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Biomedical subjects

M Kurimoto

Publications and source records attributed to M Kurimoto.

At least 145 records · Page 8Linked to original sources
PubMed1998

A critical role for IL-18 in the proliferation and activation of NK1.1+ CD3- cells.

Like IL-12, IFN-gamma-inducing factor/IL-18 has been shown to stimulate T cells for IFN-gamma production and growth promotion. Considering the NK-stimulatory capacity of IL-12, we investigated the effect of IL-18 on NK lineage cells. A CD4- CD8- surface Ig- Ia- fraction of freshly prepared C57BL/6 spleen cells proliferated strikingly in response to combinations of IL-12 + IL-18 or IL-2 + IL-18, but not to the individual cytokines or IL-2 + IL-12. Cells proliferating in response to IL-2 + IL-18 were NK1.1+ CD3-, whereas IL-12 + IL-18-responsive cells were NK1.1- CD3-. Restimulation of the former cells with IL-12 + IL-18 or the latter cells with IL-2 + IL-18 resulted in the generation of NK1.1- CD3- or NK1.1+ CD3- cells, respectively. Moreover, a NK1.1+ CD3- CD4- CD8- surface Ig- Ia- population isolated from spleen cells was found to form NK1.1+ CD3- or NK1.1- CD3- blasts by stimulation with IL-2 + IL-18 or IL-12 + IL-18, respectively, and the NK1.1 positivity on these blasts was again reversed after restimulation with an alternative combined stimulus. Both types of blasts produced enormously large amounts of IFN-gamma in response to IL-12 + IL-18 and exhibited strikingly high levels of NK activity. These results indicate that IL-18 plays an obligatory role in inducing proliferation and activation of NK1.1+ CD3- CD4- CD8- cells and that the expression of the NK1.1 marker is reversible, depending on the cytokine used for stimulation in combination with IL-18.

Animals↗
PubMed1998

Identification and characterization of a novel SH3-domain binding protein, Sab, which preferentially associates with Bruton's tyrosine kinase (BtK).

Protein interaction cloning method was used to identify a novel molecule, Sab, which binds to the SH3 domain of Bruton's tyrosine kinase (Btk), the deficient cytoplasmic tyrosine kinase in human X-linked agammaglobulinemia and murine X-linked immunodeficiency. Immunoprecipitation using the anti-Sab antibody identified the protein product of the gene as a 70 kDa molecule. While Sab does not have a proline-rich sequence, it was shown to bind to Btk through the commonly conserved structure among SH3 domains. Remarkably, Sab exhibited a high preference for binding to Btk rather than to other cytoplasmic tyrosine kinases, which suggests a unique role of Sab in the Btk signal transduction pathway.

Adaptor Proteins, Signal Transducing↗
PubMed1998

Generation of a monoclonal antibody that inhibits the procoagulant activity of various cancer cell lines.

BACKGROUND: Tumor procoagulant is one of the factors responsible for disseminated intravascular coagulation and metastasis. The authors found procoagulant activity in LK52 human squamous cell carcinoma cells, which they designated cancer cell-derived blood coagulating activity 1 (CCA-1). A monoclonal antibody (MoAb) was generated to characterize this CCA-1 procoagulant activity. To date, antibodies that show an inhibitory effect on procoagulant activity as well as high reactivity in cancer cells are well known for their tissue factor specificity. METHODS: Characterization of the procoagulant activity of CCA-1 was performed and an anti-CCA-1 MoAb, FS01, was generated. CCA-1 expression on the cancer cell surface was examined by flow cytometry. Procoagulant activity of various cancer cell lines and the inhibitory effect of the FS01 MoAb on this procoagulant activity was monitored by a clot timer. RESULTS: The enzymologic character differed from that of cancer procoagulant (CP). The FS01 MoAb inhibited the procoagulant activity of CCA-1, but did not inhibit that of tissue factor. A positive correlation was observed between the expression intensity of CCA-1 and the inhibitory effect of the FS01 MoAb on the procoagulant activity of cancer cell lines. Expression of CCA-1 was observed more frequently than that of tissue factor in human cancer cell lines. CONCLUSIONS: The FS01 MoAb generated in the current study is a new antibody that reacts with various cancer cell lines, but not with normal cells. FS01 inhibits cancer cell-derived procoagulant activity and does not react with tissue factor and CP. CCA-1, which is recognized by the FS01 MoAb, appears to play a major role in cancer cell-derived procoagulant activity.

