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Divisions of Pediatric
*
Critical Care and
Infectious Diseases, Ahmanson Department of Pediatrics, Steven Spielberg Pediatric Research Center, Cedars-Sinai Medical Center, and University of California School of Medicine, Los Angeles, CA 90048
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Abstract |
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 Top Abstract IntroductionMaterials and MethodsResultsDiscussionReferences |
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B
trans-activation shares the IL-1R signaling molecules.
Dominant negative constructs of TLR2 or TLR6 inhibit the responses of
STF and OspA-L as well as PSM in TLR2-transfected HMEC, supporting the
concept of functional cooperation between TLR2 and TLR6 for all these
TLR2 ligands. Moreover, we show that Toll-interacting protein (Tollip)
coimmunoprecipitates with TLR2 and TLR4 using HEK 293 cells, and
overexpression of Tollip inhibits NF-B activation in response to
TLR2 and TLR4 signaling. Collectively, these findings suggest that
there is functional interaction between TLR2 and TLR6 in the cellular
response to STF and OspA-L in addition to S. epidermidis
(PSM) Ags, and that engagement of TLR2 triggers a signaling cascade,
which shares the IL-1R signaling molecules, similar to the TLR4-LPS
signaling cascade. Our data also suggest that Tollip may be an
important constituent of both the TLR2 and TLR4 signaling
pathways. |
Introduction |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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In Drosophila, Toll initiates a signaling pathway homologous
to mammalian NF-B activation using a signaling cascade strikingly
similar to the IL-1R signaling complex (3, 4, 7, 9, 15).
We have previously shown that TLR4-induced NF-B activation in human
endothelial cells is mediated by IL-1R signaling molecules, including
the adapter protein myeloid differentiation protein (MyD88),
IL-1R-associated kinase (IRAK), and TNF receptor-associated
factor 6 (TRAF6), which links TLR4 to the protein kinase
NF-B-inducing kinase (NIK) (16). A recent study
described a new component of the IL-1R signaling pathway,
Toll-interacting protein (Tollip), which is present in a complex with
IRAK and links IRAK to the IL-1R, and limits IRAK phosphorylation and
NF-B activation (17).
Genetic and experimental studies have now established that TLR4 is the primary signaling receptor for LPS (10, 18, 19, 20, 21, 22, 23). Recent reports have documented that mice lacking TLR2 respond normally to LPS (24), and that neither human nor murine TLR2 can transduce LPS signals in the absence of contaminating endotoxin lipoproteins (21). TLR2 has been implicated as the signaling receptor for Gram-positive cell wall components; bacterial, mycobacterial, and spirochetal lipoproteins; and fungi (24, 25, 26, 27, 28, 29, 30). Thus, a concept of division of labor between these two receptors in sensing diverse microbial pathogens and alerting the immune system has emerged. However, it is not clear how TLRs have developed specificity for a given pathogen-associated molecular pattern and to what extent cooperation between different TLRs accounts for the recognition of a specific ligand. An emerging concept in TLR signaling is that TLRs can establish a combinatorial repertoire to discriminate among the large number of pathogen-associated molecular patterns found in nature (31). Recently, the cytoplasmic domain of TLR2 was shown to interact functionally with TLR6 in the recognition of certain TLR2 ligands, such as peptidoglycan, but not to others, i.e., lipoproteins, in mouse macrophage cell lines (31).
Recent studies have shown that a protein-free and heat-stable
Mycobacterium tuberculosis (Mtb)-conditioned culture
supernatant soluble tuberculosis factor (STF) (28), and
Borrelia burgdorferi outer surface protein A lipoprotein
(OspA-L) signal through TLR2 (26, 27). Phenol-soluble
modulin (PSM), a complex of three small secreted polypeptides from
Staphylococcus epidermidis has been shown to activate
NF-B and induce cytokine release in macrophages, suggesting that
they may contribute to the systemic manifestations of Gram-positive
sepsis (32). PSM was recently shown to signal through TLR2
and to require TLR6 as well (33). Based on the recent data
that TLR2 cooperates with TLR6 in response to certain TLR2 ligands but
not others, it is unclear whether TLR2 ligands such as STF and OspA-L
also require the cooperative effect of TLR6 to signal.
Endothelial cells participate in the early stages of the immune
response against various microbial agents and constitute an integral
component of the innate immune system. Previously we demonstrated that
human dermal microvessel endothelial cells (HMEC) respond to LPS via
TLR4, but express very little TLR2 and are unresponsive to Mtb 19-kDa
lipoprotein, a TLR2 ligand, unless transfected with TLR2
(22). In the current study we investigate the response of
endothelial cells to other biologically relevant TLR2 ligands,
including PSM, STF, and OspA-L. We further address whether TLR6 is
required for these TLR2-dependent responses in HMEC. We determined that
TLR6 functionally cooperates with TLR2 in transducing the STF-, OspA-,
and PSM-dependent signals in TLR2-transfected endothelial cells.
Downstream of TLR2, our studies explore the signaling pathway leading
to activation of NF-B in response to TLR2 ligands. Our data indicate
that the TLR2 signaling pathway shares the IL-1R signal transducer
molecules, i.e., MyD88, IRAK, and TRAF6, to activate NF-B, and that
Tollip associates with TLR2 and TLR4 and may be an important signaling
component of the TLR2 and TLR4 pathways as well as the IL-1R
pathway.
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Materials and Methods |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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The immortalized HMEC (gift from F. J. Candal, Center for
Disease Control and Prevention, Atlanta, GA) (34) were
cultured in MCDB-131 medium supplemented with 10% inactivated
FBS, 2 mM glutamine, and 100 µg/ml penicillin and streptomycin in
24-well plates and were used between passages 10 and 14 as previously
described (22). Recombinant human IL-1
was obtained
from Endogen (Cambridge, MA). PSM, which was purified by phenol
extraction of supernatants of stationary S. epidermidis, as
previously described (32), was obtained from Seymour
Klebanoff (University of Washington, Seattle, WA). OspA-L was obtained
from Tim Sellati and Justin Radolph (University of Connecticut,
Hartford, CT). STF was obtained from Terry K. Means and Matthew
J. Fenton (Boston University, Boston, MA). All reagents were verified
to be LPS free by the Limulus amebocyte lysate assay
(Pyrotell, Association of Cape Cod, MA; <0.03 EU/ml). Highly purified,
phenol-water extracted, and protein-free (< 0.0008% protein)
Escherichia coli LPS, which was prepared according to the
method described by McIntire et al. (35), was obtained
from S. N. Vogel (Uniformed Services University, Bethesda, MD). The
purity of this LPS preparation has been previously demonstrated
(36, 37), and this preparation of LPS is active on
TLR4-transfected HEK 293 cells and not on TLR2 transfectants (S.
