Izumi Ohigashi, M Matsuda-Lennikov and Yousuke Takahama : Large-scale isolation of mouse thymic epithelial cells, Nov. 2022.
(Summary)
The thymus is compartmentalized into the cortex and the medulla. Cortical and medullary thymic epithelial cells (TECs) characterize T cell-producing and T cell-selecting functions of cortical and medullary microenvironments in the thymus. Enzymatic digestion of the thymus and flow cytometric isolation of TECs and their subpopulations are useful for molecular and cellular characterization of TECs. However, the cellularity of cTECs and mTECs isolated from mouse thymus is limited. In this chapter, we describe the method for isolation of a large number of TECs using enlarged mouse thymus, which enables biochemical and proteomic analysis of TEC subpopulations.
Izumi Ohigashi, Kenta Kondou and Yousuke Takahama : 免疫生物学(原書第9版) 監訳 笹月健彦，吉開泰信, Nankodo, 東京都, Mar. 2019.
3.
Izumi Ohigashi and Yousuke Takahama : Thymocyte-mTEC cross talk for self-tolerance in T cells., Elsevier, Apr. 2016.
Academic Paper (Judged Full Paper):
1.
Izumi Ohigashi, Andrea White, Mei-Ting Yang, Sayumi Fujimori, Yu Tanaka, Alison Jacques, Hiroshi Kiyonari, Yosuke Matsushita, Sevilay Turan, Michael Kelly, Graham Anderson and Yousuke Takahama : Developmental conversion of thymocyte-attracting cells into self-antigen-displaying cells in embryonic thymus medulla epithelium., eLife, Vol.12, RP92552, 2024.
(Summary)
Thymus medulla epithelium establishes immune self-tolerance and comprises diverse cellular subsets. Functionally relevant medullary thymic epithelial cells (mTECs) include a self-antigen-displaying subset that exhibits genome-wide promiscuous gene expression promoted by the nuclear protein Aire and that resembles a mosaic of extrathymic cells including mucosal tuft cells. An additional mTEC subset produces the chemokine CCL21, thereby attracting positively selected thymocytes from the cortex to the medulla. Both self-antigen-displaying and thymocyte-attracting mTEC subsets are essential for self-tolerance. Here, we identify a developmental pathway by which mTECs gain their diversity in functionally distinct subsets. We show that CCL21-expressing mTECs arise early during thymus ontogeny in mice. Fate-mapping analysis reveals that self-antigen-displaying mTECs, including Aire-expressing mTECs and thymic tuft cells, are derived from CCL21-expressing cells. The differentiation capability of CCL21-expressing embryonic mTECs is verified in reaggregate thymus experiments. These results indicate that CCL21-expressing embryonic mTECs carry a developmental potential to give rise to self-antigen-displaying mTECs, revealing that the sequential conversion of thymocyte-attracting subset into self-antigen-displaying subset serves to assemble functional diversity in the thymus medulla epithelium.
The chemokine CCL21 regulates immune and cancer cell migration through its receptor CCR7. The gene encodes the isoform CCL21-Ser, predominantly expressed in the thymic medulla and the secondary lymphoid tissues. This study examined the roles of CCL21-Ser in the antitumor immune response in -knockout (KO) mice. The KO mice showed significantly decreased growth of B16-F10 and YUMM1.7 melanomas and increased growth of MC38 colon cancer, despite no significant difference in LLC lung cancer and EO771 breast cancer. The B16-F10 tumor in -KO mice showed melanoma-specific activated CD8 T cell and NK cell infiltration and higher Treg counts than wild-type mice. B16-F10 tumors in -KO mice showed a reduction in the positive correlation between the ratio of regulatory T cells (Tregs) to activated CD8 T cells and tumor weight. In -KO tumor, the intratumoral Tregs showed lower co-inhibitory receptors TIM-3 and TIGIT. Taken together, these results suggest that endogenous CCL21-Ser supports melanoma growth by maintaining Treg function and suppressing antitumor immunity by CD8 T cells.
B Lucas, AJ White, F Klein, C Veiga-Villauriz, A Handel, A Bacon, EJ Cosway, KD James, SM Parnell, Izumi Ohigashi, Yousuke Takahama, WE Jenkinson, GA Hollander, WY Lu and G Anderson : Embryonic keratin19+ progenitors generate multiple functionally distinct progeny to maintain epithelial diversity in the adult thymus medulla, Nature Communications, Vol.14, No.1, 2066, 2023.
(Summary)
The thymus medulla is a key site for immunoregulation and tolerance, and its functional specialisation is achieved through the complexity of medullary thymic epithelial cells (mTEC). While the importance of the medulla for thymus function is clear, the production and maintenance of mTEC diversity remains poorly understood. Here, using ontogenetic and inducible fate-mapping approaches, we identify mTEC-restricted progenitors as a cytokeratin19 (K19) TEC subset that emerges in the embryonic thymus. Importantly, labelling of a single cohort of K19 TEC during embryogenesis sustains the production of multiple mTEC subsets into adulthood, including CCL21 mTEC, Aire mTEC and thymic tuft cells. We show K19 progenitors arise prior to the acquisition of multiple mTEC-defining features including RANK and CCL21 and are generated independently of the key mTEC regulator, Relb. In conclusion, we identify and define a multipotent mTEC progenitor that emerges during embryogenesis to support mTEC diversity into adult life.
Y Zhang, L Garcia-Ibanez, C Ulbricht, LSC Lok, JA Pike, J Mueller-Winkler, TW Dennison, JR Ferdinand, CJM Burnett, JC Yam-Puc, L Zhang, RM Alfaro, Yousuke Takahama, Izumi Ohigashi, G Brown, T Kurosaki, VLJ Tybulewicz, A Rot, AE Hauser, MR Clatworthy and KM Toellner : Recycling of memory B cells between germinal center and lymph node subcapsular sinus supports affinity maturation to antigenic drift, Nature Communications, Vol.13, No.1, 2460, 2022.
(Summary)
Infection or vaccination leads to the development of germinal centers (GC) where B cells evolve high affinity antigen receptors, eventually producing antibody-forming plasma cells or memory B cells. Here we follow the migratory pathways of B cells emerging from germinal centers (B) and find that many B cells migrate into the lymph node subcapsular sinus (SCS) guided by sphingosine-1-phosphate (S1P). From the SCS, B cells may exit the lymph node to enter distant tissues, while some B cells interact with and take up antigen from SCS macrophages, followed by CCL21-guided return towards the GC. Disruption of local CCL21 gradients inhibits the recycling of B cells and results in less efficient adaption to antigenic variation. Our findings thus suggest that the recycling of antigen variant-specific B cells and transport of antigen back to GC may support affinity maturation to antigenic drift.
(Keyword)
Antigenic Drift and Shift / B-Lymphocytes / Germinal Center / Lymph Nodes / Memory B Cells
Sayumi Fujimori, Izumi Ohigashi, Hayato Abe, Yosuke Matsushita, Toyomasa Katagiri, Taketo M. Makoto, Takahama Yousuke and Takada Shinji : Fine-tuning of β-catenin in mouse thymic epithelial cells is required for postnatal T-cell development, eLife, Vol.11, e69088, 2022.
(Summary)
In the thymus, the thymic epithelium provides a microenvironment essential for the development of functionally competent and self-tolerant T cells. Previous findings showed that modulation of Wnt/β-catenin signaling in mouse thymic epithelial cells (TECs) disrupts embryonic thymus organogenesis. However, the role of β-catenin in TECs for postnatal T-cell development remains to be elucidated. Here, we analyzed gain-of-function (GOF) and loss-of-function (LOF) of β-catenin highly specific in mouse TECs. We found that GOF of β-catenin in TECs results in severe thymic dysplasia and T-cell deficiency beginning from the embryonic period. By contrast, LOF of β-catenin in TECs reduces the number of cortical TECs and thymocytes modestly and only postnatally. These results indicate that fine-tuning of β-catenin expression within a permissive range is required for TECs to generate an optimal microenvironment to support postnatal T-cell development.
Yohei Yamamoto, Naoko Matsui, Akiyuki Uzawa, Yukiko Ozawa, Tetsuya Kanai, Fumiko Oda, Hiroyuki Kondo, Izumi Ohigashi, Hiromitsu Takizawa, Kazuya Kondo, Mikio Sugano, Takashi Kitaichi, Hiroki Hata, Ryuji Kaji, Satoshi Kuwabara, Takashi Yamamura and Yuishin Izumi : Intrathymic Plasmablasts Are Affected in Patients With Myasthenia Gravis With Active Disease., Neurology® Neuroimmunology & Neuroinflammation, Vol.8, No.6, e1087, 2021.
(Summary)
Our findings confirmed a correlation between increased frequency of intrathymic plasmablasts and disease activity before thymectomy. We postulate that activated intrathymic plasmablasts endow pathogenic capacity in MG.
Noriko Mizusawa, Nagakatsu Harada, Takeo Iwata, Izumi Ohigashi, Mitsuo Itakura and Katsuhiko Yoshimoto : Identification of protease serine S1 family member 53 as a mitochondrial protein in murine islet beta cells, Islets, Vol.14, No.1, 1-13, 2021.
Izumi Ohigashi and Yousuke Takahama : Specific impact of β5t on proteasome subunit composition in cortical thymic epithelial cells, Cell Reports, Vol.36, No.10, 109657, 2021.
(Summary)
β5t is a cortical thymic epithelial cell (cTEC)-specific component of the thymoproteasome, which is essential for the optimal production of functionally competent CD8 T cells. Our recent analysis showed a specific impact of β5t on proteasome subunit composition in cTECs, supporting the possibility that the thymoproteasome optimizes CD8 T cell development through the production of MHC-I-associated unique self-peptides in cTECs. However, a recent article reports that β5t regulates the expression of hundreds of cTEC genes and affects both CD4 and CD8 thymocytes by causing oxidative stress in thymocytes. The authors further analyze our published data and describe that they confirm their conclusions. Here, we examine the issues that they raise and conclude that, rather than regulating hundreds of genes in cTECs, β5t has a highly specific impact in cTECs on proteasome subunit composition. This Matters Arising Response article addresses the Apavaloaei et al. (2021) Matters Arising paper, published concurrently in Cell Reports.
