Tomoki Ito - Academia.edu (original) (raw)

Papers by Tomoki Ito

Journal of Gastroenterology, 2012

In the above-cited article, incorrect versions of Figs. 5a and 8a were published. The correct fig... more In the above-cited article, incorrect versions of Figs. 5a and 8a were published. The correct figures appear below.

Platelets, 2014

Abstract Dendritic cells (DCs) play an integral role in cellular cascade that initiate and mainta... more Abstract Dendritic cells (DCs) play an integral role in cellular cascade that initiate and maintain Th2 responses in allergy. In this study, we examined the interaction between platelets and DCs to determine the role of platelets in the intervention of immune responses through modulation of DC functions. Blood-purified myeloid DCs, which had been stimulated with thymic stromal lymphopoietin (TSLP-DCs), formed aggregates with activated platelets. TSLP-DC maturation was induced after the interaction with TRAP6-activated platelets as indicated by an increase in the expression of CD86, CD40, and CD83. In addition, production of a Th2 cell-attracting chemokine, CCL17, was clearly upregulated by coculture of TSLP-DCs with TRAP6-activated platelets. We further found that an expression of RANK ligand (RANKL) on platelets was upregulated by the TRAP6 activation, and that, using the neutralizing antibody against RANKL, the platelet-derived RANKL induces the activation of TSLP-DCs. Thus, activated platelets can intervene in adaptive immune responses through induction of functional modulation of TSLP-DCs. Platelets have the ability to enhance the DC-mediated Th2 response and may contribute to the allergic inflammation. In conclusion, our study provides new insights in platelet functions and the possible mechanism of allergic responses that stem from DCs.

International immunology, Jan 20, 2015

Toll-like receptor (TLR) 7and 8 were considered to recognize single-strand RNA (ssRNA) from virus... more Toll-like receptor (TLR) 7and 8 were considered to recognize single-strand RNA (ssRNA) from viruses. Although these receptors also respond to synthetic small chemical ligands, such as CL075 and R848, it remains to be determined whether these receptors sense natural small molecules or not. In the structure of human TLR8 (huTLR8) with ssRNA, there are two ligand-binding sites; one binds an uridine and the other binds an oligoribonucleotide (ORN). This finding demonstrates that huTLR8 recognizes degradation products of ssRNA, suggesting the presence of natural small ligands. We here show that TLR7 works as the sensor for guanosine (G) /2'-deoxyguanosine (dG) in the presence of ORN where ORN strengthens TLR7 interaction with G/dG. In addition, modified nucleosides such as 7-methylguanosine, 8-hydroxyguanosine (8-OHG) and 8-hydroxydeoxyguanosine (8-OHdG), activated TLR7 with ORNs. Importantly, 8-OHdG -a well-known oxidative DNA damage marker with unknown function - induced strong cyt...

The function of Hassall's corpuscles, groups of epithelial cells within the thymic medulla, h... more The function of Hassall's corpuscles, groups of epithelial cells within the thymic medulla, has remained an enigma during the last 150 years since they were discovered 1 . We report our finding that human thymic Hassall's corpuscles express thymic stromal lymphopoietin (TSLP). TSLP-conditioned, thymic dendritic cells then induce the proliferation and differentiation of CD4 + CD8 - CD25 - thymic

Laboratory investigation; a journal of technical methods and pathology, 2015

Chronic obstructive pulmonary disease (COPD) is a disease common in elderly people, characterized... more Chronic obstructive pulmonary disease (COPD) is a disease common in elderly people, characterized by progressive destruction of lung parenchyma and chronic inflammation of the airways. The pathogenesis of COPD remains unclear, but recent studies suggest that oxidative stress-induced apoptosis in alveolar cells contributes to emphysematous lung destruction. The proteasome is a multicatalytic enzyme complex that plays a critical role in proteostasis by rapidly destroying misfolded and modified proteins generated by oxidative and other stresses. Proteasome activity decreases with aging in many organs including lungs, and an age-related decline in proteasomal function has been implicated in various age-related pathologies. However, the role of the proteasome system in the pathogenesis of COPD has not been investigated. Recently, we have established a transgenic (Tg) mouse model with decreased proteasomal chymotrypsin-like activity, showing age-related phenotypes. Using this model, we de...

Journal of medical case reports, 2014

Pulmonary arterial hypertension is a fatal disease characterized by progressive remodeling of the... more Pulmonary arterial hypertension is a fatal disease characterized by progressive remodeling of the pulmonary arteries and an increase in pulmonary vascular resistance. Up to 50% of patients with systemic sclerosis have pulmonary arterial hypertension, which significantly affects the prognosis. The endothelin receptor antagonist bosentan is used for the treatment of pulmonary arterial hypertension and shows a great beneficial effect. However, the most frequent side effect of bosentan is liver toxicity, which often requires dose reduction and discontinuation. We report two cases (a 64-year-old Japanese woman and a 69-year old Japanese woman) of systemic sclerosis, both with severe Raynaud's phenomenon and pulmonary arterial hypertension. Both patients had initially received bosentan monotherapy, which caused liver toxicity as indicated by increased levels of alanine aminotransferase, alkaline phosphatase, and gamma-glutamyltransferase. After dose reduction or discontinuation of bos...

