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,
Divisions of
*
Developmental Immunology and
Molecular Immunology, La Jolla Institute for Allergy and Immunology, San Diego, CA 92121; and
Department of Biology, University of California at San Diego, La Jolla, CA 92037
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Abstract |
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 Top Abstract IntroductionMaterials and MethodsResultsDiscussionReferences |
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Introduction |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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R, found on epithelial
and stromal cells but conspicuously absent on lymphocytes
(6, 7, 8). Recent evidence suggests the existence of a
soluble binding protein for LIGHT, decoy receptor 3, which can bind Fas
ligand as well as LIGHT (9). These findings underscore the
multiple regulatory mechanisms that control the function of TNF family
molecules (9, 10).
Understanding the biological functions of LIGHT is further complicated
by the fact that each of its receptors also binds to other TNF family
ligands. For example, in addition to LIGHT, the LTR binds the
LT
12 heterotrimer, while HVEM can also bind the secreted
homotrimeric form of LT, LT3 (6). Therefore, the
presence of LIGHT might either synergize with or antagonize the signals
delivered by these alternate ligands for the receptors that bind
LIGHT.
The results from several studies indicate that LIGHT can trigger
apoptosis as well as cell activation, depending in part on the
expression of its receptors on the target cells (11, 12, 13).
Expression of LIGHT by transplanted tumors led to increased lymphocytic
infiltrates, tumor necrosis, and enhanced T cell cytotoxic activity.
Consistent with a role for LIGHT in T cell activation, inhibition of
LIGHT binding with a soluble HVEM-Fc fusion protein reduced the
severity of graft-vs-host disease (13). Reduced growth of
LIGHT-expressing transplanted tumors in vivo also was observed, even in
athymic and immune-deficient recipient mice, suggesting a
LIGHT-mediated increase in apoptosis of the cancer cells in the absence
of an adaptive immune response (12). It should be noted
that LIGHT also may act as a deterrent to infection of dendritic cells
and T cells by HSV through its ability to interfere with virus entry
(6, 14). Both LIGHT-binding receptors participate in these
diverse biologic effects of LIGHT. There are data suggesting that the
enhanced activation of T cells by LIGHT occurs through its interaction
with HVEM, which is also expressed on T lymphocytes (15).
Interestingly, the activation-induced expression of LIGHT on responding
T cells has been reported to negatively regulate HVEM expression in
vitro on all activated T cell subsets, suggesting a regulatory feedback
loop for controlling this potentially immune stimulatory pathway
(16). The LTR also is involved in mediating the effects
of LIGHT, as LIGHT expression by tumor cells could induce cell death
exclusively via the LTR signaling pathway, although the tumor cells
in this case expressed both the LTR and HVEM (11).
Despite these previous studies, there remains relatively little information on the in vivo effects of LIGHT expression, particularly within the T cell compartment, where LIGHT normally is expressed. This question is of special interest because of the proposed role of LIGHT as a highly regulated costimulatory molecule for T cells and its potential role in virus defense.
In the current study, we generated transgenic mice with constitutive expression of human LIGHT in T cells, under the control of the CD2 promoter. The results demonstrate an important role for LIGHT in driving the sustained activation of T cells, indicating that the regulation of expression of this TNF ligand on T lymphocytes plays a major role in orchestrating inflammatory responses. Interruption of this regulated expression on T cells leads to chronic inflammation and the destruction of selected tissues.
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Materials and Methods |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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A human LIGHT cDNA containing 5' EcoRI and 3' SmaI sites was generated by PCR, using a LIGHT cDNA isolated from the human T cell hybridoma line II23.D7 as a template. Forward primer 5'-cccagggaattcagccctgctccagagacctt-3' and reverse primer 5'-gggtgtcagacccatgtccaat-3' were used with the following PCR parameters: 94°C for 4 min, 30 cycles at 94°C for 30 s, 53°C for 30 s, 72°C for 45 s, followed by a 10-min extension at 72°C (11). This PCR fragment was subcloned into the EcoRI and SmaI sites of a vector containing the human CD2 promoter (kindly provided by Dr. S. Hedrick, University of California at San Diego, La Jolla, CA) (17). The final DNA fragment for microinjection was generated by SalI and XbaI digestion. It contains the human CD2 promoter and human growth hormone gene 3' untranslated region, and the human LIGHT cDNA and sequence for polyadenylation. PCR analysis of tail biopsy DNA was used to screen for transgenic animals with the forward primer 5'-ctaggagagatggtcacc-3' and the reverse primer 5'-cttccttcacaccatgaaagc-3'. The same parameters were used as described above for 40 cycles to generate a 534-bp product.