(Keyword)
CD8-Positive T-Lymphocytes / Epithelial Cells / Histocompatibility Antigens Class I / Proteasome Endopeptidase Complex / Thymocytes
Izumi Ohigashi, Melina Frantzeskakis, Alison Jacques, Sayumi Fujimori, Aya Ushio, Fusano Yamashita, Naozumi Ishimaru, Da Yin, Margaret Cam, C Michael Kelly, Parirokh Awasthi, Kensuke Takada and Yousuke Takahama : The thymoproteasome hardwires the TCR repertoire of CD8+ T cells in the cortex independent of negative selection., The Journal of Experimental Medicine, Vol.218, No.4, 2021.
(Summary)
The thymoproteasome expressed specifically in thymic cortical epithelium optimizes the generation of CD8+ T cells; however, how the thymoproteasome contributes to CD8+ T cell development is unclear. Here, we show that the thymoproteasome shapes the TCR repertoire directly in cortical thymocytes before migration to the thymic medulla. We further show that the thymoproteasome optimizes CD8+ T cell production independent of the thymic medulla; independent of additional antigen-presenting cells, including medullary thymic epithelial cells and dendritic cells; and independent of apoptosis-mediated negative selection. These results indicate that the thymoproteasome hardwires the TCR repertoire of CD8+ T cells with cortical positive selection independent of negative selection in the thymus.
Ferreirinha Pedro, Ribeiro Camila, Junko Morimoto, Landry J M Jonathan, Minoru Matsumoto, Meireles Catarina, White J Andrea, Izumi Ohigashi, Araújo Leonor, Benes Vladimir, Yousuke Takahama, Anderson Graham, Mitsuru Matsumoto and Alves L Nuno : A novel method to identify Post-Aire stages of medullary thymic epithelial cell differentiation, European Journal of Immunology, Vol.51, No.2, 311-318, 2021.
(Summary)
Autoimmune regulator (Aire) medullary thymic epithelial cells (mTECs) play a critical role in tolerance induction. Several studies demonstrated that Aire mTECs differentiate further into Post-Aire cells. Yet, the identification of terminal stages of mTEC maturation depends on unique fate-mapping mouse models. Herein, we resolve this limitation by segmenting the mTEC (MHCII CD80 ) compartment into mTEC (CD24 Sca1 ), mTEC (CD24 Sca1 ), and mTEC (CD24 Sca1 ). While mTEC included mostly Aire-expressing cells, mTEC contained Aire and Aire cells and mTEC were mainly composed of cells lacking Aire. The differential expression pattern of Aire led us to investigate the precursor-product relationship between these subsets. Strikingly, transcriptomic analysis of mTEC , mTEC , and mTEC sequentially mirrored the specific genetic program of Early-, Late- and Post-Aire mTECs. Corroborating their Post-Aire nature, mTEC downregulated the expression of tissue-restricted antigens, acquired traits of differentiated keratinocytes, and were absent in Aire-deficient mice. Collectively, our findings reveal a new and simple blueprint to survey late stages of mTEC differentiation.
KD James, DF Legler, V Purvanov, Izumi Ohigashi, Yousuke Takahama, SM Parnell, AJ White, WE Jenkinson and G Anderson : Medullary stromal cells synergize their production and capture of CCL21 for T-cell emigration from neonatal mouse thymus, Blood Advances, Vol.5, No.1, 99-112, 2021.
M Lachén-Montes, N Mendizuri, K Ausín, A Pérez-Mediavilla, M Azkargorta, I Iloro, F Elortza, Hiroyuki Kondo, Izumi Ohigashi, I Ferrer, R la Torre de, P Robledo, J Fernández-Irigoyen and E Santamaría : Smelling the Dark Proteome: Functional Characterization of PITH Domain-Containing Protein 1 (C1orf128) in Olfactory Metabolism, Journal of Proteome Research, Vol.19, No.12, 4826-4843, 2020.
(Summary)
The Human Proteome Project (HPP) consortium aims to functionally characterize the dark proteome. On the basis of the relevance of olfaction in early neurodegeneration, we have analyzed the dark proteome using data mining in public resources and omics data sets derived from the human olfactory system. Multiple dark proteins localize at synaptic terminals and may be involved in amyloidopathies such as Alzheimer's disease (AD). We have characterized the dark PITH domain-containing protein 1 (PITHD1) in olfactory metabolism using bioinformatics, proteomics, in vitro and in vivo studies, and neuropathology. PITHD1 mice exhibit olfactory bulb (OB) proteome changes related to synaptic transmission, cognition, and memory. OB PITHD1 expression increases with age in wild-type (WT) mice and decreases in Tg2576 AD mice at late stages. The analysis across 6 neurological disorders reveals that olfactory tract (OT) PITHD1 is specifically upregulated in human AD. Stimulation of olfactory neuroepithelial (ON) cells with PITHD1 alters the ON phosphoproteome, modifies the proliferation rate, and induces a pro-inflammatory phenotype. This workflow applied by the Spanish C-HPP and Human Brain Proteome Project (HBPP) teams across the ON-OB-OT axis can be adapted as a guidance to decipher functional features of dark proteins. Data are available via ProteomeXchange with identifiers PXD018784 and PXD021634.
JE Cowan, Yousuke Takahama, A Bhandoola and Izumi Ohigashi : Postnatal involution and counter-involution of the thymus. Frontiers in Immunology, Frontiers in Immunology, Vol.11, No.897, 2020.
(Summary)
Thymus involution occurs in all vertebrates. It is thought to impact on immune responses in the aged, and in other clinical circumstances such as bone marrow transplantation. Determinants of thymus growth and size are beginning to be identified. Ectopic expression of factors like cyclin D1 and Myc in thymic epithelial cells (TEC)s results in considerable increase in thymus size. These models provide useful experimental tools that allow thymus function to be understood. In future, understanding TEC-specific controllers of growth will provide new approaches to thymus regeneration.
B Lucas, AJ White, EJ Cosway, SM Parnell, KD James, ND Jones, Izumi Ohigashi, Yousuke Takahama, WE Jenkinson and G Anderson : Diversity in medullary thymic epithelial cells controls the activity and availability of iNKT cells, Nature Communications, Vol.11, No.1, 2020.
(Summary)
The thymus supports multiple αβ T cell lineages that are functionally distinct, but mechanisms that control this multifaceted development are poorly understood. Here we examine medullary thymic epithelial cell (mTEC) heterogeneity and its influence on CD1d-restricted iNKT cells. We find three distinct mTEC subsets distinguished by surface, intracellular and secreted molecules, and identify LTβR as a cell-autonomous controller of their development. Importantly, this mTEC heterogeneity enables the thymus to differentially control iNKT sublineages possessing distinct effector properties. mTEC expression of LTβR is essential for the development thymic tuft cells which regulate NKT2 via IL-25, while LTβR controls CD104CCL21 mTEC that are capable of IL-15-transpresentation for regulating NKT1 and NKT17. Finally, mTECs regulate both iNKT-mediated activation of thymic dendritic cells, and iNKT availability in extrathymic sites. In conclusion, mTEC specialization controls intrathymic iNKT cell development and function, and determines iNKT pool size in peripheral tissues.
Hiroyuki Kondo, Takafumi Matsumura, Mari Kaneko, Kenichi Inoue, Hidetaka Kosako, Masahito Ikawa, Yousuke Takahama and Izumi Ohigashi : PITHD1 is a proteasome-interacting protein essential for male fertilization, The Journal of Biological Chemistry, Vol.295, No.6, 1658-1672, 2020.
(Summary)
The proteasome is a protein-degrading molecular complex that is necessary for protein homeostasis and various biological functions, including cell cycle regulation, signal transduction, and immune response. Proteasome activity is finely regulated by a variety of proteasome-interacting molecules. PITHD1 is a recently described molecule that has a domain putatively capable of interacting with the proteasome. However, it is unknown whether PITHD1 can actually bind to proteasomes and what it does Here we report that PITHD1 is detected specifically in the spermatids in the testis and the cortical thymic epithelium in the thymus. Interestingly, PITHD1 associates with immunoproteasomes in the testis, but not with thymoproteasomes in the thymus. Mice deficient in PITHD1 exhibit severe male infertility accompanied with morphological abnormalities and impaired motility of spermatozoa. Furthermore, PITHD1 deficiency reduces proteasome activity in the testis and alters the amount of proteins that are important for fertilization capability by the sperm. However, the PITHD1-deficient mice demonstrate no detectable defects in the thymus, including T cell development. Collectively, our results identify PITHD1 as a proteasome-interacting protein that plays a nonredundant role in the male reproductive system.
Jennifer E. Cowan, Justin Malin, Yongge Zhao, Mina O. Seedhom, Christelle Harly, Izumi Ohigashi, Michael Kelly, Yousuke Takahama, Jonathan W. Yewdell, Maggie Cam and Avinash Bhandoola : Myc controls a distinct transcriptional program in fetal thymic epithelial cells that determines thymus growth, Nature Communications, Vol.10, No.1, 5498, 2019.