The Journal of experimental medicine, Jan 22, 2007

Although there is evidence for distinct roles of myeloid dendritic cells (DCs [mDCs]) and plasmac... more Although there is evidence for distinct roles of myeloid dendritic cells (DCs [mDCs]) and plasmacytoid pre-DCs (pDCs) in regulating T cell-mediated adaptive immunity, the concept of functional DC subsets has been questioned because of the lack of a molecular mechanism to explain these differences. In this study, we provide direct evidence that maturing mDCs and pDCs express different sets of molecules for T cell priming. Although both maturing mDCs and pDCs upregulate the expression of CD80 and CD86, only pDCs upregulate the expression of inducible costimulator ligand (ICOS-L) and maintain high expression levels upon differentiation into mature DCs. High ICOS-L expression endows maturing pDCs with the ability to induce the differentiation of naive CD4 T cells to produce interleukin-10 (IL-10) but not the T helper (Th)2 cytokines IL-4, -5, and -13. These IL-10-producing T cells are T regulatory cells, and their generation by ICOS-L is independent of pDC-driven Th1 and Th2 differentia...

Springer seminars in immunopathology, 2005

Plasmacytoid dendritic cell (pDC) precursors, also called type I IFN (alpha/beta/omega)-producing... more Plasmacytoid dendritic cell (pDC) precursors, also called type I IFN (alpha/beta/omega)-producing cells (IPCs), are the key effectors in the innate immune system because of their extraordinary capacity to produce type I IFNs against microbial infection, particularly viral infection. In contrast to myeloid DCs, human pDC/IPCs selectively express Toll-like receptor (TLR) 7 and TLR9 within the endosomal compartment. These receptors are specifically designed to recognize the nucleoside-based products derived from RNA viruses and DNA viruses. Therefore, this expression profile potentially enables pDC/IPCs to sense a variety of viruses. Stimulation of TLR7 or TLR9 leads to type I IFN responses through the MyD88 pathway. Thus, pDC/IPCs may play a central role in host defense against viral infection through the TLR7 and TLR9 system.

Experimental and molecular pathology, 2014

Obesity is a state in which chronic low-grade inflammation persists in adipose tissues. Pro-infla... more Obesity is a state in which chronic low-grade inflammation persists in adipose tissues. Pro-inflammatory cytokines, including TNF-α, produced by adipose tissues have been implicated as active participants in the development of obesity-related diseases. Since TNF-α converting enzyme (TACE) is the major factor that induces soluble TNF-α, TACE has been noted as a pivotal regulator in this field. To reveal the role of TACE in adipose tissue inflammation, TACE-transgenic (TACE-Tg) and wild type (WT) mice were fed with high fat diet (HFD) or control diet for 16 weeks. At 13 weeks after the beginning of the diet, serum TNF-α and macrophage-related cytokine/chemokine levels were elevated in TACE-Tg mice fed with HFD (Tg-HFD mice), and the number of the so-called crown-like adipocyte was significantly increased in adipose tissues of Tg-HFD mice at the end of the experiment. Although macrophage infiltration was not detected in the adipose tissues at this time, fibrosis was observed around the...

Histopathology, Jan 2, 2015

The majority of patients with Down syndrome (DS), trisomy 21, have morphologically abnormal thymu... more The majority of patients with Down syndrome (DS), trisomy 21, have morphologically abnormal thymuses and present intrinsic immunologic abnormalities affecting mainly the cellular immune response. The aim of this study was to examine whether expression of functionally important molecules is altered in thymic stromal cells in patients with DS. We analyzed thymic tissues from patients with trisomy 13 (n = 4), trisomy 18 (n = 14), and trisomy 21 (n = 13), for histological alterations, and for expression of functionally important molecules such as β5t, a thymoproteasome subunit, and cathepsins L and S. In patients with trisomy 13 and trisomy 18, the thymus was morphologically normal or showed only mild depletion of cortical thymocytes. In contrast, the thymus showed variable histological changes in patients with trisomy 21; 6 of 13 cases showed severe depletion of thymocytes accompanied by the disappearance of thymic lobular architecture. In such thymuses, spindle-shaped keratin-positive...

