10.D2
mice is associated with a different expression of the IL-12R
ß2 subunit (31, 32).
Since IL-18 was shown to be a potent inducer of IFN- (1, 8), we
hypothesized that IL-18 might be involved in the different IFN-
levels of Yersinia-resistant and -susceptible mice and in
resistance against yersiniae. Therefore, we studied whether there are
different mechanisms involved in Yersinia-triggered IL-12-
and IL-18-promoted IFN- production. Moreover, we investigated
whether IL-18 is involved in protection of mice against yersiniae.
IL-12- as well as IL-18-induced significant levels of IFN- in
HKY-stimulated spleen cells, although lower amounts of IL-12 were
necessary compared with IL-18. Comparable with established anti-CD3
stimulated Th1 cell clones (1, 7), IL-12 and IL-18 synergistically
induced IFN- production in HKY-stimulated spleen cells. However, in
contrast to established Th1 cell clones (1, 7), IL-18-induced IFN-
production in HKY-stimulated spleen cells was highly IL-12
dependent.
Comparison of IL-18- and IL-12-induced IFN- production in
IL-2-deficient and control mice revealed that IL-2 synergizes with both
IL-18 and IL-12 in IFN- production. Therefore, high amounts of
IFN- production by anti-CD3-stimulated Th1 clones could be due
to a synergistic effect of IL-18 and IL-2. According to this
suggestion, IL-2 led to a fivefold increase of IL-18-induced IFN-
levels, while there was only a twofold increase of IL-12-induced
IFN- production by IL-2.
In HKY-stimulated spleen cells from IFN-R-deficient mice,
IL-18-induced IFN- production was strongly reduced, whereas
IL-12-induced IFN- production was only moderately reduced. The
striking difference of IL-12- and IL-18-induced IFN- production in
IFN-R mice compared with wild-type control mice could be due to a
direct and specific consequence of missing IFN-R or a general
consequence of the immunodeficiency. Nevertheless, these data led to
the suggestion that IL-12 predominantly induces IFN- production
directly and to a lesser degree by an amplification cascade involving
IFN--induced IL-12 production. In contrast to IL-12, IL-18 seems to
induce only low amounts of IFN- which in turn activates macrophages
to produce IL-12 and which may synergize with IL-18 to achieve high
amounts of IFN-.
Furthermore, studies on LPS-stimulated peritoneal macrophages showed no
evidence that IL-18 induces IL-12 directly, because LPS-triggered IL-12
production was down-regulated by IL-18 and up-regulated by
anti-IL-18 Abs in the absence of IFN- by a thus far unknown
mechanism. In accordance with previous observations (33), we found that
the addition of IFN- to LPS-stimulated peritoneal macrophages
increases IL-12 levels. In the presence of IFN-, however, the
addition of IL-18 had no impact on IL-12 production by peritoneal
macrophages. At present it is not known 1i) whether IFN- is able to
directly or indirectly suppress the inhibitory effect of IL-18 on IL-12
production and 2) whether IL-12 can modulate IL-18 production in
peritoneal macrophages. The physiologic reason for this complicated
mechanism remains unclear. By investigating IL-12 production of
IFN--deficient mice after in vivo stimulation with endotoxin,
Heinzel et al. provided evidence that IL-12 is produced by an
IFN--independent mechanism (34).
On the basis of these observations, one could speculate that after
interaction with bacterial products, macrophages produce IL-12 and
IL-18 that synergistically induce IFN- production. To balance
uncontrolled IL-12 production in a very early phase of infection, IL-18
may negatively feed back IL-12 production directly or indirectly. After
IL-12- and IL-18-induced IFN- production by NK or CD4 T cells,
additional IL-12 production is induced and leads to an amplification
cascade with high levels of IFN- production that induces optimal
protective effector mechanisms.