N. Vogel, unpublished observation).
Constructs
Plasmids used in transient transfections were prepared with an
endotoxin-free Plasmid Maxi kit (Qiagen, Valencia, CA). Flag-tagged
wild-type (wt) human TLR2 and TLR4 constructs were obtained from R.
Medzhitov (Yale University, New Haven, CT). ELAM-NF-B-luciferase
construct and the dominant negative (DN) expression vectors of MyD88,
IRAK, TRAF6, TRAF2, and NIK have been characterized and described
previously (16, 22). Human IL-8 promoter and inducible NO
synthase (iNOS) promoter luciferase constructs were provided by N.
Mukaida (Kagoshima University, Kagoshima City, Japan)
(38), and W. J. Murphy (University of Kansas, Kansas City,
KS), respectively. DN TLR2 constructs were obtained from C. J.
Kirschning (Technical University of Munich, Munich, Germany). The
C3H/HeJ TLR4 cDNA was a gift from B. Beutler (The Scripps Institute, La
Jolla, CA) and were described previously (16, 22). C3H/HeJ
mice express DN TLR4 encoding a single missense mutation, which
converts a cytoplasmic proline residue to histidine (P712H)
(18). The analogous mutation was engineered in TLR6
(P691H), which works as a DN. Wild-type and DN mouse TLR6 cDNA
expression vectors were provided by A. M. Hajjar and D. Underhill
(University of Washington). Vesicular stomatitis virus
(VSV)-Tollip cDNA expression vector was provided by J. Tschopp
(University of Lausanne, Lausanne, Switzerland). All constructs were
verified by sequencing.
Transfection and luciferase assays
HMEC were plated at 2 x 105
cells/24-well plate before transfection. Cells were transfected with
FuGene 6 transfection reagent (Roche, Indianapolis, IN) following the
manufacturer’s instructions as reported previously (16, 22). Reporter genes pCMV--galactosidase (0.1 µg),
ELAM-NF-B-luciferase (0.5 µg), and pcDNA3 empty vector or DN
mutants of MyD88, IRAK, TRAF6, TRAF2, and NIK (0.1 µg each) were used
as described previously (16, 22). In addition, wt human
TLR2 (0.5 µg), wt mouse TLR6 (0.5 µg), and different amounts of DN
human TLR2 or mouse TLR6 cDNA constructs or wt Tollip cDNA were
cotransfected. After 24-h transfection, cells were stimulated for
5 h with various TLR2 ligands, including PSM (50–200 ng/ml), STF
(10–30 µl/ml), and OspA-L (10 µg/ml), or with protein-free
E. coli LPS (20 or 50 ng/ml) in medium containing 10% FCS.
Following a 5-h incubation, cells were washed once in PBS and lysed,
and luciferase activity was measured with a kit (Promega, Madison, WI)
and a luminometer as described previously (16, 22).
-Galactosidase activity was determined by a calorimetric method to
normalize transfection efficiency as described previously (16, 22). The data shown are the mean of three independent
experiments.
RT-PCR
Total RNA was isolated from HMEC or THP1 cells using a Qiagen kit following the manufacturer’s instruction and treated with RNase-free DNase I as previously described (22). For reverse transcription reaction, the Moloney murine leukemia virus preamplification system (Life Technologies, Gaithersburg, MD) was applied. PCR amplification was performed with Taq gold polymerase (Perkin-Elmer, Foster City, CA) for 32 cycles at 95°C for 45 s, 54°C for 45 s, and 72°C for 1 min (for TLR2 and TLR4); 35 cycles at 95°C for 30 s and 65 and 72°C for 1 min (for TLR6); and 38 cycles at 95°C for 1 min, 61°C for 1 min, and 72°C for 1 min (for Tollip). The oligonucleotide primers used for RT-PCR were: TLR2, 5'-GCCAAAGTCTTGATTGATTGG and 5'-TTGAAGTTCTCCAGCTCCTG; TLR4, 5'-TGGATACGTTTCCTTATAAG and 5'-GAAATGGAGGCACCCCTTC; TLR6, 5'-AGAACTCACCAGAGGTCCAACC and 5'-GAAGGCATATCCTTCGTCATGAG; and Tollip, 5'-CAAGAATCCCCGCTGGAATAAG and 5'-ATGGCTTTCAGGTCCTCCTCGC. GAPDH primers were obtained from Clontech (Palo Alto, CA).
Immunoprecipitation
For coimmunoprecipitation of transfected proteins, 3 x
106 HEK293 cells were plated on 10-cm dishes and
transfected with 5 µg Flag-TLR2 and 5 µg VSV-Tollip or with 3.5
µg Flag-TLR4, 3.5 µg MD2, and 3.5 µg VSV-Tollip. After 24 h,
cells were collected, washed with PBS, and lysed for 20 min on ice in
500 µl lysis buffer (50 mM HEPES (pH 7.9), 250 mM NaCl, 20 mM
-glycerophosphate, 1 mM sodium orthovanadate, 2 mM DTT, protease
inhibitor cocktail (Calbiochem, San Diego, CA), and 1% Nonidet P-40).
Lysates were clarified by centrifugation at 4°C for 15 min at
10,000 x g. Half the cell lysates were incubated with
3 µg anti-Flag mAb (anti M2, Sigma, St. Louis, MO) and 20 µl
50% (v/v) Protein G Plus/Protein A-agarose (Oncogene, Cambridge, MA)
overnight at 4°C with gentle rocking. After extensive washing with
lysis buffer, precipitated complexes were solubilized by boiling in SDS
sample buffer, fractionated by 10% SDS-PAGE, and transferred to
polyvinylidene difluoride membranes, and blotted with the indicated Abs
(anti-Flag or anti-VSV (Sigma)). The reactive bands were
visualized with HRP conjugated to the appropriate secondary Abs with an
ECL system (Amersham Pharmacia Biotech, Arlington Heights,
IL).
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Results |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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We have previously shown that HMEC express low levels of TLR2 mRNA
and protein and are unresponsive to Mtb 19-kDa lipoprotein, and that
transfection of TLR2 restores their responsiveness to Mtb 19 kDa
(22). However, it is unknown whether this low level of
TLR2 expression is sufficient for the recognition and response to other
classic TLR2 ligands or whether additional TLRs can substitute
functionally for TLR2 in endothelial cells. To investigate whether HMEC
have a broader defect in recognition of other TLR2 ligands, we measured
the responses of HMEC to three additional biologically relevant TLR2
ligands, including PSM, STF, and OspA-L. Our data demonstrate that HMEC
are unresponsive to PSM, STF, and OspA-L, as measured by activation of
an NF-B-dependent reporter gene, ELAM-luciferase (Fig. 1
A). These findings suggest that HMEC have a broad inability
to respond to diverse TLR2 ligands, although they are LPS responsive
(16, 22). The failure of these ligands to activate NF-B
in HMEC confirms that these ligands are not contaminated with
LPS.