Allergology International, 2014

In Th2 immune responses, TSLP is a key player by induction of OX40-ligand (OX40L) on dendritic ce... more In Th2 immune responses, TSLP is a key player by induction of OX40-ligand (OX40L) on dendritic cells (DCs), which is the trigger to induce Th2 cell-mediated allergic cascade. Thus, TSLP-DC-OX40L axis might be the principal pathway in the inflammatory cascades in atopic dermatitis and asthma. IL-33, which is produced by epithelial cells, has been implicated in the Th2 immune responses and pathogenesis of the allergic disorders. However, the role of IL-33 in the Th2-polarizing TSLP-DC-OX40L axis still remains largely elusive. We focused on the ability of IL-33 to promote OX40L-mediated Th2 responses. Purified human naïve or memory CD4+ T cells were stimulated with recombinant OX40L or TSLP-treated DCs (TSLP-DCs) in the presence of IL-33, and the cytokine production by the primed T cells was examined. We also performed immunohistochemical analyses for the expression of IL-33 in specimens of lymph node and skin from the patients with atopic dermatitis. IL-33 remarkably enhanced TSLP-DCs-driven or OX40L-driven Th2 responses from naïve T cells and the Th2 functional attributes of CRTH2+ CD4+ Th2 memory cells by the increased production of IL-5, IL-9, and IL-13. In addition, IL-33 was expressed in the nuclei of epithelial cells in not only skin lesion but also lymph nodes of the patient with atopic dermatitis, suggesting a specialized role in adaptive T cell-priming phase. IL-33 works as a positive regulator of TSLP-DC-OX40L axis that initiates and maintains the Th2 cell-mediated inflammatory responses, and therefore, it would be a new therapeutic target for the treatment of allergic disorders.

Stem Cells, 2002

Here, we report that the number of CD11c + CD3 -B220cells increases in autoimmune-prone male (NZW... more Here, we report that the number of CD11c + CD3 -B220cells increases in autoimmune-prone male (NZW × BXSB)F1 (W/BF1) mice with age. The CD11c + CD3 -B220cells from W/BF1 mice show a typical stellate shape and induce the proliferation of T cells. In the CD11c + CD3 -B220cells from W/BF1 mice, CD11b (Mac-1α), NK 1.1, and CD95 (Fas) are upregulated in comparison with normal mice, while the expression of CD8α, CD117 (c-kit), CD135 (Flk-2/Flt-3), and Sca-1 decreases. There is a significant increase in Flt-3L (FL) mRNA in the bone marrow of W/BF1 mice with age. Moreover, activated hemopoietic cells express high levels of FL. The injection of CD11c + CD3 -B220cells from old W/BF1 mice to young W/BF1 mice transiently induces autoimmune disease (thrombocytopenia). These results suggest that hyperproduction of FL from activated hemopoietic cells induces a dramatic increase in the number of dendritic cells in aged W/BF1 mice, followed by the acceleration of autoimmunity. Stem Cells

Stem Cells, 2002

Using cynomolgus monkeys, we have previously established a new method for harvesting bone marrow ... more Using cynomolgus monkeys, we have previously established a new method for harvesting bone marrow cells (BMCs) with minimal contamination of the BMCs with T cells from the peripheral blood. We originally conducted this new "perfusion method" in the long bones (the humerus, femur, and tibia) of cynomolgus monkeys. Here, we apply the perfusion method to obtain BMCs from the ilium of cynomolgus monkeys, since BMCs are usually collected from the ilium by the conventional aspiration method in humans. The perfusion method consists of two approaches: transverse iliac perfusion and longitudinal iliac perfusion. BMCs harvested by the perfusion method from the long bones and ilium were compared with those collected from the ilium by the aspiration method. The contamination of BMCs with peripheral blood, determined by the frequencies of CD4+ and CD8+ T cells, was significantly lower in BMCs obtained from the ilium or long bones by the perfusion method (CD4+ plus CD8+ T cells <4%) than in those obtained by the iliac aspiration method (CD4+ plus CD8+ T cells >20%). However, the numbers of immature myeloid cells, such as myeloblasts, promyelocytes, myelocytes, and metamyelocytes, were higher in BMCs obtained by the iliac perfusion method than in those obtained by the iliac aspiration method. The assays for in vitro colony-forming unit in culture revealed that progenitor activity was significantly higher in BMCs obtained by the perfusion method than in those obtained by the aspiration method. These findings suggest that the contamination of BMCs with peripheral blood is much less when using the perfusion method than when using the aspiration method. To determine the best site for harvesting BMCs by the perfusion method, age-dependent changes in BMCs harvested by the perfusion method from the long bones and ilium were examined. The numbers of BMCs varied in the long bones (humerus > femur > tibia) and showed age-dependent decreases, whereas they remained similar in the ilium of cynomolgus monkeys from 3 years to 6 years of age. However, in cynomolgus monkeys, BMC harvesting by the perfusion method from the ilium (but not from the long bones) is found to involve the risk of fat emboli, particularly when the BMCs are quickly perfused under high pressure. These findings suggest, even in humans, that the perfusion method is better than the aspiration method, and that the best site for collection of BMCs is the humerus.

