Publications by authors named "Kazutaka Kitaura"

Cross-reactivity of metal allergies can make metal allergy treatment complicated because the background of immune response in cross-reactions remains unknown. In clinical settings, cross-reactivity among several metals has been suspected. However, the precise mechanism of immune response in cross-reactivity is unclear.

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Palladium (Pd) is a component of several alloy types that are widely used in our environment, including several dental alloy types that cause adverse reactions such as hypersensitivity in the oral mucosa. However, the pathological mechanism of intraoral Pd allergies remains unclear because its animal model in the oral mucosa has not been established. In this study, we established a novel murine model of Pd-induced allergies in the oral mucosa, and explored the immune response of cytokine profiles and T cell diversity in terms of the T cell receptor.

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  • - The study developed a new mouse model to explore chromium (Cr) allergies specifically in the oral mucosa, which had not been studied before due to the lack of suitable animal models
  • - Two sensitizations using Cr and a lipopolysaccharide were performed on the skin, followed by a one-time exposure to Cr in the mouth, revealing a significant immune response with T-cells infiltrating the area post-exposure
  • - Analysis showed an increase in Cr-specific T-cells and natural killer (NKT) cell activation in response to Cr exposure, suggesting they play a crucial role in the allergic reactions occurring in the mouth
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  • Rapid immune recovery is essential for successful allogeneic hematopoietic stem cell transplantation without graft-versus-host disease (GVHD).
  • The study demonstrated that the MEK inhibitor trametinib reduced GVHD symptoms and supported the growth of a varied T-cell population in a humanized mouse model.
  • In contrast to tacrolimus, which also lessened GVHD but led to a less diverse T-cell repertoire, trametinib promotes both GVHD suppression and diverse T-cell recovery, suggesting it may be a promising therapeutic strategy for human GVHD.
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Cytomegalovirus (CMV) infection is a major complication during allogeneic stem cell transplantation (allo-SCT). However, mechanisms of adaptive immunity that drive this remain unclear. To define early immunological responses to CMV after transplantation, we using next-generation sequencing to examine the repertoire of T-cell receptors in CD8/CMV pp65 tetramer cells (CMV-CTLs) in peripheral blood samples obtained from 16 allo-SCT recipients with HLA-A*24:02 at the time of CMV reactivation.

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  • Primary immune thrombocytopenia (ITP) is an autoimmune disorder characterized by a low platelet count due to IgG anti-platelet autoantibodies targeting specific glycoproteins.
  • Researchers analyzed the B-cell receptor repertoires in ITP patients and found a significant increase in the usage of the IGHV4-28 gene segment, with distinct sequences predominating among the patients.
  • The findings suggest that the expansion of certain B-cell clones in ITP may be driven by antigenic pressure, which could help to understand the underlying immune mechanisms of the disease.
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  • Nickel is a key component in various dental alloys that can trigger metal contact allergies in the mouth, but the immune responses have been poorly understood due to a lack of suitable animal models.
  • * In this study, researchers created a mouse model to investigate nickel-induced oral metal allergies, focusing on T-cell behavior and cytokine production in the affected tissues.
  • * The findings revealed that after nickel exposure, certain T cells, including natural killer T cells, were active in the oral mucosa, highlighting their role in the immune reaction to nickel allergens.
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Adult T-cell leukemia (ATL) is an aggressive mature T-cell malignancy with a poor prognosis. The anti-C-C motif chemokine receptor 4 (CCR4) antibody mogamulizumab (moga) reduces ATL cells and induces reconstitution of polyclonal T cells; however, ATL cases often remain resistant and moga sometimes causes fatal immunopathology. Epstein-Barr virus (EBV)-related B-cell lymphoma develops in severely immunocompromised subjects, and is particularly associated with impaired T-cell immunity.

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Recent advances in cancer immunotherapy have improved patient survival. However, only a minority of patients with pulmonary metastatic disease respond to treatment with checkpoint inhibitors. As an alternate approach, we have tested the ability of systemically administered 1V270, a toll-like receptor 7 (TLR7) agonist conjugated to a phospholipid, to inhibit lung metastases in two variant murine 4T1 breast cancer models, as well as in B16 melanoma, and Lewis lung carcinoma models.

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Three bisabolane-type sesquiterpenes (1-3) were isolated from the fruiting bodies of king trumpet mushrooms (Pleurotus eryngii), together with a known compound (4). All isolated compounds were evaluated for their inhibitory effects on nitric oxide (NO) production. Among these, 2 exhibited a moderate inhibitory effect on NO production with an IC of 90.

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The human immune system is a fine network consisted of the innumerable numbers of functional cells that balance the immunity and tolerance against various endogenous and environmental challenges. Although advances in modern immunology have revealed a role of many unique immune cell subsets, technologies that enable us to capture the whole landscape of immune responses against specific antigens have been not available to date. Acquired immunity against various microorganisms including host microbiome is principally founded on T cell and B cell populations, each of which expresses antigen-specific receptors that define a unique clonotype.

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Therapeutic cancer peptide vaccination is an immunotherapy designed to elicit cytotoxic T-lymphocyte (CTL) responses in patients. A number of therapeutic vaccination trials have been performed, nevertheless there are only a few reports that have analyzed the T-cell receptors (TCRs) expressed on tumor antigen-specific CTLs. Here, we use next-generation sequencing (NGS) to analyze TCRs of vaccine-induced CTL clones and the TCR repertoire of bulk T cells in peripheral blood mononuclear cells (PBMCs) from two lung cancer patients over the course of long-term vaccine therapy.

