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Biomedical subjects

E Azuma

Publications and source records attributed to E Azuma.

At least 19 recordsLinked to original sources
PubMed2001

A pivotal role of Rho GTPase in the regulation of morphology and function of dendritic cells.

Dendritic cell (DC) is the most potent activator of CD4+ T cells and has unique dendrites and veils. To explore the function of Rho in DC, exoenzyme C3 from Clostridium botulinum was used as a specific inhibitor of Rho. Treatment of DC with C3 (DC/C3) resulted in profound morphological changes by losing dendrites and emerging of shrunk membrane processes that were in parallel with marked reduction of polymerized actin in the marginal area. Inactivation of Rho-associated coiled coil-containing kinase (p160ROCK) by a specific ROCK inhibitor Y-27632 also led to disappearance of dendrites of DC with retaining large membrane expansions. In scanning electron microscopy, untreated DCs interacted with CD4+ T cells more efficiently than DC/C3. Conjugate formation assay showed that the number of DCs associated with CD4+ T cells was 2-fold higher in untreated DCs than that of DC/C3. Alloantigen-presenting capacity of DC/C3 was significantly suppressed in a dose-dependent manner. Because C3 treatment did not affect the surface expression of HLA, costimulatory, and adhesion molecules of DC, we examined cytokine production of DC and naive CD4+ T cells to further elucidate the inhibitory mechanism of MLR. Unexpectedly, DC/C3 increased IL-12 production after LPS stimulation. Naive CD4+ T cells cocultured with DC/C3 produced the increased percentage of IFN-gamma-producing cells, whereas the percentage of IL-2-producing T cells was decreased. These results demonstrate that Rho GTPase in DC controls both characteristic shape and immunogenic capacity.

ADP Ribose Transferases↗
PubMed2001

Involvement of urban living environments in atopy and enhanced eosinophil activity: potential risk factors of airway allergic symptoms.

BACKGROUND: Airway allergic diseases, such as bronchial asthma and allergic rhinitis, have increased, especially in urban areas. These diseases are characterized by airway inflammation with enhanced eosinophil activity, and the risk of disease development has been shown to increase with the prevalence of atopy. METHODS: Questionnaires were administered to 426 healthy adult women aged 30-74 years, living in an urban area of Osaka, Japan, to survey individual living environments and airway allergic symptoms such as cough, sputum, and wheezing. Moreover, serum house-dust-mite (Dermatophagoides pteronyssinus, [Der p])-specific immunoglobulin E (IgE) and serum eosinophil cationic protein (ECP) were examined by radioimmunoassay, and the atopic status (atopic sensitization) and enhanced eosinophil activity were assessed as Der p-specific IgE RAST scores of 2-6 and ECP levels of more than 10 ng/ml, respectively. RESULTS: Intensive use of electric air conditioners in hot weather (odds ratio: 2.07 [95% CI: 1.11-3.87]) and mold proliferation in the kitchen (2.77 [1.34-5.73]) significantly increased the risk of atopic sensitization. Poor home ventilation and family smoking appeared to be positively but not significantly associated with atopic sensitization. Personal smoking and intensive use of the air conditioner appeared to be positively related to enhanced eosinophil activity. Atopic status showed significant involvement in the development of wheezing, and the development of cough was significantly associated with enhanced eosinophil activity. CONCLUSIONS: The results suggest that some urban styles of living are involved in atopic sensitization and enhanced eosinophil activity in the Japanese urban population, probably due to living conditions, such as indoor dampness and poor home ventilation, caused by tight insulation, which increase exposure to indoor air pollutants, such as respirable mite allergens and tobacco smoke.

Adult↗
PubMed2001

Successful unrelated BMT in a patient with Kostmann syndrome complicated by pre-transplant pulmonary 'bacterial' abscesses.