Comparison of IL-18 mRNA expression of Yersinia-resistant
and Yersinia-susceptible mice showed that IL-18 is
constitutively expressed in liver tissue but on an at least fourfold
higher level in C57BL/6 compared with BALB/c mice. Although activation
of ICE which cleaves precursor IL-18 and processes it into mature IL-18
could be more critical for controlling amounts of biologic active IL-18
(3), the different levels of IL-18 mRNA could nevertheless indicate
that after activation mature IL-18 protein levels may be higher in
C57BL/6 than in BALB/c mice. This in turn may lead in cooperation with
IL-12 to higher initial IFN- levels and a more efficient
amplification cascade of production of proinflammatory cytokines in
C57BL/6 mice.
Administration of anti-IL-18 Abs in vivo rendered BALB/c and
C57BL/6 more susceptible against Y. enterocolitica
infection. These data demonstrate that IL-18 plays a protective role in
clearance of bacterial infections. Previous studies demonstrated (14)
that IFN- production of HKY-stimulated splenocytes derived from
anti-IL-12-treated mice was reduced compared with control mice,
indicating that IL-12-mediated protection is due to induction of
IFN- production. Splenocytes derived from
Yersinia-infected mice and stimulated with HKY in the
presence of anti-IL-18 Abs as well as HKY-stimulated splenocytes
derived from anti-IL-18 mAb-treated Yersinia-infected
mice produced similar or only slightly reduced amounts of IFN-
compared with control mice. These data indicate that IL-18-mediated
protective mechanisms seem to be different from induction of
IFN--mediated effector mechanisms. Administration of rIL-18 in vivo
did not improve clearance of Yersinia infection in BALB/c or
C57BL/6 mice. Thus, IL-18 seems to have no theurapeutic potential in
infection with Gram-negative enteropathogenic bacteria.
Taken together, we found that 1) IL-18 is involved in regulation of
cytokine production in bacterial infections by interfering with IL-12
and that 2) IL-18 is involved in clearance of Yersinia
infection by a rather IFN--independent mechanism. Whether different
production of IL-18 might account for different susceptibility of mice
for Y. enterocolitica infection must be established.
|
Acknowledgments |
|---|
|
Footnotes |
|---|
2 Address correspondence and reprint requests to Dr. Ingo B. Autenrieth, Max-von-Pettenkofer-Institute, Ludwig-Maximilians-University, Pettenkoferstrasse 9a, D-80336, Munich, Germany.E-mail address:
3 Abbreviations used in this paper: ICE, IL-1ß-converting enzyme; HKY, heat-killed yersiniae; p.i., postinfection.
4 E. Bohn, E. Schmitt, C. Bielfeldt, A. Noll, R. Schulte, I. B. Autenrieth. Role of IL-12 and TGF-ß in bacterial infections: different mechanisms of protection against Yersinia enterocolitica in susceptible and resistant mouse strains. Submitted for publication.
Received for publication June 23, 1997. Accepted for publication September 18, 1997.
|
References |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
-inducing factor (IGIF) is a costimulatory factor on the activation of Th1 but not Th2 cells and exerts its activity independently of IL-12. J. Immunol. 158:1541.[Abstract]
This article has been cited by other articles:
|
|
 |
|
  R Dessein, M Gironella, C Vignal, L Peyrin-Biroulet, H Sokol, T Secher, S Lacas-Gervais, J-J Gratadoux, F Lafont, J-C Dagorn, et al. Toll-like receptor 2 is critical for induction of Reg3{beta} expression and intestinal clearance of Yersinia pseudotuberculosis Gut, June 1, 2009; 58(6): 771 - 776. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. S. Haring and J. T. Harty Interleukin-18-Related Genes Are Induced during the Contraction Phase but Do Not Play Major Roles in Regulating the Dynamics or Function of the T-Cell Response to Listeria monocytogenes Infection Infect. Immun., May 1, 2009; 77(5): 1894 - 1903. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
