Biomedical subjects

B S Kwon

Publications and source records attributed to B S Kwon.

At least 19 recordsLinked to original sources

PubMed2006

Involvement of 4-1BB (CD137)-4-1BBligand interaction in the modulation of CD4 T cell-mediated inflammatory colitis.

4-1BB ligand (4-1BBL) expressed on antigen-presenting cells interacts with 4-1BB on activated T cells (especially CD8+ cells) and co-stimulates the latter to secrete cytokines and to proliferate. The role of 4-1BB-4-1BBL interaction was studied here in a model of colitis based on naive CD4+ T cell transfer to SCID mice, a disease model in which CD8 cells do not take part. We found that CD4+ T cells from 4-1BB-deficient mice, after transfer in SCID mice, proliferated more rapidly compared to wild-type CD4+ T cells. Mice reconstituted with naive CD4+ T cells from 4-1BB-deficient mice developed colitis, however, with a mixed Th1/Th2 response, in contrast to the Th1-type response in mice reconstituted with wild-type naive CD4+ T cells. Importantly, this altered cytokine response did not temper colitis severity. Although it has been reported previously that 4-1BB co-stimulation may contribute to regulatory T cell functioning, we found that CD4+CD25+ regulatory T cells from 4-1BB-deficient mice were perfectly able to prevent naive CD4+ T cell-induced colitis. In conclusion, our data provide evidence that 4-1BB-4-1BBL interaction modulates the effector CD4+ T cell-driven immune response and cytokine production in experimental colitis without affecting regulatory T cell function.

4-1BB Ligand↗

PubMed2004

Blockade of 4-1BB (CD137)/4-1BB ligand interactions increases allograft survival.

We investigated the role of 4-1BB, a T cell co-stimulatory molecule, in alloimmune responses. In vivo mixed lymphocyte reactions showed that 4-1BB was preferentially expressed on actively dividing CD4(+) and CD8(+) T cells. Furthermore, following alloantigen challenge, the draining lymph nodes contained subpopulations of 4-1BB-expressing CD4(+) and CD8(+) T cells. 4-1BB-deficient C57BL/6 mice showed a delayed rejection of cardiac transplants mismatched for the major histocompatibility complex. Longer transplant survival was induced by blockade of 4-1BB/4-1BB ligand (4-1BBL) interactions using an anti-4-1BBL monoclonal antibody. Histological analysis showed that prolonged transplant survival in the 4-1BB-deficient and anti-4-1BBL-treated mice correlated with reduced lymphocytic infiltration and vasculitis in the donor heart tissue. Taken together, our data suggest that blockade of 4-1BB/4-1BBL interactions inhibited the expansion of alloreactive T cells and reduced CTL activity against host alloantigen, which in turn resulted in the prolongation of allograft survival. Blockade of the 4-1BB co-stimulatory pathway may be useful for preventing allograft rejection.

4-1BB Ligand↗

PubMed2003

Cloning and characterization of GITR ligand.

The gene encoding the natural ligand of murine glucocorticoid-induced tumor necrosis factor receptor (GITR) was cloned and characterized. The putative GITR ligand (GITRL) is composed of 173 amino acids with features resembling those of type II membrane proteins and is 51% identical to the human activation-inducible TNF receptor (AITR) ligand, TL6. Expression of the GITRL is restricted to immature and mature splenic dendritic cells. GITRL binds GITR expressed on HEK 293 cells and triggers NF-kappaB activation. Functional studies reveal that soluble CD8-GITRL prevents CD4+CD25+ regulatory T-cell-mediated suppressive activities.

Amino Acid Sequence↗

PubMed2002

Molecular cloning of agonistic and antagonistic monoclonal antibodies against human 4-1BB.

Previously, we prepared two different monoclonal antibodies (mAbs) against human 4-1BB (CD137): an agonistic mAb BBK-1 and an antagonistic mAb BBK-2. In this paper, we describe the molecular cloning of these two mAbs and present comparisons of their amino acid sequences. cDNAs encoding the heavy (H) and light (L) chains of the two mAbs were cloned by screening of cDNA libraries constructed from hybridomas secreting these mAbs. Comparisons of amino acid sequences of the two mAbs showed that, while the constant regions of the H and L chains were identical between the two mAbs, the variable region showed 45% identity in H chains and 48% identity in L chains. This suggests that these two mAbs recognize different epitopes of 4-1BB and may have different effects on the activity of 4-1BB.