Kostmann syndrome, severe congenital neutropenia, is often associated with life-threatening bacterial infections. A 5-year-old girl with Kostmann syndrome developed pulmonary abscesses. She was refractory to granulocyte colony-stimulating factor and antibiotics. She underwent unrelated HLA-matched BMT. Myeloablative conditioning consisted of 12-Gy TBI with lung shielding, antithymocyte globulin, etoposide, and cyclophosphamide. After successful engraftment, the pulmonary abscesses resolved by day 75 post-transplant. Although the option of transplantation is not established in the setting of unrelated HLA-matched BMT in Kostmann syndrome, this case may provide useful information. Furthermore, pre-transplant pulmonary bacterial abscesses may not be a contraindication for BMT in some patients with Kostmann syndrome.

Bone Marrow Transplantation↗
PubMed2001

Differential responsiveness of cord and adult blood monocytes to hepatocyte growth factor.

Monocytes as antigen-presenting cells play an important role in host defence. There are several cytokines affecting monocyte function. We demonstrate that both adult and cord blood monocytes constitutively express hepatocyte growth factor (HGF) receptor, MET. HGF significantly down-regulated MET expression of adult blood monocytes, compared with cord blood monocytes, when cultured either in RPMI-1640 containing 10% FBS or serum-free medium. Surface levels of MET correlated with c-met mRNA levels both in adult and cord blood when cultured. MET expression was down-regulated by treating with actinomycin D or cycloheximide. HGF stimulated DNA synthesis of adult monocytes, but not cord blood. HGF enhanced antigen-presenting capacity of adult blood monocytes but not cord blood monocytes. HGF up-regulated HLA class I expression in adult monocytes but not in cord blood monocytes. The current results suggest that the failure of cord blood monocytes to respond to HGF may be responsible, in large part, for their functional immaturity.

Adult↗
PubMed2001

Functional immaturity of cord blood monocytes as detected by impaired response to hepatocyte growth factor.

BACKGROUND: Monocytes as antigen-presenting cells play an important role in host defense and transplantation. However, there are little reports on cord blood monocytes, and the role of monocytes in cord blood transplantation is largely unknown. METHODS AND RESULTS: There are several cytokines affecting monocyte function. These include interferon-gamma, interleukin-4, interleukin-10, granulocyte macrophage-colony stimulating factor and hepatocyte growth factor (HGF). We investigated the effect of these cytokines on antigen-presenting capacity (APC) of cord and adult blood monocytes. Using either mononuclear cells or purified CD4+ T cells as responder cells, HGF enhanced APC of adult monocytes most effectively among these cytokines. In contrast, cord blood monocytes failed to respond to HGF. As HLA, costimulatory and adhesion molecules may affect APC function, we examined these antigens of monocytes following HGF stimulation. The HGF upregulated integrin alpha5 subunit (CD49e) and intercellular adhesion molecule-1 (CD54) was expressed in adult blood monocytes, but not in cord blood. In kinetic studies, HGF downregulated c-met protein/HGF receptor expression of adult monocytes in lower concentrations and at shorter incubation time as compared with that of cord blood. CONCLUSIONS: The results suggest that impaired response of cord blood monocytes to HGF may be responsible, in large part, for their functional immaturity.

Adult↗
PubMed2000

Neonatal (cord blood) T cells can competently raise type 1 and 2 immune responses upon polyclonal activation.

In the neonate, cellular immunity has generally been hypothesized as being incompetent. Accumulating evidence from several recent studies, together with our present report, contradicts this hypothesis. T-helper cell and T cytotoxic type 1 and 2 (Th1/Th2 and Tc1/Tc2, respectively) cytokine responses to polyclonal T cell receptor (TCR) activation were assessed in medium-term cultures of human cord blood T cells using intracellular cytokine staining, which could measure the frequencies of cytokine-producing cells. In this study, we examined the responses of cord blood CD4(+) and CD8(+) T cells in regard to the production of interferon (IFN)-gamma and interleukin (IL)-4 and compared the responses with those obtained from T cells of healthy adults. We found that the responses in cord blood T cells activated with TCR stimulation were comparable to those of their adult counterparts. Moreover, the Th/Tc cells that developed in cord blood were as competent as adult cells for both IFN-gamma and IL-4 secretion. In addition, IL-12 production, which is critical for both Th1 and Tc1 responses, was equally comparable in the two groups. The production of two major cross-regulatory cytokines, tumor necrosis factor-alpha and IL-10, was similarly comparable and not significantly different between the two groups. Taken together, these results indicate that, though naive, the neonatal T cell is competent to respond to TCR-mediated stimulation and to produce both type 1 and type 2 cytokines.