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B, proinflammatory cytokines, or iNOS production.
To test whether the low level of TLR2 expression was the reason for
defective endothelial cell responses to classic TLR2 ligands, we
transiently expressed TLR2 in HMEC. Transfection of wtTLR2 restored the
responsiveness of HMEC to PSM, STF, and OspA-L, as measured by
NF-B-dependent ELAM-promoter reporter (Fig. 1
A), iNOS
(Fig. 1B), and IL-8 promoter-reporter gene activation (Fig. 1C). We used purified protein-free LPS (50 ng/ml) as an
internal control for the TLR4 signaling pathway in HMEC. Expression of
TLR2 did not affect LPS-induced response in HMEC (data not shown).
These results demonstrate that the low level of TLR2 expression is the
cause of the defective responses of HMEC to these ligands. These data
further suggest that the intracellular pathway leading to
proinflammatory responses is intact in HMEC.
TLR2 uses MyD88, IRAK, and TRAF6 to activate NF-B in response to
TLR2 ligands
We (16) and others (15, 39) have
previously shown that the molecular signaling pathway induced by
LPS-TLR4 interaction to activate NF-B shares the IL-1R signaling
molecules, MyD88, IRAK, TRAF6, and NIK. It has been shown that TLR2
signaling shares the signaling molecule MyD88 in macrophages
(33), but the remainder of the signaling pathway leading
from TLR2 to NF-B has not been clearly demonstrated. Yang et al.
(40) described the signaling pathway emanating from TLR2;
however, they used LPS as a ligand, which was subsequently determined
to signal via TLR4 and not TLR2. To determine whether TLR2 ligands use
the same IL-1R signaling molecules as TLR4, we assessed the ability of
DN forms of MyD88, IRAK, TRAF6, and NIK to inhibit the responses of
various TLR2 ligands, i.e., PSM and OspA-L, in TLR2-transfected HMEC.
This approach has been used successfully in HMEC to characterize the
LPS-TLR4 signaling pathway (16). DN constructs of MyD88,
IRAK, TRAF6, and NIK significantly blocked the PSM (Fig. 2A), OspA-L (Fig. 2B), and STF responses (data not
shown) in TLR2-HMEC. The expression of a DN TRAF2 construct, a
signaling molecule involved in TNF-
signaling, did not block the
response to PSM (Fig. 2A), whereas it completely blocked
TNF--induced NF-B activation (data not shown). Because the
pathways for IL-1 and TNF- signaling converge at the level of NIK
for NF-B activation, DN NIK blocked both PSM-induced (Fig. 2A) and TNF--induced (data not shown) NF-B activation.
In control experiments DN constructs of MyD88, IRAK, TRAF6, and NIK
significantly blocked the IL-1 response in HMEC (data not shown).
These results indicate that the TLR2 signaling pathway shares IL-1R
signaling molecules, including MyD88, IRAK, and TRAF6, to activate the
transcription factor NF-B.
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B in STF-,
OspA-L-, or PSM-stimulated cells
A recent study has shown that TLR2 and TLR6 cooperate to activate
macrophages in response to Gram-positive bacteria and Gram-positive
bacterial peptidoglycan, whereas TLR2 is able to recognize bacterial
lipopeptide without TLR6 cooperation (31). Although PSM
was reported to be a TLR2 ligand, which requires TLR6, in studies using
293-HEK cells (33), it is not clear whether it requires
the cooperation of TLRs in human endothelial cells. Furthermore, there
are no data to suggest that other TLR2 ligands, such as STF and OspA-L,
require TLR6 as well to signal. We investigated whether STF-, OspA-L-,
and PSM-dependent TLR2 activations in HMEC require TLR6 cooperation. We
first determined whether TLR6 is expressed in HMEC. To investigate the
expression of TLR2 and TLR6 mRNA in HMEC, we used RT-PCR. We have
previously shown that HMEC express TLR1, TLR3, TLR4, and TLR5 and very
low levels of TLR2 mRNA (16, 22). Here we show that HMEC
express high levels of TLR6 mRNA compared with TLR4, to which the cells
respond (Fig. 3). To determine whether TLR6 functionally contributes to the
TLR2-mediated STF, OspA-L, and PSM responses in endothelial cells, we
cotransfected HMEC with TLR6 or TLR2 cDNA. Fig. 4
shows the NF-B responses of TLR2- or TLR6-transfected HMEC. All
transfectants expressed equivalent amounts of flag-tagged TLR as judged
by anti-flag Western blots (data not shown). HMEC were unresponsive
to STF, OspA-L, and PSM unless transfected with TLR2 as shown in Fig. 1A. We then asked whether overexpression of TLR6 could
overcome the TLR2 signaling defect in HMEC. Transfection of TLR6 alone
was unable to restore PSM responsiveness in HMEC (Fig. 4);
cotransfection of both TLR2 and TLR6 did not result in an enhanced
response to PSM compared with TLR2-transfected HMEC (Fig. 4).
LPS-mediated induction of the NF-B reporter construct was not
different in untransfected or TLR2- and/or TLR6-transfected HMEC, and
transfection of TLR2 alone or with TLR6 did not enhance the baseline
activity of the reporter gene in these cells (data not shown). These
findings suggest that the unresponsiveness of HMEC to various TLR2
ligands is primarily the result of their very low level expression of
TLR2, and transfection of exogenous TLR6 is unable to overcome the
unresponsiveness to PSM. Our data further suggest that the endogenous
level of TLR6 in HMEC does not limit TLR2-dependent activation.
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) and DN TLR2 (data not shown) significantly blocked the STF, OspA-L,
and PSM responses in TLR2-HMEC. Fig. 5A shows the
dose-dependent inhibition of DN TLR6 for PSM responses. These DN
mutants were unable to affect LPS-induced NF-B activation in native
(data not shown) and TLR2 transfected HMEC (Fig. 5A),
supporting the specificity of these mutants. In additional control
experiments, the DN construct of TLR4 (C3H/HeJ TLR4) (22)
was unable to inhibit PSM responses in TLR2-transfected HMEC, whereas
the LPS response was completely inhibited by C3H/HeJ TLR4 cDNA (data
not shown). Thus, the TLR signaling complex, which recognizes STF,
OspA-L, and PSM in TLR2-HMEC, can be inhibited by DN TLR2 and DN TLR6,
suggesting a functional cooperation between TLR2 and TLR6 for all three
TLR2 ligands tested.