Stem Cells, 2000

To minimize contamination of bone marrow cells (BMCs) with T cells from the peripheral blood, a n... more To minimize contamination of bone marrow cells (BMCs) with T cells from the peripheral blood, a new "perfusion method" for collecting BMCs is proposed using cynomolgus monkeys. Two BM puncture needles are inserted into a long bone such as the humerus, femur, or tibia. One needle is connected to an extension tube and the end of the tube is inserted into a culture flask to collect the BM fluid. The other needle is connected to a syringe containing 30 ml of phosphate-buffered saline. The solution is pushed gently from the syringe into the medullary cavity, and the medium containing the BM fluid is collected into the culture flask. There is significantly less contamination with peripheral blood, determined from the frequencies of CD4(+) and CD8(+) T cells, when using this method (<6%) than when using the conventional method (>20%) consisting of multiple BM aspirations from the iliac crest. Furthermore, the number and progenitor activities of the cells harvested using this "perfusion method" are greater than those harvested using the conventional aspiration method. This perfusion method was carried out 42 times using 15 cynomolgus monkeys, and no complications such as pulmonary infarction or paralysis were observed. These findings suggest that the "perfusion method" is safe and simple and would be of great advantage in obtaining pure BMCs, resulting in a less frequent occurrence of acute graft-versus-host-disease in allogeneic BM transplantation.

Proceedings of the National Academy of Sciences, 2006

IL-10-producing CD4 ؉ type 1 regulatory T (Tr1) cells play a critical role in the maintenance of ... more IL-10-producing CD4 ؉ type 1 regulatory T (Tr1) cells play a critical role in the maintenance of peripheral tolerance. Although immunosuppressive drugs, cytokines, costimulatory molecules, and immature dendritic cells are implicated in the induction of Tr1 cells, the signals that negatively regulate the generation and function of Tr1 cells have been elusive. We report that OX40 ligand (OX40L) completely inhibited the generation of IL-10-producing Tr1 cells from naïve and memory CD4 ؉ T cells induced by the immunosuppressive drugs dexamethasone and vitamin D3. This unique function of OX40L was not shared by two costimulatory TNF family members, GITR ligand and 4-1BB ligand. OX40L strongly inhibited the generation of IL-10-producing Tr1 cells induced by two physiologic stimuli, the inducible costimulatory ligand and immature dendritic cells. In addition, OX40L strongly inhibited IL-10 production and suppressive function of differentiated IL-10-producing Tr1 cells. These two novel functions of OX40L shed light on the mechanism by which OX40͞OX40L regulates immunity and tolerance.

Nature, 2005

Hassall's corpuscles-first described in the human thymus over 150 years ago 1 -are groups of epit... more Hassall's corpuscles-first described in the human thymus over 150 years ago 1 -are groups of epithelial cells within the thymic medulla. The physical nature of these structures differs between mammalian species 2 . Although Hassall's corpuscles have been proposed to act in both the removal of apoptotic thymocytes and the maturation of developing thymocytes 5 within the thymus, the function of Hassall's corpuscles has remained an enigma. Here we report that human Hassall's corpuscles express thymic stromal lymphopoietin (TSLP). Human TSLP activates thymic CD11cpositive dendritic cells to express high levels of CD80 and CD86. These TSLP-conditioned dendritic cells are then able to induce the proliferation and differentiation of CD4 1 CD8 2 CD25 2 thymic T cells into CD4 1 CD25 1 FOXP3 1 (forkhead box P3) regulatory T cells. This induction depends on peptide-major histocompatibility complex class II interactions, and the presence of CD80 and CD86, as well as interleukin 2. Immunohistochemistry studies reveal that CD25 1 CTLA4 1 (cytotoxic T-lymphocyte-associated protein 4) regulatory T cells associate in the thymic medulla with activated or mature dendritic cells and TSLP-expressing Hassall's corpuscles. These findings suggest that Hassall's corpuscles have a critical role in dendritic-cell-mediated secondary positive selection of medium-to-high affinity self-reactive T cells, leading to the generation of CD4 1 CD25 1 regulatory T cells within the thymus.

Modern Rheumatology, 2008

Adult-onset Still's disease (AOSD) is a rheumatoid disorder characterized by high fever, polyarth... more Adult-onset Still's disease (AOSD) is a rheumatoid disorder characterized by high fever, polyarthritis, leukocytosis, hyperferritinaemia, and mild liver involvement. We describe the case of a patient with AOSD with severe liver dysfunction. His serum levels of interleukin-10 and 18 showed a similar trend to his disease activity. Drug lymphocyte stimulation tests were positive for three drugs in the patient. Hypercytokinaemia was controlled by plasma exchange therapy.

Modern Rheumatology, 2011

We report a 60-year-old woman with rheumatoid arthritis complicated by pericarditis. Treatment wi... more We report a 60-year-old woman with rheumatoid arthritis complicated by pericarditis. Treatment with tocilizumab improved her polyarthritis, but the pericardial effusion increased so rapidly as to cause cardiac tamponade before the treatment could prove its efficacy. Pericardial effusion disappeared after pericardiocentesis. The pericardial fluid contained a remarkably high concentration of interleukin-6 (IL-6; 351,000 pg/mL), which tocilizumab appeared to have made yet higher compared to the reported IL-6 levels in rheumatoid pericarditis. No further exacerbation of pericarditis was observed after retreatment with tocilizumab. This case has important implications in that it suggests that the prominently elevated IL-6 level in pericardial fluid during tocilizumab treatment may be an indicator of its efficacy for pericarditis.