Adult↗
PubMed2000

Activation-induced T cell death occurs at G1A phase of the cell cycle.

Peripheral negative selection of cycling T cells after TCR engagement and deletion of activated T cells after an immune response occur by an apoptotic process termed activation-induced cell death (AICD). The cross-linking of TCR-CD3 complex with anti-CD3 monoclonal antibody led to significant apoptotic cell death in peripheral blood T cells. To further define cell cycle restriction points for triggering AICD in T cells, we evaluated the association between cell cycle progression and death signal transduction. Simultaneous DNA / RNA quantification analysis revealed that T cells entering G1A phase of the cell cycle may acquire sensitivity to AICD. The activation of caspase-3 was induced when T cells entered G1A phase. Up-regulation of cyclin-dependent kinases (Cdk4 and Cdk6) and cyclin D3 was initiated in TCR-stimulated T cells entering G1A phase and expression of these markers steadily increased as T cells progressed from G1A into G1B phase. Interestingly, caspase-3 inhibitors could inhibit the up-regulation of these G1 cell cycle regulators and induce G0 / G1A arrest as well as the inhibition of AICD. On the basis of these results, AICD signals are most likely transduced into TCR-stimulated T cells entering G1A phase. T cells that fail to progress from G1A into G1B phase undergo AICD.

Apoptosis↗
PubMed2000

Intracellular cytokine profile of T cells from children with acute lymphoblastic leukemia.

PURPOSE: During an ongoing immune response, cytokines produced by T helper types 1 (Th1) and 2 (Th2) together with T cytotoxic types 1 (Tc1) and 2 (Tc2) are critical to the effectiveness of that response. Dysregulated expansion of one or the other subset may contribute to the impaired function of the T-cell-mediated immune system in cancer patients. In the present study we have investigated whether such dysregulation might exist in children with acute lymphoblastic leukemia (ALL). METHODS: We analyzed 61 blood samples from 45 children with B cell precursor ALL and 16 healthy children. Interleukin(IL)-2, IL-4, and interferon gamma (IFN gamma) production of their respective purified CD4+ and CD8+ T cells were assessed at the single-cell level by intracellular-cytokine-staining flow cytometry. RESULTS: At the time of diagnosis, IL-2-producing cell populations in CD4+ and CD8+ T cells were reduced below the normal range in 31 of 44 (70.5%) and 23 of 38 (60.5%) cases respectively. Similarly, IFN gamma-producing cell populations in CD4+ and CD8+ T cells decreased in 17 of 44 (38.6%) and 18 of 38 (47.4%) cases respectively. Conversely cell populations capable of IL-4 production in CD4+ and CD8+ T cell subsets were increased in 13 of 30 (43.3%) and 15 of 30 (50.0%) cases respectively. Therefore, the Th1-to-Th2 and Tc1-to-Tc2 ratios (1.6 +/- 2.2 and 7.7 +/- 6.7 respectively) were significantly lower in peripheral blood T cells of ALL patients (n = 30) than those (6.0 +/- 2.9 and 20.1 +/- 10.3 respectively) in 15 healthy controls (P < 0.0001). Although both CD45RA+/CD4+ and CD45RA+/CD8+ cells significantly increased in 43 ALL patients (P < 0.05), there existed no apparent correlation between CD45 isoform expression and cytokine (IL-2 and IFN gamma) production. Interestingly, the ability to produce both IL-2 and IFN gamma was recovered in 8 cases examined, after complete remission had been achieved. CONCLUSION: These observations suggest that, in both CD4+ and CD8+ T cells of ALL patients, there is a dysregulation in the functionality of Th1 (Tc1) and Th2 (Tc2) cells with a gross reduction of Th1 (Tc1) cell populations and an expansion in Th2 (Tc2).

