Biology subjects

Mikami, N.

Publications and source records attributed to Mikami, N..

8 recordsLinked to original sources

bioRxiv2025

Generation of antigen-specific and functionally stable Treg cells from effector/memory T cells for cell therapy of immunological diseases

One strategy for antigen-specific immunosuppression is to convert antigen-specific conventional T cells (Tconvs) into Foxp3+ regulatory T cells (Tregs) that are as stably suppressive as naturally occurring Tregs (nTregs). To achieve the conversion in vitro for mice and humans, we induced high Foxp3 expression in antigen- and IL-2-stimulated Tconvs by CDK8/19 inhibition, and established Treg-specific epigenetic changes by depriving CD28 co-stimulation during in vitro Treg induction to specifically promote the expression of Treg signature genes, especially Foxp3. Repeating this process, with intermittent resting cultures containing IL-2 only, enabled in a short duration efficient conversion of naive as well as effector/memory CD4+ Tconvs, including Th1, Th2 and Th17 cells, into Foxp3+ Tregs, which were similar to nTregs in transcription and epigenetic modification. Induced Tregs (iTregs) thus generated were indeed functionally and phenotypically stable in vivo and effectively suppressed inflammatory bowel disease and graft-versus-host disease in mouse models. Adoptive cell therapy with such effector/memory Tconv-derived, functionally stable, iTregs would be able to achieve antigen- and disease-specific treatment of immunological diseases. One Sentence SummaryAntigen-specific and functionally stable Treg cells can be generated in vitro from effector/memory T cells for cell therapy of immunological diseases.

immunology↗

bioRxiv2025

Oral antigen exposure under co-stimulation blockade generates Treg cells to establish immune tolerance despite prior sensitization

Antigen-specific oral tolerance is effective in preventing harmful immune responses in antigen-non-sensitized animals but difficult to be induced in those already antigen-primed. Here, we show in mice that feeding of antigen-containing diet generates peripherally derived regulatory T (pTreg) cells that exhibit a tissue-adapted effector phenotype. The antigen feeding also enables the generated pTreg cells to acquire Treg-specific epigenomic changes in Treg signature genes including Foxp3, hence the stability of Treg-specific function. Cessation of antigen feeding, however, results in decline in oral tolerance with diminution of pTreg cells. Transcriptomic analysis has revealed that the induced pTreg cells predominantly express CD101. CD101+ Treg cells with a similar phenotype and epigenetic alterations can also be generated in vitro from antigen-primed naive CD4+ T cells by blockade of CD28-mediated co-stimulation during TGF-{beta}-dependent Treg induction. Furthermore, in vivo CD28 signal blockade by CTLA-4-immunoglobulin fusion protein (CTLA4-Ig) before antigen feeding can establish oral tolerance in the mice precedingly antigen-sensitized by a non-oral route. The blockade facilitates differentiation of antigen-specific conventional T cells into CD101+ pTreg cells. Thus, continuous oral antigen administration combined with CD28 co-stimulation blockade generates CD101+ antigen-specific functionally stable pTreg cells, which can establish long-term systemic antigen-specific immune tolerance even in antigen-pre-sensitized animals.

immunology↗

bioRxiv2023

Single-cell transcriptome landscape of circulating CD4+ T cell populations in human autoimmune diseases

CD4+ T cells are a key mediator of various autoimmune diseases; however, how they contribute to disease development remains obscure primarily because of their cellular heterogeneity. Here, we evaluated CD4+ T cell subpopulations by decomposition-based transcriptome characterization together with canonical clustering strategies. This approach identified 12 independent transcriptional gene programs governing whole CD4+ T cell heterogeneity, which can explain the ambiguity of canonical clustering. In addition, we performed a meta-analysis using public single-cell data sets of over 1.8M peripheral CD4+ T cells from 953 individuals by projecting cells onto the reference and cataloged cell frequency and qualitative alterations of the populations in 20 diseases. The analyses revealed that the 12 transcriptional programs were useful in characterizing each autoimmune disease and predicting its clinical status. Moreover, genetic variants associated with autoimmune diseases showed disease-specific enrichment within the 12 gene programs. The results collectively provide a landscape of single-cell transcriptomes of CD4+ T cell subpopulations involved in autoimmune disease.

immunology↗

bioRxiv2020

DAJIN-assisted multiplex genotyping to validate the outcomes of CRISPR-Cas-based genome editing

Genome editing can introduce designed mutations into a target genomic site. Recent research has revealed that it can also induce various unintended events such as structural variations, small indels, and substitutions at, and in some cases, away from the target site. These rearrangements may result in confounding phenotypes in biomedical research samples and cause a concern in clinical or agricultural applications. However, current genotyping methods do not allow a comprehensive analysis of diverse mutations for phasing and mosaic variant detection. Here, we developed a genotyping method with an on-target site analysis software named Determine Allele mutations and Judge Intended genotype by Nanopore sequencer (DAJIN) that can automatically identify and classify both intended and unintended diverse mutations, including point mutations, deletions, inversions, and cis double knock-in at single-nucleotide resolution. Our approach with DAJIN can handle approximately 100 samples under different editing conditions in a single run. With its high versatility, scalability, and convenience, DAJIN-assisted multiplex genotyping may become a new standard for validating genome editing outcomes.