Amino Acid Sequence↗

PubMed2001

A novel leucine-rich repeat protein (LRR-1): potential involvement in 4-1BB-mediated signal transduction.

4-1BB, a member of the tumor necrosis factor receptor (TNFR) superfamily, is induced on CD4+ and CD8+ T cells upon engagement of the T cell receptor (TCR)/ CD3 complex with the antigen bound to MHC. 4-1BB plays an important role in transmitting costimulatory signal during T cell activation. However, 4-1BB-mediatded signal transduction pathways have remained elusive. We conducted the yeast two-hybrid screening to identify intracellular signaling molecules that associate with 4-1BB. A novel leucine-rich repeat (LRR)-containing protein, herein named LRR-1, was found to specifically interact with the cytoplasmic domain of 4-1BB. Overexpression of LRR-1 suppressed the activation of NF-KB induced by 4-1BB or TNF receptor-associated factor (TRAF) 2. In addition, LRR-1 down-regulated JNK1 activity was induced by 4-1BB. These results indicate that LRR-1 negatively regulates the 4-1BB-mediated signaling cascades which result in the activation of NF-kappaB and JNK1.

Amino Acid Sequence↗

PubMed2001

The seventh transmembrane domain of cc chemokine receptor 5 is critical for MIP-1beta binding and receptor activation: role of MET 287.

CC chemokine receptor 5 (CCR5) is a high-affinity receptor for macrophage inflammatory protein (MIP)-1beta and functions as the major coreceptor for entry of macrophage-tropic (M-tropic) human immunodeficiency virus type 1 (HIV-1). To evaluate the role of transmembrane domains (TM) in the receptor function of CCR5, the seventh transmembrane domain (TM7) was examined in a series of chimeric receptor constructs including CCR5TM (CCR5 backbone/CCR5 TM7 replaced with CCR1 TM7) and mutants of CCR5TM. The CCR5TM chimera exhibited a dramatic reduction in receptor activation, as well as little or no MIP-1beta binding. Further mutational analysis revealed that Met 287 in TM7 of CCR5 is a critical molecular determinant for both MIP-1beta binding and receptor activation. Interestingly, all of the chimeric/mutated receptors were biologically active in an HIV-1 coreceptor fusion assay, demonstrating that chemokine binding is independent of HIV-1 coreceptor activity.

Amino Acid Sequence↗

PubMed2001

Ligation of 4-1BB (CDw137) regulates graft-versus-host disease, graft-versus-leukemia, and graft rejection in allogeneic bone marrow transplant recipients.

4-1BB is expressed on activated CD4(+) and CD8(+) T cells; its ligand, 4-1BB ligand is expressed on APCs. Despite expression on both T cell subpopulations, 4-1BB has been reported to predominantly affect CD8(+) T cell responses. By quantifying graft-vs-host disease alloresponses in vivo, we demonstrate that both CD4(+) and CD8(+) T cell-mediated alloresponses are regulated by 4-1BB/4-1BB ligand interactions to approximately the same extent. 4-1BB receptor-facilitated CD4(+) T cell-mediated alloresponses were partly CD28 independent. In two distinct marrow graft rejection systems, host CD8(+) and CD4(+) T cells each separately contributed to host anti-donor T cell-mediated allograft rejection. alpha 4-1BB mAb increased the graft-vs-leukemia effect of a suboptimal number of donor splenocytes given later post bone marrow transplantation by bolstering allogeneic responses resulting in leukemia elimination. In summary, 4-1BB ligation is a potent regulator of CD4(+) and CD8(+) T cell-mediated allogeneic responses in vivo. Modifying the ligation of 4-1BB represents a new approach to altering the graft-vs-host disease and graft-vs-leukemia effects of allogeneic T cells post bone marrow transplantation.