Adult↗
PubMed1998

Differential capacities of CD4+, CD8+, and CD4-CD8- T cell subsets to express IL-18 receptor and produce IFN-gamma in response to IL-18.

IL-12 and IL-18 have the capacity to stimulate IFN-gamma production by T cells. Using a T cell clone, we reported that IL-18 responsiveness is generated only after exposure to IL-12. Here, we investigated the induction of IL-18 responsiveness in resting CD8+, CD4+, and CD4-CD8- T cells. Resting T cells respond to neither IL-12 nor IL-18. After stimulation with anti-CD3 plus anti-CD28 mAbs, CD8+, CD4+, and CD4-CD8- T cells expressed IL-12R, but not IL-18R, and produced IFN-gamma in response to IL-12. Cultures of T cells with anti-CD3/anti-CD28 in the presence of rIL-12 induced IL-18R expression and IL-18-stimulated IFN-gamma production, which reached higher levels than that induced by IL-12 stimulation. However, there was a substantial difference in the expression of IL-18R and IL-18-stimulated IFN-gamma production among T cell subsets. CD4+ cells expressed marginal levels of IL-18R and produced small amounts of IFN-gamma, whereas CD8+ cells expressed higher levels of IL-18R and produced more IFN-gamma than CD4+ cells. Moreover, CD4-CD8- cells expressed levels of IL-18R comparable to those for CD8+ cells but produced IFN-gamma one order higher than did CD8+ cells. These results indicate that the induction of IL-18R and IL-18 responsiveness by IL-12 represents a mechanism underlying enhanced IFN-gamma production by resting T cells, but the operation of this mechanism differs depending on the T cell subset stimulated.

Animals↗
PubMed1998

Interleukin-18 activates the IRAK-TRAF6 pathway in mouse EL-4 cells.

The pleiotropic biological activities of interleukin-18 (IL-18) are mediated by IL-18 receptor (IL-18R). When the ligand binds to the IL-18R, IL-18R initiates a signaling cascade that results in the activation of nuclear factor kappa B (NF-kappa B). When mouse EL-4 cells were exposed to IL-18, IL-1 receptor-associated kinase (IRAK) was recruited to IL-18R and was phosphorylated. In addition, tumor necrosis factor receptor-associated factor-6 (TRAF6) was associated with IRAK. Therefore, we concluded that IL-18/IL-18R-mediated signaling may share the IRAK/TRAF6 pathway through NF-kappa B activation with the IL-1/IL-1 receptor system.

Animals↗
PubMed1998

IFN-gamma-inducing factor/IL-18 administration mediates IFN-gamma- and IL-12-independent antitumor effects.

We evaluated the mechanism of the antitumor effects of mouse rIFN-gamma-inducing factor/IL-18 protein on the growth of mouse tumor cell lines in vivo. Mice received IL-18 before or after challenge with CL8-1, a mouse melanoma cell line. Both regimens significantly suppressed tumor growth and reduced the number of mice with growth of tumor from 60% (3/5) to 20% (1/5). Furthermore, IL-18 administered before and after tumor inoculation completely abrogated the establishment of CL8-1 in all animals. IL-18 administration also significantly suppressed the growth of MCA205, a sarcoma cell line, even when treatment was delayed to 7 days following tumor inoculation. Although IL-18/IL-12 combination therapy had the most significant and immediate antitumor effects, many mice so treated succumbed with markedly elevated serum IFN-gamma levels. The antitumor effects of IL-18 were abrogated almost completely when NK cells were eliminated using anti-asialo GM1 Ab administration, but only marginally impaired in IFN-gamma or IL-12 gene-disrupted mice. Immunohistochemical staining revealed that the number of the CD8+ T cells, but not CD4+ T cells, found at the tumor site was reduced in animals treated with IL-18. These results indicate that IL-18 has potent antitumor effects mediated by CD4+ T cells and NK cells, but in IFN-gamma- and IL-12-independent pathways.