Necropsy of transgenic mice
Two LIGHT-transgenic founder mice were generated by injecting (C3H x C57BL/6) F1 eggs that were fertilized by C57BL/6 males. Fertility of the mice was limited, but one female LIGHT-transgenic offspring was generated by mating a founder to a C57BL/6 male. Mice were necropsied when they appeared ill, at 5 and 8 mo of age for the founders and at 4 mo of age for the offspring. Transgenic mice and littermate control animals were sacrificed and dissected, and portions of the salivary gland, lungs, liver, spleen, mesenteric lymph nodes, peripheral lymph nodes, uterus, and small and large intestine were placed in either formalin and/or OCT compound for histology analysis. Tissue was also flash frozen using liquid nitrogen for RNA preparation. Sera were prepared using serum separator tubes (Fisher Scientific, Pittsburgh, PA) and stored at -80°C. Following mechanical disruption, portions of the tissues (liver, spleen, mesenteric lymph nodes, peripheral lymph nodes, small and large intestine, and bone marrow) were used to prepare cell suspensions for flow cytometry analysis. Mononuclear cell preparations were prepared from liver as previously described (18). Intraepithelial lymphocytes (IEL) and lamina propria lymphocytes (LPL) from the small and large intestine were prepared essentially as described previously (19).
Flow cytometry
Cell preparations were used for flow cytometry analysis with the
following mAbs: rat anti-mouse CD4, CD8, CD122, B220, CD2, CD44,
CD45RB, and CD19, and hamster anti-mouse CD3
, TCR and TCR
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Monoclonal Abs were directly conjugated to either FITC, CyChrome, or PE
(BD Biosciences, San Diego, CA). Mouse HVEM was detected with rat
anti-mouse HVEM mAb 4CG4 (IgM) derived from a rat immunized with
mouse HVEM-Fc and secondary mouse anti rat-IgM-FITC (clone G53–238; BD
Biosciences). The presence of the LIGHT transgene was detected by flow
cytometry using a human HVEM-Fc fusion protein (6) (10
µg/ml) followed by an anti-human IgG secondary Ab conjugated to
PE (Southern Biotechnology Associates, Birmingham, AL). Human IgG1
(Sigma-Ald-rich, St. Louis, MO) was used as a control for staining
with receptor-Fc fusion proteins, and the analyzed cells were
pretreated with the 2.4G2 anti-Fc
R mAb to prevent nonspecific
secondary Ig binding. Analyses were performed on a FACSCalibur (BD
Biosciences) flow cytometer. Profiles consist of lymphocytes that were
gated by analysis of forward and side angle light scatter, or in some
cases by gating on expression of CD2.
Human LIGHT receptor binding assay
HEK293 cells expressing either human or mouse LIGHT were
generated as described previously (6). Mouse LTR and
HVEM-Fc fusion proteins were produced in a baculovirus-mediated protein
production system (6, 20) and purified by protein G
affinity chromatography (11). Binding assays for LTR-Fc
or HVEM-Fc to human or mouse LIGHT were accomplished by staining stably
transfected HEK293 cells (105 cells in 100 µl
of FACS binding buffer) with graded concentrations of Fc proteins for
60 min at 0°C followed by addition of 5 µg/ml goat Fab
anti-human IgG conjugated to R-PE. The specific mean fluorescence
intensity (MFI) was calculated by subtracting the background MFI
obtained with the equivalent amount of human IgG from the MFI of
LTR-Fc or HVEM-Fc. EC50 values were determined
by nonlinear regression analysis of the fusion protein binding (Prism
GraphPad software; San Diego, CA).
Bone marrow chimeras
129SV Rag 2-/- mice aged 6–8 wk (Jackson ImmunoResearch Laboratories, West Grove, PA) were lethally irradiated (1100 rad) before injection via the tail vein of 3–5 x 106 bone marrow cells. Full necropsies were performed as described above, 8–10 wk after cell transfer.
Intracellular cytokine staining
Suspensions containing freshly isolated spleen, small intestine
IEL, or large intestine IEL were seeded at 5 x
105–1 x 106 cells/ml
in 24-well plates coated with 10 µg/ml coated anti-CD3 (2C11)
mAb. These cells were incubated at 37°C for 5–7 h in the presence of
GolgiStop (BD Biosciences). A kit was then used to permeabilize and
stain the cells according to the manufacturer’s protocol (BD
Biosciences). Rat anti-mouse IFN-, IL-4, TNF, and rat IgG
isotype control PE Abs were used to stain for intracellular cytokines,
and TCR CyChrome Abs were used to identify T cells.
Ig isotype measurements
Ig isotype levels in sera were detected using standard capture ELISAs according to the manufacturer’s protocol (Southern Biotechnology Associates), with biotinylated anti-Ig Abs and streptavidin-labeled HRP for detection.
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Results |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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R
Human LIGHT was investigated for its ability to bind to mouse
receptors as measured by the binding of surrogate receptor Fc fusion
proteins to human or mouse LIGHT-transfected cells. Human LIGHT binds
to mouse LTR-Fc and mouse HVEM-Fc nearly as efficiently as these
receptors bind mouse LIGHT (Fig. 1
A). Thus, the in vivo effects
of human LIGHT are likely to be due to its interaction with either one
or both of these receptors. It should be noted that mixed heterotrimers
of human and mouse LIGHT can be formed in cotransfected cell lines
(data not shown), suggesting that human LIGHT is unlikely to
interfere with the cell surface expression of endogenous mouse LIGHT.
However, as endogenous mouse LIGHT is normally only transiently
expressed by T cells, it is likely that human LIGHT homotrimers are the
predominant species in transgenic mice with constitutive human LIGHT
expression.
