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Biomedical subjects

Tomoo Ueno

Publications and source records attributed to Tomoo Ueno.

13 recordsLinked to original sources
PubMed2006

Developmental kinetics, turnover, and stimulatory capacity of thymic epithelial cells.

Despite the importance of thymic stromal cells to T-cell development, relatively little is known about their biology. Here, we use single-cell analysis of stromal cells to analyze extensive changes in the number and composition of thymic stroma throughout life, revealing a surprisingly dynamic population. Phenotypic progression of thymic epithelial subsets was assessed at high resolution in young mice to provide a developmental framework. The cellular and molecular requirements of adult epithelium were studied, using various mutant mice to demonstrate new cross talk checkpoints dependent on RelB in the cortex and CD40 in the medulla. With the use of Ki67 and BrdU labeling, the turnover of thymic epithelium was found to be rapid, but then diminished on thymic involution. The various defects in stromal turnover and composition that accompanied involution were rapidly reversed following sex steroid ablation. Unexpectedly, mature cortical and medullary epithelium showed a potent capacity to stimulate naive T cells, comparable to that of thymic dendritic cells. Overall, these studies show that the thymic stroma is a surprisingly dynamic population and may have a more direct role in negative selection than previously thought.

Aging↗
PubMed2006

CCR7-dependent cortex-to-medulla migration of positively selected thymocytes is essential for establishing central tolerance.

Immature CD4+CD8+ thymocytes, which are generated in the thymic cortex, are induced upon positive selection to differentiate into mature T lymphocytes and relocate to the thymic medulla. It was recently shown that a chemokine signal via CCR7 is essential for the cortex-to-medulla migration of positively selected thymocytes in the thymus. However, the role of the cortex-to-medulla migration in T cell development and selection has remained unclear. The present study shows that the developmental kinetics and the thymic export of mature thymocytes were undisturbed in adult mice lacking CCR7 or its ligands (CCR7L). The inhibition of sphingosine-1-phosphate-mediated lymphocyte egress from the thymus led to the accumulation of mature thymocytes in the cortex of CCR7- or CCR7L-deficient mice, unlike the accumulation in the medulla of normal mice, thereby suggesting that mature thymocytes may be exported directly from the cortex in the absence of CCR7 signals. However, the thymocytes that were generated in the absence of CCR7 or CCR7L were potent in causing autoimmune dacryoadenitis and sialadenitis in mice and were thus incapable of establishing central tolerance to organ-specific antigens. These results indicate that CCR7-mediated cortex-to-medulla migration of thymocytes is essential for establishing central tolerance rather than for supporting the maturation or export of thymocytes.

Animals↗
PubMed2005

Development of autoimmunity against transcriptionally unrepressed target antigen in the thymus of Aire-deficient mice.

Autoimmune regulator (AIRE) gene mutation is responsible for the development of organ-specific autoimmune disease with monogenic autosomal recessive inheritance. Although Aire has been considered to regulate the elimination of autoreactive T cells through transcriptional control of tissue-specific Ags in thymic epithelial cells, other mechanisms of AIRE-dependent tolerance remain to be investigated. We have established Aire-deficient mice and examined the mechanisms underlying the breakdown of self-tolerance. The production and/or function of immunoregulatory T cells were retained in the Aire-deficient mice. The mice developed Sjogren's syndrome-like pathologic changes in the exocrine organs, and this was associated with autoimmunity against a ubiquitous protein, alpha-fodrin. Remarkably, transcriptional expression of alpha-fodrin was retained in the Aire-deficient thymus. These results suggest that Aire regulates the survival of autoreactive T cells beyond transcriptional control of self-protein expression in the thymus, at least against this ubiquitous protein. Rather, Aire may regulate the processing and/or presentation of self-proteins so that the maturing T cells can recognize the self-Ags in a form capable of efficiently triggering autoreactive T cells. With the use of inbred Aire-deficient mouse strains, we also demonstrate the presence of some additional factor(s) that determine the target-organ specificity of the autoimmune disease caused by Aire deficiency.

Animals↗
PubMed2005

Controlling the thymic microenvironment.

T-cell development in the thymus is a stepwise process, mediated by a variety of stromal cells in different regions of the organ. Although the cellular composition of the thymic microenvironment has been known for over a decade, the molecular cues that govern its formation are only beginning to be understood. Stromal-derived chemokines attract T-cell precursors to the thymus and direct maturing thymocytes to appropriate niches for their further development. Reciprocal signals from developing T cells provide crosstalk that is essential for establishment and maintenance of the thymic microenvironment. Elucidation of the molecular players involved and their context within the organ is the challenge for the field today. This knowledge could then be translated to clinical restoration of thymic function and T-cell reconstitution.