4-1BB Ligand↗

PubMed2001

Osteoclastogenesis is enhanced by activated B cells but suppressed by activated CD8(+) T cells.

Host immune response is known to contribute to the progression of periodontitis, and alveolar bone destruction in periodontitis is associated with enhanced osteoclast activity. Therefore, we evaluated the roles of activated lymphocyte subsets in osteoclastogenesis. Osteoclast precursors were co-cultured with activated lymphocytes (B, CD4(+) T, CD8(+) T) in the presence of either macrophage colony-stimulating factor (M-CSF) alone or M-CSF plus soluble receptor activator of NF-kappaB ligand (sRANKL), and subsequent differentiation into active osteoclasts was evaluated by a resorption assay. The activated B and CD4(+) cells, but not CD8(+) T cells, induced osteoclast differentiation in the presence of M-CSF alone. In the presence of M-CSF and sRANKL, B cells induced the formation of small but highly active osteoclasts and increased resorption, while CD8(+) T cells profoundly suppressed osteoclastogenesis. Co-culture using an insert well or supernatant suggested that both B and CD8(+) T cells acted on osteoclasts mostly via soluble proteins. Activated B cells expressed many osteoclastogenic factors including RANKL, TNF-alpha, IL-6, MIP-1alpha, and MCP-3. CD8(+) T cells expressed a substantial amount of osteoprotegerin (OPG) along with RANKL. However, blocking antibody to OPG did not reverse the suppression by CD8(+) T cells, suggesting that other factor(s) are involved. Taken together, activated B cells promoted osteoclastogenesis, while CD8(+) T cells inhibited the osteoclast formation via direct interaction. The results imply the importance of lymphocyte subpopulations in the development of periodontitis.

Animals↗

PubMed2001

Murine keratocytes function as antigen-presenting cells.

Keratocytes express MHC class I molecules constitutively, and keratocytes stimulated with IFN-gamma express MHC class II molecules. Unstimulated keratocytes constitutively express B7-1 and ICAM-1, as well as low levels of CD40 and 4-1BBL. These findings indicate that keratocytes may deliver both antigen-specific and costimulatory signals to CD4(+) and CD8(+) T cells. To demonstrate that keratocytes expressing B7-1 provide a costimulatory signal to T cells, CD4(+) or CD8(+) mouse T cells were incubated with anti-CD3 mAb and irradiated keratocytes. Enhanced proliferation of both CD4(+) and CD8(+) T cells occurred, and could be inhibited by anti-B7-1 mAb, indicating T cell costimulatory activity by B7-1 on the keratocytes. To demonstrate that keratocytes can deliver an antigen-specific signal, CD4(+) and CD8(+) T cells from herpes-infected mice were incubated with HSV-1-infected, irradiated keratocytes. The resulting T cell proliferation and production of Th1 cytokines (IL-2, IFN-gamma) indicated T cell activation by antigens presented by the infected keratocytes. These results show that keratocytes in the corneal stroma of the mouse can function as antigen-presenting cells and, thus, may play a role in immune-mediated stromal inflammation such as herpetic stromal keratitis.

Animals↗

PubMed2001

Gene expression analyzed by microarrays in HSV-1 latent mouse trigeminal ganglion following heat stress.

An understanding of the cellular genes whose expression is altered during HSV reactivation will enable us to better understand host responses and biochemical pathways involved in the process. Furthermore, this knowledge could allow us to develop gene-targeted inhibitors to prevent viral reactivation. Mice latent with HSV-1 strain McKrae and uninfected control mice were subjected to hyperthermic stress (43 degrees C for 10 min) and their trigeminal ganglia (TG) collected 1 h later. Two additional groups included HSV-1 latently infected and uninfected mice not subjected to hyperthermic stress. Poly A+ mRNA was enriched from total mouse TG RNA and reverse transcribed using MMLV RT. Radioactively labeled cDNAs were analyzed by microarray analysis. A stress/toxicology array of 149 mouse genes on a nylon membrane was used. The labeled cDNAs prepared from latently infected, stressed mice demonstrated 3-fold or greater increases in certain mRNA-early response genes (ERGs) compared to cDNAs from uninfected, stressed control mice. The ERG mRNAs that showed increases included two heat shock proteins (HSP60 and HSP40), a basic transcription factor (BTF T62), a DNA repair enzyme, two kinases [MAP kinase and a stress-induced protein kinase (SADK)], an oxidative stress-induced protein, a manganese superoxide dismutase precursor-2 (SOD-2), and cyclooxygenase 2 (COX-2). The gene expression in unstressed, infected TGs was similar to the gene expression in unstressed, uninfected controls. These results suggest that there is a significant difference in the ERG expression profile in latently infected TGs undergoing stress-induced reactivation compared to uninfected TGs.