Journal of Gastroenterology, 2012

In the above-cited article, incorrect versions of Figs. 5a and 8a were published. The correct fig... more In the above-cited article, incorrect versions of Figs. 5a and 8a were published. The correct figures appear below.

Platelets, 2014

Abstract Dendritic cells (DCs) play an integral role in cellular cascade that initiate and mainta... more Abstract Dendritic cells (DCs) play an integral role in cellular cascade that initiate and maintain Th2 responses in allergy. In this study, we examined the interaction between platelets and DCs to determine the role of platelets in the intervention of immune responses through modulation of DC functions. Blood-purified myeloid DCs, which had been stimulated with thymic stromal lymphopoietin (TSLP-DCs), formed aggregates with activated platelets. TSLP-DC maturation was induced after the interaction with TRAP6-activated platelets as indicated by an increase in the expression of CD86, CD40, and CD83. In addition, production of a Th2 cell-attracting chemokine, CCL17, was clearly upregulated by coculture of TSLP-DCs with TRAP6-activated platelets. We further found that an expression of RANK ligand (RANKL) on platelets was upregulated by the TRAP6 activation, and that, using the neutralizing antibody against RANKL, the platelet-derived RANKL induces the activation of TSLP-DCs. Thus, activated platelets can intervene in adaptive immune responses through induction of functional modulation of TSLP-DCs. Platelets have the ability to enhance the DC-mediated Th2 response and may contribute to the allergic inflammation. In conclusion, our study provides new insights in platelet functions and the possible mechanism of allergic responses that stem from DCs.

International immunology, Jan 20, 2015

Toll-like receptor (TLR) 7and 8 were considered to recognize single-strand RNA (ssRNA) from virus... more Toll-like receptor (TLR) 7and 8 were considered to recognize single-strand RNA (ssRNA) from viruses. Although these receptors also respond to synthetic small chemical ligands, such as CL075 and R848, it remains to be determined whether these receptors sense natural small molecules or not. In the structure of human TLR8 (huTLR8) with ssRNA, there are two ligand-binding sites; one binds an uridine and the other binds an oligoribonucleotide (ORN). This finding demonstrates that huTLR8 recognizes degradation products of ssRNA, suggesting the presence of natural small ligands. We here show that TLR7 works as the sensor for guanosine (G) /2'-deoxyguanosine (dG) in the presence of ORN where ORN strengthens TLR7 interaction with G/dG. In addition, modified nucleosides such as 7-methylguanosine, 8-hydroxyguanosine (8-OHG) and 8-hydroxydeoxyguanosine (8-OHdG), activated TLR7 with ORNs. Importantly, 8-OHdG -a well-known oxidative DNA damage marker with unknown function - induced strong cyt...

The function of Hassall's corpuscles, groups of epithelial cells within the thymic medulla, h... more The function of Hassall's corpuscles, groups of epithelial cells within the thymic medulla, has remained an enigma during the last 150 years since they were discovered 1 . We report our finding that human thymic Hassall's corpuscles express thymic stromal lymphopoietin (TSLP). TSLP-conditioned, thymic dendritic cells then induce the proliferation and differentiation of CD4 + CD8 - CD25 - thymic

Laboratory investigation; a journal of technical methods and pathology, 2015

Chronic obstructive pulmonary disease (COPD) is a disease common in elderly people, characterized... more Chronic obstructive pulmonary disease (COPD) is a disease common in elderly people, characterized by progressive destruction of lung parenchyma and chronic inflammation of the airways. The pathogenesis of COPD remains unclear, but recent studies suggest that oxidative stress-induced apoptosis in alveolar cells contributes to emphysematous lung destruction. The proteasome is a multicatalytic enzyme complex that plays a critical role in proteostasis by rapidly destroying misfolded and modified proteins generated by oxidative and other stresses. Proteasome activity decreases with aging in many organs including lungs, and an age-related decline in proteasomal function has been implicated in various age-related pathologies. However, the role of the proteasome system in the pathogenesis of COPD has not been investigated. Recently, we have established a transgenic (Tg) mouse model with decreased proteasomal chymotrypsin-like activity, showing age-related phenotypes. Using this model, we de...

Journal of medical case reports, 2014

Pulmonary arterial hypertension is a fatal disease characterized by progressive remodeling of the... more Pulmonary arterial hypertension is a fatal disease characterized by progressive remodeling of the pulmonary arteries and an increase in pulmonary vascular resistance. Up to 50% of patients with systemic sclerosis have pulmonary arterial hypertension, which significantly affects the prognosis. The endothelin receptor antagonist bosentan is used for the treatment of pulmonary arterial hypertension and shows a great beneficial effect. However, the most frequent side effect of bosentan is liver toxicity, which often requires dose reduction and discontinuation. We report two cases (a 64-year-old Japanese woman and a 69-year old Japanese woman) of systemic sclerosis, both with severe Raynaud's phenomenon and pulmonary arterial hypertension. Both patients had initially received bosentan monotherapy, which caused liver toxicity as indicated by increased levels of alanine aminotransferase, alkaline phosphatase, and gamma-glutamyltransferase. After dose reduction or discontinuation of bos...