Adolescent↗
PubMed2000

The reconstitution of CD45RBhiCD4+ naive T cells is inversely correlated with donor age in murine allogeneic haematopoietic stem cell transplantation.

A high incidence of opportunistic infections after unrelated bone marrow transplantation has been reported. Delayed lymphocyte recovery may be associated with opportunistic infections. Immune reconstitution is influenced by recipient age and graft-vs-host disease (GVHD). In fact, children develop GVHD less frequently than adults. However, the role of donor age is largely unknown. We examined the effect of donor age on lymphocyte reconstitution after transplant. Three-month-old BALB/c recipient mice were lethally irradiated and transplanted with allogeneic haematopoietic stem cells from A/J donor mice of different ages, ranging from 0 d to 12 months. The recovery of absolute lymphocyte counts and those of CD3+ T cells, CD4+ T cells and CD45RBhi CD4+ naive T cells in the early post-transplant period correlated inversely with donor age. Recipient mice transplanted with haematopoietic stem cells from younger donors showed significantly higher survival rates and mitogenic responses than adult donors. As T cells, especially CD4+ naive T cells, play an important role in host defence, faster recovery of CD4+ naive T cells in younger donors may contribute to reduced mortality in the early post-transplant period. The results suggest that it could be better to choose a younger donor if sufficient cell dose is available.

Aging↗
PubMed2000

Somnolence syndrome in a child following 1200-cGy total body irradiation in an unrelated bone marrow transplantation.

Neurological complications may occur following intensive chemotherapy and hematopoietic cell transplantation. Postirradiation somnolence syndrome has been observed in children with acute lymphoblastic leukemia who received central nervous system preventive therapy with 1800-2400 cGy cranial irradiation. The authors report a 16-year-old boy with chronic myelogenous leukemia in chronic phase, who developed symptoms compatible with the somnolence syndrome (SS) 6 weeks following HLA-matched unrelated bone marrow transplantation (BMT). The preparative regimen consisted of 1200 cGy total body irradiation (TBI), cytosine arabinoside and cyclophosphamide. The patient developed lethargy and low-grade fever, with intermittent rhythmical delta activity in electroencephalograph. He recovered spontaneously without specific therapy 3 weeks after developing symptoms. This is the first report describing that as low as 1200 cGy TBI can induce SS in a child. After allogeneic BMT, some patients develop neurological symptoms. The authors suggest that somnolence syndrome should be included in differential diagnosis in these patients.

Adolescent↗
PubMed1999

mRNA expression of variant Fas molecules in acute leukemia cells.

Fas (Apo-1/CD95) is a cell membrane receptor involved in apoptotic cell death. Soluble variant forms (sFas) lacking the transmembrane domain due to alternative splicing have been identified. Up-regulation of sFas expression is reportedly implicated in prereceptorial blockage of Fas-induced apoptosis in a dose-dependent manner. We examined mRNA expression of Fas and sFas in fresh leukemia cells. All leukemia cells expressed both mRNAs of full-length Fas (FasFull) and sFas with deletion of exon6 (FasDel6). The ratio of FasFull/FasDel6 mRNA expression was not always correlated with Fas-mediated growth inhibition. Interestingly, in a 6-year-old boy with acute myelogenous leukemia, blast cells obtained at onset and at the time of bone marrow relapses expressed distinct amounts of FasDel6 mRNA. Furthermore, the level of FasDel6 expression appeared to be correlated with Fas-resistance in leukemia blasts. In addition, sFas protein levels were elevated in patients' sera at onset with subsequent return to normal levels after complete remission. These results indicated that sFas could be synthesized and released by leukemia blasts and suggested that up-regulation of Fas variant transcript might render leukemia blasts resistant to Fas-mediated growth inhibition in certain cases.