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Although the anti-CCR4 antibody mogamulizumab (moga) shows striking antitumor activity against adult T cell leukemia (ATL), it can also cause fatal immunological pathology such as severe skin rash and graft-versus-host disease, which might be attributed to depletion of CCR4 regulatory T cells. We previously showed that next generation sequencing enables precise analysis of the T cell receptor (TCR) repertoire, and we here used the technique to reveal the immunological dynamics in moga-treated ATL patients. Treatment with moga resulted in remarkable reduction or elimination of clonal cells, and enhanced reconstitution of non-tumor polyclonal CD4 T cells and oligoclonal CD8 T cells.

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To facilitate the optimization of cancer immunotherapy lacking immune-related adverse events, we performed TCR repertoire analysis of tumor-infiltrating CD8 T-cells in B16 melanoma-bearing mice receiving anti-PD-1, anti-CTLA-4, anti-4-1BB, anti-CD4 or a combination of anti-PD-1 and 4-1BB antibodies. Although CD8 T-cells in the tumor were activated and expanded to a greater or lesser extent by these therapies, tumor growth suppression was achieved only by anti-PD-1, anti-PD-1/4-1BB combined, or by anti-CD4 treatment, but not by anti-CTLA-4 or anti-4-1BB monotherapy. Increased CD8 T cell effector function and TCR diversity with enrichment of certain TCR clonotypes in the tumor was associated with anti-tumor effects.

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Dengue virus (DENV) is one of the major infectious diseases in tropical regions and approximately half of the world population is at risk of infection. Vaccines would offer an effective control measure against this disease. We previously reported on the utility of marmosets as an animal model for studying primary and secondary dengue infections.

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Checkpoint inhibitors have demonstrated efficacy in patients with recurrent or metastatic head and neck squamous cell carcinoma (HNSCC). However, the majority of patients do not benefit from these agents. To improve the efficacy of checkpoint inhibitors, intratumoral (i.

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Palladium is frequently used in dental materials, and sometimes causes metal allergy. It has been suggested that the immune response by palladium-specific T cells may be responsible for the pathogenesis of delayed-type hypersensitivity in study of palladium allergic model mice. In the clinical setting, glucocorticoids and antihistamine drugs are commonly used for treatment of contact dermatitis.

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To expand our knowledge of the ontogeny of the T-cell receptor (TCR) repertoire of antigen-specific T-cell subsets, we combined next-generation deep sequencing and single-cell multiplex clonotype analysis to evaluate the diversity and frequency of paired TCRs, their functions and whether clonotypic TCRs are shared among different individuals. Using an HLA-A*02-restricted cytomegalovirus (CMV) pp65-derived immunogenic peptide, we found that the more dominant pp65-specific TCR clonotypes in the blood of healthy donors have higher binding affinities for the CMV peptide and arise from clonotypes that are highly shared among individuals. Interestingly, these highly shared HLA-A*02-restricted CMV-specific TCRs were detected in a CMV-seronegative individual as well as in HLA-A*02-negative donors albeit at lower frequency.

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A diverse antibody repertoire is primarily generated by the rearrangement of V, D, and J genes and subsequent somatic hypermutation (SHM). Class-switch recombination (CSR) produces various isotypes and subclasses with different functional properties. Although antibody isotypes and subclasses are considered to be produced by both direct and sequential CSR, it is still not fully understood how SHMs accumulate during the process in which antibody subclasses are generated.

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Background: High-throughput sequencing of T cell receptor (TCR) genes is a powerful tool for analyses of antigen specificity, clonality and diversity of T lymphocytes. Here, we developed a new TCR repertoire analysis method using 454 DNA sequencing technology in combination with an adaptor-ligation mediated polymerase chain reaction (PCR). This method allows the amplification of all TCR genes without PCR bias.

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Objective: Overexpression of the epidermal growth factor receptor (EGFR) family is common in oral squamous cell carcinoma (OSCC). Therefore, we analyzed the expression profiles of the four EGFR family members (ErbB1, ErbB2, ErbB3, and ErbB4) in OSCC of Japanese patients.

Study Design: Sixty-eight primary tumors and 18 normal oral mucosal tissue specimens were evaluated in this study.

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The regulatory T cells (Treg) with the most potent immunosuppressive activity are the effector Tregs (eTreg) with a CD45RA(-)Foxp3(++)CCR4(+) phenotype. Adult T-cell leukemia (ATL) cells often share the Treg phenotype and also express CCR4. Although mogamulizumab, a monoclonal antibody to CCR4, shows marked antitumor effects against ATL and peripheral T-cell lymphoma, concerns have been raised that it may induce severe autoimmune immunopathology by depleting eTregs.

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The present study investigated the expression profiles of the epidermal growth factor receptor (EGFR) family, which consists of four transmembrane tyrosine kinase receptors and their eight ligands, in 122 patients with colorectal cancer (CRC) using reverse transcription-quantitative polymerase chain reaction analysis. On comparison of the CRC primary tumor and matched adjacent normal mucosa (ANM) tissue samples, the mRNA expression levels of ErbB3, but not ErbB1, were significantly increased in CRC tissue samples, compared with those in the ANM tissues. The expression levels of the ligands exhibited opposing trends to their corresponding receptors, including EGF, BTC, AREG, EREG and HB‑EGF, which were increased in the CRC tissues, whereas NRG1 and NGR2 were decreased in thee CRC tissues, compared with those in the AMN tissues.

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Metal often causes delayed-type hypersensitivity reactions, which are possibly mediated by accumulating T cells in the inflamed skin, called irritant or allergic contact dermatitis. However, accumulating T cells during development of a metal allergy are poorly characterized because a suitable animal model is unavailable. We have previously established novel murine models of metal allergy and found accumulation of both metal-specific T cells and natural killer (NK) T cells in the inflamed skin.

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