W. J. Wiersinga, C. W. Wieland, G. J. W. van der Windt, A. de Boer, S. Florquin, A. Dondorp, N. P. Day, S. J. Peacock, and T. van der Poll Endogenous Interleukin-18 Improves the Early Antimicrobial Host Response in Severe Melioidosis Infect. Immun., August 1, 2007; 75(8): 3739 - 3746. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. Orozco, E. Gemmell, M. Bickel, and G.J. Seymour Interleukin 18 and Periodontal Disease Journal of Dental Research, July 1, 2007; 86(7): 586 - 593. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. A. Rowland, G. Lertmemongkolchai, A. Bancroft, A. Haque, M. S. Lever, K. F. Griffin, M. C. Jackson, M. Nelson, A. O'Garra, R. Grencis, et al. Critical Role of Type 1 Cytokines in Controlling Initial Infection with Burkholderia mallei Infect. Immun., September 1, 2006; 74(9): 5333 - 5340. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 L. Fernandez-Lago, A. Orduna, and N. Vizcaino Reduced interleukin-18 secretion in Brucella abortus 2308-infected murine peritoneal macrophages and in spleen cells obtained from B. abortus 2308-infected mice J. Med. Microbiol., June 1, 2005; 54(6): 527 - 531. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
G K Paterson, C E Blue, and T J Mitchell Role of interleukin-18 in experimental infections with Streptococcus pneumoniae J. Med. Microbiol., April 1, 2005; 54(4): 323 - 326. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. E. Erfurth, S. Grobner, U. Kramer, D. S. J. Gunst, I. Soldanova, M. Schaller, I. B. Autenrieth, and S. Borgmann Yersinia enterocolitica Induces Apoptosis and Inhibits Surface Molecule Expression and Cytokine Production in Murine Dendritic Cells Infect. Immun., December 1, 2004; 72(12): 7045 - 7054. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. A. Akhiani, K. Schon, and N. Lycke Vaccine-Induced Immunity against Helicobacter pylori Infection Is Impaired in IL-18-Deficient Mice J. Immunol., September 1, 2004; 173(5): 3348 - 3356. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. A. Handley, P. H. Dube, P. A. Revell, and V. L. Miller Characterization of Oral Yersinia enterocolitica Infection in Three Different Strains of Inbred Mice Infect. Immun., March 1, 2004; 72(3): 1645 - 1656. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 B. Liu, I. Mori, M. J. Hossain, L. Dong, K. Takeda, and Y. Kimura Interleukin-18 improves the early defence system against influenza virus infection by augmenting natural killer cell-mediated cytotoxicity J. Gen. Virol., February 1, 2004; 85(2): 423 - 428. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
V. Cusumano, A. Midiri, V. V. Cusumano, A. Bellantoni, G. De Sossi, G. Teti, C. Beninati, and G. Mancuso Interleukin-18 Is an Essential Element in Host Resistance to Experimental Group B Streptococcal Disease in Neonates Infect. Immun., January 1, 2004; 72(1): 295 - 300. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. Weijer, M. E. Sewnath, A. F. de Vos, S. Florquin, K. van der Sluis, D. J. Gouma, K. Takeda, S. Akira, and T. van der Poll Interleukin-18 Facilitates the Early Antimicrobial Host Response to Escherichia coli Peritonitis Infect. Immun., October 1, 2003; 71(10): 5488 - 5497. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Mohty, A. Vialle-Castellano, J. A. Nunes, D. Isnardon, D. Olive, and B. Gaugler IFN-{alpha} Skews Monocyte Differentiation into Toll-Like Receptor 7-Expressing Dendritic Cells with Potent Functional Activities J. Immunol., October 1, 2003; 171(7): 3385 - 3393. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. M. Gherardi, J. C. Ramirez, and M. Esteban IL-12 and IL-18 act in synergy to clear vaccinia virus infection: involvement of innate and adaptive components of the immune system J. Gen. Virol., August 1, 2003; 84(8): 1961 - 1972. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. S. Di Genaro, M. Waidmann, U. Kramer, N. Hitziger, E. Bohn, and I. B. Autenrieth Attenuated Yersiniaenterocolitica Mutant Strains Exhibit Differential Virulence in Cytokine-Deficient Mice: Implications for the Development of Novel Live Carrier Vaccines Infect. Immun., April 1, 2003; 71(4): 1804 - 1812. [Abstract] [Full Text]