(Summary)
Interactions between thymic epithelial cells (TEC) and developing thymocytes are essential for T cell development, but molecular insights on TEC and thymus homeostasis are still lacking. Here we identify distinct transcriptional programs of TEC that account for their age-specific properties, including proliferation rates, engraftability and function. Further analyses identify Myc as a regulator of fetal thymus development to support the rapid increase of thymus size during fetal life. Enforced Myc expression in TEC induces the prolonged maintenance of a fetal-specific transcriptional program, which in turn extends the growth phase of the thymus and enhances thymic output; meanwhile, inducible expression of Myc in adult TEC similarly promotes thymic growth. Mechanistically, this Myc function is associated with enhanced ribosomal biogenesis in TEC. Our study thus identifies age-specific transcriptional programs in TEC, and establishes that Myc controls thymus size.
Shahina Umme Khanom, Izumi Ohigashi, Sayumi Fujimori, Kenta Kondou, Kensuke Takada and Yousuke Takahama : TCR affinity for in vivo peptide-induced thymic positive selection fine-tunes TCR responsiveness of peripheral CD8+ T cells, The Journal of Immunology, Vol.203, No.4, 881-887, 2019.
(Summary)
The affinity for TCR interactions with self-peptide/MHC complexes (pMHC) in the thymus critically affects immature thymocytes that newly express TCRs. Previous fetal thymus organ culture experiments have indicated that difference in the affinity for thymic TCR/pMHC interactions not only determines thymocyte fate between positive and negative selection, but also affects Ag responsiveness of positively selected thymocytes. In the current study, we examined whether TCR/pMHC affinity during positive selection in the thymus would further affect Ag responsiveness of mature T cells in the periphery. To do so, OVA peptide variants were in vivo administered to TAP1-deficient OT-I/TCR-transgenic mice in which T cell development was otherwise arrested at CD4CD8 thymocytes because of the lack of self-pMHC presentation in thymic APCs. We found that a group of peptide variants induced the transient generation of OT-I CD8 T cells in the thymus and the periphery. We also noticed that the affinity threshold for positive and negative selection detected in adult mice in vivo was higher than that measured in fetal thymus organ culture experiments in vitro. Interestingly, we further found that the affinity for positively selecting peptides proportionally affected TCR responsiveness of peripheral naive CD8 T cells. These results indicate that in vivo administration of a peptide can promote T cell selection in the thymus and the affinity for TCR/pMHC interaction during positive selection fine-tunes Ag responsiveness of peripheral T cells.
Kenta Kondou, Izumi Ohigashi and Y Takahama : Thymus machinery for T-cell selection, International Immunology, Vol.31, No.3, 119-125, 2019.
(Summary)
An immunocompetent and self-tolerant pool of naive T cells is formed in the thymus through the process of repertoire selection. T cells that are potentially capable of responding to foreign antigens are positively selected in the thymic cortex and are further selected in the thymic medulla to help prevent self-reactivity. The affinity between T-cell antigen receptors expressed by newly generated T cells and self-peptide-major histocompatibility complexes displayed in the thymic microenvironments plays a key role in determining the fate of developing T cells during thymic selection. Recent advances in our knowledge of the biology of thymic epithelial cells have revealed unique machinery that contributes to positive and negative selection in the thymus. In this article, we summarize recent findings on thymic T-cell selection, focusing on the machinery unique to thymic epithelial cells.
Yousuke Takahama, Izumi Ohigashi, Shigeo Murata and Keiji Tanaka : Thymoproteasome and peptidic self, Immunogenetics, Vol.71, No.3, 217-221, 2019.
(Summary)
Positive selection of T cells in the thymus is induced by low-affinity TCR recognition of self-peptide-MHC complexes expressed by cortical thymic epithelial cells (cTECs). cTECs express a specialized type of proteasomes, the thymoproteasome, which generates a unique spectrum of MHC class I-associated peptides and plays a critical role in thymic positive selection of CD8 T cells. However, it remains unclear how the thymoproteasome contributes to the thymic positive selection. More than 30 years ago, the "peptidic self" hypothesis proposed that TCRs recognize MHC-presented peptides only, without interacting with MHC molecules, which turned out to be incorrect. Interestingly, however, by implying that a set of MHC-associated peptides forms immunological self, this hypothesis also predicted that positive selection in the thymus is the primary immune response to "foreign epitope" peptides during T cell development. The thymoproteasome-dependent unique self-peptides may create those foreign epitope peptides displayed in the thymus for positive selection of T cells.
(Keyword)
Animals / Antigen Presentation / Histocompatibility Antigens Class I / Humans / Peptide Fragments / Proteasome Endopeptidase Complex / T lymphocytes / Thymus Gland
A Takeuchi, M Ozawa, Y Kanda, M Kozai, Izumi Ohigashi, Y Kurosawa, MA Rahman, T Kawamura, Y Shichida, E Umemoto, M Miyasaka, B Ludewig, Y Takahama, T Nagasawa and T Katakai : A Distinct Subset of Fibroblastic Stromal Cells Constitutes the Cortex-Medulla Boundary Subcompartment of the Lymph Node, Frontiers in Immunology, Vol.9, 2196, 2018.
(Summary)
The spatiotemporal regulation of immune responses in the lymph node (LN) depends on its sophisticated tissue architecture, consisting of several subcompartments supported by distinct fibroblastic stromal cells (FSCs). However, the intricate details of stromal structures and associated FSC subsets are not fully understood. Using several gene reporter mice, we sought to discover unrecognized stromal structures and FSCs in the LN. The four previously identified FSC subsets in the cortex are clearly distinguished by the expression pattern of reporters including PDGFRβ, CCL21-ser, and CXCL12. Herein, we identified a unique FSC subset expressing both CCL21-ser and CXCL12 in the deep cortex periphery (DCP) that is characterized by preferential B cell localization. This subset was clearly different from CXCL12LepR FSCs in the medullary cord, which harbors plasma cells. B cell localization in the DCP was controlled chiefly by CCL21-ser and, to a lesser extent, CXCL12. Moreover, the optimal development of the DCP as well as medulla requires B cells. Together, our findings suggest the presence of a unique microenvironment in the cortex-medulla boundary and offer an advanced view of the multi-layered stromal framework constructed by distinct FSC subsets in the LN.
Emilie J. Cosway, Izumi Ohigashi, Karin Schauble, Sonia M. Parnell, William E. Jenkinson, Sanjiv Luther, Yousuke Takahama and Graham Anderson : Formation of the intrathymic dendritic cell pool requires CCL21-mediated recruitment of CCR7+ progenitors to the thymus, The Journal of Immunology, Vol.201, No.2, 516-523, 2018.
(Summary)
During αβ T cell development in the thymus, migration of newly selected CD4 and CD8 thymocytes into medullary areas enables tolerance mechanisms to purge the newly selected αβ TCR repertoire of autoreactive specificities. Thymic dendritic cells (DC) play key roles in this process and consist of three distinct subsets that differ in their developmental origins. Thus, plasmacytoid DC and Sirpα conventional DC type 2 are extrathymically derived and enter into the thymus via their respective expression of the chemokine receptors CCR9 and CCR2. In contrast, although Sirpα conventional DC type 1 (cDC1) are known to arise intrathymically from immature progenitors, the precise nature of such thymus-colonizing progenitors and the mechanisms controlling their thymus entry are unclear. In this article, we report a selective reduction in thymic cDC1 in mice lacking the chemokine receptor CCR7. In addition, we show that the thymus contains a CD11cMHC class IISirpαFlt3 cDC progenitor population that expresses CCR7, and that migration of these cells to the thymus is impaired in mice. Moreover, thymic cDC1 defects in mice are mirrored in mice, with further analysis of mice individually lacking the CCR7 ligands CCL21Ser ( ) or CCL19 ( demonstrating an essential role for CCR7-CCL21Ser during intrathymic cDC1 development. Collectively, our data support a mechanism in which CCR7-CCL21Ser interactions guide the migration of cDC progenitors to the thymus for correct formation of the intrathymic cDC1 pool.
Mie Sakata, Izumi Ohigashi and Yousuke Takahama : Cellularity of Thymic Epithelial Cells in the Postnatal Mouse., The Journal of Immunology, Vol.200, No.4, 1382-1388, 2018.
(Summary)
The molecular and cellular biology of thymic epithelial cells (TECs) often relies on the analysis of TECs isolated in enzymatically digested single-cell suspensions derived from mouse thymus. Many independent studies have reported that the estimated cellularity of total TECs isolated from one adult mouse is on the order of up to 10 However, these numbers appear extremely small given that the cellularity of total thymocytes exceeds 10 and that TECs play multiple roles in thymocyte development and repertoire formation. In the present study, we aimed to measure the numbers of β5t-expressing cortical TECs and Aire-expressing medullary TECs in postnatal mouse thymus in situ without enzymatic digestion. The numbers of these TECs were manually counted in individual thymic sections and were three-dimensionally summed throughout the entire thymic lobes. The results show that the cellularity of total TECs in one 5-wk-old female mouse exceeds 10, containing 9 × 10 β5t cortical TECs and 1.1 × 10 Aire medullary TECs. These results suggest that the use of conventional enzymatic digestion methods for the isolation of TECs may have resulted in the underestimation of the cellularity, and possibly the biology, of TECs.
Mina Kozai, Yuki Kubo, Tomoya Katakai, Hiroyuki Kondo, Hiroshi Kiyonari, Karin Schaeuble, Sanjiv A. Luther, Naozumi Ishimaru, Izumi Ohigashi and Yousuke Takahama : Essential role of CCL21 in establishment of central self-tolerance in T cells, The Journal of Experimental Medicine, Vol.214, No.7, 1925-1935, 2017.
(Summary)
The chemokine receptor CCR7 directs T cell relocation into and within lymphoid organs, including the migration of developing thymocytes into the thymic medulla. However, how three functional CCR7 ligands in mouse, CCL19, CCL21Ser, and CCL21Leu, divide their roles in immune organs is unclear. By producing mice specifically deficient in CCL21Ser, we show that CCL21Ser is essential for the accumulation of positively selected thymocytes in the thymic medulla. CCL21Ser-deficient mice were impaired in the medullary deletion of self-reactive thymocytes and developed autoimmune dacryoadenitis. T cell accumulation in the lymph nodes was also defective. These results indicate a nonredundant role of CCL21Ser in the establishment of self-tolerance in T cells in the thymic medulla, and reveal a functional inequality among CCR7 ligands in vivo.