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B activation
Tollip, a recently discovered signaling molecule involved in IL-1R
signaling, is present in a complex with IRAK and links IRAK to the
IL-1R (17). Recently, Tollip was shown to impair NF-B
activation in response to IL-1, but not TNF-, in 293T cells
(17). The role of Tollip in TLR-dependent signaling is
unknown. We hypothesized that because TLR2 and TLR4 share the IL-1R
signaling molecules, Tollip may also be associated with TLR2 and TLR4
and modify TLR-mediated NF-B activation. To test these hypothesis,
we cotransfected HEK293 cells with epitope Flag-TLR2 or Flag-TLR4 and
MD2 with VSV-Tollip cDNA. Cell lysates were immunoprecipitated with
anti-Flag Ab and immunoblotted with anti-VSV Ab. In resting
cells and in cells stimulated with PSM or LPS, we found that Tollip was
coimmunoprecipitated with either TLR2 or TLR4 (Fig. 6). Furthermore, we found that endogenous Tollip is present in HMEC and
THP1 cells by RT-PCR (data not shown). To investigate the effects of
Tollip overexpression in endothelial cells, we cotransfected HMEC and
TLR2-HMEC with ELAM-NF-B reporter and increasing amounts of Tollip
cDNA and measured luciferase activity following stimulation with LPS or
TLR2 ligands (STF, OspA-L, and PSM), respectively. Expression of Tollip
cDNA inhibited the LPS response via TLR4 signaling in HMEC (Fig. 7) and STF, OspA-L, and PSM responses in TLR2-transfected HMEC (Fig. 7)
in a dose-dependent manner. In control experiments expression of Tollip
in HMEC inhibited IL-1-induced NF-B activation, whereas it did
not affect TNF--induced NF-B activation (data not shown). These
results indicate that in addition to IL-1R signaling, Tollip is an
important constituent of the TLR4 and TLR2 signaling pathways.
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Discussion |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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and IFN-
(47), suggesting that the responsiveness of
endothelial cells to diverse TLR2 ligands may be modulated by external
stimuli.
We have previously shown in endothelial cells and monocytic cell lines
that LPS-induced NF-B activation is mediated by IL-1R signaling
molecules that are engaged by TLR4 (16). The molecules
transducing the signal from TLR2 to NF-B have not been clearly
reported. Here we determined that TLR2 signaling also shares the IL-1R
signaling molecules, including MyD88, IRAK, and TRAF6, to activate
NF-B. MyD88 appears to represent the most upstream mediator of the
IL-1-, TLR4-, and TLR2-induced signaling cascade, which ultimately
activates NF-B, thus driving transcriptional activation of several
inflammatory cytokines. Therefore, MyD88 may represent a potentially
useful therapeutic target to control the molecular switch from innate
to the adaptive immune responses.
Tollip is a recently discovered signaling molecule involved in IL-1R
signaling (17). Before IL-1 stimulation, endogenous
Tollip is present in a complex with IRAK, and recruitment of
Tollip-IRAK complexes to the activated IL-1R complex occurs through
association of Tollip with IL-1R accessory protein
(17). Corecruited MyD88 then triggers IRAK
autophosphorylation, which in turn leads to rapid dissociation of IRAK
from Tollip and IL-1 receptors. Burns et al. have shown that
overexpression of Tollip inhibits IL-1-induced, and not
TNF--induced, activation of NF-B and c-Jun N-terminal kinase in a
dose-dependent manner in 293T cells (17). Therefore,
Tollip not only links IRAK to IL-1R, but may also inhibit
phosphorylation of IRAK, either by blocking IRAK autophosphorylation or
by interfering with binding of a crucial signaling molecule, such as a
second kinase (48). This may serve to keep IRAK in an off
state before formation of an IL-1-induced complex with its activator
MyD88. It is also possible that the regulated release of IRAK from
Tollip is required for signal termination, to release phosphorylated
IRAK for degradation by proteasomes (49). We now show that
Tollip coimmunoprecipitates with TLR2 and TLR4 and has a functional
role in TLR2- and TLR4-mediated signaling in HMEC. Furthermore,
overexpression of Tollip inhibits TLR4- and TLR2-mediated NF-B
activation in a dose-dependent manner, suggesting that this signaling
molecule is also shared among the IL-1R, TLR4, and TLR2 signaling
pathways. Further studies are needed to determine the kinetics of the
IRAK-Tollip complexes recruited to TLR4 and TLR2. Thus, Tollip is an
endogenously expressed molecule that limits proinflammatory signals
from both the innate and adaptive immune systems and may be exploited
as an anti-inflammatory strategy.
PSM, a complex of three small secreted polypeptides from S.
epidermidis, has been shown to activate NF-B and
proinflammatory cytokine release (32). Although PSM was
recently shown to activate TLR2 with the cooperation of TLR6
(33), it is unknown whether additional TLR2 ligands, such
as STF and OspA-L, also require the cooperative effect of TLR6 to
signal. Ozinsky et al. (31) observed that TLR2 and TLR6
coordinate macrophage activation by intact Gram-positive bacteria and
yeast, whereas TLR2 recognizes bacterial lipopeptide without TLR6. Here
we show that in addition to the polypeptide PSM, STF and OspA-L require
the functional cooperation of TLR6 and TLR2 to signal. We observed that
cotransfection of TLR2 and TLR6 in HMEC did not enhance the
TLR2-mediated PSM response. This observation differs from the data
reported by Hajjar et al., showing that the TLR2-mediated response to
PSM is enhanced by TLR6 in HEK 293 cells (33). This
difference is most likely explained by cell specificity, given the
relative abundance of TLR6 within HMEC, and suggests that TLR2, and not
TLR6, is the limiting factor in HMEC responses to TLR2 ligands such as
PSM. These observations suggest that the ratio of different TLRs within
a cell type may modify the response to a given ligand. Our data support
the importance of combinatorial repertoires of TLRs for innate immune
recognition in diverse cell types, including endothelial cells, to
discriminate among the large number of pathogen-associated molecular
patterns in nature. These combinations of TLRs facilitate mammalian
responsiveness to a wide array of pathogen-associated molecular
patterns and diversify the repertoire of Toll-mediated responses.
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Acknowledgments |
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Footnotes |
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2 Y.B. and E.F. contributed equally to this work.