Acute Disease↗
PubMed1999

Expression of homing-associated cell adhesion molecule (H-CAM/CD44) on human CD34+ hematopoietic progenitor cells.

We investigated the expression of CD44 molecule on CD34+ hematopoietic progenitor cells. Significantly lower expression of CD44 was observed on bone marrow (BM) CD34+ cells compared with circulating CD34+ cells in cord blood and peripheral blood. Using fluorescence-activated cell sorting, human CD34+ BM cells were fractionated into CD44+ and CD44- populations. Immunofluorescence analysis revealed that the majority of CD34+CD44- cells expressed B-lymphocyte-associated CD10 and CD19 antigens, whereas only a part of CD34+CD44+ cells were positive for CD19. Myeloid and erythroid progenitor cells were found predominantly in CD34+ CD44+ cell fractions. In short-term suspension cultures, cell proliferation and G1-->S transition in the cell cycle were enhanced in CD34+CD44+ cells. In contrast, a large part of CD34+CD44- cells underwent apoptotic cell death. Although co-culture with BM stromal cells could partially prevent CD34+CD44- cells from undergoing apoptosis, significant increase of apoptotic cells was consistently observed. Furthermore, CD34+CD44- cells plated on BM stromal cells could differentiate into CD34-CD44-CD10-CD19+ cells. These findings suggest that CD34+CD44- cells expressing CD19 would represent unique B-lymphocyte-committed precursors in BM, which might undergo apoptotic cell death in the early steps of B-cell differentiation.

Adult↗
PubMed1999

Human dendritic cells express the thrombopoietin receptor, c-Mpl.

Human thrombopoietin (TPO) is a haemopoietic growth factor that is essential for the growth and development of megakaryocytes. However, c-Mpl, the TPO receptor, has been detected in human leukaemic cell lines with a myelomonocytic phenotype. These results raise the possibility that dendritic cells (DC), a putative myeloid lineage cell, may also express c-Mpl and respond to TPO. In haemopoietic stem cell transplantation, DC could induce graft-versus-host disease by its strong antigen-presenting capacity. In this study we have examined the effect of TPO on differentiation and the antigen-presenting capacity of DC. To differentiate DC, cord blood CD34+ cells were cultured in the presence of a cytokine cocktail either in serum-free medium or RPMI1640 containing 10% fetal bovine serum. Flow cytometric analysis and immunocytochemical staining demonstrated that c-Mpl was expressed on DC. Furthermore, the expression of c-Mpl mRNA was detected in DC by RNase protection assay. However, when TPO was added to the culture system there were no significant changes in the differentiation and mixed leucocyte-stimulating capacity of DC. These findings suggest that TPO may be administered following cord blood transplantation without significant augmentation of antigen presentation mediated by DC.

Cell Division↗
PubMed1999

Epitopes and functional responses defined by a panel of anti-Fas (CD95) monoclonal antibodies.

Fas (CD95) is a cell surface glycoprotein that mediates apoptotic cell death when cross-linked with agonistic anti-Fas monoclonal antibodies (MAbs) or the endogenous Fas ligand. In this study, we investigated the in vitro biological properties of a panel of anti-human Fas MAbs. We found that five anti-Fas MAbs of IgG1 subclass (B.E28, B.G30, B.L25, DX2, and B.G34) induced marked apoptotic cell death in Fas-expressing leukemia cells, although this killing was delayed when compared to the cytolytic effect mediated by the prototypic anti-Fas MAb of IgM subclass (clone CH-11). On the other hand, four clones (ZB4, B.G27, B.D29, and B.K14) efficiently blocked apoptotic cell death induced by the CH-11 MAb or Fas ligand. The ability of these MAbs to inhibit cell death appeared to correlate with their relative affinity for the Fas molecule. Furthermore, different clones recognized the same epitope and elicited different effects (induction or inhibition of cell killing); conversely, different clones elicited the same effect but recognized different epitopes. These results suggest that the different biological effects of anti-Fas MAbs would not be mediated in an epitope-restricted manner. The relative binding affinity might correlate to some extent with the biological properties of the MAb.