genomics↗

bioRxiv2020

EXOC1 regulates cell morphology of spermatogonia and spermatocytes in mice

Spermatogenesis requires high regulation of germ cell morphology. The spermatogonia regulates its differentiation state by its own migration. The male germ cells differentiate and mature with the formation of syncytia, failure of forming the appropriate syncytia results in the arrest of spermatogenesis at the spermatocyte stage. However, the detailed molecular mechanisms of male germ cell morphological regulation are unknown. Here, we found that EXOC1 is important for the pseudopod formation of spermatogonia and spermatocyte syncytia in mice. We found that while EXOC1 contributes to the inactivation of Rac1 in the pseudopod formation of spermatogonia, in spermatocyte syncytium formation, EXOC1 and SNAP23 cooperate with STX2. Our results showed that EXOC1 functions in concert with various cell morphology regulators in spermatogenesis. Since EXOC1 is known to bind to several cell morphogenesis factors, this study is expected to be the starting point for the discovery of many morphological regulators of male germ cells.

developmental biology↗

bioRxiv2020

Swimming ghosts of the halophilic archaeon, Haloferax volcanii

Motility is seen across all domains of life1. Prokaryotes exhibit various types of motilities, such as gliding, swimming, and twitching, driven by supramolecular motility machinery composed of multiple different proteins2. In archaea only swimming motility is reported, driven by the archaellum (archaeal flagellum), a reversible rotary motor consisting of a torque-generating motor and a helical filament which acts as a propeller3,4. Unlike the bacterial flagellar motor (BFM), adenosine triphosphate (ATP) hydrolysis probably drives both motor rotation and filamentous assembly in the archaellum5,6. However, direct evidence is still lacking due to the lack of a versatile model system. Here we present a membrane-permeabilized ghost system that enables the manipulation of intracellular contents, analogous to the triton model in eukaryotic flagella7 and gliding Mycoplasma8,9. We observed high nucleotide selectivity for ATP driving motor rotation, negative cooperativity in ATP hydrolysis and the energetic requirement for at least 12 ATP molecules to be hydrolyzed per revolution of the motor. The response regulator CheY increased motor switching from counterclockwise (CCW) to clockwise (CW) rotation, which is the opposite of a previous report10. Finally, we constructed the torque-speed curve at various [ATP]s and discuss rotary models in which the archaellum has characteristics of both the BFM and F1-ATPase. Because archaea share similar cell division and chemotaxis machinery with other domains of life11,12, our ghost model will be an important tool for the exploration of the universality, diversity, and evolution of biomolecular machinery.

microbiology↗

bioRxiv2018

TOMVi: A Tool for Overviewing Metadata Visualization

DNA sequencing technology has been improved drastically in the recent decades, which allows comprehensively analyze microbial community and gene expression. Simultaneously with the improvements, many tools and software for much amount of sequence data have been released. These analysis tools/software can produce statistic information. However, to interpret and to find the relationships and/or associations between the information and the experimental condition may be a complex task, especially for non-bioinformaticians. In this article, an open source software TOMVi (Tool for Overviewing Metadata Visualization) which visualized similarity and relationships between the samples corresponding to the experimental conditions was introduced. TOMVi allows researcher to interactively manipulate the composition data in each sample toward to each experimental condition such as location, time-series and others with graphical user interface (GUI), and to visualize the existence and behavior of each OTU. The figure illustrated by this tool can provide an intuitive suggestion but not always correct as statistically, and will be helpful to decide further analyzing tactics.\n\nThe TOMVi is available at http://github.com/Daisuke-Kyoui/tomvi.

bioinformatics↗

bioRxiv2018

Risk of hypoglycemia induced by pivalate-conjugated antibiotics in young children: a population-based retrospective study in Japan

Infection is a common cause for an outpatient visit for young children. Pivalate-conjugated antibiotics (PCAs) are often used for these patients in Japan. However, a few case reports have shown that PCAs can provoke hypoglycemia in children, but no larger study has shown that PCAs increase the risk of hypoglycemia. The current study was performed as a retrospective review of children aged 1 month to 5 years old with at least once prescription of PCAs or other beta-lactam antibiotics from January 2011 to December 2013, using a medical and pharmacy claims database. Hypoglycemia was defined based on the International Statistical Classification of Diseases and Related Health Problems 10th Revision code or prescription of 10% or 20% glucose injection, and the incidence of hypoglycemic events was investigated. Logistic regression analysis was performed to examine the risk of hypoglycemia with PCAs compared with control antibiotics. The study cohort contained 179,594 eligible patients (male: 52.2%, mean age: 3.2 years). The numbers of prescriptions were 454,153 and 417,287 for PCAs and control antibiotics, respectively. Multivariate analysis showed that PCAs were associated with hypoglycemia (adjusted OR 1.18, 95% CI 1.12 to 1.24, P < 0.01), and the risk of hypoglycemia was also significantly increased with use of PCAs for [≤]7 days (adjusted OR 1.17, 95% CI 1.11 to 1.24, P < 0.01). These results suggest that prescription of PCAs to young children should be avoided, even for a short time period.

pharmacology and toxicology↗