Adjuvants, Immunologic↗
PubMed1998

Interleukin 18 inhibits osteoclast formation via T cell production of granulocyte macrophage colony-stimulating factor.

IL-18 inhibits osteoclast (OCL) formation in vitro independent of IFN-gamma production, and this was abolished by the addition of neutralizing antibodies to GM-CSF. We now establish that IL-18 was unable to inhibit OCL formation in cocultures using GM-CSF-deficient mice (GM-CSF -/-). Reciprocal cocultures using either wild-type osteoblasts with GM-CSF -/- spleen cells or GM-CSF -/- osteoblasts with wild-type spleen cells were examined. Wild-type spleen cells were required to elicit a response to IL-18 indicating that cells of splenic origin were the IL-18 target. As T cells comprise a large proportion of the spleen cell population, the role of T cells in osteoclastogenesis was examined. Total T cells were removed and repleted in various combinations. Addition of wild-type T cells to a GM-CSF -/- coculture restored IL-18 inhibition of osteoclastogenesis. Major subsets of T cells, CD4+ and CD8+, were also individually depleted. Addition of either CD4+ or CD8+ wild-type T cells restored IL-18 action in a GM-CSF -/- background, while IL-18 was ineffective when either CD4+ or CD8+ GM-CSF -/- T cells were added to a wild-type coculture. These results highlight the involvement of T cells in IL-18-induced OCL inhibition and provide evidence for a new OCL inhibitory pathway whereby IL-18 inhibits OCL formation due to action upon T cells promoting the release of GM-CSF, which in turn acts upon OCL precursors.

Animals↗
PubMed1998

Deficient expression of Bruton's tyrosine kinase in monocytes from X-linked agammaglobulinemia as evaluated by a flow cytometric analysis and its clinical application to carrier detection.

The B-cell defect in X-linked agammaglobulinemia (XLA) is caused by mutations in the gene for Bruton's tyrosine kinase (BTK). Using the anti-BTK monoclonal antibody (48-2H), a flow cytometric analysis of intracytoplasmic BTK protein expressed in monocytes was successfully performed. To examine the possible identification of XLA patients and female carriers by this assay, we studied 41 unrelated XLA families with (35) or without (6) known BTK mutations. A flow cytometric assay showed deficient expression of the BTK protein in 40 of 41 patients, complete BTK deficiency in 35, and partial BTK deficiency in 5. One patient exhibited a normal level of BTK expression. All 6 patients with partial BTK deficiency or normal BTK expression had missense BTK mutations. The cellular mosaicism of BTK expression in monocytes from obligate carriers was clearly shown in 35 of 41 families. The results suggested that most BTK mutations in XLA might result in deficient expression of the BTK protein. We conclude that deficient expression of BTK protein can be evaluated by a flow cytometric assay, and the clinical usefulness and limitations in diagnosis of XLA patients and carriers are discussed.

Adolescent↗
PubMed1998

IL-18 (IFN-gamma-inducing factor) regulates early cytokine production in, and promotes resolution of, bacterial infection in mice.

IL-12-induced IFN-gamma production is essential for clearance of Yersinia enterocolitica infection. Similar to IL-12, the recently described cytokine IL-18 (IFN-gamma-inducing factor) is produced by macrophages and induces IFN-gamma production in spleen cells. Therefore, we have investigated the role of IL-18 in Yersinia infection of mice. Heat-killed yersinia-triggered IL-18-promoted IFN-gamma production of splenocytes was predominantly dependent on endogenous IL-12 production, whereas IL-12-promoted IFN-gamma production was not IL-18 dependent. IL-18-induced IFN-gamma production was to a higher degree dependent on IFN-gammaR-mediated mechanisms and in synergism with IL-2 resulted in at least fivefold higher IFN-gamma levels as compared with the combination of IL-12 plus IL-2. Analysis of the effect of IL-18 on IL-12 production of LPS-stimulated peritoneal macrophages revealed that IL-18 decreased LPS-induced IL-12 production, indicating that IL-18 might be involved in negative regulation of IL-12 production. In vivo studies revealed that Yersinia-resistant C57BL/6 mice expressed fourfold higher IL-18 mRNA levels than did susceptible BALB/c mice. Administration of anti-IL-18 Abs caused a 100- to 1000-fold increase in bacterial counts in the spleen of infected mice but did not change IFN-gamma production levels. Taken together, our data demonstrate that IL-18 is involved in regulation of cytokine production during the early phase of bacterial infections as well as in clearance of Yersinia infection.