The Psmb11-encoded β5t subunit of the thymoproteasome, which is specifically expressed in cortical thymic epithelial cells (cTECs), is essential for the optimal positive selection of functionally competent CD8+ T cells in mice. Here, we report that a human genomic PSMB11 variation, which is detectable at an appreciable allele frequency in human populations, alters the β5t amino acid sequence that affects the processing of catalytically active β5t proteins. The introduction of this variation in the mouse genome revealed that the heterozygotes showed reduced β5t expression in cTECs and the homozygotes further exhibited reduction in the cellularity of CD8+ T cells. No severe health problems were noticed in many heterozygous and 5 homozygous human individuals. Long-term analysis of health status, particularly in the homozygotes, is expected to improve our understanding of the role of the thymoproteasome-dependent positive selection of CD8+ T cells in humans.
(Keyword)
thymus / thymoproteasome / single nucleotide polymorphism
Uddin Myn Muhammad, Izumi Ohigashi, Ryo Motosugi, Tomomi Nakayama, Mie Sakata, Jun Hamazaki, Yasumasa Nishito, Immanuel Rode, Keiji Tanaka, Tatsuya Takemoto, Shigeo Murata and Yousuke Takahama : Foxn1-5t transcriptional axis controls CD8+ T-cell production in the thymus., Nature Communications, Vol.8, 14419, 2017.
(Summary)
The thymus is an organ that produces functionally competent T cells that protect us from pathogens and malignancies. Foxn1 is a transcription factor that is essential for thymus organogenesis; however, the direct target for Foxn1 to actuate thymic T-cell production is unknown. Here we show that a Foxn1-binding cis-regulatory element promotes the transcription of β5t, which has an essential role in cortical thymic epithelial cells to induce positive selection of functionally competent CD8(+) T cells. A point mutation in this genome element results in a defect in β5t expression and CD8(+) T-cell production in mice. The results reveal a Foxn1-β5t transcriptional axis that governs CD8(+) T-cell production in the thymus.
Izumi Ohigashi, Mina Kozai and Yousuke Takahama : Development and developmental potential of cortical thymic epithelial cells, Immunological Reviews, Vol.271, No.1, 10-22, 2016.
(Summary)
The thymic cortex provides a microenvironment for the development and positive selection of immature T cells. Cortical thymic epithelial cells (cTECs), which structurally and functionally support the thymic cortical microenvironment, originate from endodermal epithelial progenitors that arise in the third pharyngeal pouch. Recent studies have revealed that thymic epithelial progenitors pass through a stage where the cells express cTEC-associated molecules prior to lineage separation into cTECs and medullary TECs (mTECs). Here, we review the molecular signatures of cTECs and highlight the development and developmental potential of cTECs.
CE Mayer, S Zuklys, S Zhanybekova, Izumi Ohigashi, HY Teh, SN Sansom, N Shikama-Dorn, K Hafen, IC Macaulay, ME Deadman, CP Ponting, Yousuke Takahama and GA Hollander : Dynamic spatio-temporal contribution of single β5t+ cortical epithelial precursors to the thymus medulla, European Journal of Immunology, Vol.46, No.4, 846-856, 2016.
(Summary)
Intrathymic T-cell development is critically dependent on cortical and medullary thymic epithelial cells (TECs). Both epithelial subsets originate during early thymus organogenesis from progenitor cells that express the thymoproteasome subunit β5t, a typical feature of cortical TECs. Using in vivo lineage fate mapping, we demonstrate in mice that β5t(+) TEC progenitors give rise to the medullary TEC compartment early in life but significantly limit their contribution once the medulla has completely formed. Lineage-tracing studies at single cell resolution demonstrate for young mice that the postnatal medulla is expanded from individual β5t(+) cortical progenitors located at the cortico-medullary junction. These results therefore not only define a developmental window during which the expansion of medulla is efficiently enabled by progenitors resident in the thymic cortex, but also reveal the spatio-temporal dynamics that control the growth of the thymic medulla.
Izumi Ohigashi and Yousuke Takahama : Flow Cytometry Analysis of Thymic Epithelial Cells and Their Subpopulations, Methods in Molecular Biology, Vol.1323, 65-73, 2016.
(Summary)
The parenchyma of the thymus is compartmentalized into the cortex and the medulla, which are constructed by cortical thymic epithelial cells (cortical TECs, cTECs) and medullary thymic epithelial cells (mTECs), respectively. cTECs and mTECs essentially and differentially regulate the development and repertoire selection of T cells. Consequently, the biology of T cell development and selection includes the study of TECs in addition to the study of developing T cells and other hematopoietic cells including dendritic cells. In this chapter, we describe the methods for flow cytometric analysis and sorting of TECs and their subpopulations, including cTECs and mTECs.
Izumi Ohigashi, Saulius Zuklys, Mie Sakata, Carlos E. Mayer, Yoko Hamazaki, Nagahiro Minato, Georg A Hollander and Yousuke Takahama : Adult thymic medullary epithelium is maintained and regenerated by lineage-restricted cells rather than bipotent progenitors, Cell Reports, Vol.13, No.7, 1432-1443, 2015.
(Summary)
Medullary thymic epithelial cells (mTECs) play an essential role in establishing self-tolerance in T cells. mTECs originate from bipotent TEC progenitors that generate both mTECs and cortical TECs (cTECs), although mTEC-restricted progenitors also have been reported. Here, we report in vivo fate-mapping analysis of cells that transcribe β5t, a cTEC trait expressed in bipotent progenitors, during a given period in mice. We show that, in adult mice, most mTECs are derived from progenitors that transcribe β5t during embryogenesis and the neonatal period up to 1 week of age. The contribution of adult β5t(+) progenitors was minor even during injury-triggered regeneration. Our results further demonstrate that adult mTEC-restricted progenitors are derived from perinatal β5t(+) progenitors. These results indicate that the adult thymic medullary epithelium is maintained and regenerated by mTEC-lineage cells that pass beyond the bipotent stage during early ontogeny.
L Nuno Alves, Yousuke Takahama, Izumi Ohigashi, R Ana Ribeiro, Song Baik, Graham Anderson and E William Jenkinson : Serial progression of cortical and medullary thymic epithelial microenvironments., European Journal of Immunology, Vol.44, No.1, 16-22, 2014.
(Summary)
Thymic epithelial cells (TECs) provide key instructive signals for T-cell differentiation. Thymic cortical (cTECs) and medullary (mTECs) epithelial cells constitute two functionally distinct microenvironments for T-cell development, which derive from a common bipotent TEC progenitor. While seminal studies have partially elucidated events downstream of bipotent TECs in relation to the emergence of mTECs and their progenitors, the control and timing of the emergence of the cTEC lineage, particularly in relation to that of mTEC progenitors, has remained elusive. In this review, we describe distinct models that explain cTEC/mTEC lineage divergence from common bipotent progenitors. In particular, we summarize recent studies in mice providing evidence that mTECs, including the auto-immune regulator(+) subset, derive from progenitors initially endowed with phenotypic properties typically associated with the cTEC lineage. These observations support a novel "serial progression" model of TEC development, in which progenitors serially acquire cTEC lineage markers, prior to their commitment to the mTEC differentiation pathway. Gaining a better understanding of the phenotypic properties of early stages in TEC progenitor development should help in determining the mechanisms regulating cTEC/mTEC lineage development, and in strategies aimed at thymus reconstitution involving TEC therapy.
Kensuke Takada, Izumi Ohigashi, Michiyuki Kasai, Hiroshi Nakase and Yousuke Takahama : Development and function of cortical thymic epithelial cells., Current Topics in Microbiology and Immunology, Vol.373, 1-17, 2014.
(Summary)
The thymic cortex provides a microenvironment that supports the generation and T cell antigen receptor (TCR)-mediated selection of CD4(+)CD8(+)TCR(+) thymocytes. Cortical thymic epithelial cells (cTECs) are the essential component that forms the architecture of the thymic cortex and induces the generation as well as the selection of newly generated T cells. Here we summarize current knowledge on the development, function, and heterogeneity of cTECs, focusing on the expression and function of 5t, a cTEC-specific subunit of the thymoproteasome.
Izumi Ohigashi and Yousuke Takahama : CCRL1 marks heterogeneity in cortical and medullary thymic epithelial cells., European Journal of Immunology, Vol.44, No.10, 2872-2875, 2014.
(Summary)
Cortical thymic epithelial cells (cTECs) and medullary thymic epithelial cells (mTECs), which play essential roles in the establishment of a functionally competent and self-tolerant repertoire of T cells, are derived from common thymic epithelial progenitor cells (pTECs). Recent findings indicate that mTECs are derived from cells that express molecules that are abundant in cTECs rather than mTECs, and provide fresh insight into the characteristics of pTECs and their diversification pathways into TEC subpopulations. In this issue of the European Journal of Immunology, Ribeiro et al. [Eur. J. Immunol. 2014. 44: 2918-2924] focus on CCRL1, an atypical chemokine receptor that is highly expressed by cTECs rather than mTECs, and show that CCRL1-expressing embryonic TECs can give rise to mTECs. Interestingly, Ribeiro et al. further report that a fraction of postnatal mTECs express CCRL1 at a low level, suggesting novel complexity in mTECs.
Naoko Matsui, Izumi Ohigashi, Keijirou Tanaka, Mie Sakata, Takahiro Furukawa, Yasushi Nakagawa, Kazuya Kondo, Tetsuya Kitagawa, Sumimasa Yamashita, Yoshiko Nomura, Yousuke Takahama and Ryuji Kaji : Increased number of Hassall's corpuscles in myasthenia gravis patients with thymic hyperplasia., Journal of Neuroimmunology, Vol.269, No.1-2, 56-61, 2014.