Animals↗
PubMed2005

Development of T-lymphocytes in mouse fetal thymus organ culture.

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 the reconstitution of thymus lobes with T-lymphoid progenitor cells, high-oxygen submersion culture, time-lapse visualization of thymic emigration, reaggregation culture, and retrovirus-mediated gene transfer to developing thymocytes in FTOC.

Animals↗
PubMed2004

The role of CCL21 in recruitment of T-precursor cells to fetal thymi.

During embryonic development, T-lymphoid precursor cells colonize the thymus. Chemoattraction by the fetal thymus is thought to mediate T-precursor cell colonization. However, the molecules that attract T-precursor cells to the thymus remain unclear. By devising time-lapse visualization in culture, the present results show that alymphoid fetal thymus lobes attract T-precursor cells from fetal liver or fetal blood. CD4(-)CD8(-)CD25(-)CD44+ fetal thymocytes retained the activity to specifically re-enter the thymus. The attraction was predominantly due to I-A-expressing thymic epithelial cells and was mediated by pertussis toxin-sensitive G-protein signals. Among the chemokines produced by the fetal thymus, CCL21, CCL25, and CXCL12 could attract CD4(-)CD8(-)CD25(-)CD44+ fetal thymocytes. However, fetal thymus colonization was markedly diminished by neutralizing antibodies specific for CCL21 and CCL25, but not affected by anti-CXCL12 antibody. Fetal thymus colonization was partially defective in CCL21-deficient plt/plt mice and was further diminished by anti-CCL25 antibody. These results indicate that CCL21 is involved in the recruitment of T-cell precursors to the fetal thymus and suggest that the combination of CCL21 and CCL25 plays a major role in fetal thymus colonization.

Animals↗
PubMed2004

CCR7 signals are essential for cortex-medulla migration of developing thymocytes.

Upon TCR-mediated positive selection, developing thymocytes relocate within the thymus from the cortex to the medulla for further differentiation and selection. However, it is unknown how this cortex-medulla migration of thymocytes is controlled and how it controls T cell development. Here we show that in mice deficient for CCR7 or its ligands mature single-positive thymocytes are arrested in the cortex and do not accumulate in the medulla. These mutant mice are defective in forming the medullary region of the thymus. Thymic export of T cells in these mice is compromised during the neonatal period but not in adulthood. Thymocytes in these mice show no defects in maturation, survival, and negative selection to ubiquitous antigens. TCR engagement of immature cortical thymocytes elevates the cell surface expression of CCR7. These results indicate that CCR7 signals are essential for the migration of positively selected thymocytes from the cortex to the medulla. CCR7-dependent cortex-medulla migration of thymocytes plays a crucial role in medulla formation and neonatal T cell export but is not essential for maturation, survival, negative selection, and adult export of thymocytes.

Animals↗
PubMed2004

NF-kappa B-inducing kinase establishes self-tolerance in a thymic stroma-dependent manner.

Physical contact between thymocytes and the thymic stroma is essential for T cell maturation and shapes the T cell repertoire in the periphery. Stromal elements that control these processes still remain elusive. We used a mouse strain with mutant NF-kappaB-inducing kinase (NIK) to examine the mechanisms underlying the breakdown of self-tolerance. This NIK-mutant strain manifests autoimmunity and disorganized thymic structure with abnormal expression of Rel proteins in the stroma. Production of immunoregulatory T cells that control autoreactive T cells was impaired in NIK-mutant mice. The autoimmune disease seen in NIK-mutant mice was reproduced in athymic nude mice by grafting embryonic thymus from NIK-mutant mice, and this was rescued by supply of exogenous immunoregulatory T cells. Impaired production of immunoregulatory T cells by thymic stroma without normal NIK was associated with altered expression of peripheral tissue-restricted Ags, suggesting an essential role of NIK in the thymic microenvironment in the establishment of central tolerance.

Animals↗
PubMed2004

Expression patterns of claudin family of tight junction membrane proteins in developing mouse submandibular gland.

Here, we investigated the expression of the claudin family of tight junction transmembrane proteins in the developing mouse submandibular gland. Data obtained by reverse transcriptase-polymerase chain reaction, Western blot, and immunofluorescence microscopy showed the expression and localization of claudin-3 to -8, -10, and -11 at epithelial tight junctions. Examination of the glands taken from embryonic day (E) 14, E16, and newborn mice revealed differential expression patterns of these claudins in the developing epithelium. Claudin-3, -5, and -7 were expressed in all of the luminal epithelial cells of the ducts at all of the developmental stages examined and in those of terminal tubules at E16 and later. Claudin-4 was expressed mainly in the ducts at all the developmental stages. The expression of claudin-6 and -8 was also restricted to the ducts at E14 and E16; but after birth, the former was undetectable, whereas the latter was expressed in both the ducts and terminal tubules. Claudin-10 and -11 were detectable mainly in the terminal tubules at E16 and later. In addition to being found in the epithelium, claudin-5 was also expressed in certain mesenchymal cells, probably endothelial cells. These results will provide a valuable resource for further investigation of tubulogenesis and physiological regulation of claudin-based tight junctions.