Animals↗
PubMed1998

Production of functional IL-18 by different subtypes of murine and human dendritic cells (DC): DC-derived IL-18 enhances IL-12-dependent Th1 development.

IL-18 is a recently described cytokine that shares biological activities with IL-12 in driving the development of Th1-type T cells. As dendritic cells (DC) are very potent inducers of T cell proliferation and differentiation we wondered whether they utilize IL-18 as a factor driving Th1 development. We demonstrate by Northern blot and reverse transcription-PCR that various subtypes of human and murine DC as well as the DC-line XS contain IL-18 mRNA. When supernatants of either enriched Langerhans cells (LC) or bone marrow-derived DC were analyzed for production of IL-18 protein, IL-18 production was detected in an IL-18-specific ELISA. To assess whether the IL-18 protein released by DC is functional, we performed a sensitive bioassay using the IL-18-dependent stimulation of concanavalin A-stimulated T cells. Both, supernatants from bone marrow-derived DC and enriched LC induced IFN-gamma production in the T cells. This production was partially inhibitable by addition of anti-IL-18 antiserum. In a TCR-transgenic mouse system we further demonstrate that DC-derived IL-18 potentiates IL-12-dependent Th1 development. Using DC derived from IL-12 knockout animals, we show that DC-derived IL-18 by itself is not capable of inducing Th1 cell differentiation. Together the data demonstrate that subtypes of DC are able to release functional IL-18 that is able to induce IFN-gamma production and Th1 differentiation in primed T cells.

Animals↗
PubMed1998

Interleukin-18/interferon-gamma-inducing factor, a novel cytokine, up-regulates ICAM-1 (CD54) expression in KG-1 cells.

Intercellular adhesion molecule-1 (ICAM-1, CD54) is a membrane glycoprotein and a member of the immunoglobulin superfamily. It plays a central role in cell to cell-mediated immune responses and is a ligand for leukocyte function-associated antigen-1 (LFA-1). We report here that a newly discovered cytokine, interferon-gamma-inducing factor (IGIF) [H. Okamura et al. (1995) Nature 378, 88] recently proposed to be designated as IL-18, selectively up-regulates ICAM-1 expression in KG-1 cells, a human myelomonocytic cell line, in which IL-18 also enhances interferon-gamma production. IL-18 induced heterotypic aggregation between KG-1 and Peer T cells, which was blocked by anti-ICAM-1 and/or LFA-1 antibodies. Anti-interferon-gamma antibody did not block the IL-18-induced up-regulation of ICAM-1 on KG-1 cells. These results thus show that IGIF/IL-18, enhances ICAM-1 expression in KG-1 cells in an interferon-gamma-independent pathway, up-regulates ICAM-1 functions, and that IL-18 might play a potential role in immunoregulation by mediating immune cell infiltration into the tissues.

Cell Line↗
PubMed1998

Vasa vasorum of the intracranial arteries.

Most of the major extracranial arteries have vasa vasorum which play an important role in some pathological conditions. However, in the intracranial arteries, the existence of vasa vasorum and their pathological implication have not been adequately investigated. We examined the distribution and incidence of vasa vasorum in the major cerebral arteries and their relationships to certain clinical factors in 50 autopsy cases performed between 1987 and 1994. By light microscopy, vasa vasorum were found in 36 of 50 patients. Of 36 patients, vasa vasorum in 30 cases were localizedly observed in the tunica adventitia and the in other 6 were distributed in the tunica media accompanied by intramural haemorrhage. Existence of vasa vasorum was more common in the proximal arteries (vertebral, internal carotid, and basilar arteries) than in the distal arteries (middle cerebral and anterior cerebral arteries). Vasa vasorum were found more frequently in aged patients with severe atherosclerosis and those with cerebrovascular diseases. Our results indicated that intracranial vasa vasorum existed with a higher frequency in the tunica adventitia of the vertebral and internal cerebral arteries, and the incidence of vasa vasorum related to severity of atherosclerosis. The development of vasa vasorum in the tunica media may reflect some pathological changes of cerebral arteries.