(Summary)
The thymus is implicated as an organ that contributes to autoimmunity in myasthenia gravis (MG) patients. Hassall's corpuscles (HCs) are assumed to represent the terminally differentiated stage of medullary thymic epithelial cells (mTECs). By using multicolor immunohistofluorescence analysis, we examined HCs in thymuses that were therapeutically excised from MG (+) and MG (-) patients. We found that the number of HCs per unit area of the thymic medulla was significantly elevated in the thymuses of MG (+) patients with thymic hyperplasia. CCL21 expression increased in the hyperplastic MG thymuses. We speculate that the altered differentiation of mTECs is associated with the thymic hyperplasia and the onset of MG.
A Joy Williams, Jingjing Zhang, Hyein Jeon, Takeshi Nitta, Izumi Ohigashi, David Klug, J Michael Kruhlak, Baishakhi Choudhury, O Susan Sharrow, Larry Granger, Anthony Adams, A Michael Eckhaus, Rhiannon S Jenkinson, R Ellen Richie, E Ronald Gress, Yousuke Takahama and J Richard Hodes : Thymic medullary epithelium and thymocyte self-tolerance require cooperation between CD28-CD80/86 and CD40-CD40L costimulatory pathways., The Journal of Immunology, Vol.192, No.2, 630-640, 2014.
(Summary)
A critical process during thymic development of the T cell repertoire is the induction of self-tolerance. Tolerance in developing T cells is highly dependent on medullary thymic epithelial cells (mTEC), and mTEC development in turn requires signals from mature single-positive thymocytes, a bidirectional relationship termed thymus crosstalk. We show that CD28-CD80/86 and CD40-CD40L costimulatory interactions, which mediate negative selection and self-tolerance, upregulate expression of LT, LT, and receptor activator for NF-B in the thymus and are necessary for medullary development. Combined absence of CD28-CD80/86 and CD40-CD40L results in profound deficiency in mTEC development comparable to that observed in the absence of single-positive thymocytes. This requirement for costimulatory signaling is maintained even in a TCR transgenic model of high-affinity TCR-ligand interactions. CD4 thymocytes maturing in the altered thymic epithelial environment of CD40/CD80/86 knockout mice are highly autoreactive in vitro and are lethal in congenic adoptive transfer in vivo, demonstrating a critical role for these costimulatory pathways in self-tolerance as well as thymic epithelial development. These findings demonstrate that cooperativity between CD28-CD80/86 and CD40-CD40L pathways is required for normal medullary epithelium and for maintenance of self-tolerance in thymocyte development.
Rhiannon S Jenkinson, A Joy Williams, Hyein Jeon, Jingjing Zhang, Takeshi Nitta, Izumi Ohigashi, Michael Kruhlak, Saulius Zuklys, Susan Sharrow, Anthony Adams, Larry Granger, Yongwon Choi, Ulrich Siebenlist, A Gail Bishop, A Georg Hollander, Yousuke Takahama and J Richard Hodes : TRAF3 enforces the requirement for T cell cross-talk in thymic medullary epithelial development., Proceedings of the National Academy of Sciences of the United States of America, Vol.110, No.52, 21107-21112, 2013.
(Summary)
Induction of self-tolerance in developing T cells depends on medullary thymic epithelial cells (mTECs), whose development, in turn, requires signals from single-positive (SP) thymocytes. Thus, the absence of SP thymocytes in Tcra(-/-) mice results in a profound deficiency in mTECs. Here, we have probed the mechanism that underlies this requirement for cross-talk with thymocytes in medullary development. Previous studies have implicated nonclassical NF-B as a pathway important in the development of mTECs, because mice lacking RelB, NIK, or IKK, critical components of this pathway, have an almost complete absence of mTECs, with resulting autoimmune pathology. We therefore assessed the effect of selective deletion in TEC of TNF receptor-associated factor 3 (TRAF3), an inhibitor of nonclassical NF-B signaling. Deletion of TRAF3 in thymic epithelial cells allowed RelB-dependent development of normal numbers of AIRE-expressing mTECs in the complete absence of SP thymocytes. Thus, mTEC development can occur in the absence of cross-talk with SP thymocytes, and signals provided by SP T cells are needed to overcome TRAF3-imposed arrest in mTEC development mediated by inhibition of nonclassical NF-B. We further observed that TRAF3 deletion is also capable of overcoming all requirements for LTR and CD40, which are otherwise necessary for mTEC development, but is not sufficient to overcome the requirement for RANKL, indicating a role for RANKL that is distinct from the signals provided by SP thymocytes. We conclude that TRAF3 plays a central role in regulation of mTEC development by imposing requirements for SP T cells and costimulation-mediated cross-talk in generation of the medullary compartment.
Izumi Ohigashi, Saulius Zuklys, Mie Sakata, E Carlos Mayer, Saule Zhanybekova, Shigeo Murata, Keiji Tanaka, A Georg Holländer and Yousuke Takahama : Aire-expressing thymic medullary epithelial cells originate from β5t-expressing progenitor cells., Proceedings of the National Academy of Sciences of the United States of America, Vol.110, No.24, 9885-9890, 2013.
(Summary)
The thymus provides multiple microenvironments that are essential for the development and repertoire selection of T lymphocytes. The thymic cortex induces the generation and positive selection of T lymphocytes, whereas the thymic medulla establishes self-tolerance among the positively selected T lymphocytes. Cortical thymic epithelial cells (cTECs) and medullary TECs (mTECs) constitute the major stromal cells that structurally form and functionally characterize the cortex and the medulla, respectively. cTECs and mTECs are both derived from the endodermal epithelium of the third pharyngeal pouch. However, the molecular and cellular characteristics of the progenitor cells for the distinct TEC lineages are unclear. Here we report the preparation and characterization of mice that express the recombinase Cre instead of 5t, a proteasome subunit that is abundant in cTECs and not detected in other cell types, including mTECs. By crossing 5t-Cre knock-in mice with loxP-dependent GFP reporter mice, we found that 5t-Cre-mediated recombination occurs specifically in TECs but not in any other cell types in the mouse. Surprisingly, in addition to cTECs, 5t-Cre-loxP-mediated GFP expression was detected in almost all mTECs. These results indicate that the majority of mTECs, including autoimmune regulator-expressing mTECs, are derived from 5t-expressing progenitor cells.
Enkhsaikhan Lkhagvasuren, Mie Sakata, Izumi Ohigashi and Yousuke Takahama : Lymphotoxin receptor regulates the development of CCL21-expressing subset of postnatal medullary thymic epithelial cells., The Journal of Immunology, Vol.190, No.10, 5110-5117, 2013.
(Summary)
Medullary thymic epithelial cells (mTECs) play a pivotal role in the establishment of self-tolerance in T cells by ectopically expressing various tissue-restricted self-Ags and by chemoattracting developing thymocytes. The nuclear protein Aire expressed by mTECs contributes to the promiscuous expression of self-Ags, whereas CCR7-ligand (CCR7L) chemokines expressed by mTECs are responsible for the attraction of positively selected thymocytes. It is known that lymphotoxin signals from the positively selected thymocytes preferentially promote the expression of CCR7L rather than Aire in postnatal mTECs. However, it is unknown how lymphotoxin signals differentially regulate the expression of CCR7L and Aire in mTECs and whether CCR7L-expressing mTECs and Aire-expressing mTECs are distinct populations. In this study, we show that the majority of postnatal mTECs that express CCL21, a CCR7L chemokine, represent an mTEC subpopulation distinct from the Aire-expressing mTEC subpopulation. Interestingly, the development of CCL21-expressing mTECs, but not Aire-expressing mTECs, is impaired in mice deficient in the lymphotoxin receptor. These results indicate that postnatal mTECs consist of heterogeneous subsets that differ in the expression of CCL21 and Aire, and that lymphotoxin receptor regulates the development of the CCL21-expressing subset rather than the Aire-expressing subset of postnatal mTECs.
Takeshi Nitta, Izumi Ohigashi and Yousuke Takahama : The development of T lymphocytes in fetal thymus organ culture., Methods in Molecular Biology, Vol.946, 85-102, 2013.
(Summary)
Fetal thymus organ culture (FTOC) is a unique and powerful culture system that allows intrathymic T-lymphocyte development in vitro. T-cell development in FTOC well represents fetal thymocyte development in vivo. Here we describe the basic method for FTOC as well as several related techniques, including reconstitution of thymus lobes with T-lymphoid progenitor cells, high-oxygen submersion culture, reaggregation thymus organ culture, retrovirus-mediated gene transfer to developing thymocytes in FTOC, and coculture of progenitor cells with OP9-DL1 cells.
NM Roberts, AJ White, WE Jenkinson, G Turchinovich, K Nakamura, DR Withers, FM McConnell, GE Desanti, C Benezech, SM Parnell, AF Cunningham, M Paolino, J Penninger, K Simon, T Nitta, Izumi Ohigashi, Yousuke Takahama, JH Caamano, AC Hayday, PJ Lane, EJ Jenkinson and G Anderson : Rank signaling links the development of invariant γδ T cell progenitors and Aire+ medullary epithelium., Immunity, Vol.36, No.3, 427-437, 2012.