|
|
|
|
 |
|
 J. A. Gracie, S. E. Robertson, and I. B. McInnes Interleukin-18 J. Leukoc. Biol., February 1, 2003; 73(2): 213 - 224. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Komai-Koma, J. A. Gracie, X.-q. Wei, D. Xu, N. Thomson, I. B. McInnes, and F. Y. Liew Chemoattraction of Human T Cells by IL-18 J. Immunol., January 15, 2003; 170(2): 1084 - 1090. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
V. D. Joshi, D. V. Kalvakolanu, J. R. Hebel, J. D. Hasday, and A. S. Cross Role of Caspase 1 in Murine Antibacterial Host Defenses and Lethal Endotoxemia Infect. Immun., December 1, 2002; 70(12): 6896 - 6903. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
V. D. Joshi, D. V. Kalvakolanu, J. D. Hasday, R. J. Hebel, and A. S. Cross IL-18 Levels and the Outcome of Innate Immune Response to Lipopolysaccharide: Importance of a Positive Feedback Loop with Caspase-1 in IL-18 Expression J. Immunol., September 1, 2002; 169(5): 2536 - 2544. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Y. Kinjo, K. Kawakami, K. Uezu, S. Yara, K. Miyagi, Y. Koguchi, T. Hoshino, M. Okamoto, Y. Kawase, K. Yokota, et al. Contribution of IL-18 to Th1 Response and Host Defense Against Infection by Mycobacterium tuberculosis: A Comparative Study with IL-12p40 J. Immunol., July 1, 2002; 169(1): 323 - 329. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. L. Hodge, W. B. Schill, J. M. Wang, I. Blanca, D. A. Reynolds, J. R. Ortaldo, and H. A. Young IL-2 and IL-12 Alter NK Cell Responsiveness to IFN-{gamma}-Inducible Protein 10 by Down-Regulating CXCR3 Expression J. Immunol., June 15, 2002; 168(12): 6090 - 6098. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
N. J. Mueller, R. A. Wilkinson, and J. A. Fishman Listeria monocytogenes Infection in Caspase-11-Deficient Mice Infect. Immun., May 1, 2002; 70(5): 2657 - 2664. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 L.-P. Ho, M. Davis, A. Denison, F. T. Wood, and A. P. Greening Reduced Interleukin-18 Levels in BAL Specimens From Patients With Asthma Compared to Patients With Sarcoidosis and Healthy Control Subjects* Chest, May 1, 2002; 121(5): 1421 - 1426. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. P. Singh, S.-i. Kashiwamura, P. Rao, H. Okamura, A. Mukherjee, and V. S. Chauhan The Role of IL-18 in Blood-Stage Immunity Against Murine Malaria Plasmodium yoelii265 and Plasmodium bergheiANKA J. Immunol., May 1, 2002; 168(9): 4674 - 4681. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. Wang, C. Feliciani, B. G. Howell, I. Freed, Q. Cai, H. Watanabe, and D. N. Sauder Contribution of Langerhans Cell-Derived IL-18 to Contact Hypersensitivity J. Immunol., April 1, 2002; 168(7): 3303 - 3308. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. Gatti, J. Beck, G. Fantuzzi, T. Bartfai, and C. A. Dinarello Effect of interleukin-18 on mouse core body temperature Am J Physiol Regulatory Integrative Comp Physiol, March 1, 2002; 282(3): R702 - R709. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. Sing, A. Roggenkamp, A. M. Geiger, and J. Heesemann Yersiniaenterocolitica Evasion of the Host Innate Immune Response by V Antigen-Induced IL-10 Production of Macrophages Is Abrogated in IL-10-Deficient Mice J. Immunol., February 1, 2002; 168(3): 1315 - 1321. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. DE PERROT, Y. SEKINE, S. FISCHER, T. K. WADDELL, K. MCRAE, M. LIU, D. A. WIGLE, and S. KESHAVJEE Interleukin-8 Release during Early Reperfusion Predicts Graft Function in Human Lung Transplantation Am. J. Respir. Crit. Care Med., January 15, 2002; 165(2): 211 - 215. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