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B). Saturation binding was reached
with both LIGHT homologs, but the midpoint (EC50)
is consistent with a nearly 10-fold greater affinity of human HVEM-Fc
for human LIGHT. This preferential binding allowed the use of human
HVEM-Fc (at 10 µg/ml) to specifically detect human LIGHT on cells
from the transgenic mice. Expression of human LIGHT in transgenic mice
Cell suspensions from the LIGHT-transgenic mice were analyzed for
surface expression of human LIGHT. Although the expression of the CD2
promoter-driven transgene correlates with the expression of endogenous
mouse CD2, the correlation is only partial (data not shown). This could
be due to several factors, including the restriction in humans of CD2
expression to the T cell lineage, while in mouse CD2 has a broader
expression pattern, including B cells as well as T cells. As expected,
in the absence of activation, CD2+ mononuclear
cells isolated from nontransgenic control animals did not express high
levels of LIGHT when detected with either a human HVEM-Fc (Fig. 2) or a mouse HVEM-Fc (data not shown).
Because many IEL are CD2- (21), we
analyzed total lymphocytes in IEL preparations that were gated by light
scatter. In control mice, IEL did not express high levels of LIGHT.
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). Additionally, a fraction
of the cells from peripheral lymph node (Fig. 2) and mesenteric lymph
node (data not shown) were highly positive for LIGHT expression. The
percentage of lymphocytes present in the spleen of transgenic mice was
greatly reduced (see below), and the level of HVEM-Fc staining
on these splenic lymphocytes was not significantly different from the
endogenous LIGHT expressed by control splenocytes. Similar to the
spleen, the CD2+ population in the liver was
reduced in the LIGHT-transgenic animals and expression of the LIGHT
transgene was limited (Fig. 2). The greatest percentage of cells
expressing high levels of human LIGHT in the transgenic mice was
observed on IEL (Fig. 2) and LPL (data not shown) from the small and
large intestine. Reduced viability and infertility in LIGHT-transgenic mice
Mice expressing the human LIGHT transgene were small compared with
their nontransgenic littermates, and they appeared sick by several
months of age. Necropsies of the mice showed visible changes in the
gross anatomy of these transgenic animals (Table I). They were anemic, and the small
intestine, cecum, mesenteric and peripheral lymph nodes, and spleen
were all enlarged, while the thymus was drastically reduced in size
when compared with an age-matched nontransgenic littermate (Fig. 3A). However, the large
intestine was not increased in size and the mice did not have diarrhea.
As noted in Materials and Methods, there were two
LIGHT-transgenic founder mice, which were both females. One of these
mice produced one litter with one transgenic offspring, and the other
failed to reproduce. Gross morphology of these mice indicated that
their inability to produce litters correlated with severe atrophy of
the reproductive organs (Fig. 3B). However, the colon and
liver appeared not to be inflamed upon necropsy.
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Analysis of fixed tissues of transgenic mice consistently showed
pathologic changes that were relatively selective with respect to
different organs. Spleen and lymph nodes were enlarged. H&E staining of
spleen tissue demonstrated a marked increase in extramedullary
hematopoiesis (primarily cells in the erythroid series were
evident) and an absence of a well-defined red and white pulp
separation and reactive lymphoid follicles (Fig. 3C). The
enlarged small intestine showed signs of chronic inflammation with
substantial infiltration of mononuclear cells, loss of goblet cells,
distortion and hyperplasia of crypts, and villus atrophy (Fig. 3D). Liver sections stained with H&E showed cellular
infiltrates into the portal areas, characterized by marked bile duct
hyperplasia and accompanied by a moderate, mixed inflammation of
neutrophils and lymphocytes (Fig. 3E). The reproductive
organs showed extensive changes, although a massive mononuclear
infiltrate was not observed (data not shown). The effect of
constitutive LIGHT expression in lung tissue was less pronounced. There
was a slight increase in polymorphonuclear cells in the septi in some
mice (data not shown).
Altered composition of lymphoid tissues in LIGHT-transgenic mice
Dramatic alterations in the number and composition of lymphocyte
populations were observed in both peripheral and central lymphoid
organs of the LIGHT-transgenic mice. The constitutive expression of
human LIGHT on thymocytes greatly reduced the cellularity as well as
the size of the thymus. The double positive thymocytes showed the
greatest reduction in percentage, while the percentage of single
positive CD8 and CD4 thymocytes increased (Fig. 4A). A subset of these mature,
single positive thymocytes had an activated phenotype, as determined by
high levels of CD44 as well as CD25 expression (Fig. 4A).
The spleen, although grossly enlarged, had a significant decrease in
the percent of CD3+ T cells as well as
B220+CD19+ B cells (Fig. 4B). In contrast, the enlarged lymph nodes of the
LIGHT-transgenic mice did contain a significant population of T cells,
although the percentage of B cells was drastically reduced (Fig. 4C). Similar to the mature thymocytes of these
LIGHT-transgenic animals, the T cells in the spleen and lymph nodes
also expressed high levels of CD44, suggesting an activated phenotype
(data not shown). IEL in the LIGHT-transgenic mice also were increased,
due to a strong and selective accumulation of activated T cells with a
conventional TCR and coreceptor phenotype, namely
TCR+ cells that are either
CD8+ or CD4+ (Fig. 4D). By contrast, the TCR+ and
TCR+CD8+ IEL
populations, which are characteristic of the intestine, were greatly
decreased in percentage, reflecting a lack of increase in these
populations (Fig. 4D). Surprisingly, the population of LPL
of the intestine did not show a decrease in the percentage of B cells
(B220+CD19+) in both the
small (Fig. 4E) and large intestine (data not shown), and in
fact a slight increase was observed. This was in sharp contrast to the
reduced B cell populations observed in the other tissues analyzed.