(Summary)
The thymic medulla provides a specialized microenvironment for the negative selection of T cells, with the presence of autoimmune regulator (Aire)-expressing medullary thymic epithelial cells (mTECs) during the embryonic-neonatal period being both necessary and sufficient to establish long-lasting tolerance. Here we showed that emergence of the first cohorts of Aire(+) mTECs at this key developmental stage, prior to αβ T cell repertoire selection, was jointly directed by Rankl(+) lymphoid tissue inducer cells and invariant Vγ5(+) dendritic epidermal T cell (DETC) progenitors that are the first thymocytes to express the products of gene rearrangement. In turn, generation of Aire(+) mTECs then fostered Skint-1-dependent, but Aire-independent, DETC progenitor maturation and the emergence of an invariant DETC repertoire. Hence, our data attributed a functional importance to the temporal development of Vγ5(+) γδ T cells during thymus medulla formation for αβ T cell tolerance induction and demonstrated a Rank-mediated reciprocal link between DETC and Aire(+) mTEC maturation.
Izumi Ohigashi, Takeshi Nitta, E Lkhagvasuren, H Yasuda and Yousuke Takahama : Effects of RANKL on the thymic medulla, European Journal of Immunology, Vol.41, No.7, 1822-1827, 2011.
(Summary)
The thymic medulla provides a microenvironment where medullary thymic epithelial cells (mTECs) contribute to the establishment of self-tolerance by the deletion of self-reactive T cells and the generation of regulatory T cells. The progression of thymocyte development critically regulates the optimum formation of the thymic medulla, as discussed in this article. Of note, it was recently identified that RANKL produced by positively selected thymocytes plays a major role in the thymocyte-mediated medulla formation. Indeed, transgenic expression of soluble RANKL increased the number of mTECs and enlarged the thymic medulla in mice. The effects of RANKL on the thymic medulla may be useful for the engineering of self-tolerance in T cells.
Yu Lei, Adiratna Mat Ripen, Naozumi Ishimaru, Izumi Ohigashi, Takashi Nagasawa, Lukas T. Jeker, Michael R. Bösl, Georg A. Holländer, Yoshio Hayashi, Rene Waal de Malefyt, Takeshi Nitta and Yousuke Takahama : Aire-dependent production of XCL1 mediates medullary accumulation of thymic dendritic cells and contributes to regulatory T cell development, The Journal of Experimental Medicine, Vol.208, No.2, 383-394, 2011.
(Summary)
Dendritic cells (DCs) in the thymus (tDCs) are predominantly accumulated in the medulla and contribute to the establishment of self-tolerance. However, how the medullary accumulation of tDCs is regulated and involved in self-tolerance is unclear. We show that the chemokine receptor XCR1 is expressed by tDCs, whereas medullary thymic epithelial cells (mTECs) express the ligand XCL1. XCL1-deficient mice are defective in the medullary accumulation of tDCs and the thymic generation of naturally occurring regulatory T cells (nT reg cells). Thymocytes from XCL1-deficient mice elicit dacryoadenitis in nude mice. mTEC expression of XCL1, tDC medullary accumulation, and nT reg cell generation are diminished in Aire-deficient mice. These results indicate that the XCL1-mediated medullary accumulation of tDCs contributes to nT reg cell development and is regulated by Aire.
Takeshi Nitta, Izumi Ohigashi, Yasushi Nakagawa and Yousuke Takahama : Cytokine crosstalk for thymic medulla formation, Current Opinion in Immunology, Vol.23, No.2, 190-197, 2011.
(Summary)
The medullary microenvironment of the thymus plays a crucial role in the establishment of self-tolerance through the deletion of self-reactive thymocytes and the generation of regulatory T cells. Crosstalk or bidirectional signal exchanges between developing thymocytes and medullary thymic epithelial cells (mTECs) contribute to the formation of the thymic medulla. Recent studies have identified the molecules that mediate thymic crosstalk. Tumor necrosis factor superfamily cytokines, including RANKL, CD40L, and lymphotoxin, produced by positively selected thymocytes and lymphoid tissue inducer cells promote the proliferation and differentiation of mTECs. In return, CCR7 ligand chemokines produced by mTECs facilitate the migration of positively selected thymocytes to the medulla. The cytokine crosstalk between developing thymocytes and mTECs nurtures the formation of the thymic medulla and thereby regulates the establishment of self-tolerance.
Izumi Ohigashi, Yuki Yamasaki, Tsukasa Hirashima and Yousuke Takahama : Identification of the Transgenic Integration Site in Immunodeficient tgϵ26 Human CD3ϵ Transgenic Mice, PLoS ONE, Vol.5, No.12, e14391, 2010.
(Summary)
A strain of human CD3ϵ transgenic mice, tgϵ26, exhibits severe immunodeficiency associated with early arrest of T cell development. Complete loss of T cells is observed in homozygous tgϵ26 mice, but not in heterozygotes, suggesting that genomic disruption due to transgenic integration may contribute to the arrest of T cell development. Here we report the identification of the transgenic integration site in tgϵ26 mice. We found that multiple copies of the human CD3ϵ transgene are inserted between the Sstr5 and Metrn loci on chromosome 17, and that this is accompanied by duplication of the neighboring genomic region spanning 323 kb. However, none of the genes in this region were abrogated. These results suggest that the severe immunodeficiency seen in tgϵ26 mice is not due to gene disruption resulting from transgenic integration.
Naoko Matsui, Shunya Nakane, Fumi Saitou, Izumi Ohigashi, Yasushi Nakagawa, Hirotsugu Kurobe, Hiromitsu Takizawa, Takao Mitsui, Kazuya Kondo, Tetsuya Kitagawa, Yousuke Takahama and Ryuji Kaji : Undiminished regulatory T cells in the thymus of myathenia gravis patients, Neurology, Vol.74, No.10, 816-820, 2010.
(Summary)
The thymus has been implicated as a possible site of origin that triggers autoimmunity in myasthenia gravis (MG). Although several groups have suggested that the decrease in the number of regulatory T (Treg) cells contributes to the onset of MG, the exact role of Treg cells in MG remains unclear. To address this point, we examined the number and distribution of Treg cells in a large number of patients with MG. Immunohistofluorescence analysis of Foxp3 along with CD4 and CD8 was performed in thymic sections of MG (+) (n = 24) and MG (-) patients (n = 27). Circulating CD4(+)CD25(+) cells in the peripheral blood of patients with MG (n = 15) and age-matched healthy subjects (n = 15) were also analyzed. Foxp3(+)CD4(+)CD8(-) cells were predominantly found in the thymic medulla and their number declined with age. There was no significant difference in the number or the distribution of Foxp3(+)CD4(+)CD8(-) cells in the thymus between MG (+) and MG (-) patients. The number of circulating CD4(+)CD25(+) cells in the peripheral blood of patients with MG was not significantly altered compared to that in healthy subjects. The cellularity of Treg cells in the thymus and circulation is not diminished in patients with myasthenia gravis.
(Keyword)
Age Factors / Antigens, CD / Cell Count / Female / Flow Cytometry / Forkhead Transcription Factors / Humans / Male / Myasthenia Gravis / T-Lymphocytes, Regulatory / Thymus Gland
DA Sultana, Shuhei Tomita, M Hamada, Y Iwanaga, Y Kitahama, NV Khang, S Hirai, Izumi Ohigashi, S Nitta, T Amagai, S Takahashi and Yousuke Takahama : Gene expression profile of the third pharyngeal pouch reveals role of mesenchymal MafB in embryonic thymus development, Blood, Vol.113, No.13, 2976-2987, 2009.
(Summary)
The thymus provides a microenvironment that induces the differentiation of T-progenitor cells into functional T cells and that establishes a diverse yet self-tolerant T-cell repertoire. However, the mechanisms that lead to the development of the thymus are incompletely understood. We report herein the results of screening for genes that are expressed in the third pharyngeal pouch, which contains thymic primordium. Polymerase chain reaction (PCR)-based cDNA subtraction screening for genes expressed in microdissected tissues of the third pharyngeal pouch rather than the second pharyngeal arch yielded one transcription factor, MafB, which was predominantly expressed in CD45(-)IA(-)PDGFRalpha(+) mesenchymal cells and was detectable even in the third pharyngeal pouch of FoxN1-deficient nude mice. Interestingly, the number of CD45(+) cells that initially accumulated in the embryonic thymus was significantly decreased in MafB-deficient mice. Alterations of gene expression in the embryonic thymi of MafB-deficient mice included the reduced expression of Wnt3 and BMP4 in mesenchymal cells and of CCL21 and CCL25 in epithelial cells. These results suggest that MafB expressed in third pharyngeal pouch mesenchymal cells critically regulates lymphocyte accumulation in the embryonic thymus.
Yu Hikosaka, Takeshi Nitta, Izumi Ohigashi, Kouta Yano, Naozumi Ishimaru, Yoshio Hayashi, Mitsuru Matsumoto, Koichi Matsuo, Josef M Penninger, Hiroshi Takayanagi, Yoshifumi Yokota, Hisakata Yamada, Yasunobu Yoshikai, Jun-ichiro Inoue, Taishin Akiyama and Yousuke Takahama : The cytokine RANKL produced by positively selected thymocytes fosters medullary thymic epithelial cells that express autoimmune regulator., Immunity, Vol.29, No.3, 438-450, 2008.
(Summary)
The thymic medulla provides a microenvironment where medullary thymic epithelial cells (mTECs) express autoimmune regulator and diverse tissue-restricted genes, contributing to launching self-tolerance. Positive selection is essential for thymic medulla formation via a previously unknown mechanism. Here we show that the cytokine RANK ligand (RANKL) was produced by positively selected thymocytes and regulated the cellularity of mTEC by interacting with RANK and osteoprotegerin. Forced expression of RANKL restored thymic medulla in mice lacking positive selection, whereas RANKL perturbation impaired medulla formation. These results indicate that RANKL produced by positively selected thymocytes is responsible for fostering thymic medulla formation, thereby establishing central tolerance.
Takeshi Nitta, Mariam Nasreen, Takafumi Seike, Atsushi Goji, Izumi Ohigashi, Tadaaki Miyazaki, Tsutomu Ohta, Masamoto Kanno and Yousuke Takahama : IAN family critically regulates survival and development of T lymphocytes, PLoS Biology, Vol.4, No.4, e103-e115, 2006.