F. N. Lauw, J. Branger, S. Florquin, P. Speelman, S. J. H. van Deventer, S. Akira, and T. van der Poll IL-18 Improves the Early Antimicrobial Host Response to Pneumococcal Pneumonia J. Immunol., January 1, 2002; 168(1): 372 - 378. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. G. Mordue, F. Monroy, M. La Regina, C. A. Dinarello, and L. D. Sibley Acute Toxoplasmosis Leads to Lethal Overproduction of Th1 Cytokines J. Immunol., October 15, 2001; 167(8): 4574 - 4584. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 T. Ogura, H. Ueda, K. Hosohara, R. Tsuji, Y. Nagata, S.-i. Kashiwamura, and H. Okamura Interleukin-18 stimulates hematopoietic cytokine and growth factor formation and augments circulating granulocytes in mice Blood, October 1, 2001; 98(7): 2101 - 2107. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Quiding-Jarbrink, D. A. Smith, and G. J. Bancroft Production of Matrix Metalloproteinases in Response to Mycobacterial Infection Infect. Immun., September 1, 2001; 69(9): 5661 - 5670. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. P. Leung, S. Culshaw, J. A. Gracie, D. Hunter, C. A. Canetti, C. Campbell, F. Cunha, F. Y. Liew, and I. B. McInnes A Role for IL-18 in Neutrophil Activation J. Immunol., September 1, 2001; 167(5): 2879 - 2886. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Neighbors, X. Xu, F. J. Barrat, S. R. Ruuls, T. Churakova, R. Debets, J. F. Bazan, R. A. Kastelein, J. S. Abrams, and A. O'Garra A Critical Role for Interleukin 18 in Primary and Memory Effector Responses to Listeria monocytogenes That Extends Beyond Its Effects on Interferon {gamma} Production J. Exp. Med., August 6, 2001; 194(3): 343 - 354. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
L. Del Rio, A. J. Buendia, J. Sanchez, M. C. Gallego, M. R. Caro, N. Ortega, J. Seva, F. J. Pallares, F. Cuello, and J. Salinas Endogenous Interleukin-12 Is Not Required for Resolution of Chlamydophila abortus (Chlamydia psittaci Serotype 1) Infection in Mice Infect. Immun., August 1, 2001; 69(8): 4808 - 4815. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C Hanck, T Manigold, U Bocker, M Kurimoto, C B Kolbel, M V Singer, and S Rossol Gene expression of interleukin 18 in unstimulated peripheral blood mononuclear cells of patients with alcoholic cirrhosis Gut, July 1, 2001; 49(1): 106 - 111. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
L. Yao, J. Setsuda, C. Sgadari, B. Cherney, and G. Tosato Interleukin-18 expression induced by Epstein-Barr virus-infected cells J. Leukoc. Biol., May 1, 2001; 69(5): 779 - 784. [Abstract] [Full Text]
|
|
|
|
 |
|
 H.-R. Jiang, X.-q. Wei, W. Niedbala, L. Lumsden, F. Y. Liew, and J. V. Forrester IL-18 Not Required for IRBP Peptide-Induced EAU: Studies in Gene-Deficient Mice Invest. Ophthalmol. Vis. Sci., January 1, 2001; 42(1): 177 - 182. [Abstract] [Full Text]
|
|
|
|
|
|
T. Merlin, A. Sing, P. J. Nielsen, C. Galanos, and M. A. Freudenberg Inherited IL-12 Unresponsiveness Contributes to the High LPS Resistance of the Lpsd C57BL/10ScCr Mouse J. Immunol., January 1, 2001; 166(1): 566 - 573. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
G. Cai, R. Kastelein, and C. A. Hunter Interleukin-18 (IL-18) Enhances Innate IL-12-Mediated Resistance to Toxoplasma gondii Infect. Immun., December 1, 2000; 68(12): 6932 - 6938. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. Mencacci, A. Bacci, E. Cenci, C. Montagnoli, S. Fiorucci, A. Casagrande, R. A. Flavell, F. Bistoni, and L. Romani Interleukin 18 Restores Defective Th1 Immunity to Candida albicans in Caspase 1-Deficient Mice Infect. Immun., September 1, 2000; 68(9): 5126 - 5131. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