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To determine whether the in vivo effect of constitutively
expressed LIGHT is due solely to transgene expression by bone
marrow-derived cells, we generated chimeric mice by reconstituting
lethally irradiated immune-deficient RAG 2-/-
mice with bone marrow from the LIGHT-transgenic or littermate control
mice. The rate of successful bone marrow reconstitution, defined as
survival beyond 4 wk post-transfer, was relatively low when
LIGHT-transgenic bone marrow was transferred. Only three of eight mice
reconstituted with LIGHT bone marrow survived, whereas eight of nine
recipients survived when reconstituted with bone marrow from control
donor mice. The LIGHT bone marrow chimeras were similar to the
LIGHT-transgenic mice with regard to phenotype and gross anatomy (Table I). The recipients of LIGHT-transgenic bone marrow had a hunched
appearance, a reduction in body fat, and a >20% decrease in weight,
and they were also anemic. The LIGHT bone marrow chimeras also had
enlarged lymph nodes, both peripheral and mesenteric. Similar to the
donor mice, the LIGHT bone marrow recipient mice showed signs of
inflammation of the intestine with enlarged cecum, and two of three
recipients had patchy to severe inflammation of the small intestine and
ascites in their peritoneal cavity. The atrophy of the reproductive
organs was recapitulated in all LIGHT bone marrow chimeras as
well, indicating that the destruction of this tissue was mediated by
LIGHT-expressing hematopoietic cells, as opposed to unanticipated LIGHT
expression in the reproductive tract. Control chimeras generated by
transfer of bone marrow from littermate control mice appeared healthy
and did not show any of these abnormalities.
Although the histopathologic changes are consistent with those observed in the intact LIGHT-transgenic mice, they were less severe in the chimeric mice. This difference most likely reflects the low reconstitution efficiency of the lymphocyte populations in the LIGHT bone marrow-chimeric animals and the relatively short time post-transfer before analysis of the recipient mice. While the intact transgenic animals were analyzed between 16 and 32 wk of age, bone marrow-chimeric animals were aged 14–18 wk, but were analyzed between 8 and 10 wk post-transfer.
The phenotype of the lymphocytes reconstituted in the chimera that
received transgenic bone marrow also showed similarities with those
observed in the intact LIGHT-transgenic mice. A reduced percentage of
double positive thymocytes together with an increase in the percentage
of CD8 and CD4 single thymocytes was observed (Fig. 5A). Similar to the
LIGHT-transgenic animals, the percentage of lymphocytes among the
splenocytes of the LIGHT bone marrow-chimeric mice was significantly
reduced when compared with the splenocytes of the control chimeric
mice. The reduction was seen among the T cells (Fig. 5B) as
well as among the B cells (data not shown). The lymph nodes in the
LIGHT chimeric animals contained an increased population of mature CD4
and CD8 single positive T cells (Fig. 5C), while as
was the case in the LIGHT-transgenic donor animals, B cells were
drastically reduced (data not shown). Additionally, the IEL in the
small intestine of the LIGHT bone marrow chimeras showed a decreased
percentage of the typical intestinal CD8+ T
cells, including the TCR+ cells, while an
increased percentage of conventional TCR T cells was observed
(Fig. 5D). Consistent with the less severe alterations seen
in the chimeras, there was no significant lymphocyte infiltration
observed in either the liver or the lungs of the chimeric animals (data
not shown).
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To assay for changes in the function of T cells from the
LIGHT-transgenic mice, intracellular cytokine staining was done on
splenocytes and IEL from LIGHT-transgenic bone marrow chimeras and
control chimeras. Cytokines were measured after a brief in vitro
activation with plate-bound CD3 Ab. These experiments showed a
significant increase in the percentage of cells with intracellular
IFN- in small intestine IEL of LIGHT-transgenic bone marrow-chimeric
mice (Fig. 6A), while
the percentage of cytokine producing TCR+
cells in the spleen of these animals was not changed when compared with
control chimeric animals (data not shown). IEL from the large intestine
also showed increased levels of intracellular IFN-, although less
pronounced (data not shown). In no case did cells from the chimeric
mice show production of intracellular IL-4.
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B). This finding of
increased production of IgA is consistent with the singular increase in
the B cell population observed in the lamina propria of the
LIGHT-transgenic animals. Constitutive expression of LIGHT does not down-regulate HVEM
The induction of LIGHT expression on activated T cells has been
reported to correlate with a reciprocal in vitro down-regulation of
HVEM on those cells (16). Surprisingly, when analyzed for
HVEM expression using a specific Ab, lymph node cells of chimeric mice
that received LIGHT-transgenic bone marrow, which express significant
levels of the LIGHT transgene, also expressed equivalent or even higher
levels of HVEM compared with the control mice (Fig. 7). This suggests that this
ligand-receptor interaction does not initiate sustained down-regulation
of HVEM in vivo. Alternatively, the level of transgene-derived LIGHT
expressed, or differences in binding HVEM between mouse and human
LIGHT, could account for the difference in receptor
down-modulation.