(Summary)
The IAN (immune-associated nucleotide-binding protein) family is a family of functionally uncharacterized GTP-binding proteins expressed in vertebrate immune cells and in plant cells during antibacterial responses. Here we show that all eight IAN family genes encoded in a single cluster of mouse genome are predominantly expressed in lymphocytes, and that the expression of IAN1, IAN4, and IAN5 is significantly elevated upon thymic selection of T lymphocytes. Gain-of-function experiments show that the premature overexpression of IAN1 kills immature thymocytes, whereas short hairpin RNA-mediated loss-of-function studies show that IAN4 supports positive selection. The knockdown of IAN5 perturbs the optimal generation of CD4/CD8 double-positive thymocytes and reduces the survival of mature T lymphocytes. We also show evidence suggesting that IAN4 and IAN5 are associated with anti-apoptotic proteins Bcl-2 and Bcl-xL, whereas IAN1 is associated with pro-apoptotic Bax. Thus, the IAN family is a novel family of T cell-receptor-responsive proteins that critically regulate thymic development and survival of T lymphocytes and that potentially exert regulatory functions through the association with Bcl-2 family proteins.
Noriko Mizusawa, Tomoko Hasegawa, Izumi Ohigashi, Chisato Kosugi, Nagakatsu Harada, Mitsuo Itakura and Katsuhiko Yoshimoto : Differentiation Penotypes of Pancreatic Islet β- and α-cells are Closely Related with Homeotic Genes and a Group of Differentially Expressed Genes., Gene, Vol.331, No.28, 53-63, 2004.
(Summary)
To identify the genes that determine differentiation phenotypes, we compared gene expression of pancreatic islet beta- and alpha-cells, which are derived from the common precursor and secrete insulin and glucagon, respectively. The expression levels of homeotic genes including Hox genes known to determine region specificity in the antero-posterior (AP) body axis, tissue-specific homeobox genes, and other 8,734 genes were compared in a beta- and alpha-cell line of MIN6 and alpha TC1.6. The expression of homeotic genes were surveyed with reverse transcription-polymerase chain reaction (RT-PCR) using degenerate primers corresponding to invariant amino acid sequences within the homeodomain and subsequently with specific primers. Expression of Hoxc6, Hoxc9, Hoxc10, Pdx1, Cdx2, Gbx2, Pax4, and Hlxb9 genes in MIN6 was higher than those in alpha TC1.6, while expression of Hoxa2, Hoxa3, Hoxa5, Hoxa6, Hoxa7, Hoxa9, Hoxa10, Hoxa13, Hoxb3, Hoxb5, Hoxb6, Hoxb13, Hoxb8, and Brain4 genes in alpha TC1.6 was higher than those in MIN6. Out of 8,734 mouse genes screened with high-density mouse cDNA microarrays for MIN6- and alpha TC1.6-derived cDNA, 58 and 25 genes were differentially over- and under-expressed in MIN6, respectively. GLUTag, which is derived from a large bowel tumor and expresses the proglucagon gene, showed a comparatively similar expression profile to that of alpha TC1.6 in both homeotic and other genes analyzed in cDNA microarray. Our results are consistent with the interpretation that not only the tissue-specific homeotic genes, but also Hox genes are related to differentiation phenotypes of pancreatic beta- and alpha-cells rather than their regional specification of the body in vertebrates.
Sayumi Fujimori and Izumi Ohigashi : Diversity and differentiation pathways of medullary thymic epithelial cells, Clinical Immunology & Allergology, Vol.81, No.4, 385-390, Apr. 2024.
2.
Sayumi Fujimori and Izumi Ohigashi : The role of thymic epithelium in thymus development and age-related thymic involution., The Journal of Medical Investigation : JMI, Vol.71, No.1.2, 29-39, 2024.
(Summary)
The establishment of an adaptive immune system is critical for protecting our bodies from neoplastic cancers and invading pathogens such as viruses and bacteria. As a primary lymphoid organ, the thymus generates lymphoid T cells that play a major role in the adaptive immune system. T cell generation in the thymus is controlled by interactions between thymocytes and other thymic cells, primarily thymic epithelial cells. Thus, the normal development and function of thymic epithelial cells are important for the generation of immunocompetent and self-tolerant T cells. On the other hand, the degeneration of the thymic epithelium due to thymic aging causes thymic involution, which is associated with the decline of adaptive immune function. Herein we summarize basic and current knowledge of the development and function of thymic epithelial cells and the mechanism of thymic involution. J. Med. Invest. 71 : 29-39, February, 2024.
M Matsuda-Lennikov, Izumi Ohigashi and Yousuke Takahama : Tissue-specific proteasomes in generation of MHC class I peptides and CD8+ T cells, Current Opinion in Immunology, Vol.77, 102217, Aug. 2022.
(Summary)
Thymoproteasomes and immunoproteasomes are two types of tissue-specific proteasomes, which contribute to the production of major histocompatibility complex (MHC) class I (MHC-I)-associated peptides that are important for the development and function of CD8 cytotoxic T cells. Thymoproteasomes are specifically expressed by cortical thymic epithelial cells and are important for MHC-I-dependent positive selection of developing thymocytes, whereas immunoproteasomes are abundant in many other cells, including hematopoietic cells and medullary thymic epithelial cells. Here we summarize the role of these two tissue-specific proteasomes, focusing on their functions in the development of CD8 T cells in the thymus.
Izumi Ohigashi and Yousuke Takahama : Thymoproteasome optimizes positive selection of CD8+ T cells without contribution of negative selection, Advances in Immunology, Vol.149, 1-23, May 2021.
Melina Frantzeskakis, Yousuke Takahama and Izumi Ohigashi : The role of proteasomes in the thymus, Frontiers in Immunology, Vol.12, No.646209, Mar. 2021.
Yousuke Takahama, Izumi Ohigashi, Song Baik and Graham Anderson : Generation of diversity in thymic epithelial cells, Nature Reviews. Immunology, Vol.17, No.5, 295-305, May 2017.
(Summary)
In the thymus, diverse populations of thymic epithelial cells (TECs), including cortical and medullary TECs and their subpopulations, have distinct roles in coordinating the development and repertoire selection of functionally competent and self-tolerant T cells. Here, we review the expanding diversity in TEC subpopulations in relation to their functions in T cell development and selection as well as their origins and development.
Sayumi Fujimori, Shinji Takada, Yousuke Takahama and Izumi Ohigashi : Role of β-catenin in mouse thymic epithelial cells for postnatal thymic development, The 18th International Symposium of the Institute Network for Biomedical Sciences, Oct. 2023.
2.
Sayumi Fujimori, Shinji Takada, Yousuke Takahama and Izumi Ohigashi : Role of β-catenin in thymic epithelial cells for postnatal thymic development and involution, ThymOz International Conference on T Cells: ThymOz 2023, Mar. 2023.
3.
Izumi Ohigashi, White J. Andrea, Yang Mei-Ting, Sayumi Fujimori, Anderson Graham and Yousuke Takahama : Developmental conversion of thymocyte-attracting cells into self-antigen-displaying cells in thymus medulla epithelium, ThymOz International Conference on T Cells: ThymOz 2023, Mar. 2023.
4.
Sayumi Fujimori, Izumi Ohigashi, Takahama Yousuke and Takada Shinji : β-catenin in mouse thymic epithelial cells fine-tunes postnatal T-cell production, EMBO Workshop co-supported by The Company of Biologists and Yamada Science Foundation: Wnt 2022, Nov. 2022.
5.
Izumi Ohigashi : Trnas-omics profiling of thymic epithelial cells, The 4th Symposium of the inter-university research network for trans-omics medicine, Nov. 2019.
6.
Sayumi Fujimori, Izumi Ohigashi, Takahama Yousuke and Takada Shinji : Role of β-catenin in thymic epithelial progenies of β5t positive progenitors, ThymE: T cell and thymus biology, May 2019.
7.
Izumi Ohigashi, Yu Tanaka, Kenta Kondou, Sayumi Fujimori, Amy C. Palin, Hiroyuki Kondo, Hidetaka Kosako and Yousuke Takahama : Trans-omics impact of thymoproteasome in cortical thymic epithelial cells, ThymE: T cell and thymus biology, May 2019.
8.
Izumi Ohigashi and Yousuke Takahama : Human PSMB11 polymorphisms that affect thymoproteasome processing and CD8+ T cell generation, 8th THYMOZ, Mar. 2018.
9.
Uddin Myn, Izumi Ohigashi and Yousuke Takahama : Foxn1-b5t transcriptional axis controls CD8+ T-cell production in the thymus, IMMUNOLOGY 2017, AAI Annual Meeting, May 2017.
10.
Kondo Hiroyuki, Izumi Ohigashi, Kozai Mina, Kubo Yuki, Katakai Tomoya, Luther A. Sanjiv and Yousuke Takahama : Essential role of CCL21 in establishment of central self-tolerance in T cells, 7th International Workshop of Kyoto T Cell Conference, Mar. 2017.
11.
Izumi Ohigashi, Ohte Yuki, Setoh Kazuya, Matsuda Fumihiko, Murata Shigeo and Yousuke Takahama : A human Psmb11 polymorphism affects molecular processing of thymoproteasome and thymic production of CD8+ T cells, 7th International Workshop of Kyoto T Cell Conference, Mar. 2017.
12.
Sayumi Fujimori, Izumi Ohigashi, Tatsuya Takemoto, Yousuke Takahama and Takada Shinji : Activation of Wnt/β-catenin signaling in thymic epithelial progenitors, 7th International Workshop of Kyoto T Cell Conference, Kyoto, Mar. 2017.
13.