Animals↗
PubMed2003

T cell-specific disruption of arylhydrocarbon receptor nuclear translocator (Arnt) gene causes resistance to 2,3,7,8-tetrachlorodibenzo-p-dioxin-induced thymic involution.

The arylhydrocarbon receptor nuclear translocator (ARNT) is a member of the basic helix-loop-helix, PER-ARNT-SIM family of heterodimeric transcription factors, and serves as a dimerization partner for arylhydrocarbon receptor (AHR) and hypoxia-inducible factor-1alpha. To assess the function of ARNT in T cells, we disrupted the Arnt gene specifically in T cells of mice by conditional gene targeting using T cell-specific p56(lck)-Cre (Lck-Cre) transgenic Arnt-floxed mice. Thus generated, T cell-specific Arnt-disrupted mice (Lck-Cre;Arnt(flox/Delta) transgenic mice) exhibited complete loss of the expression of ARNT protein only in T cells, and were viable and appeared normal. The Arnt-disrupted T cells in the thymus were phenotypically and histologically normal. The Arnt-deficient T cells in the spleen were capable of responding to TCR stimulation in vitro. However, unlike normal mice in which exposure to the environmental pollutant 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), an AHR ligand, resulted in thymic involution, the thymus of Lck-Cre;Arnt(flox/Delta) mice were resistant to TCDD treatment in vivo. In contrast, benzo(a)pyrene, another AHR ligand, still caused thymic involution in Lck-Cre;Arnt(flox/Delta) mice. Finally, fetal thymus organ culture using Lck-Cre;Arnt(flox/Delta) and K5-Cre;Arnt(flox/Delta) (epithelial cell-specific Arnt-disrupted mice) showed that thymocytes rather than thymic epithelial cells are predominantly responsible for TCDD-induced thymic atrophy. Our results indicate that ARNT in T lineage cells is essential for TCDD-mediated thymic involution.

Animals↗
PubMed2003

In vivo treatment of class II MHC-deficient mice with anti-TCR antibody restores the generation of circulating CD4 T cells and optimal architecture of thymic medulla.

TCR ligation by the self-peptide-associated MHC molecules is essential for T cell development in the thymus, so that class II MHC-deficient mice do not generate CD4(+)CD8(-) T cells. The present results show that the administration of anti-TCR mAb into class II MHC-deficient mice restores the generation of CD4(+)CD8(-) T cells in vivo. The CD4 T cells were recovered in the thymus, peripheral blood, and the spleen, indicating that the anti-TCR treatment is sufficient for peripheral supply of newly generated CD4 T cells. Unlike peripheral CD4 T cells that disappeared within 5 wk after the treatment, CD4(+)CD8(-) thymocytes remained undiminished even after 5 wk, suggesting that CD4 T cells in the thymus are maintained separately from circulating CD4 T cells and even without class II MHC molecules. It was also found that the mass of medullary region in the thymus, which was reduced in class II MHC-deficient mice, was restored by the anti-TCR administration, suggesting that the medulla for CD4(+)CD8(-) thymocytes is formed independently of the medulla for CD4(-)CD8(+) thymocytes. These results indicate that in vivo anti-TCR treatment in class II MHC-deficient mice restores the generation of circulating CD4 T cells and optimal formation of the medulla in the thymus, suggesting that anti-TCR Ab may be useful for clinical treatment of class II MHC deficiencies.

Animals↗
PubMed2002

Role for CCR7 ligands in the emigration of newly generated T lymphocytes from the neonatal thymus.

Most T lymphocytes are generated within the thymus. It is unclear, however, how newly generated T cells relocate out of the thymus to the circulation. The present study shows that a CC chemokine CCL19 attracts mature T cells out of the fetal thymus organ culture. Another CC chemokine CCL21, which shares CCR7 with CCL19 but has a unique C-terminal extension containing positively charged amino acids, failed to show involvement in thymic emigration. Neonatal appearance of circulating T cells was defective in CCL19-neutralized mice as well as in CCR7-deficient mice but not in CCL21-neutralized mice. In the thymus, CCL19 is predominantly localized in the medulla including endothelial venules. These results indicate a CCL19- and CCR7-dependent pathway of thymic emigration, which represents a major pathway of neonatal T cell export.

Animals↗