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Discussion |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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The inflammation observed was particularly severe in the intestine, and
this correlated with other changes in the mucosal immune system of
these transgenic mice, including selective increases in lamina propria
B cells along with increases in serum IgA, despite decreases in B
lymphocytes in other sites. The accumulation of mature IgA-producing
plasma cells in the lamina propria of the intestine and the terminal
differentiation of plasma cells to IgA secretion are T cell-mediated
phenomena that are up-regulated during inflammation. Additionally,
increased production of IFN- was obtained from the IEL of
LIGHT-transgenic mice. This is consistent with previous data indicating
that LIGHT is a costimulatory molecule that induces a Th1-type
proinflammatory cytokine response in vitro (13).
Interestingly, the typical intestinal intraepithelial
CD8+ T cells, including the
TCR+ T cells, were not increased in these
mice, and few cells could be detected. Such alterations in IEL
subpopulations are a characteristic feature of several colitis models
in mice (22, 23). Evidence consistent with an important
role for LIGHT in the induction of inflammation in the intestine also
comes from the analysis of immune-deficient mice in which colitis is
induced by transfer of
CD4+CD45RBhigh T cells. In
these recipient mice, blocking of both LIGHT and LT with soluble
LTR-Fc decoy receptor prevented colitis (24), but there
is other evidence suggesting that expression of LT in recipient
mice is not required for pathogenesis (25), implicating
LIGHT as the relevant ligand neutralized by the LTR-Fc and
responsible for the beneficial effects of this treatment. Overall,
these results support the hypothesis that increased or sustained
expression of LIGHT on activated T cells is one factor causing the
induction and/or persistence of inflammation in the intestine.
Mice expressing the LIGHT transgene also presented with altered lymphoid tissues, including enlarged lymph nodes and decreased thymic cellularity. The spleen, although enlarged, was lymphopenic, and the normal splenic architecture was not present with the loss of clearly defined marginal zones and an altered cellular composition. Histology showed that the splenomegaly was probably due to dividing erythrocyte precursors. In contrast, the thymus showed a significant reduction in CD4/CD8 double positive cells. It cannot be determined whether this reduction in thymocytes and the presence of single positive cells with an activated phenotype is purely a developmental effect, or whether it is secondary to the inflammatory phenotype exhibited by these LIGHT-transgenic animals. The presence of increased T cell populations in several peripheral tissues of these mice, together with the observation that some of these activated T cells might display autoreactivity resulting in tissue destruction, indicate that a general enhancement of negative selection, or failure of positive selection, are most likely not the sole causes of the reduced double positive thymocyte population.
Chimeric recipients of LIGHT-transgenic bone marrow exhibited a similar pathology as the transgenic donor mice. Although the effects were less severe, changes in lymphoid organs, the intestine, and the reproductive tract were observed, indicating that the effects of constitutive LIGHT expression are due to bone marrow-derived cells. Because the LIGHT transgene is expressed under the control of the CD2 promoter, it is likely that the constitutive expression of LIGHT by activated T lymphocytes is responsible for the inflammatory and autoimmune-like phenotype observed in both the transgenic mice and chimeric recipients of transgenic bone marrow.
The potent inflammatory effect of LIGHT expression in vivo may reveal its importance for viral immunity and evasion. In particular, the use of the LIGHT receptor HVEM by HSV as a point of access to the immune system is not likely to be fortuitous. Rather, this pathway may have been specifically targeted to suppress immune function by HSV (14, 26). The ability of envelope glycoprotein D of HSV to compete with LIGHT-HVEM binding supports this notion (6). In an opposite strategy, as a consequence of the action of the nef gene product of HIV, LIGHT expression at the cell surface is significantly sustained on activated T cells (27), possibly contributing to nonspecific T cell-mediated pathogenesis, similar to that observed in the LIGHT-transgenic animals.
The effects of LIGHT in the transgenic mice could be the result of its
interaction with the LTR, HVEM, or both (6, 12).
Signaling through the LTR by binding of its other ligand, LT,
is critical for the normal morphogenesis of the spleen
(28, 29). Although both LIGHT and LT can effectively
interact with the LTR, the downstream signaling pattern may differ.