Animals↗

PubMed2001

Tumor necrosis factor receptor superfamily 14 is involved in atherogenesis by inducing proinflammatory cytokines and matrix metalloproteinases.

Tumor necrosis factor (TNF) receptor superfamily 14 (TNFRSF14) is the cellular receptor for TNF superfamily 14 (LIGHT). Immunohistochemical staining of human carotid atherosclerotic plaques revealed a high level of expression of the TNFRSF14 in regions rich in macrophages/foam cells. To investigate the role of TNFRSF14 in the functioning of monocytes in relation to atherogenesis, we have analyzed TNFRSF14 expression levels and cellular events after stimulation of TNFRSF14 in peripheral blood monocytes or the human macrophage-like cell line, THP-1. A high level of expression of TNFRSF14 was detected in activated monocytes, in macrophages derived from monocytes, and in THP-1 cells. Concomitant activation of THP-1 cells with interferon-gamma and immobilized anti-TNFRSF14 monoclonal antibody resulted in synergistic induction of proatherogenic cytokines, such as TNF-alpha and interleukin-8. Activation of THP-1 cells with immobilized anti-TNFRSF14 monoclonal antibody induced expression of matrix metalloproteinase (MMP)-1, MMP-9, MMP-13, and tissue inhibitors of metalloproteinase-1 and -2. Furthermore, immunohistochemical staining of atherosclerotic plaques with severe infiltration of foam cells revealed that the expression patterns of TNFRSF14 and MMP-1, -9, and -13 overlapped. Treatment of THP-1 cells with soluble LIGHT also caused induction of MMP-9 and interleukin-8. These data suggest that TNFRSF14 is involved in atherosclerosis via the induction of proatherogenic cytokines and decreasing plaque stability by inducing extracellular matrix-degrading enzymes.

Aged↗

PubMed2001

Tumor necrosis factor receptor superfamily 12 may destabilize atherosclerotic plaques by inducing matrix metalloproteinases.

Immunohistochemical staining of human atherosclerotic plaques revealed expression of the tumor necrosis factor receptor superfamily (TNFRSF) 12 in regions rich in macrophage/foam cells. The role of TNFRSF12 in the functioning of monocytes in relation to atherogenesis was investigated by analysis of cellular events after stimulation of TNFRSF12 in a human macrophage-like cell line, THP-1. Activation of the THP-1 cells on plates coated with monoclonal antibody against TNFRSF12 induced the expression of matrix metalloproteinases (MMPs) -1, -9, and -13. Furthermore, the expression patterns of TNFRSF12 and the MMPs overlapped in atherosclerotic plaques. Signaling of TNFRSF12 may thus contribute to the induction of extracellular matrix degrading enzymes in macrophages.

Arteriosclerosis↗

PubMed2001

Increased severity of HSV-1 keratitis and mortality in mice lacking the 2-5A-dependent RNase L gene.