W. E. Carson, J. E. Dierksheide, S. Jabbour, M. Anghelina, P. Bouchard, G. Ku, H. Yu, H. Baumann, M. H. Shah, M. A. Cooper, et al. Coadministration of interleukin-18 and interleukin-12 induces a fatal inflammatory response in mice: critical role of natural killer cell interferon-gamma production and STAT-mediated signal transduction Blood, August 15, 2000; 96(4): 1465 - 1473. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. Kawakami, Y. Koguchi, M. H. Qureshi, A. Miyazato, S. Yara, Y. Kinjo, Y. Iwakura, K. Takeda, S. Akira, M. Kurimoto, et al. IL-18 Contributes to Host Resistance Against Infection with Cryptococcus neoformans in Mice with Defective IL-12 Synthesis Through Induction of IFN-{gamma} Production by NK Cells J. Immunol., July 15, 2000; 165(2): 941 - 947. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. P. Leung, I. B. McInnes, E. Esfandiari, X.-Q. Wei, and F. Y. Liew Combined Effects of IL-12 and IL-18 on the Induction of Collagen-Induced Arthritis J. Immunol., June 15, 2000; 164(12): 6495 - 6502. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H. Kohka, M. Nishibori, H. Iwagaki, N. Nakaya, T. Yoshino, K. Kobashi, K. Saeki, N. Tanaka, and T. Akagi Histamine Is a Potent Inducer of IL-18 and IFN-{gamma} in Human Peripheral Blood Mononuclear Cells J. Immunol., June 15, 2000; 164(12): 6640 - 6646. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
G. YAMADA, N. SHIJUBO, K. SHIGEHARA, H. OKAMURA, M. KURIMOTO, and S. ABE Increased Levels of Circulating Interleukin-18 in Patients with Advanced Tuberculosis Am. J. Respir. Crit. Care Med., June 1, 2000; 161(6): 1786 - 1789. [Abstract] [Full Text]
|
|
|
|
|
|
G. M. Monteforte, K. Takeda, M. Rodriguez-Sosa, S. Akira, J. R. David, and A. R. Satoskar Genetically Resistant Mice Lacking IL-18 Gene Develop Th1 Response and Control Cutaneous Leishmania major Infection J. Immunol., June 1, 2000; 164(11): 5890 - 5893. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Y.-X. Zhao, G. Lajoie, H. Zhang, B. Chiu, U. Payne, and R. D. Inman Tumor Necrosis Factor Receptor p55-Deficient Mice Respond to Acute Yersinia enterocolitica Infection with Less Apoptosis and More Effective Host Resistance Infect. Immun., March 1, 2000; 68(3): 1243 - 1251. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. Hein, V. A. J. Kempf, J. Diebold, N. Bucheler, S. Preger, I. Horak, A. Sing, U. Kramer, and I. B. Autenrieth Interferon Consensus Sequence Binding Protein Confers Resistance against Yersinia enterocolitica Infect. Immun., March 1, 2000; 68(3): 1408 - 1417. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
E. Kuroda, T. Sugiura, K. Zeki, Y. Yoshida, and U. Yamashita Sensitivity Difference to the Suppressive Effect of Prostaglandin E2 Among Mouse Strains: A Possible Mechanism to Polarize Th2 Type Response in BALB/c Mice J. Immunol., March 1, 2000; 164(5): 2386 - 2395. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
G. Hansen, V. P. Yeung, G. Berry, D. T. Umetsu, and R. H. DeKruyff Vaccination with Heat-Killed Listeria as Adjuvant Reverses Established Allergen-Induced Airway Hyperreactivity and Inflammation: Role of CD8+ T Cells and IL-18 J. Immunol., January 1, 2000; 164(1): 223 - 230. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. K. Dybing, N. Walters, and D. W. Pascual Role of Endogenous Interleukin-18 in Resolving Wild-Type and Attenuated Salmonella typhimurium Infections Infect. Immun., December 1, 1999; 67(12): 6242 - 6248. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. C. Leite-de-Moraes, A. Hameg, A. Arnould, F. Machavoine, Y. Koezuka, E. Schneider, A. Herbelin, and M. Dy A Distinct IL-18-Induced Pathway to Fully Activate NK T Lymphocytes Independently from TCR Engagement J. Immunol., December 1, 1999; 163(11): 5871 - 5876. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. T. Brady, S. M. O'Neill, J. P. Dalton, and K. H. G. Mills Fasciola hepatica Suppresses a Protective Th1 Response against Bordetella pertussis Infect. Immun., October 1, 1999; 67(10): 5372 - 5378. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 N. Rayhane, C. Fitting, and J.-M. Cavaillon Dissociation of IFN-{gamma} from IL-12 and IL-18 production during endotoxin tolerance Innate Immunity, October 1, 1999; 5(5-6): 319 - 324. [Abstract] [PDF]
|
|
|
|
|
|
L. Kremer, L. Dupre, I. Wolowczuk, and C. Locht In Vivo Immunomodulation Following Intradermal Injection with DNA Encoding IL-18 J. Immunol., September 15, 1999; 163(6): 3226 - 3231. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
X.-q. Wei, B. P. Leung, W. Niedbala, D. Piedrafita, G.-j. Feng, M. Sweet, L. Dobbie, A. J. H. Smith, and F. Y. Liew Altered Immune Responses and Susceptibility to Leishmania major and Staphylococcus aureus Infection in IL-18-Deficient Mice J. Immunol., September 1, 1999; 163(5): 2821 - 2828. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 K. Fassbender, O. Mielke, T. Bertsch, F. Muehlhauser, M. Hennerici, M. Kurimoto, and S. Rossol Interferon-{gamma}-inducing factor (IL-18) and interferon-{gamma} in inflammatory CNS diseases Neurology, September 1, 1999; 53(5): 1104 - 1104. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
W. Walker, M. Aste-Amezaga, R. A. Kastelein, G. Trinchieri, and C. A. Hunter IL-18 and CD28 Use Distinct Molecular Mechanisms to Enhance NK Cell Production of IL-12-Induced IFN-{gamma} J. Immunol., May 15, 1999; 162(10): 5894 - 5901. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
V. E. Garcia, K. Uyemura, P. A. Sieling, M. T. Ochoa, C. T. Morita, H. Okamura, M. Kurimoto, T. H. Rea, and R. L. Modlin IL-18 Promotes Type 1 Cytokine Production from NK Cells and T Cells in Human Intracellular Infection J. Immunol., May 15, 1999; 162(10): 6114 - 6121. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. A. R. C. Daemen, C. v.'t Veer, T. G. A. M. Wolfs, and W. A. Buurman Ischemia/Reperfusion-Induced IFN-{gamma} Up-Regulation: Involvement of IL-12 and IL-18 J. Immunol., May 1, 1999; 162(9): 5506 - 5510. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. A. Fehniger, M. H. Shah, M. J. Turner, J. B. VanDeusen, S. P. Whitman, M. A. Cooper, K. Suzuki, M. Wechser, F. Goodsaid, and M. A. Caligiuri Differential Cytokine and Chemokine Gene Expression by Human NK Cells Following Activation with IL-18 or IL-15 in Combination with IL-12: Implications for the Innate Immune Response J. Immunol., April 15, 1999; 162(8): 4511 - 4520. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H. H. Balkhy and F. P. Heinzel Endotoxin Fails to Induce IFN-{gamma} in Endotoxin-Tolerant Mice: Deficiencies in Both IL-12 Heterodimer Production and IL-12 Responsiveness J. Immunol., March 15, 1999; 162(6): 3633 - 3638. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 N. Fujioka, R. Akazawa, K. Ohashi, M. Fujii, M. Ikeda, and M. Kurimoto Interleukin-18 Protects Mice against Acute Herpes Simplex Virus Type 1 Infection J. Virol., March 1, 1999; 73(3): 2401 - 2409. [Abstract] [Full Text]
|
|
|
|
|
|
P. Mastroeni, S. Clare, S. Khan, J. A. Harrison, C. E. Hormaeche, H. Okamura, M. Kurimoto, and G. Dougan Interleukin 18 Contributes to Host Resistance and Gamma Interferon Production in Mice Infected with Virulent Salmonella typhimurium Infect. Immun., February 1, 1999; 67(2): 478 - 483. [Abstract] [Full Text] [PDF]
|
|
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