The Journal of experimental medicine, Jan 22, 2007

Although there is evidence for distinct roles of myeloid dendritic cells (DCs [mDCs]) and plasmac... more Although there is evidence for distinct roles of myeloid dendritic cells (DCs [mDCs]) and plasmacytoid pre-DCs (pDCs) in regulating T cell-mediated adaptive immunity, the concept of functional DC subsets has been questioned because of the lack of a molecular mechanism to explain these differences. In this study, we provide direct evidence that maturing mDCs and pDCs express different sets of molecules for T cell priming. Although both maturing mDCs and pDCs upregulate the expression of CD80 and CD86, only pDCs upregulate the expression of inducible costimulator ligand (ICOS-L) and maintain high expression levels upon differentiation into mature DCs. High ICOS-L expression endows maturing pDCs with the ability to induce the differentiation of naive CD4 T cells to produce interleukin-10 (IL-10) but not the T helper (Th)2 cytokines IL-4, -5, and -13. These IL-10-producing T cells are T regulatory cells, and their generation by ICOS-L is independent of pDC-driven Th1 and Th2 differentia...

Springer seminars in immunopathology, 2005

Plasmacytoid dendritic cell (pDC) precursors, also called type I IFN (alpha/beta/omega)-producing... more Plasmacytoid dendritic cell (pDC) precursors, also called type I IFN (alpha/beta/omega)-producing cells (IPCs), are the key effectors in the innate immune system because of their extraordinary capacity to produce type I IFNs against microbial infection, particularly viral infection. In contrast to myeloid DCs, human pDC/IPCs selectively express Toll-like receptor (TLR) 7 and TLR9 within the endosomal compartment. These receptors are specifically designed to recognize the nucleoside-based products derived from RNA viruses and DNA viruses. Therefore, this expression profile potentially enables pDC/IPCs to sense a variety of viruses. Stimulation of TLR7 or TLR9 leads to type I IFN responses through the MyD88 pathway. Thus, pDC/IPCs may play a central role in host defense against viral infection through the TLR7 and TLR9 system.

Experimental and molecular pathology, 2014

Obesity is a state in which chronic low-grade inflammation persists in adipose tissues. Pro-infla... more Obesity is a state in which chronic low-grade inflammation persists in adipose tissues. Pro-inflammatory cytokines, including TNF-α, produced by adipose tissues have been implicated as active participants in the development of obesity-related diseases. Since TNF-α converting enzyme (TACE) is the major factor that induces soluble TNF-α, TACE has been noted as a pivotal regulator in this field. To reveal the role of TACE in adipose tissue inflammation, TACE-transgenic (TACE-Tg) and wild type (WT) mice were fed with high fat diet (HFD) or control diet for 16 weeks. At 13 weeks after the beginning of the diet, serum TNF-α and macrophage-related cytokine/chemokine levels were elevated in TACE-Tg mice fed with HFD (Tg-HFD mice), and the number of the so-called crown-like adipocyte was significantly increased in adipose tissues of Tg-HFD mice at the end of the experiment. Although macrophage infiltration was not detected in the adipose tissues at this time, fibrosis was observed around the...

Histopathology, Jan 2, 2015

The majority of patients with Down syndrome (DS), trisomy 21, have morphologically abnormal thymu... more The majority of patients with Down syndrome (DS), trisomy 21, have morphologically abnormal thymuses and present intrinsic immunologic abnormalities affecting mainly the cellular immune response. The aim of this study was to examine whether expression of functionally important molecules is altered in thymic stromal cells in patients with DS. We analyzed thymic tissues from patients with trisomy 13 (n = 4), trisomy 18 (n = 14), and trisomy 21 (n = 13), for histological alterations, and for expression of functionally important molecules such as β5t, a thymoproteasome subunit, and cathepsins L and S. In patients with trisomy 13 and trisomy 18, the thymus was morphologically normal or showed only mild depletion of cortical thymocytes. In contrast, the thymus showed variable histological changes in patients with trisomy 21; 6 of 13 cases showed severe depletion of thymocytes accompanied by the disappearance of thymic lobular architecture. In such thymuses, spindle-shaped keratin-positive...