PURPOSE: The2',5'-oligoadenylate-dependent RNase L gene functions in the interferon-inducible RNA decay pathway known as the 2-5A system. The purpose of this study was to determine whether the absence of this gene affects the pathogenesis of herpes simplex virus type 1 (HSV-1) ocular infection in the mouse. METHODS: HSV-1 (strain McKrae) was applied bilaterally to unscarified corneas of RNase L-null mice and congenic controls. To evaluate the severity of herpetic keratitis, slit lamp examinations (SLE) were performed every other day for 14 days. To study corneal histology and apoptosis, HSV-1-inoculated RNase-L-null and congenic control mice, as well as mock-inoculated mice (apoptosis negative control), were killed at 6 and 18 hours postinoculation (PI). Uninoculated mice that underwent corneal scarification (apoptosis positive control) were killed 2 hours after scarification. Eyes were dissected and the corneas processed for light and transmission electron microscopy and the TUNEL assay. RESULTS: In comparison with the congenic control mice, RNase L-null mice showed significantly more severe herpetic keratitis (PI day 8, SLE score, mean +/- SEM: 3.27 +/- 0.10 vs. 2.34 +/- 0.06; P: < 0.001) and significantly higher mortality (PI day 14, 70% vs. 20%; P: < 0.001). Few apoptotic cells were seen in HSV-1-infected RNase L-null mice, although DNA fragmentation consistent with apoptosis was detected in the corneas of congenic control mice 6 and 18 hours after HSV-1 inoculation and in uninfected mice with scarified corneas. Signs of apoptosis were not present in the mock-infected corneas. Electron microscopic evidence of keratocytic apoptosis was detected only in the uninfected scarified corneas and the HSV-1-infected congenic control corneas. CONCLUSIONS: The increased severity of ocular disease and increased mortality in the RNase L-null mice provides evidence, for the first time, that the 2-5A system contributes to protection during ocular herpetic infection. The reduced frequency of apoptosis in these mice suggests that one possible mechanism for this protective effect could be the induction of apoptosis in corneal cells as a means of reducing the spread of infectious virus.

Animals↗

PubMed2000

4-1BB: still in the midst of darkness.

4-1BB is a member of the tumor necrosis factor receptor superfamily. The receptor functions mainly as a costimulatory molecule in T lymphocytes. In addition, several lines of evidence have shown that interactions between 4-1BB and its ligand are involved in the antigen presentation process and the generation of cytotoxic T cells. Recent studies, however, have demonstrated that 4-1BB plays more diverse roles: Signals through 4-1BB are important for long-term survival of CD8+ T cells and the induction of helper T cell anergy. Clinically, there is great interest in 4-1BB, because T-cell activation induced by anti-4-1BB monoclonal antibodies is highly efficient in the eradication of established tumor cells in mice. Now, since mice deficient in 4-1BB or the 4-1BB ligand are available, subtle roles played by 4-1BB may be revealed in the near future.

4-1BB Ligand↗

PubMed2000

Co-stimulation of antigen-specific CD4 T cells by 4-1BB ligand.

4-1BB is a member of the TNF receptor family predominantly expressed on activated T cells, and binds an inducible ligand found on B cells, macrophages and dendritic cells. Whereas ligation of 4-1BB has been shown to enhance response of purified CD8 T cells to mitogens, and to augment NK activity and generation of cytotoxic T lymphocytes in vivo, there are little direct data on 4-1BB action during CD4 responses. Using pigeon cytochrome c-presenting fibroblast antigen-presenting cells transfected with 4-1BB ligand (4-1BBL), we show that engaging 4-1BB on naive CD4 cells promotes proliferation, cell cycle progression and IL-2 secretion, and suppresses cell death, all to a similar extent as B7-1 engagement of CD28. In addition, 4-1BBL synergizes with B7 and ICAM to enhance naive CD4 proliferation when antigen is limiting. 4-1BBL alone, and to a greater extent with B7, also augmented IL-2 secretion resting antigen-experienced CD4 cells, as typified by T helper clones, whereas short-term effector cells showed similar levels of proliferation and cytokine secretion regardless of whether 4-1BB was engaged. A major role in augmenting IFN-gamma, IL-4 or IL-5 was not demonstrated. Blocking studies with activated B cells presenting antigen showed that 4-1BB participates in promoting IL-2 production by resting CD4 cells, confirming that 4-1BBL can play a role in antigen-specific CD4 T cell responses.

4-1BB Ligand↗

PubMed1999

A newly identified member of tumor necrosis factor receptor superfamily (TR6) suppresses LIGHT-mediated apoptosis.

