K Kato

Juntendo University, Tokyo, Tokyo-to, Japan

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Publications (84)202.13 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Immunosuppressive potentials of the blockade of intercellular adhesion molecule-1 (ICAM)-1/leukocyte function-associated antigen 1 (LFA-1) were examined in a murine islet allotransplantation model by using blocking monoclonal antibodies (MAbs) against these molecules. Isolated islets from ICR mice were transplanted into the renal subcapsular space of streptozotocin-induced diabetic C57BL/6 mice. Antibodies were administered immediately after transplantation at a dose of 100 micrograms/mouse/d for 3 or 7 d. In non-treated mice, islet grafts were rejected within 16 d, but the treatment with an anti-ICAM-1 MAb (KAT-1) alone, with anti-LFA-1 MAb (KBA) alone, or with both MAbs significantly prolonged the graft survival. In particular, the combination of KAT-1 and KBA in a 7-d course produced a marked prolongation and induced indefinite graft survivals over 100 d in 88% of recipients. Expression of cytokine transcripts within the islet allografts was analyzed by reverse transcriptase polymerase chain reaction (RT-PCR). In the mice treated with KAT-1 and KBA, the transcripts for Th1 cytokines (interleukin 2 [IL-2] and interferon gamma [IFN-gamma]) were not detected, but the expression of Th2 cytokines (IL-4 and IL-10) was enhanced and persisted over 140 d. In contrast, Th1 cytokines were dominantly expressed in the grafts from untreated mice. These results indicate that administration of anti-ICAM-1 and/or anti-LFA-1 MAbs prolongs murine islet allograft survival potentially by indicating a Th2 deviation.
    International journal of pancreatology: official journal of the International Association of Pancreatology 09/1999; 26(1):23-31.
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    ABSTRACT: To explore effective therapeutic strategy against cancer of the gastrointestinal tract, tumor vaccination using fibroblasts secreting interleukin-12 (IL-12) was developed as an adjuvant therapy against murine tumor after surgical resection. Initially, IL-12 was genetically engineered into fibroblasts (IL-12/3T3 cells), and then we evaluated in vivo and in vitro antitumor effects. In the vaccination model, irradiated C-26 tumor mass was reinoculated intradermally with IL-12/3T3 cells in mice as a tumor vaccine to examine how much it suppresses tumor recurrence. IL-12/3T3 cells producing 7.2 ng/10(6) cells/24 h murine IL-12 in vitro exerted dose-dependent potent tumor suppression when coinoculated with C-26 cells in vivo. Specific immunity was also acquired in 63% of mice in vivo. In the vaccination model, protective immunity was developed in 70% of mice that were inoculated with irradiated tumor mass and IL-12/3T3 cells. In addition, local recurrence was not observed in vaccinated mice, although 44% of control mice had recurrence. Coinoculation of genetically engineered fibroblasts secreting IL-12 with irradiated tumor mass was proved to be an effective tumor vaccine. This system of vaccination is easily applicable to clinical situations, particularly to human gastrointestinal tract cancers.
    Surgery 04/1999; 125(3):257-64. · 3.37 Impact Factor
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    ABSTRACT: An angiolipoma is a common benign neoplasm with a characteristic vascular component that occurs in the subcutaneous tissue and rarely in the gastrointestinal tract. We report on a 69-year-old man with a submucosal angiolipoma in the cecum. This patient was treated with a laparoscopy-assisted ileocecostomy, and a side-to-side anastomosis was performed extracorporeally. A light microscopic study supported the diagnosis of an angiolipoma of the colon. After 5 years of follow-up, the patient has no symptoms or signs of recurrence. The colonic angiolipoma was successfully removed using a minimally invasive laparoscopic technique.