It is therefore possible that LIGHT competes with LT when it is
expressed constitutively, thus interrupting the formation of normal
splenic architecture in these transgenic animals. HVEM is the only
known receptor for LIGHT expressed on T cells, and in vitro studies
suggest that LIGHT-induced increases in proinflammatory Th1 cytokine
production are most likely due to its interaction with HVEM expressed
on the activated effector T cells (13). However, it
remains to be determined if HVEM is the only receptor for the induction
of LIGHT-mediated inflammatory changes seen in the mucosal tissues and
elsewhere in these transgenic mice. Interestingly, increased expression
of HVEM was observed in T cells from the LIGHT-transgenic mice,
indicating that the balanced expression of LIGHT and its receptor on T
cells may be disrupted. We speculate that dysregulation of the
LIGHT-HVEM system (e.g., by sustained expression) could result in an
exaggerated T cell-mediated immune response, which consequently could
lead to chronic inflammation and autoimmune disease. The distribution
of the activated effector cells in the LIGHT-transgenic and bone
marrow-chimeric animals indicates that mucosal tissues are a prominent
target for this receptor-ligand deregulation. These results suggest
that targeting the LIGHT-HVEM ligand-receptor pair may provide new
opportunities for intervention in inflammatory and autoimmune-based
diseases, in particular those involving mucosal tissues.
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Acknowledgments |
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Footnotes |
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2 This publication is number 422 from the La Jolla Institute for Allergy and Immunology.
3 Current address: Research School of Biological Sciences, Australian National University, Canberra, Australian Capital Territory, Australia.
4 Address correspondence and reprint requests to Dr. Carl F. Ware or Dr. Hilde Cheroutre, La Jolla Institute for Allergy and Immunology, 10355 Science Center Drive, San Diego, CA 92121. E-mail addresses: carl_ware@liai.org or hilde{at}liai.org
5 Abbreviations used in this paper: LIGHT, homologous to lymphotoxin, exhibits inducible expression, and competes with HSV glycoprotein D for herpesvirus entry mediator, a receptor expressed by T lymphocytes; LT, lymphotoxin; HVEM, herpesvirus entry mediator; IEL, intraepithelial lymphocyte; LPL, lamina propria lymphocyte; MFI, mean fluorescence intensity.
Received for publication July 9, 2001. Accepted for publication October 2, 2001.
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References |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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are ligands for herpesvirus entry mediator. Immunity 8:21.[Medline]
receptor induces the death of some adenocarcinoma tumor lines. J. Exp. Med. 183:867. receptor is necessary and sufficient for LIGHT mediated apoptosis of tumor cells. J. Biol. Chem. 275:14307. receptor and TR2/HVEM induces apoptosis and suppresses in vivo tumor formation via gene transfer. J. Clin. Invest. 102:1142.[Medline]
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receptor IgG1 fusion protein. Proc. Natl. Acad. Sci. USA 93:13102./ complex is required for the development of peripheral lymphoid organs. J. Exp. Med. 184:1999.This article has been cited by other articles:
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M. Pierer, A. Schulz, M. Rossol, E. Kendzia, D. Kyburz, H. Haentzschel, C. Baerwald, and U. Wagner Herpesvirus Entry Mediator-Ig Treatment during Immunization Aggravates Rheumatoid Arthritis in the Collagen-Induced Arthritis Model J. Immunol., March 1, 2009; 182(5): 3139 - 3145. [Abstract] [Full Text] [PDF]
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 W. J. Sandberg, B. Halvorsen, A. Yndestad, C. Smith, K. Otterdal, F. R. Brosstad, S. S. Froland, P. S. Olofsson, J. K. Damas, L. Gullestad, et al. Inflammatory Interaction Between LIGHT and Proteinase-Activated Receptor-2 in Endothelial Cells: Potential Role in Atherogenesis Circ. Res., January 2, 2009; 104(1): 60 - 68. [Abstract] [Full Text] [PDF]
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C. A. Nelson, M. D. Fremont, J. R. Sedy, P. S. Norris, C. F. Ware, K. M. Murphy, and D. H. Fremont Structural Determinants of Herpesvirus Entry Mediator Recognition by Murine B and T Lymphocyte Attenuator J. Immunol., January 15, 2008; 180(2): 940 - 947. [Abstract] [Full Text] [PDF]
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G. Xu, D. Liu, I. Okwor, Y. Wang, H. Korner, S. K. P. Kung, Y.-X. Fu, and J. E. Uzonna LIGHT Is Critical for IL-12 Production by Dendritic Cells, Optimal CD4+ Th1 Cell Response, and Resistance to Leishmania major J. Immunol., November 15, 2007; 179(10): 6901 - 6909. [Abstract] [Full Text] [PDF]