3 Address correspondence and reprint requests to Dr. Moshe Arditi, Department of Pediatrics, Cedars-Sinai Medical Center, 8700 Beverly Boulevard, Room 4310, Los Angeles, CA 90048. E-mail address: moshe.arditi{at}cshs.org
4 Abbreviations used in this paper: TLR, Toll-like receptor; DN, dominant negative; HMEC, human dermal microvessel endothelial cells; iNOS, inducible NO synthase; IRAK, IL-1R-associated kinase; MyD88, myeloid differentiation protein; Mtb, Mycobacterium tuberculosis; NIK, NF-B-inducing kinase; Tollip, Toll-interacting protein; TRAF, TNF receptor-associated factor; PSM, phenol-soluble modulin; STF, soluble tuberculosis factor; wt, wild type; VSV, vesicular stomatitis virus; OspA-L, outer surface protein A lipoprotein.
Received for publication January 18, 2001. Accepted for publication May 8, 2001.
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  Y.-C. Chang, W.-C. Kao, W.-Y. Wang, W.-Y. Wang, R.-B. Yang, and K. Peck Identification and characterization of oligonucleotides that inhibit Toll-like receptor 2-associated immune responses FASEB J, September 1, 2009; 23(9): 3078 - 3088. [Abstract] [Full Text] [PDF]
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 S. Onishi, K. Honma, S. Liang, P. Stathopoulou, D. Kinane, G. Hajishengallis, and A. Sharma Toll-Like Receptor 2-Mediated Interleukin-8 Expression in Gingival Epithelial Cells by the Tannerella forsythia Leucine-Rich Repeat Protein BspA Infect. Immun., January 1, 2008; 76(1): 198 - 205. [Abstract] [Full Text] [PDF]
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H. Chen, M. J. Cowan, J. D. Hasday, S. N. Vogel, and A. E. Medvedev Tobacco Smoking Inhibits Expression of Proinflammatory Cytokines and Activation of IL-1R-Associated Kinase, p38, and NF-{kappa}B in Alveolar Macrophages Stimulated with TLR2 and TLR4 Agonists J. Immunol., November 1, 2007; 179(9): 6097 - 6106. [Abstract] [Full Text] [PDF]
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C. Garlanda, D. Di Liberto, A. Vecchi, M. P. La Manna, C. Buracchi, N. Caccamo, A. Salerno, F. Dieli, and A. Mantovani Damping Excessive Inflammation and Tissue Damage in Mycobacterium tuberculosis Infection by Toll IL-1 Receptor 8/Single Ig IL-1-Related Receptor, a Negative Regulator of IL-1/TLR Signaling J. Immunol., September 1, 2007; 179(5): 3119 - 3125. [Abstract] [Full Text] [PDF]
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Z. Zhao, R. Fleming, B. McCloud, and M. S. Klempner CD14 Mediates Cross Talk between Mononuclear Cells and Fibroblasts for Upregulation of Matrix Metalloproteinase 9 by Borrelia burgdorferi Infect. Immun., June 1, 2007; 75(6): 3062 - 3069. [Abstract] [Full Text] [PDF]
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S. Danese, E. Dejana, and C. Fiocchi Immune Regulation by Microvascular Endothelial Cells: Directing Innate and Adaptive Immunity, Coagulation, and Inflammation J. Immunol., May 15, 2007; 178(10): 6017 - 6022. [Abstract] [Full Text] [PDF]
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T. Into, J.-i. Dohkan, M. Inomata, M. Nakashima, K.-i. Shibata, and K. Matsushita Synthesis and Characterization of a Dipalmitoylated Lipopeptide Derived from Paralogous Lipoproteins of Mycoplasma pneumoniae Infect. Immun., May 1, 2007; 75(5): 2253 - 2259. [Abstract] [Full Text] [PDF]
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T. Kielian, N. K. Phulwani, N. Esen, M. Md. Syed, A. C. Haney, K. McCastlain, and J. Johnson MyD88-Dependent Signals Are Essential for the Host Immune Response in Experimental Brain Abscess J. Immunol., April 1, 2007; 178(7): 4528 - 4537. [Abstract] [Full Text] [PDF]
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 T. Into, Y. Kanno, J.-i. Dohkan, M. Nakashima, M. Inomata, K.-i. Shibata, C. J. Lowenstein, and K. Matsushita Pathogen Recognition by Toll-like Receptor 2 Activates Weibel-Palade Body Exocytosis in Human Aortic Endothelial Cells J. Biol. Chem., March 16, 2007; 282(11): 8134 - 8141. [Abstract] [Full Text] [PDF]
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H. D'Avila, P. E. Almeida, N. R. Roque, H. C. Castro-Faria-Neto, and P. T. Bozza Toll-Like Receptor-2-Mediated C-C Chemokine Receptor 3 and Eotaxin-Driven Eosinophil Influx Induced by Mycobacterium bovis BCG Pleurisy Infect. Immun., March 1, 2007; 75(3): 1507 - 1511. [Abstract] [Full Text] [PDF]
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S. C. Mullaly and P. Kubes The Role of TLR2 In Vivo following Challenge with Staphylococcus aureus and Prototypic Ligands J. Immunol., December 1, 2006; 177(11): 8154 - 8163. [Abstract] [Full Text] [PDF]
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M. Yadav and J. S. Schorey The beta-glucan receptor dectin-1 functions together with TLR2 to mediate macrophage activation by mycobacteria Blood, November 1, 2006; 108(9): 3168 - 3175. [Abstract] [Full Text] [PDF]
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J. Heidemann, W. Domschke, T. Kucharzik, and C. Maaser Intestinal microvascular endothelium and innate immunity in inflammatory bowel disease: a second line of defense? Infect. Immun., October 1, 2006; 74(10): 5425 - 5432. [Full Text] [PDF]
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 A. E. Medvedev, I. Sabroe, J. D. Hasday, and S. N. Vogel Invited review: Tolerance to microbial TLR ligands: molecular mechanisms and relevance to disease Innate Immunity, June 1, 2006; 12(3): 133 - 150. [Abstract] [PDF]
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J.-S. Chang, J. F. Huggett, K. Dheda, L. U. Kim, A. Zumla, and G. A. W. Rook Myobacterium tuberculosis Induces Selective Up-Regulation of TLRs in the Mononuclear Leukocytes of Patients with Active Pulmonary Tuberculosis. J. Immunol., March 1, 2006; 176(5): 3010 - 3018. [Abstract] [Full Text] [PDF]