Kozai Mina, Izumi Ohigashi and Yousuke Takahama : CCL21 regulates T-cell self-tolerance in thymic medulla, 11th International Symposium of The Institute Network Frontiers in Biomedical Sciences, Jan. 2017.
14.
Izumi Ohigashi, Uddin Myn, Tatsuya Takemoto and Yousuke Takahama : Foxn1-binding cis-regulatory element required for optimal CD8+ T cell production in the thymus, 11th International Symposium of The Institute Network Frontiers in Biomedical Sciences, Jan. 2017.
15.
Izumi Ohigashi and Yousuke Takahama : Foxn1-binding cis-regulatory element required for optimal CD8+ T cell production in the thymus, The Fifth Bizan Immunology symposium, 徳島県徳島市, Mar. 2016.
16.
Izumi Ohigashi and Yousuke Takahama : Adult thymus medullary epithelium is maintained and regenerated by lineage restricted cells rather than bipotent progenitors, The Fourth BIZAN Immunology Symposium at University of TokushimaImmune System Development, Deviation, and Regulation, Jan. 2015.
17.
Izumi Ohigashi, Zuklys Saulius, Hollander Georg and Yousuke Takahama : mTECs derived from embryonic and postnatal beta5t+ progenitors, The 7th ThymOZ International Conference, Apr. 2014.
18.
Izumi Ohigashi and Yousuke Takahama : Development and developmental potential of 5t-expressing thymic epithelial cells, The Third Bizan Immunology Symposium at The University of Tokushima (BISUT3) "Immune System Development, Deviation, and Regulation", Feb. 2014.
19.
Yousuke Takahama and Izumi Ohigashi : Serial development of cortical and medullary thymic epithelia, Fourth Synthetic Immunology WorkshopEngineering in Immunity, Nov. 2013.
Yousuke Takahama and Izumi Ohigashi : Development and developmental potential of 5t-expressing thymic epithelial cells, KTCC 2013 International Workshop on T Lymphocytes, Jun. 2013.
22.
Lkhagvasuren Enkhsaikhan, Sakata Mie, Izumi Ohigashi and Yousuke Takahama : Lymphotoxin receptor regulates the development of CCL21-expressing subset of postnatal medullary thymic epithelial cells, KTCC 2013 International Workshop on T Lymphocytes, Jun. 2013.
23.
Naoko Matsui, Izumi Ohigashi, Kazuya Kondo, Nomura Yoshiko, Yousuke Takahama and Ryuji Kaji : Increased Hassalls Corpuscles In Myasthenia Gravis Patients Carrying Thymic Hyperplasia, 11th International congress of neuroimmunology, Nov. 2012.
24.
Izumi Ohigashi, Takeshi Nitta, ENOMOTO Tetsuro, TOMIMORI Toshiya, YASUDA Hisataka and Yousuke Takahama : RANKL PROMOTES THYMIC MEDULLA FORMATION, The 2nd Workshop of Synthetic Immunology, Kyoto, Dec. 2010.
Proceeding of Domestic Conference:
1.
Izumi Ohigashi, White J. Andrea, Yang Mei-Ting, Sayumi Fujimori, Anderson Graham and Yousuke Takahama : ケモカインCCL21を発現する胎仔期の胸腺髄質上皮細胞は自己抗原発現髄質上皮細胞への分化活性を有する, 第46回日本分子生物学会年会, Dec. 2023.
2.
Izumi Ohigashi, J. Andrea White, Mei-Ting Yang, Sayumi Fujimori, Grahama Anderson and Yousuke Takahama : ケモカインCCL21を発現する胸腺髄質上皮細胞は自己抗原発現髄質上皮細胞への分化活性を有する, 第32回 Kyoto T Cell Conference, Jun. 2023.
3.
藤江 亮之介, 藤原 翔, 黒蕨 馨, Izumi Ohigashi and 早坂 晴子 : Ccl21a 欠損マウスでの抗腫瘍免疫応答亢進における制御性 T 細胞の関与, 第45回日本分子生物学会年会, Nov. 2022.
4.
Izumi Ohigashi, Frantzeskakis Melina and Yousuke Takahama : The thymoproteasome hardwires the TCR repertoire of CD8+ T cells in the cortex independent of negative selection, 第45回日本分子生物学会年会, Nov. 2022.
5.
Sayumi Fujimori, Izumi Ohigashi, Yousuke Takahama and 高田 慎治 : Fine-tuning of beta-catenin in mouse thymic epithelial cells is required for postnatal T-cell development, 第45回日本分子生物学会年会, Nov. 2022.
6.
Sayumi Fujimori, Yousuke Takahama, 高田 慎治 and Izumi Ohigashi : 出生後T細胞の産生における胸腺上皮細胞のβ-cateninの役割, 第31回Kyoto T Cell Conference(KTCC), May 2022.
Izumi Ohigashi, Hidetaka Kosako and Yousuke Takahama : Trans-omics impact of thymoproteasome in cortical thymic epithelial cells, 第42回日本分子生物学会年会, Dec. 2019.
10.
Sayumi Fujimori, Izumi Ohigashi, Yousuke Takahama and 高田 慎治 : Fine-tuning of the β-catenin-dependent signaling in mouse thymic epithelial cells is required for thymic development, 第42回日本分子生物学会年会, Dec. 2019.
Sayumi Fujimori, Izumi Ohigashi, Takada Shinji and Yousuke Takahama : Enforced activation of β-catenin signaling in mouse thymic epithelial cells induces thymic dysplasia, The 41st Annual Meeting of the Molecular Biology Society of Japan, Nov. 2018.
16.
Yamamoto Yohhei, Naoko Matsui, Kazuya Kondo, Izumi Ohigashi, Yousuke Takahama, Nakagawa Hidewaki, Yuishin Izumi and Ryuji Kaji : Analysis of human thymic epithelial cells, 第59回日本神経学会学術大会, May 2018.
17.
Izumi Ohigashi, Naozumi Ishimaru, Katakai Tomoya and Yousuke Takahama : Essential role of CCL21 in establishment of central tolerance in T cells, 第40回 日本分子生物学会年会, Dec. 2017.
Naoko Matsui, Izumi Ohigashi, Yamamoto Yohei, Kazuya Kondo, Yousuke Takahama and Ryuji Kaji : Approach for analysis of human thymic epithelial cells, XX World Congress of Neurology, Sep. 2017.
21.
Uddin Myn, Izumi Ohigashi and Yousuke Takahama : Foxn1-binding cis-regulatory element required for optimal CD8+ T cell production in the thymus, 第46回日本免疫学会学術集会, Dec. 2016.
金 喜栄, Naoko Matsui, Izumi Ohigashi, 古川 貴大, Yousuke Takahama and Ryuji Kaji : ヒト胸腺を用いた胸腺上皮細胞解析への試み, 第57日本神経学会学術大会, 367, May 2016.
25.
Myn Uddin, Izumi Ohigashi and Yousuke Takahama : Foxn1-binding cis-regulatory element for optimal CD8+ T cell production in the thymus, 第26回 Kyoto T cell Conference, May 2016.
Mina Kozai, Izumi Ohigashi and Yousuke Takahama : Defective self-tolerance in CCL21-deficient mice, 第44回日本免疫学会総会学術集会, Nov. 2015.
28.
Izumi Ohigashi and Yousuke Takahama : Differentiation potential of b5t+ thymic epithelial progenitors, 第44回日本免疫学会総会学術集会, Nov. 2015.
29.
Izumi Ohigashi and Yousuke Takahama : 成体の胸腺髄質上皮は髄質系列細胞によって維持・再生される, 第25回 Kyoto T Cell Conference, May 2015.
30.
Bongju Kim, Izumi Ohigashi and Yousuke Takahama : 胸腺上皮細胞におけるミトコンドリアの役割, 第92回日本生理学会大会, Mar. 2015.
31.
Bongju Kim, Izumi Ohigashi and Yousuke Takahama : Role of mitochondria in thymic epithelial cells, 第43回日本免疫学会学術集会, Dec. 2014.
32.
Bongju Kim, Izumi Ohigashi and Yousuke Takahama : Role of mitochondria in thymic epithelial cells, 第43回日本免疫学会学術集会, Dec. 2014.
33.
Izumi Ohigashi and Yousuke Takahama : 5t+ progenitors contribute to the maintenance and regeneration of medullary thymic epithelial cells, 第43回日本免疫学会学術集会, Dec. 2014.
34.
香西 美奈, Izumi Ohigashi and Yousuke Takahama : Defective T cell tolerance in CCL21 knockout mice, 第43回日本免疫学会学術集会, Dec. 2014.
Naoko Matsui, Izumi Ohigashi and Yousuke Takahama : Increased Hassalls corpuscles in myasthenia gravis patients carrying thymic hyperplasia, 41st Annual Meeting of The Japanese Society for Immunology, Dec. 2012.
Takeshi Nitta, Izumi Ohigashi, Yasushi Nakagawa and Yousuke Takahama : Lympho-epithelial complexes in the thymic cortex, 第40回日本免疫学会学術集会, Nov. 2011.
48.
Izumi Ohigashi and Yousuke Takahama : Identification of the transgenic integration site in immunodeficient tgε26 human CD3ε transgenic mice, 第40回日本免疫学会学術集会, Nov. 2011.
The mechanism regulating the development of thymic epithelial cells (Project/Area Number: 17K08884 )
Positive selection of T cells in the thymic cortex (Project/Area Number: 16H02630 )
Molecular mechanism of the development of thymic epithelial cells (Project/Area Number: 15K19130 )
Development and developmental potential of beta5t-expressing thymic epithelial cells (Project/Area Number: 25860361 )
The challenge for the development of therapy for autoimmune disorder by the establishment of artificial thymic medullary organ (Project/Area Number: 23659241 )
Molecular basis for the thymic microenvironments that characterize the immune system (Project/Area Number: 23249025 )