Animals↗
PubMed1999

[Latent factors aggravating airway allergic symptom in urban population: the involvement of urban living environments].

The involvement of urban living environments in IgE-increase (atopy) and ECP-increase (enhanced eosinophil activity), the inter-relationship of IgE-increase and ECP-increase, and their involvement in developing airway allergic symptoms were studied on a population of adult nonsmoking women, in order to elucidate the latent factors aggravating airway allergic symptoms in an urban population. In our earlier study on child asthma in 1994, we examined the relationship between living environments and mite proliferation in asthma and non-asthma groups and the involvement of mite proliferation in developing atopy in the non-asthma group. The asthma group consisted of 190 children under 12 years old who had been recently diagnosed as having bronchial asthma and under the care of Osaka Prefectural Habikino Hospital. The non-asthma group consisted of 78 children under 12 years old who had been under care at Osaka Prefectural Hospital but had no present history of allergic symptom. The adult woman group consisted of 423 non-smoking women who had been diagnosed as having no allergic disease by the medical examination done at Yao City, Osaka, each March from 1995 to 1997. Individual living environments such as housing and heating styles were surveyed by questionnaire. Also, the amount of mite allergen (Dp: Dermatophagoides pteronyssinus, Df: Dermatophagoides farinae) in room and bedding dust (only in the case of children) and the concentration of continine in urine were examined as objective indicators for the load of environmental allergen and the indoor air pollution by tobacco smoke, respectively. Atopy was diagnosed according to whether Dp-specific immunoglobulin E (Dp-IgE) was present/absent (positive/negative), and ECP-increase was defined as serum ECP concentration over 10 ng/ml. The results were as follows: 1. An environment of higher humidity (dampness) causing a room to become moldy appeared to enhance mite proliferation, while heating only with an electric heater or kotatsu appeared to suppress it. 2. Living environments were involved in the development of atopy in children and adult women through the effects on mite proliferation. In the case of children, heating with oil or gas heater appeared to have a positive effect while reinforced concrete housing a negative effect, probably by effects on the immune system. However, in the case of adult women, such modification was not observed. 3. Passive smoking in adult women was related to ECP-increase. 4. IgE-increase and ECP-increase appeared to be involved in each other. 5. Among airway allergic symptoms such as cough, sputum and wheeze, atopy was involved in wheeze, and ECP-increase in cough.

Adult↗
PubMed1998

Down-regulation of Fas-associated phosphatase-1 (FAP-1) in interleukin-2-activated T cells.

Peripheral T cells are resistant to Fas receptor (FasR/CD95)-mediated apoptosis. After prolonged treatment with interleukin-2 (IL-2), these T cells develop a Fas-sensitive phenotype. To clarify the molecular mechanism of apoptosis susceptibility, mRNA expression of FasR-associated proteins [Fas-associating protein with death domain (FADD), receptor-interacting protein (RIP), and Fas-associated phosphatase-1 (FAP-1)] has been investigated in IL-2 activated T cells. Competitive reverse transcriptase-polymerase chain reaction analysis revealed that FADD and RIP mRNA were equally expressed in freshly isolated resting T cells and IL-2-activated T cells. In contrast, FAP-1 mRNA was produced more abundantly by Fas-resistant resting T cells than by Fas-sensitive activated T cells. These findings suggested that sensitivity to FasR-mediated apoptosis in T cells could be correlated with down-regulation of FAP-1 expression. Additionally, CD45RO+ memory T cells expressed a larger amount of FAP-1 mRNA than did CD45RA+ naive T cells.

Adaptor Proteins, Signal Transducing↗