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 A. Didierlaurent, B. Brissoni, D. Velin, N. Aebi, A. Tardivel, E. Kaslin, J. C. Sirard, G. Angelov, J. Tschopp, and K. Burns Tollip Regulates Proinflammatory Responses to Interleukin-1 and Lipopolysaccharide Mol. Cell. Biol., February 1, 2006; 26(3): 735 - 742. [Abstract] [Full Text] [PDF]
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K. O. Omueti, J. M. Beyer, C. M. Johnson, E. A. Lyle, and R. I. Tapping Domain Exchange between Human Toll-like Receptors 1 and 6 Reveals a Region Required for Lipopeptide Discrimination J. Biol. Chem., November 4, 2005; 280(44): 36616 - 36625. [Abstract] [Full Text] [PDF]
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Y. Naiki, K. S. Michelsen, N. W. J. Schroder, R. Alsabeh, A. Slepenkin, W. Zhang, S. Chen, B. Wei, Y. Bulut, M. H. Wong, et al. MyD88 Is Pivotal for the Early Inflammatory Response and Subsequent Bacterial Clearance and Survival in a Mouse Model of Chlamydia pneumoniae Pneumonia J. Biol. Chem., August 12, 2005; 280(32): 29242 - 29249. [Abstract] [Full Text] [PDF]
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 C. Feterowski, A. Novotny, S. Kaiser-Moore, P. F. Muhlradt, T. Rossmann-Bloeck, M. Rump, B. Holzmann, and H. Weighardt Attenuated pathogenesis of polymicrobial peritonitis in mice after TLR2 agonist pre-treatment involves ST2 up-regulation Int. Immunol., August 1, 2005; 17(8): 1035 - 1046. [Abstract] [Full Text] [PDF]
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 B. Fournier and D. J. Philpott Recognition of Staphylococcus aureus by the Innate Immune System Clin. Microbiol. Rev., July 1, 2005; 18(3): 521 - 540. [Abstract] [Full Text] [PDF]
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T. A. Schneeman, M. E. C. Bruno, H. Schjerven, F.-E. Johansen, L. Chady, and C. S. Kaetzel Regulation of the Polymeric Ig Receptor by Signaling through TLRs 3 and 4: Linking Innate and Adaptive Immune Responses J. Immunol., July 1, 2005; 175(1): 376 - 384. [Abstract] [Full Text] [PDF]
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Y. Bulut, K. S. Michelsen, L. Hayrapetian, Y. Naiki, R. Spallek, M. Singh, and M. Arditi Mycobacterium Tuberculosis Heat Shock Proteins Use Diverse Toll-like Receptor Pathways to Activate Pro-inflammatory Signals J. Biol. Chem., June 3, 2005; 280(22): 20961 - 20967. [Abstract] [Full Text] [PDF]
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R. Liu-Bryan, K. Pritzker, G. S. Firestein, and R. Terkeltaub TLR2 Signaling in Chondrocytes Drives Calcium Pyrophosphate Dihydrate and Monosodium Urate Crystal-Induced Nitric Oxide Generation J. Immunol., April 15, 2005; 174(8): 5016 - 5023. [Abstract] [Full Text] [PDF]
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H. Stoll, J. Dengjel, C. Nerz, and F. Gotz Staphylococcus aureus Deficient in Lipidation of Prelipoproteins Is Attenuated in Growth and Immune Activation Infect. Immun., April 1, 2005; 73(4): 2411 - 2423. [Abstract] [Full Text] [PDF]
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A. Lentschat, H. Karahashi, K. S. Michelsen, L. S. Thomas, W. Zhang, S. N. Vogel, and M. Arditi Mastoparan, a G Protein Agonist Peptide, Differentially Modulates TLR4- and TLR2-Mediated Signaling in Human Endothelial Cells and Murine Macrophages J. Immunol., April 1, 2005; 174(7): 4252 - 4261. [Abstract] [Full Text] [PDF]
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S. Totemeyer, P. Kaiser, D. J. Maskell, and C. E. Bryant Sublethal Infection of C57BL/6 Mice with Salmonella enterica Serovar Typhimurium Leads to an Increase in Levels of Toll-Like Receptor 1 (TLR1), TLR2, and TLR9 mRNA as Well as a Decrease in Levels of TLR6 mRNA in Infected Organs Infect. Immun., March 1, 2005; 73(3): 1873 - 1878. [Abstract] [Full Text] [PDF]
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Y. Nakao, K. Funami, S. Kikkawa, M. Taniguchi, M. Nishiguchi, Y. Fukumori, T. Seya, and M. Matsumoto Surface-Expressed TLR6 Participates in the Recognition of Diacylated Lipopeptide and Peptidoglycan in Human Cells J. Immunol., February 1, 2005; 174(3): 1566 - 1573. [Abstract] [Full Text] [PDF]
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 K.-M. Choe, H. Lee, and K. V. Anderson Drosophila peptidoglycan recognition protein LC (PGRP-LC) acts as a signal-transducing innate immune receptor PNAS, January 25, 2005; 102(4): 1122 - 1126. [Abstract] [Full Text] [PDF]
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 C. W. Wieland, S. Knapp, S. Florquin, A. F. de Vos, K. Takeda, S. Akira, D. T. Golenbock, A. Verbon, and T. van der Poll Non-Mannose-capped Lipoarabinomannan Induces Lung Inflammation via Toll-like Receptor 2 Am. J. Respir. Crit. Care Med., December 15, 2004; 170(12): 1367 - 1374. [Abstract] [Full Text] [PDF]
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D. Nicolle, C. Fremond, X. Pichon, A. Bouchot, I. Maillet, B. Ryffel, and V. J. F. Quesniaux Long-Term Control of Mycobacterium bovis BCG Infection in the Absence of Toll-Like Receptors (TLRs): Investigation of TLR2-, TLR6-, or TLR2-TLR4-Deficient Mice Infect. Immun., December 1, 2004; 72(12): 6994 - 7004. [Abstract] [Full Text] [PDF]
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W. Li, T. Yajima, K. Saito, H. Nishimura, T. Fushimi, Y. Ohshima, Y. Tsukamoto, and Y. Yoshikai Immunostimulating Properties of Intragastrically Administered Acetobacter-Derived Soluble Branched (1,4)-{beta}-D-Glucans Decrease Murine Susceptibility to Listeria monocytogenes Infect. Immun., December 1, 2004; 72(12): 7005 - 7011. [Abstract] [Full Text] [PDF]
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 I. Glezer and S. Rivest Glucocorticoids: Protectors of the Brain during Innate Immune Responses Neuroscientist, December 1, 2004; 10(6): 538 - 552. [Abstract] [PDF]