Allergology International, 2014

In Th2 immune responses, TSLP is a key player by induction of OX40-ligand (OX40L) on dendritic ce... more In Th2 immune responses, TSLP is a key player by induction of OX40-ligand (OX40L) on dendritic cells (DCs), which is the trigger to induce Th2 cell-mediated allergic cascade. Thus, TSLP-DC-OX40L axis might be the principal pathway in the inflammatory cascades in atopic dermatitis and asthma. IL-33, which is produced by epithelial cells, has been implicated in the Th2 immune responses and pathogenesis of the allergic disorders. However, the role of IL-33 in the Th2-polarizing TSLP-DC-OX40L axis still remains largely elusive. We focused on the ability of IL-33 to promote OX40L-mediated Th2 responses. Purified human naïve or memory CD4+ T cells were stimulated with recombinant OX40L or TSLP-treated DCs (TSLP-DCs) in the presence of IL-33, and the cytokine production by the primed T cells was examined. We also performed immunohistochemical analyses for the expression of IL-33 in specimens of lymph node and skin from the patients with atopic dermatitis. IL-33 remarkably enhanced TSLP-DCs-driven or OX40L-driven Th2 responses from naïve T cells and the Th2 functional attributes of CRTH2+ CD4+ Th2 memory cells by the increased production of IL-5, IL-9, and IL-13. In addition, IL-33 was expressed in the nuclei of epithelial cells in not only skin lesion but also lymph nodes of the patient with atopic dermatitis, suggesting a specialized role in adaptive T cell-priming phase. IL-33 works as a positive regulator of TSLP-DC-OX40L axis that initiates and maintains the Th2 cell-mediated inflammatory responses, and therefore, it would be a new therapeutic target for the treatment of allergic disorders.

Stem Cells, 2002

Here, we report that the number of CD11c + CD3 -B220cells increases in autoimmune-prone male (NZW... more Here, we report that the number of CD11c + CD3 -B220cells increases in autoimmune-prone male (NZW × BXSB)F1 (W/BF1) mice with age. The CD11c + CD3 -B220cells from W/BF1 mice show a typical stellate shape and induce the proliferation of T cells. In the CD11c + CD3 -B220cells from W/BF1 mice, CD11b (Mac-1α), NK 1.1, and CD95 (Fas) are upregulated in comparison with normal mice, while the expression of CD8α, CD117 (c-kit), CD135 (Flk-2/Flt-3), and Sca-1 decreases. There is a significant increase in Flt-3L (FL) mRNA in the bone marrow of W/BF1 mice with age. Moreover, activated hemopoietic cells express high levels of FL. The injection of CD11c + CD3 -B220cells from old W/BF1 mice to young W/BF1 mice transiently induces autoimmune disease (thrombocytopenia). These results suggest that hyperproduction of FL from activated hemopoietic cells induces a dramatic increase in the number of dendritic cells in aged W/BF1 mice, followed by the acceleration of autoimmunity. Stem Cells

Stem Cells, 2002

Using cynomolgus monkeys, we have previously established a new method for harvesting bone marrow ... more Using cynomolgus monkeys, we have previously established a new method for harvesting bone marrow cells (BMCs) with minimal contamination of the BMCs with T cells from the peripheral blood. We originally conducted this new "perfusion method" in the long bones (the humerus, femur, and tibia) of cynomolgus monkeys. Here, we apply the perfusion method to obtain BMCs from the ilium of cynomolgus monkeys, since BMCs are usually collected from the ilium by the conventional aspiration method in humans. The perfusion method consists of two approaches: transverse iliac perfusion and longitudinal iliac perfusion. BMCs harvested by the perfusion method from the long bones and ilium were compared with those collected from the ilium by the aspiration method. The contamination of BMCs with peripheral blood, determined by the frequencies of CD4+ and CD8+ T cells, was significantly lower in BMCs obtained from the ilium or long bones by the perfusion method (CD4+ plus CD8+ T cells <4%) than in those obtained by the iliac aspiration method (CD4+ plus CD8+ T cells >20%). However, the numbers of immature myeloid cells, such as myeloblasts, promyelocytes, myelocytes, and metamyelocytes, were higher in BMCs obtained by the iliac perfusion method than in those obtained by the iliac aspiration method. The assays for in vitro colony-forming unit in culture revealed that progenitor activity was significantly higher in BMCs obtained by the perfusion method than in those obtained by the aspiration method. These findings suggest that the contamination of BMCs with peripheral blood is much less when using the perfusion method than when using the aspiration method. To determine the best site for harvesting BMCs by the perfusion method, age-dependent changes in BMCs harvested by the perfusion method from the long bones and ilium were examined. The numbers of BMCs varied in the long bones (humerus > femur > tibia) and showed age-dependent decreases, whereas they remained similar in the ilium of cynomolgus monkeys from 3 years to 6 years of age. However, in cynomolgus monkeys, BMC harvesting by the perfusion method from the ilium (but not from the long bones) is found to involve the risk of fat emboli, particularly when the BMCs are quickly perfused under high pressure. These findings suggest, even in humans, that the perfusion method is better than the aspiration method, and that the best site for collection of BMCs is the humerus.