    Digestive Surgery 02/1999; 16(5):441-4. · 1.47 Impact Factor
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    ABSTRACT: Hepatocyte transplantation is a potential therapeutic modality for overcoming the shortage of liver donors, and the clinical application of allogeneic hepatocyte transplantation has been considered. However, there are two major problems with allogeneic hepatocyte transplantation: protection of transplanted hepatocytes from rejection and stimulation of the rapid proliferation of surviving cells. Without immunosuppression, allogeneic hepatocytes are rapidly rejected within a few days after transplantation, even though it is relatively easy to induce immunotolerance after allogeneic whole liver transplantation. Accordingly, different rejection mechanisms seem to operate after allogeneic hepatocyte transplantation and whole liver transplantation. To overcome the rejection of transplanted hepatocytes, induction of donor-specific unresponsiveness to graft without compromising the host immune system would be ideal. We previously reported that the Fas-Fas ligand system plays a critical role in the CD28-independent pathway of hepatocyte rejection. Therefore, blockade of rejection using CTLA4 immunoglobulin (CTLA4Ig) or anti-CD80/86 monoclonal antibodies and anti-FasL monoclonal antibody may prolong the survival of transplanted allogeneic hepatocytes. Furthermore, administration of hepatocyte growth factor (HGF) can promote the proliferation of allogeneic hepatocytes and this may lead to the development of a functioning liver substitute.
    Journal of Gastroenterology and Hepatology 10/1998; 13 Suppl:S119-23. · 3.33 Impact Factor
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    ABSTRACT: Tenascin (TN) is an extracellular matrix protein which interferes with fibronectin (FN)-dependent cell attachment and activation as a natural antagonist to FN action. In this study, we examined the inhibitory effect of TN on T cell proliferation induced by immobilized anti-CD3 Ab combined with various costimulators in a serum-free condition. Consistent with previous studies, human T cell activation induced by anti-CD3 plus FN was completely inhibited by the addition of TN. Interestingly, TN could interfere with T cell proliferations costimulated by various very late activation antigen (VLA) integrin/ligand interactions such as VLA-4/FN, VLA-5/FN and VLA-6/laminin. Furthermore, lymphocyte function-associated antigen 1 (LFA-1)-, CD2- and CD28-costimulated T cell activation were also inhibited by TN, while TN could not affect the phorbol ester-stimulated T cell proliferation. Collectively, TN inhibits anti-CD3-induced T cell proliferation irrespectively of costimulatory molecules, suggesting that TN acts as a generally immunosuppressive extracellular matrix protein which potentially interferes with T cell receptor/CD3-mediated T cell activation.
    Biochemical and Biophysical Research Communications 10/1998; 250(1):119-24. · 2.41 Impact Factor
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    ABSTRACT: The expression and enzymatic activity of the cytochrome P450 LAomega within intrasplenically transplanted hepatocytes was investigated. Fetal hepatocytes were harvested from spontaneously hypertensive rats and transplanted into recipient adult spontaneously hypertensive rat spleens. Microscopic examination revealed masses of hepatocytes in the red pulp. Immunochemical studies detected cytochrome P450 LAomega in transplanted hepatocytes by 6 and 10 weeks after transplantation. Cytochrome P450 LAomega mRNA accumulates at 6 weeks after transplantation. Cytochrome P450-arachidonic acid omega/omega-1 hydroxylase activity (formation of 20/19-hydroxyeicosatetraenoic acid) was detected at 10 weeks after transplantation. These results demonstrated that fetal hepatocytes grow in the spleen and function similarly to adult hepatocytes.