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 O. Equils, A. Shapiro, Z. Madak, C. Liu, and D. Lu Human Immunodeficiency Virus Type 1 Protease Inhibitors Block Toll-Like Receptor 2 (TLR2)- and TLR4-Induced NF-{kappa}B Activation Antimicrob. Agents Chemother., October 1, 2004; 48(10): 3905 - 3911. [Abstract] [Full Text] [PDF]
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 S. C. Mullaly and P. Kubes Toll Gates and Traffic Arteries: From Endothelial TLR2 to Atherosclerosis Circ. Res., October 1, 2004; 95(7): 657 - 659. [Full Text] [PDF]
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V. M. Abrahams, P. Bole-Aldo, Y. M. Kim, S. L. Straszewski-Chavez, T. Chaiworapongsa, R. Romero, and G. Mor Divergent Trophoblast Responses to Bacterial Products Mediated by TLRs J. Immunol., October 1, 2004; 173(7): 4286 - 4296. [Abstract] [Full Text] [PDF]
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 M. S. Hayden and S. Ghosh Signaling to NF-{kappa}B Genes & Dev., September 15, 2004; 18(18): 2195 - 2224. [Abstract] [Full Text] [PDF]
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N. W. J. Schroder, H. Heine, C. Alexander, M. Manukyan, J. Eckert, L. Hamann, U. B. Gobel, and R. R. Schumann Lipopolysaccharide Binding Protein Binds to Triacylated and Diacylated Lipopeptides and Mediates Innate Immune Responses J. Immunol., August 15, 2004; 173(4): 2683 - 2691. [Abstract] [Full Text] [PDF]
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D. Torres, M. Barrier, F. Bihl, V. J. F. Quesniaux, I. Maillet, S. Akira, B. Ryffel, and F. Erard Toll-Like Receptor 2 Is Required for Optimal Control of Listeria monocytogenes Infection Infect. Immun., April 1, 2004; 72(4): 2131 - 2139. [Abstract] [Full Text] [PDF]
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 H.-J. Anders, B. Banas, and D. Schlondorff Signaling Danger: Toll-Like Receptors and their Potential Roles in Kidney Disease J. Am. Soc. Nephrol., April 1, 2004; 15(4): 854 - 867. [Abstract] [Full Text] [PDF]
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V. J. Quesniaux, D. M. Nicolle, D. Torres, L. Kremer, Y. Guerardel, J. Nigou, G. Puzo, F. Erard, and B. Ryffel Toll-Like Receptor 2 (TLR2)-Dependent-Positive and TLR2-Independent-Negative Regulation of Proinflammatory Cytokines by Mycobacterial Lipomannans J. Immunol., April 1, 2004; 172(7): 4425 - 4434. [Abstract] [Full Text] [PDF]
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A. Hasebe, A. Yoshimura, T. Into, H. Kataoka, S. Tanaka, S. Arakawa, H. Ishikura, D. T. Golenbock, T. Sugaya, N. Tsuchida, et al. Biological Activities of Bacteroides forsythus Lipoproteins and Their Possible Pathological Roles in Periodontal Disease Infect. Immun., March 1, 2004; 72(3): 1318 - 1325. [Abstract] [Full Text] [PDF]
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J. Branger, J. C. Leemans, S. Florquin, S. Weijer, P. Speelman, and T. van der Poll Toll-like receptor 4 plays a protective role in pulmonary tuberculosis in mice Int. Immunol., March 1, 2004; 16(3): 509 - 516. [Abstract] [Full Text] [PDF]
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 A.C. Ogus, B. Yoldas, T. Ozdemir, A. Uguz, S. Olcen, I. Keser, M. Coskun, A. Cilli, and O. Yegin The Arg753Gln polymorphism of the human Toll-like receptor 2 gene in tuberculosis disease Eur. Respir. J., February 1, 2004; 23(2): 219 - 223. [Abstract] [Full Text] [PDF]
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 M. B. Drennan, D. Nicolle, V. J. F. Quesniaux, M. Jacobs, N. Allie, J. Mpagi, C. Fremond, H. Wagner, C. Kirschning, and B. Ryffel Toll-Like Receptor 2-Deficient Mice Succumb to Mycobacterium tuberculosis Infection Am. J. Pathol., January 1, 2004; 164(1): 49 - 57. [Abstract] [Full Text] [PDF]
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S. Totemeyer, N. Foster, P. Kaiser, D. J. Maskell, and C. E. Bryant Toll-Like Receptor Expression in C3H/HeN and C3H/HeJ Mice during Salmonella enterica Serovar Typhimurium Infection Infect. Immun., November 1, 2003; 71(11): 6653 - 6657. [Abstract] [Full Text] [PDF]
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K. Saito, T. Yajima, H. Nishimura, K. Aiba, R. Ishimitsu, T. Matsuguchi, T. Fushimi, Y. Ohshima, Y. Tsukamoto, and Y. Yoshikai Soluble Branched {beta}-(1,4)Glucans from Acetobacter Species Show Strong Activities to Induce Interleukin-12 in Vitro and Inhibit T-helper 2 Cellular Response with Immunoglobulin E Production in Vivo J. Biol. Chem., October 3, 2003; 278(40): 38571 - 38578. [Abstract] [Full Text] [PDF]
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M. Fujita, T. Into, M. Yasuda, T. Okusawa, S. Hamahira, Y. Kuroki, A. Eto, T. Nisizawa, M. Morita, and K.-i. Shibata Involvement of Leucine Residues at Positions 107, 112, and 115 in a Leucine-Rich Repeat Motif of Human Toll-Like Receptor 2 in the Recognition of Diacylated Lipoproteins and Lipopeptides and Staphylococcus aureus Peptidoglycans J. Immunol., October 1, 2003; 171(7): 3675 - 3683. [Abstract] [Full Text] [PDF]
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K. Sau, S. S. Mambula, E. Latz, P. Henneke, D. T. Golenbock, and S. M. Levitz The Antifungal Drug Amphotericin B Promotes Inflammatory Cytokine Release by a Toll-like Receptor- and CD14-dependent Mechanism J. Biol. Chem., September 26, 2003; 278(39): 37561 - 37568. [Abstract] [Full Text] [PDF]
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N. W. J. Schroder, U. Schombel, H. Heine, U. B. Gobel, U. Zahringer, and R. R. Schumann Acylated Cholesteryl Galactoside as a Novel Immunogenic Motif in Borrelia burgdorferi Sensu Stricto J. Biol. Chem., September 5, 2003; 278(36): 33645 - 33653. [Abstract] [Full Text] [PDF]
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A. J. Gehring, R. E. Rojas, D. H. Canaday, D. L. Lakey, C. V. Harding, and W. H. Boom The Mycobacterium tuberculosis 19-Kilodalton Lipoprotein Inhibits Gamma Interferon-Regulated HLA-DR and Fc{gamma}R1 on Human Macrophages through Toll-Like Receptor 2 Infect. Immun., August 1, 2003; 71(8): 4487 - 4497. [Abstract] [Full Text] [PDF]