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 M. Pierer, F. Brentano, J. Rethage, U. Wagner, H. Hantzschel, R. E. Gay, S. Gay, and D. Kyburz The TNF superfamily member LIGHT contributes to survival and activation of synovial fibroblasts in rheumatoid arthritis Rheumatology, July 1, 2007; 46(7): 1063 - 1070. [Abstract] [Full Text] [PDF]
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 Y. Xu, A. S. Flies, D. B. Flies, G. Zhu, S. Anand, S. J. Flies, H. Xu, R. A. Anders, W. W. Hancock, L. Chen, et al. Selective targeting of the LIGHT-HVEM costimulatory system for the treatment of graft-versus-host disease Blood, May 1, 2007; 109(9): 4097 - 4104. [Abstract] [Full Text] [PDF]
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 Y. Wang, P. H. Dennehy, H. L. Keyserling, K. Tang, J. R. Gentsch, R. I. Glass, and B. Jiang Rotavirus Infection Alters Peripheral T-Cell Homeostasis in Children with Acute Diarrhea J. Virol., April 15, 2007; 81(8): 3904 - 3912. [Abstract] [Full Text] [PDF]
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 J. C. Lo, Y. Wang, A. V. Tumanov, M. Bamji, Z. Yao, C. A. Reardon, G. S. Getz, and Y.-X. Fu Lymphotoxin {beta} Receptor-Dependent Control of Lipid Homeostasis Science, April 13, 2007; 316(5822): 285 - 288. [Abstract] [Full Text] [PDF]
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 B. J Sedgmen, W. Dawicki, J. L Gommerman, K. Pfeffer, and T. H Watts LIGHT is dispensable for CD4+ and CD8+ T cell and antibody responses to influenza A virus in mice Int. Immunol., May 1, 2006; 18(5): 797 - 806. [Abstract] [Full Text] [PDF]
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Z. Fan, P. Yu, Y. Wang, Y. Wang, M. L. Fu, W. Liu, Y. Sun, and Y.-X. Fu NK-cell activation by LIGHT triggers tumor-specific CD8+ T-cell immunity to reject established tumors Blood, February 15, 2006; 107(4): 1342 - 1351. [Abstract] [Full Text] [PDF]
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 S.-K. Heo, S.-A Ju, S.-C. Lee, S.-M. Park, S.-Y. Choe, B. Kwon, B. S. Kwon, and B.-S. Kim LIGHT enhances the bactericidal activity of human monocytes and neutrophils via HVEM J. Leukoc. Biol., February 1, 2006; 79(2): 330 - 338. [Abstract] [Full Text] [PDF]
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Y.-G. Wang, K. D. Kim, J. Wang, P. Yu, and Y.-X. Fu Stimulating Lymphotoxin {beta} Receptor on the Dendritic Cells Is Critical for Their Homeostasis and Expansion J. Immunol., November 15, 2005; 175(10): 6997 - 7002. [Abstract] [Full Text] [PDF]
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 T. C. Cheung, I. R. Humphreys, K. G. Potter, P. S. Norris, H. M. Shumway, B. R. Tran, G. Patterson, R. Jean-Jacques, M. Yoon, P. G. Spear, et al. From The Cover: Evolutionarily divergent herpesviruses modulate T cell activation by targeting the herpesvirus entry mediator cosignaling pathway PNAS, September 13, 2005; 102(37): 13218 - 13223. [Abstract] [Full Text] [PDF]
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J. Wang, R. A. Anders, Y. Wang, J. R. Turner, C. Abraham, K. Pfeffer, and Y.-X. Fu The Critical Role of LIGHT in Promoting Intestinal Inflammation and Crohn's Disease J. Immunol., June 15, 2005; 174(12): 8173 - 8182. [Abstract] [Full Text] [PDF]
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T. A. Banks, S. Rickert, C. A. Benedict, L. Ma, M. Ko, J. Meier, W. Ha, K. Schneider, S. W. Granger, O. Turovskaya, et al. A Lymphotoxin-IFN-{beta} Axis Essential for Lymphocyte Survival Revealed during Cytomegalovirus Infection J. Immunol., June 1, 2005; 174(11): 7217 - 7225. [Abstract] [Full Text] [PDF]
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G. Shi, J. Mao, G. Yu, J. Zhang, and J. Wu Tumor Vaccine Based on Cell Surface Expression of DcR3/TR6 J. Immunol., April 15, 2005; 174(8): 4727 - 4735. [Abstract] [Full Text] [PDF]
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K. A. Papadakis, D. Zhu, J. L. Prehn, C. Landers, A. Avanesyan, G. Lafkas, and S. R. Targan Dominant Role for TL1A/DR3 Pathway in IL-12 plus IL-18-Induced IFN-{gamma} Production by Peripheral Blood and Mucosal CCR9+ T Lymphocytes J. Immunol., April 15, 2005; 174(8): 4985 - 4990. [Abstract] [Full Text] [PDF]
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 Y.-S. Kim, S. A. Nedospasov, and Z.-g. Liu TRAF2 Plays a Key, Nonredundant Role in LIGHT-Lymphotoxin {beta} Receptor Signaling Mol. Cell. Biol., March 15, 2005; 25(6): 2130 - 2137. [Abstract] [Full Text] [PDF]
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O. Cohavy, J. Zhou, C. F. Ware, and S. R. Targan LIGHT Is Constitutively Expressed on T and NK Cells in the Human Gut and Can Be Induced by CD2-Mediated Signaling J. Immunol., January 15, 2005; 174(2): 646 - 653. [Abstract] [Full Text] [PDF]
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O. Cohavy, J. Zhou, S. W. Granger, C. F. Ware, and S. R. Targan LIGHT Expression by Mucosal T Cells May Regulate IFN-{gamma} Expression in the Intestine J. Immunol., July 1, 2004; 173(1): 251 - 258. [Abstract] [Full Text] [PDF]