    Transplantation 09/1998; 66(4):441-5. · 3.78 Impact Factor
  • Transplantation Proceedings 03/1998; 30(1):13-5. · 0.95 Impact Factor
  • Transplantation Proceedings 03/1998; 30(1):16-8. · 0.95 Impact Factor
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    ABSTRACT: The mechanisms behind tolerance induction by portal venous (pv) injection of allogeneic cells are investigated. When a hematopoietic stem cell (HSC)-enriched population of BALB/c bone marrow was pv injected into C57BL/6 mice, the response of the T cells in the B6 mice to BALB/c alloantigens in mixed lymphocyte reaction (MLR) decreased until day 4 after the injection. Neither clonal deletion of V beta 11+ T cell nor donor-specific suppressor activity was observed. When recipient T cells were separated into CD4+ and CD8+ cells, only the CD8+ cell population showed donor-specific tolerance. The donor cells were trapped and retained in the host liver. MHC class I antigens were highly expressed on the trapped cells whereas class II antigens or B7 costimulatory molecules were not. The tolerance to BALB/c alloantigens in MLR was obtained also by the pv injection of Meth A, a BALB/c-derived sarcoma cell line. However, tolerance was not induced by the pv injection of B7-transfected Meth A cells. In addition to MLR, tolerance was also observed in DTH responses, and this was also due to the unresponsiveness of CD8+ cells to the donor alloantigens. However, the BALB/c-specific DTH responses were not suppressed after the pv injection of B7-transfected Meth A cells. These results strongly suggest that the tolerance induced by pv injection of allogeneic cells is due to clonal anergy generated by the absence of costimulatory signals in the interaction between donor-specific CD8+ T cells and donor hematopoietic cells trapped in the host liver.
    Immunobiology 12/1997; 197(5):460-77. · 2.81 Impact Factor
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    ABSTRACT: Cytolytic induction of T cells requires both the T-cell receptor (TCR)-mediated antigenic stimulation and the CD28-mediated co-stimulatory signal. Blockade of the interactions between CD28 and its ligands, CD80 and CD86, prolongs the survival of allografts in some transplantation models. However, we found that allogeneic hepatocytes were completely rejected within 7 days after intrasplenic transplantation, even when treated with monoclonal antibodies (mAbs) against CD80 and CD86 (anti-CD80/86). Recent studies have shown that there are two main mechanisms of T-cell-mediated cytotoxicity, perforin-based and Fas-based ones. It has been shown that the liver is highly sensitive to induction of apoptosis by an agonistic anti-Fas mAb. We then investigated the role of the Fas/Fas ligand (FasL) system in the CD28-independent allogeneic hepatocyte rejection. With the anti-CD80/86 mAb treatment, hepatocytes from C57BL/6 lpr/lpr (B6 lpr) mice, which express little Fas antigen, could survive for 7 days after intrasplenic transplantation, and hepatocytes from C57BL/6 (B6) mice could also survive for 7 days in the spleen of C3H/ He gld/gld (C3H gld) mice, which express no functional FasL. CD28-independent induction of cytotoxicity against allogeneic hepatocytes was not observed when the effector cells were derived from C3H gld mice. These results indicated that the Fas/FasL system plays a critical role in the CD28-independent pathway of allogeneic hepatocyte rejection.
    Hepatology 11/1997; 26(4):944-8. · 12.00 Impact Factor
  • Transplantation Proceedings 07/1997; 29(4):2029-31. · 0.95 Impact Factor
  • Transplantation Proceedings 07/1997; 29(4):2187-8. · 0.95 Impact Factor
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    ABSTRACT: We report the advantage of employing transanal endoscopic microsurgery (TEM) using the contact Nd:YAG laser for the treatment of a rectal anastomotic stenosis. A 72-year-old woman was admitted to our hospital with a postoperative rectal anastomotic stenosis. Twenty months prior to admission, the patient underwent a low anterior resection for the treatment of the rectal cancer using an EEA stapling device. A barium enema and colonoscopy revealed a rectal stenosis, 0.8-cm diameter. This stenosis was at the anastomotic site, approximately 4.0 from the dental line. An endoscopic treatment was performed transanally using the contact Nd:YAG laser. The stenotic rectal wall was fulgurated or vaporized completely. There were no intraoperative or postoperative complications. We concluded that TEM appears to be a safe and minimally invasive procedure. Furthermore, the contact Nd:YAG laser is very effective in treating the gastrointestinal stenotic area. To our knowledge, this is the first successful report of this novel procedure.