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R. I. Tapping and P. S. Tobias Mycobacterial lipoarabinomannan mediates physical interactions between TLR1 and TLR2 to induce signaling Innate Immunity, August 1, 2003; 9(4): 264 - 268. [Abstract] [PDF]
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L.-Y. Huang, J. Aliberti, C. A. Leifer, D. M. Segal, A. Sher, D. T. Golenbock, and B. Golding Heat-Killed Brucella abortus Induces TNF and IL-12p40 by Distinct MyD88-Dependent Pathways: TNF, Unlike IL-12p40 Secretion, Is Toll-Like Receptor 2 Dependent J. Immunol., August 1, 2003; 171(3): 1441 - 1446. [Abstract] [Full Text] [PDF]
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A. Yoder, X. Wang, Y. Ma, M. T. Philipp, M. Heilbrun, J. H. Weis, C. J. Kirschning, R. M. Wooten, and J. J. Weis Tripalmitoyl-S-Glyceryl-Cysteine-Dependent OspA Vaccination of Toll-Like Receptor 2-Deficient Mice Results in Effective Protection from Borrelia burgdorferi Challenge Infect. Immun., July 1, 2003; 71(7): 3894 - 3900. [Abstract] [Full Text] [PDF]
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 G. Fenhalls, G. R. Squires, L. Stevens-Muller, J. Bezuidenhout, G. Amphlett, K. Duncan, and P. T. Lukey Associations between Toll-Like Receptors and Interleukin-4 in the Lungs of Patients with Tuberculosis Am. J. Respir. Cell Mol. Biol., July 1, 2003; 29(1): 28 - 38. [Abstract] [Full Text] [PDF]
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P.-Y. Bochud, T. R. Hawn, and A. Aderem Cutting Edge: A Toll-Like Receptor 2 Polymorphism That Is Associated with Lepromatous Leprosy Is Unable to Mediate Mycobacterial Signaling J. Immunol., April 1, 2003; 170(7): 3451 - 3454. [Abstract] [Full Text] [PDF]
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G. Melmed, L. S. Thomas, N. Lee, S. Y. Tesfay, K. Lukasek, K. S. Michelsen, Y. Zhou, B. Hu, M. Arditi, and M. T. Abreu Human Intestinal Epithelial Cells Are Broadly Unresponsive to Toll-Like Receptor 2-Dependent Bacterial Ligands: Implications for Host-Microbial Interactions in the Gut J. Immunol., February 1, 2003; 170(3): 1406 - 1415. [Abstract] [Full Text] [PDF]
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 R. Girard, T. Pedron, S. Uematsu, V. Balloy, M. Chignard, S. Akira, and R. Chaby Lipopolysaccharides from Legionella and Rhizobium stimulate mouse bone marrow granulocytes via Toll-like receptor 2 J. Cell Sci., January 15, 2003; 116(2): 293 - 302. [Abstract] [Full Text] [PDF]
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D. Schilling, K. Thomas, K. Nixdorff, S. N. Vogel, and M. J. Fenton Toll-Like Receptor 4 and Toll-IL-1 Receptor Domain-Containing Adapter Protein (TIRAP)/Myeloid Differentiation Protein 88 Adapter-Like (Mal) Contribute to Maximal IL-6 Expression in Macrophages J. Immunol., November 15, 2002; 169(10): 5874 - 5880. [Abstract] [Full Text] [PDF]
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H. Weighardt, S. Kaiser-Moore, R. M. Vabulas, C. J. Kirschning, H. Wagner, and B. Holzmann Cutting Edge: Myeloid Differentiation Factor 88 Deficiency Improves Resistance Against Sepsis Caused by Polymicrobial Infection J. Immunol., September 15, 2002; 169(6): 2823 - 2827. [Abstract] [Full Text] [PDF]
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T. H. Flo, L. Ryan, E. Latz, O. Takeuchi, B. G. Monks, E. Lien, O. Halaas, S. Akira, G. Skjak-Brak, D. T. Golenbock, et al. Involvement of Toll-like Receptor (TLR) 2 and TLR4 in Cell Activation by Mannuronic Acid Polymers J. Biol. Chem., September 13, 2002; 277(38): 35489 - 35495. [Abstract] [Full Text] [PDF]
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S. E. Applequist, R. P. A. Wallin, and H.-G. Ljunggren Variable expression of Toll-like receptor in murine innate and adaptive immune cell lines Int. Immunol., September 1, 2002; 14(9): 1065 - 1074. [Abstract] [Full Text] [PDF]
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R. Jacinto, T. Hartung, C. McCall, and L. Li Lipopolysaccharide- and Lipoteichoic Acid-Induced Tolerance and Cross-Tolerance: Distinct Alterations in IL-1 Receptor-Associated Kinase J. Immunol., June 15, 2002; 168(12): 6136 - 6141. [Abstract] [Full Text] [PDF]
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K. Ruckdeschel, O. Mannel, and P. Schrottner Divergence of Apoptosis-Inducing and Preventing Signals in Bacteria-Faced Macrophages Through Myeloid Differentiation Factor 88 and IL-1 Receptor-Associated Kinase Members J. Immunol., May 1, 2002; 168(9): 4601 - 4611. [Abstract] [Full Text] [PDF]
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R. van Crevel, T. H. M. Ottenhoff, and J. W. M. van der Meer Innate Immunity to Mycobacterium tuberculosis Clin. Microbiol. Rev., April 1, 2002; 15(2): 294 - 309. [Abstract] [Full Text] [PDF]
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R. N. Fichorova, A. O. Cronin, E. Lien, D. J. Anderson, and R. R. Ingalls Response to Neisseria gonorrhoeae by Cervicovaginal Epithelial Cells Occurs in the Absence of Toll-Like Receptor 4-Mediated Signaling J. Immunol., March 1, 2002; 168(5): 2424 - 2432. [Abstract] [Full Text] [PDF]
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Y. Bulut, E. Faure, L. Thomas, H. Karahashi, K. S. Michelsen, O. Equils, S. G. Morrison, R. P. Morrison, and M. Arditi Chlamydial Heat Shock Protein 60 Activates Macrophages and Endothelial Cells Through Toll-Like Receptor 4 and MD2 in a MyD88-Dependent Pathway J. Immunol., February 1, 2002; 168(3): 1435 - 1440. [Abstract] [Full Text] [PDF]
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G. Zhang and S. Ghosh Negative Regulation of Toll-like Receptor-mediated Signaling by Tollip J. Biol. Chem., February 22, 2002; 277(9): 7059 - 7065. [Abstract] [Full Text] [PDF]
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