Adolescent↗
PubMed1998

Establishment of a human fibroblast cell line producing tumor necrosis factor alpha (KMST-6/TNF) and growth inhibitory effects of its conditioned medium on malignant cells in culture.

To develop a new gene therapy model for cancer, a clonal cell line (KMST-6/TNF) which produces human tumor necrosis factor alpha (hTNF-alpha) has been developed by introducing hTNF-alpha cDNA into a human immortal fibroblast cell line (KMST-6). The conditioned medium (CM) of KMST-6/TNF cells inhibited the growth of various malignant human cell lines, but not that of normal human fibroblasts. Although the growth inhibitory effects of KMST-6/TNF CM were neutralized to a considerable degree by anti-TNF-alpha antibody, its inhibitory effects were more marked than the purified human natural TNF-alpha itself in the same units, suggesting that KMST-6/TNF CM contains some growth inhibitory substances other than TNF-alpha. However, interferons alpha, beta, and gamma were undetectable in the KMST-6/TNF CM.

Blotting, Northern↗
PubMed1998

Characterization of glial filament-cytoskeletal interactions in human astrocytomas: an immuno-ultrastructural analysis.

The role that glial filaments play in cells and tumors of glial origin is not well understood. We therefore undertook the present study to determine the relationships between glial and vimentin intermediate filaments (IFs), actin microfilaments, and CD44, a cell surface glycoprotein important in cell migration and invasion, in human astrocytoma cells. Three astrocytoma cell lines, U343 MG-A (U343), U251 MG (U251), and antisense GFAP-transfected U251 (asU251) were studied using immunofluorescence confocal and immunoelectron microscopy. Furthermore, we studied the phenotypic behaviour of these astrocytoma cell lines by analyzing their migration through Matrigel in vitro. U343 astrocytoma cells had the highest expression levels of glial fibrillary acidic protein (GFAP), whereas asU251 had virtually no expression of GFAP. Parental U251 cells had intermediate expression levels of GFAP. The elimination of GFAP expression in as U251 cells was accompanied by a marked increase in vimentin, actin microfilaments and CD44 levels. Gold labeling density counts of cytoskeletal and cell surface elements demonstrated that the differences between GFAP, actin, CD44 and vimentin levels in the different astrocytoma cell lines were statistically significant (p < 0.05). Results from the in vitro invasion assay revealed that U343 cells demonstrated the least invasive potential, whereas asU251 astrocytoma cells demonstrated the most. Our results show that elimination of GFAP expression by antisense leads to marked alterations in cell morphology and phenotypic behaviour. These data imply that GFAP may be linked spatially and functionally to cytoskeletal elements which may be altered when this IF is deleted in astrocytomas.

Astrocytoma↗
PubMed1998

IL-12 promotes the accessory cell function of epidermal Langerhans cells.

The objective of this study was to investigate the effects of cytokines regulating cutaneous immune responses, on the accessory cell function of epidermal cells (EC). EC were treated with various cytokines, and the accessory cell function of the cytokine-pretreated EC was examined by the allogeneic mixed epidermal cell-lymphocyte reaction (MECLR). Among the cytokines examined, IFN-gamma- and IL-12-pretreated EC augmented IFN-gamma production in the MECLR, while none of the other cytokines was effective. However, the cytokine-pretreated EC did neither affect T cell proliferation nor IL-4 production in the MECLR. Next we attempted to analyze the mechanisms by which IL-12-pretreated EC increase IFN-gamma production in the MECLR. Endogenous IFN-gamma produced during the IL-12 pretreatment of EC was found to play only a minor role in modulating the function of EC. The expression of MHC class II, CD80 and CD86 on EC was not affected by IL-12. On the other hand, soluble mediators that induce IFN-gamma production during the MECLR containing IL-12-pretreated EC were identified as endogenously produced IL-12 (the major mediator) and IL-18 (the minor mediator). Furthermore, the results of depletion experiments indicate that IL-12 promotes the accessory cell function of Langerhans cells to responder T cells in inducing IFN-gamma production in the MECLR.

Adjuvants, Immunologic↗