    Surgical Endoscopy 06/1997; 11(5):485-7. · 3.43 Impact Factor
  • K Kato, K Okumura, H Yagita
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    ABSTRACT: Our recent studies using various costimulatory molecules have demonstrated that antitumor effect could be induced by B7- or B70-transduced mouse tumors. To augment antitumor effect in vivo, the combination therapy with a costimulatory gene and a cytokine, interkeukin 12 (IL-12), gene to treat metastatic mouse lung tumor was investigated. We transfected with mouse B7 and/or IL-12 into mouse lung carcinoma 3LL, and three transfectants (IL-12/3LL, B7/3LL and IL-12/B7/3LL) were generated. CTL activity induced by the inoculation of IL-12/B7/3LL was increased about 10-fold compared with parental 3LL inoculation. We then examined the therapeutic efficacy of combination with B7 and IL-12-transduced tumors. Four weeks after 3LL inoculation, lung metastasis was significantly reduced by IL-12/B7/3LL post-inoculation, indicating that potent therapeutic antitumor immunity can be induced by combination with costimulators B7 and IL-12. Recently, it was reported that p40 subunit of IL-12 appeared to be a specific inhibitor for IL-12 heterodimer in vitro. To clarify the biological functions of p40 in vivo, we generated the myoblast transfectants which produced IL-12 p40 alone. Local production of IL-12 p40 from transfectant could suppress allogenic CTL induction and Th1-type antibodies (IgG2a/2b/3) production in vivo. Furthermore, IL-12 p40 producing myoblast are less susceptible to rejection compared with parental myoblast, indicating that IL-12 p40 gene transfer may be useful therapeutically in Th1-mediated transplantation and autoimmune disorders.
    Leukemia 05/1997; 11 Suppl 3:572-6. · 10.16 Impact Factor
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    ABSTRACT: Experimental autoimmune uveoretinitis (EAU) induced by immunization with interphotoreceptor retinoid-binding protein (IRBP), a retinal self antigen, has been regarded to be a typical T helper type 1 (Th1)-mediated inflammatory disease. In this study, we examined the effect of a neutralizing monoclonal antibody (mAb) to interleukin-12 (IL-12), which has been known to play a critical role in the Th1 differentiation, on the development of EAU. While 9 of 13 control mice developed EAU by the immunization with IRBP, none of 12 mice developed EAU when given anti-IL-12 mAb 1 day before immunization. These mice did not develop EAU even after a rechallenge with IRBP on day 30, indicating that a protective mechanism had been established by the anti-IL-12 treatment. The proliferative response of splenocytes to IRBP in vitro was not significantly impaired, but the production of IL-2 and IFN-gamma was greatly reduced by the anti-IL-12 treatment. Moreover, production of IL-5 and expression of IL-4 mRNA were increased by the anti-IL-12 treatment. Consistently, IgG2a anti-IRBP serum antibodies were decreased and IgG1 were increased. Administration of a neutralizing anti-IL-4 mAb at the time of IRBP rechallenge reversed the protection established by the anti-IL-12 treatment at the primary immunization. These results indicate that the anti-IL-12 treatment at the IRBP priming not only prevented the development of pathogenic Th1 cells, but also induced suppressive Th2 cells that protect the animals from further challenge with the same antigen.
    European Journal of Immunology 04/1997; 27(3):641-6. · 4.97 Impact Factor
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    ABSTRACT: Laparoscopic cholecystectomy (LC) has become the standard treatment for removing a diseased gallbladder. Endoscopic surgical techniques are used to perform appendectomies, bowel resections, and gastrectomies. This minimally invasive surgery is favored because it decreases the patients' postoperative pain and length of hospitalization. However the incidence of complications with this technique is not negligible. As a new technique is evolving, the potential for complications is high. This increase in complication rate is undoubtedly due to inexperience during the initial phase of the surgeon's learning curve. Demand for the procedure has required rapid training and credentialing of many surgeons with limited experience in endoscopy and the use of instruments that allow only limited viewing of abdominal structures.
    Surgical technology international 02/1997; 6:127-31.