Stem Cells, 2000

To minimize contamination of bone marrow cells (BMCs) with T cells from the peripheral blood, a n... more To minimize contamination of bone marrow cells (BMCs) with T cells from the peripheral blood, a new "perfusion method" for collecting BMCs is proposed using cynomolgus monkeys. Two BM puncture needles are inserted into a long bone such as the humerus, femur, or tibia. One needle is connected to an extension tube and the end of the tube is inserted into a culture flask to collect the BM fluid. The other needle is connected to a syringe containing 30 ml of phosphate-buffered saline. The solution is pushed gently from the syringe into the medullary cavity, and the medium containing the BM fluid is collected into the culture flask. There is significantly less contamination with peripheral blood, determined from the frequencies of CD4(+) and CD8(+) T cells, when using this method (<6%) than when using the conventional method (>20%) consisting of multiple BM aspirations from the iliac crest. Furthermore, the number and progenitor activities of the cells harvested using this "perfusion method" are greater than those harvested using the conventional aspiration method. This perfusion method was carried out 42 times using 15 cynomolgus monkeys, and no complications such as pulmonary infarction or paralysis were observed. These findings suggest that the "perfusion method" is safe and simple and would be of great advantage in obtaining pure BMCs, resulting in a less frequent occurrence of acute graft-versus-host-disease in allogeneic BM transplantation.

Proceedings of the National Academy of Sciences, 2006

IL-10-producing CD4 ؉ type 1 regulatory T (Tr1) cells play a critical role in the maintenance of ... more IL-10-producing CD4 ؉ type 1 regulatory T (Tr1) cells play a critical role in the maintenance of peripheral tolerance. Although immunosuppressive drugs, cytokines, costimulatory molecules, and immature dendritic cells are implicated in the induction of Tr1 cells, the signals that negatively regulate the generation and function of Tr1 cells have been elusive. We report that OX40 ligand (OX40L) completely inhibited the generation of IL-10-producing Tr1 cells from naïve and memory CD4 ؉ T cells induced by the immunosuppressive drugs dexamethasone and vitamin D3. This unique function of OX40L was not shared by two costimulatory TNF family members, GITR ligand and 4-1BB ligand. OX40L strongly inhibited the generation of IL-10-producing Tr1 cells induced by two physiologic stimuli, the inducible costimulatory ligand and immature dendritic cells. In addition, OX40L strongly inhibited IL-10 production and suppressive function of differentiated IL-10-producing Tr1 cells. These two novel functions of OX40L shed light on the mechanism by which OX40͞OX40L regulates immunity and tolerance.

Nature, 2005

Hassall's corpuscles-first described in the human thymus over 150 years ago 1 -are groups of epit... more Hassall's corpuscles-first described in the human thymus over 150 years ago 1 -are groups of epithelial cells within the thymic medulla. The physical nature of these structures differs between mammalian species 2 . Although Hassall's corpuscles have been proposed to act in both the removal of apoptotic thymocytes and the maturation of developing thymocytes 5 within the thymus, the function of Hassall's corpuscles has remained an enigma. Here we report that human Hassall's corpuscles express thymic stromal lymphopoietin (TSLP). Human TSLP activates thymic CD11cpositive dendritic cells to express high levels of CD80 and CD86. These TSLP-conditioned dendritic cells are then able to induce the proliferation and differentiation of CD4 1 CD8 2 CD25 2 thymic T cells into CD4 1 CD25 1 FOXP3 1 (forkhead box P3) regulatory T cells. This induction depends on peptide-major histocompatibility complex class II interactions, and the presence of CD80 and CD86, as well as interleukin 2. Immunohistochemistry studies reveal that CD25 1 CTLA4 1 (cytotoxic T-lymphocyte-associated protein 4) regulatory T cells associate in the thymic medulla with activated or mature dendritic cells and TSLP-expressing Hassall's corpuscles. These findings suggest that Hassall's corpuscles have a critical role in dendritic-cell-mediated secondary positive selection of medium-to-high affinity self-reactive T cells, leading to the generation of CD4 1 CD25 1 regulatory T cells within the thymus.

Modern Rheumatology, 2008

Adult-onset Still's disease (AOSD) is a rheumatoid disorder characterized by high fever, polyarth... more Adult-onset Still's disease (AOSD) is a rheumatoid disorder characterized by high fever, polyarthritis, leukocytosis, hyperferritinaemia, and mild liver involvement. We describe the case of a patient with AOSD with severe liver dysfunction. His serum levels of interleukin-10 and 18 showed a similar trend to his disease activity. Drug lymphocyte stimulation tests were positive for three drugs in the patient. Hypercytokinaemia was controlled by plasma exchange therapy.

Modern Rheumatology, 2011

We report a 60-year-old woman with rheumatoid arthritis complicated by pericarditis. Treatment wi... more We report a 60-year-old woman with rheumatoid arthritis complicated by pericarditis. Treatment with tocilizumab improved her polyarthritis, but the pericardial effusion increased so rapidly as to cause cardiac tamponade before the treatment could prove its efficacy. Pericardial effusion disappeared after pericardiocentesis. The pericardial fluid contained a remarkably high concentration of interleukin-6 (IL-6; 351,000 pg/mL), which tocilizumab appeared to have made yet higher compared to the reported IL-6 levels in rheumatoid pericarditis. No further exacerbation of pericarditis was observed after retreatment with tocilizumab. This case has important implications in that it suggests that the prominently elevated IL-6 level in pericardial fluid during tocilizumab treatment may be an indicator of its efficacy for pericarditis.