Biomedical subjects

Ken Matsui

Publications and source records attributed to Ken Matsui.

5 recordsLinked to original sources

PubMed2006

Screening for candidate genes involved in tolerance to organic solvents in yeast.

Saccharomyces cerevisiae mutant strain, KK-211, isolated from serial culture in medium containing isooctane showed an extremely higher tolerance to the hydrophobic organic-solvents, which are toxic to yeast cells compared to the wild-type parent strain, DY-1. To detect genes that are related to this tolerance, a DNA microarray analysis was performed using mRNAs isolated from strains DY-1 and KK-211. Fourteen genes were identified as being related to the tolerance. The expression of 12 genes including ICT1, YNL190W, and PRY3, was induced while the expression of two genes including PHO84 was repressed in strain KK-211. Two genes, ICT1 and YNL190W showed the same profile in the DNA microarray analysis and a differential display-polymerase chain reaction analysis. But, there is no detectable difference in the expression profile of KK-211 cells cultured with or without isooctane. The results suggest that change in expression levels of multiple genes that confer the modification function of the cell surface, not by a single gene, might be required for yeast cell tolerance to organic solvents.

Culture Media↗

PubMed2005

Costimulation through NKG2D enhances murine CD8+ CTL function: similarities and differences between NKG2D and CD28 costimulation.

Multiple studies have demonstrated that the NK cell activating receptor NKG2D can function as a costimulatory receptor for both mouse and human CD8+ T cells. However, it has recently been suggested that stimulation through NKG2D is insufficient for costimulation of CD8+ T cells. To aid in the delineation of NKG2D function in CTL responses, we investigated whether stimulation of NKG2D by the natural ligand RAE1epsilon was able to costimulate effector functions of a murine CTL line generated from DUC18 TCR transgenic mice. We found that NKG2D was able to costimulate DUC CTL responses and did so in a manner similar to CD28 costimulation. The T cells exhibited increased proliferation, IFN-gamma release, and cytotoxicity when presented antigenic peptide by P815 cells expressing RAE1epsilon or B7-1 compared with untransfected P815. In addition, both RAE1epsilon and B7-1 enhanced Ag-independent IFN-gamma secretion in response to IL-12 and IL-18 by DUC CTL. However, only costimulation through CD28 allowed for DUC CTL survival upon secondary stimulation, whereas ligation of NKG2D, but not CD28, induced DUC CTL to form an immune synapse with target cells in the absence of TCR stimulation. Understanding the outcomes of these differences may allow for a better understanding of T cell costimulation in general.

Animals↗

PubMed2004

CD4-directed peptide vaccination augments an antitumor response, but efficacy is limited by the number of CD8+ T cell precursors.

Peptide vaccination is an immunotherapeutic strategy being pursued as a method of enhancing Ag-specific antitumor responses. To date, most studies have focused on the use of MHC class I-restricted peptides, and have not shown a correlation between Ag-specific CD8(+) T cell expansion and the generation of protective immune responses. We investigated the effects of CD4-directed peptide vaccination on the ability of CD8(+) T cells to mount protective antitumor responses in the DUC18/CMS5 tumor model system. To accomplish this, we extended the amino acid sequence of the known MHC class I-restricted DUC18 rejection epitope from CMS5 to allow binding to MHC class II molecules. Immunization with this peptide (tumor-derived extracellular signal-regulated kinase-II (tERK-II)) induced Ag-specific CD4(+) T cell effector function, but did not directly prime CD8(+) T cells. Approximately 31% of BALB/c mice immunized with tERK-II were protected from subsequent tumor challenge in a CD40-dependent manner. Priming of endogenous CD8(+) T cells in immunized mice was detected only after CMS5 challenge. Heightened CD4(+) Th cell function in response to tERK II vaccination allowed a 12-fold reduction in the number of adoptively transferred CD8(+) DUC18 T cells needed to protect recipients against tumor challenge as compared with previous studies using unimmunized mice. Furthermore, tERK-II immunization led to a more rapid and transient expansion of transferred DUC18 T cells than was seen in unimmunized mice. These findings illustrate that CD4-directed peptide vaccination augments antitumor immunity, but that the number of tumor-specific precursor CD8(+) T cells will ultimately dictate the success of immunotherapy.

Adjuvants, Immunologic↗

PubMed2004

Quantitation and visualization of tumor-specific T cells in the secondary lymphoid organs during and after tumor elimination by PET.

Increased understanding in the area of trafficking behavior of adoptively transferred tumor-specific T cells could help develop better therapeutic protocols. We utilized the DUC18/CMS5 tumor model system in conjunction with a microPET scanner to study the DUC18 T cell distribution pattern in spleens and lymph nodes in live mice. Anti-Thy1.2 antibodies conjugated to 1,4,7,10-tetraazacyclododecane-N,N',N'',N''-tetraacetic acid (DOTA) and radiolabeled with (64)Cu were administered to three groups of BALB-Thy1.1 mice on days 4, 7, or 14 post-DUC18 T cell transfer. We were able to detect the transferred cells in all the major lymph nodes, spleens, and in tumors. Our findings suggest that tumor-specific T cells do not all preferentially localize to the tumors but they also home to all the major lymphoid organs; additionally the number of DUC18 T cells remains relatively constant during and after tumor elimination within each lymphoid organ.

Animals↗

PubMed2003

Successful elimination of large established tumors and avoidance of antigen-loss variants by aggressive adoptive T cell immunotherapy.

Utilization of ex vivo-expanded epitope-specific cytotoxic T lymphocytes has become a clinical standard in the adoptive immunotherapy of tumors. One of the obstacles faced by T cell-based immunotherapy is the development of tumor immune-escape variants. Using our previously reported CMS5 tumor/DUC18 CD8(+) TCR transgenic system, we sought to investigate whether large established tumors can be successfully eliminated before the development of escape variants. Using BALB/c mice that were s.c. transplanted with two tumors that had been growing for 8 days (double 8-day tumors), we assessed the in vivo anti-tumor activity of in vitro peptide-stimulated DUC18 T cells. A single infusion of activated DUC18 T cells showed a modest effect against the double 8-day tumors, whereas two and three administrations led to regression of both tumors within 10 days. However, in some mice, the tumors re-grew approximately 10 days after the regression. We found these tumors to be antigen-loss variants. These relapsed tumor cells progressively grew in DUC18 transgenic mice and did not express tERK-specific message. When four doses of activated DUC18 T cells were infused, the double 8-day tumors were successfully eliminated and the tumors did not grow out in any mice. Our results demonstrate that mono-specific CD8(+) T cells can effectively eliminate large established tumors before the development of antigen-loss variants when a high number of T cells is rapidly administered.

Animals↗