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    ABSTRACT: We examined the expression and enzymatic activity of cytochrome P450 LA omega within transplanted hepatocytes. Fetal hepatocytes were harvested at day 20 of gestation from spontaneously hypertensive rats (SHRs) and transplanted into recipient adult SHR spleens. Microscopic examination of the recipient spleens at 4 and 10 wk after transplantation revealed masses of hepatocytes with cord-like structures in the red pulp. Immunochemical studies detected cytochrome (cyto) P450 LA omega in the fetal hepatocytes before transplantation without prior induction. Although the cyto P450 LA omega was not detected by the second week after transplantation, by the 6th and 10th wk after transplantation, it was. Cyto P450-arachidonic acid omega/omega-1 hydroxylase activity (formation of 20- and 19-hydroxyeicosatetraenoic acid) was detected at 10 wk after transplantation, but not 2 or 6 wk after transplantation. These results demonstrated that fetal hepatocytes can be transplanted successfully into recipient spleens and then grow in the spleens, as in the case of the adult hepatocyte response.
    Cell Transplantation 01/1997; 6(5):531-4. · 4.42 Impact Factor
  • Nippon Shokakibyo Gakkai zasshi The Japanese journal of gastro-enterology 09/1996; 93(8):565-8.
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    ABSTRACT: The p40 subunit of interleukin 12 (IL-12p40) has been known to act as an IL-12 antagonist in vitro. We here describe the immunosuppressive effect of IL-12p40 in vivo. A murine myoblast cell line, C2C12, was transduced with retro-virus vectors carrying the lacZ gene as a marker and the IL-12p40 gene. IL-12p40 secreted from the transfectant inhibited the IL-12-induced interferon gamma (IFN-gamma) production by splenocytes in vitro. Survival of C2C12 transplanted into allogeneic recipients was substantially prolonged when transduced with IL-12p40. Cytokine (IL-2 and IFN-gamma) production and cytotoxic T lymphocyte induction against allogeneic C2C12 were impaired in the recipients transplanted with the IL-12p40 transfectant. Delayed-type hypersensitivity response against C2C12 was also diminished in the IL-12p40 recipients. Furthermore, serum antibodies against beta-galactosidase of the T-helper 1-dependent isotypes (IgG2 and IgG3) were decreased in the IL-12p40 recipients. These results indicate that locally produced IL-12p40 exerts a potent immunosuppressive effect on T-helper 1-mediated immune responses that lead to allograft rejection. Therefore, IL-12p40 gene transduction would be useful for preventing the rejection of allografts and genetically modified own cells that are transduced with potentially antigenic molecules in gene therapy.
    Proceedings of the National Academy of Sciences 09/1996; 93(17):9085-9. · 9.81 Impact Factor
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    ABSTRACT: We report on a patient with colon cancer and a very high serum alpha-fetoprotein level. This 75-yr-old man presented with right lower quadrant abdominal pain. An abdominal CT scan as well as ultrasonography showed a tumor in the cecum. Serum alpha-fetoprotein level was extremely high (3,070 ng/ml). At laparotomy, a large mass was found in the cecum, and a right hemicolectomy was performed. Histological examination, including immunohistochemical study, showed an adenocarcinoma of the colon producing alpha-fetoprotein.
    The American Journal of Gastroenterology 06/1996; 91(5):1045-6. · 7.55 Impact Factor

Publication Stats

783 Citations
202.13 Total Impact Points

Institutions

  • 1991–1999
    • Juntendo University
      • • Department of Immunology
      • • Second Department of Surgery
      • • Division of Respiratory Medicine
      Tokyo, Tokyo-to, Japan
  • 1998
    • Nippon Medical School
      • Fourth Department of Internal Medicine
      Tokyo, Tokyo-to, Japan
  • 1993–1998
    • New York Medical College
      • Department of Medicine
      New York City, New York, United States
  • 1989–1991
    • Tohoku University
      • Graduate School of Pharmaceutical Sciences
      Sendai-shi, Miyagi-ken, Japan
  • 1970–1971
    • Nagoya University
      • Division of of Internal Medicine
      Nagoya, Aichi, Japan