TR6 (decoy receptor 3 (DcR3)) is a new member of the tumor necrosis factor receptor (TNFR) family. TR6 mRNA is expressed in lung tissues and colon adenocarcinoma, SW480. In addition, the expression of TR6 mRNA was shown in the endothelial cell line and induced by phorbol 12-myristate 13-acetate/ionomycin in Jurkat T leukemia cells. The open reading frame of TR6 encodes 300 amino acids with a 29-residue signal sequence but no transmembrane region. Using histidine-tagged recombinant TR6, we screened soluble forms of TNF-ligand proteins with immunoprecipitation. Here, we demonstrate that TR6 specifically binds two cellular ligands, LIGHT (herpes virus entry mediator (HVEM)-L) and Fas ligand (FasL/CD95L). These bindings were confirmed with HEK 293 EBNA cells transfected with LIGHT cDNA by flow cytometry. TR6 inhibited LIGHT-induced cytotoxicity in HT29 cells. It has been shown that LIGHT triggers apoptosis of various tumor cells including HT29 cells that express both lymphotoxin beta receptor (LTbetaR) and HVEM/TR2 receptors. Our data suggest that TR6 inhibits the interactions of LIGHT with HVEM/TR2 and LTbetaR, thereby suppressing LIGHT- mediated HT29 cell death. Thus, TR6 may play a regulatory role for suppressing in FasL- and LIGHT-mediated cell death.

Amino Acid Sequence↗

PubMed1999

Differential effects of leukotactin-1 and macrophage inflammatory protein-1 alpha on neutrophils mediated by CCR1.

The human CC chemokine leukotactin-1 (Lkn-1) is both a strong chemoattractant for neutrophils, monocytes, and lymphocytes and a potent agonist for CCR1 and CCR3. However, human neutrophils do not migrate when the cells are stimulated with other human CC chemokines, such as human macrophage inflammatory protein-1 alpha (hMIP-1 alpha) and eotaxin, which also use the CCR1 and CCR3 as their receptors. In this report, we demonstrate that while hMIP-1 alpha induced a negligible level of calcium flux and chemotaxis, Lkn-1 produced a high level of calcium flux and chemotaxis in human neutrophils. Lkn-1 cross-desensitized hMIP-1 alpha-induced calcium flux, but hMIP-1 alpha had little effect on the Lkn-1-induced response in human neutrophils. The same pattern was observed in peritoneal neutrophils from wild-type mice, whereas neutrophils from CCR1-/- mice failed to respond to either MIP-1 alpha or Lkn-1. Scatchard analysis revealed a single class of receptor for both hMIP-1 alpha and Lkn-1 on human neutrophils with dissociation constants (Kd) of 3.2 nM and 1.1 nM, respectively. We conclude that CCR1 is a receptor mediating responses to both MIP-1 alpha and Lkn-1 on neutrophils and produces different biological responses depending on the ligand bound.

Adjuvants, Immunologic↗

PubMed1999

Identification of a novel activation-inducible protein of the tumor necrosis factor receptor superfamily and its ligand.

Among members of the tumor necrosis factor receptor (TNFR) superfamily, 4-1BB, CD27, and glucocorticoid-induced tumor necrosis factor receptor family-related gene (GITR) share a striking homology in the cytoplasmic domain. Here we report the identification of a new member, activation-inducible TNFR family member (AITR), which belongs to this subfamily, and its ligand. The receptor is expressed in lymph node and peripheral blood leukocytes, and its expression is up-regulated in human peripheral mononuclear cells mainly after stimulation with anti-CD3/CD28 monoclonal antibodies or phorbol 12-myristate 13-acetate/ionomycin. AITR associates with TRAF1 (TNF receptor-associated factor 1), TRAF2, and TRAF3, and induces nuclear factor (NF)-kappaB activation via TRAF2. The ligand for AITR (AITRL) was found to be an undescribed member of the TNF family, which is expressed in endothelial cells. Thus, AITR and AITRL seem to be important for interactions between activated T lymphocytes and endothelial cells.

Amino Acid Sequence↗