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K. A. Papadakis, J. L. Prehn, C. Landers, Q. Han, X. Luo, S. C. Cha, P. Wei, and S. R. Targan TL1A Synergizes with IL-12 and IL-18 to Enhance IFN-{gamma} Production in Human T Cells and NK Cells J. Immunol., June 1, 2004; 172(11): 7002 - 7007. [Abstract] [Full Text] [PDF]
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 M. T. Fisher, M. Nagarkatti, and P. S. Nagarkatti Combined Screening of Thymocytes Using Apoptosis-Specific cDNA Array and Promoter Analysis Yields Novel Gene Targets Mediating TCDD-Induced Toxicity Toxicol. Sci., March 1, 2004; 78(1): 116 - 124. [Abstract] [Full Text] [PDF]
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J. Liu, C. S. Schmidt, F. Zhao, A. J. Okragly, A. Glasebrook, N. Fox, E. Galbreath, Q. Zhang, H. Y. Song, S. Na, et al. LIGHT-deficiency impairs CD8+ T cell expansion, but not effector function Int. Immunol., July 1, 2003; 15(7): 861 - 870. [Abstract] [Full Text] [PDF]
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R. A. Fava, E. Notidis, J. Hunt, V. Szanya, N. Ratcliffe, A. Ngam-ek, A. R. de Fougerolles, A. Sprague, and J. L. Browning A Role for the Lymphotoxin/LIGHT Axis in the Pathogenesis of Murine Collagen-Induced Arthritis J. Immunol., July 1, 2003; 171(1): 115 - 126. [Abstract] [Full Text] [PDF]
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J. Wang and Y.-X. Fu LIGHT (a Cellular Ligand for Herpes Virus Entry Mediator and Lymphotoxin Receptor)-Mediated Thymocyte Deletion Is Dependent on the Interaction Between TCR and MHC/Self-Peptide J. Immunol., April 15, 2003; 170(8): 3986 - 3993. [Abstract] [Full Text] [PDF]
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 D. M. Koelle and L. Corey Recent Progress in Herpes Simplex Virus Immunobiology and Vaccine Research Clin. Microbiol. Rev., January 1, 2003; 16(1): 96 - 113. [Abstract] [Full Text] [PDF]
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X. Wan, J. Zhang, H. Luo, G. Shi, E. Kapnik, S. Kim, P. Kanakaraj, and J. Wu A TNF Family Member LIGHT Transduces Costimulatory Signals into Human T Cells J. Immunol., December 15, 2002; 169(12): 6813 - 6821. [Abstract] [Full Text] [PDF]
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 H. Matsui, Y. Hikichi, I. Tsuji, T. Yamada, and Y. Shintani LIGHT, a Member of the Tumor Necrosis Factor Ligand Superfamily, Prevents Tumor Necrosis Factor-alpha -mediated Human Primary Hepatocyte Apoptosis, but Not Fas-mediated Apoptosis J. Biol. Chem., December 13, 2002; 277(51): 50054 - 50061. [Abstract] [Full Text] [PDF]
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 R. M. Gill, J. Ni, and J. S. Hunt Differential Expression of LIGHT and Its Receptors in Human Placental Villi and Amniochorion Membranes Am. J. Pathol., December 1, 2002; 161(6): 2011 - 2017. [Abstract] [Full Text] [PDF]
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R. Castellano, C. Van Lint, V. Peri, E. Veithen, Y. Morel, R. Costello, D. Olive, and Y. Collette Mechanisms Regulating Expression of the Tumor Necrosis Factor-related light Gene. ROLE OF CALCIUM-SIGNALING PATHWAY IN THE TRANSCRIPTIONAL CONTROL J. Biol. Chem., November 1, 2002; 277(45): 42841 - 42851. [Abstract] [Full Text] [PDF]
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G. Shi, H. Luo, X. Wan, T. W. Salcedo, J. Zhang, and J. Wu Mouse T cells receive costimulatory signals from LIGHT, a TNF family member Blood, October 16, 2002; 100(9): 3279 - 3286. [Abstract] [Full Text] [PDF]
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S. Scheu, J. Alferink, T. Potzel, W. Barchet, U. Kalinke, and K. Pfeffer Targeted Disruption of LIGHT Causes Defects in Costimulatory T Cell Activation and Reveals Cooperation with Lymphotoxin {beta} in Mesenteric Lymph Node Genesis J. Exp. Med., June 17, 2002; 195(12): 1613 - 1624. [Abstract] [Full Text] [PDF]
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K. Tamada, J. Ni, G. Zhu, M. Fiscella, B. Teng, J. M. A. van Deursen, and L. Chen Cutting Edge: Selective Impairment of CD8+ T Cell Function in Mice Lacking the TNF Superfamily Member LIGHT J. Immunol., May 15, 2002; 168(10): 4832 - 4835. [Abstract] [Full Text] [PDF]
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Q. Ye, C. C. Fraser, W. Gao, L. Wang, S. J. Busfield, C. Wang, Y. Qiu, A. J. Coyle, J.-C. Gutierrez-Ramos, and W. W. Hancock Modulation of LIGHT-HVEM Costimulation Prolongs Cardiac Allograft Survival J. Exp. Med., March 18, 2002; 195(6): 795 - 800. [Abstract] [Full Text] [PDF]
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) or mouse (
) LIGHT were stained with human
HVEM-Fc. HVEM-Fc binding was detected by incubation with a goat
anti-human R-PE-conjugated secondary Ab and analyzed by flow
cytometry.
