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Biomedical subjects

M Azuma

Publications and source records attributed to M Azuma.

At least 199 records · Page 11Linked to original sources
PubMed1996

Decreased inducible expression of CD80 and CD86 in human monocytes after ultraviolet-B irradiation: its involvement in inactivation of allogenecity.

Ultraviolet-B (UV-B) irradiation of antigen presenting cells (APCs) modifies their allogenecity, resulting in inhibition of the proliferative response of T cells in mixed lymphocyte reaction (MLR). Costimulation by the CD28 ligand CD80 (B7/B7-1) and CD86 (B70/B7-2) plays an important role during T-cell proliferation by augmenting synthesis of interleukin-2 (IL-2) and other cytokines. In this study, we demonstrated induced expression of both CD80 and CD86 during allogeneic MLR, though human freshly isolated monocytes express CD86 constitutively with a much lower level of CD80. A monoclonal antibody (MoAb) against CD86, but not CD80, efficiently inhibited allogeneic T-cell proliferative responses stimulated with highly purified monocytes. UV-B exposure (0 to 1,000 J/m2) of monocytes inhibited the proliferation of T lymphocytes in MLR in a dose-dependent manner. Flow cytometric analysis showed that UV-B exposure of monocytes impaired the constitutive expression of CD54 (intercellular adhesion molecule-1) by 24 hours after irradiation, but the effect on CD86 was relatively less. The surface expression of CD80, CD86, CD54, and HLA-DR on monocytes was further augmented by interferon (IFN)-gamma; this cytokine-induced expression was dose-dependently reduced by UV-B irradiation. Similarly, the upregulation of these molecules following allogeneic MLR was downregulated by UV-B irradiation. UV-B irradiation of monocytes inhibited the expression of IL-2 mRNA in monocyte-stimulated allogeneic MLR. In contrast, the addition of anti-CD28 MoAb at the onset of MLR prevented, at least partially, the reduction of IL-2 mRNA. These results strongly suggest that the impairment of inducible expression of CD86 and CD80 may contribute to the reduced MLR response following exposure of monocytes of UV-B.

Antibodies, Monoclonal↗
PubMed1996

The presence of costimulatory molecules CD86 and CD28 in rheumatoid arthritis synovium.

OBJECTIVE: To investigate the expressions of co-stimulatory molecules CD86 (B7-2, B70) and CD28 by cells obtained from the synovial tissues (ST) and synovial fluids (SF) of patients with rheumatoid arthritis (RA). METHODS: Monoclonal antibodies (MAb) against CD86 and CD28 were used for immunochemical study of synovia from 18 RA patients, 4 osteoarthritis (OA) patients, and 4 normal subjects. These MAb were also used for flow cytometry of isolated ST cells from 8 RA and 5 OA patients and of SF mononuclear cells from 5 RA and 5 OA patients. RESULTS: Immunohistochemical examination revealed that CD86+ cells occurred in 11 of the 18 RA synovia, but in none of the 4 OA or 4 normal synovia. Most of the positive cells had macrophage-like morphology, and surrounded lymphoid aggregates. Most cells within lymphoid aggregates were stained positively for CD28. Flow cytometry showed that CD86+ cells comprised 2.9-33.4% (average 14.3%) of the total ST cells and 2.1-14.9% (average 6.1%) of the total SF mononuclear cells from RA patients. Approximately 40% of the CD86+ cells expressed CD14. A majority (mean 72%, range 57-89%) of the T cells in ST and SF expressed CD28. RA synovia expressed more CD86 molecules than did OA synovia (mean frequency of positive cells 14.3% versus 2.8%; mean fluorescence intensity 104.6 versus 40.9).

Antigens, CD↗
PubMed1996

B7-1 synergizes with interleukin-12 in interleukin-2 receptor alpha expression by mouse T helper 1 clones.

Expression of interleukin-2 receptor alpha (IL-2R alpha) is critical to induce interleukin (IL)-2-dependent proliferation of T helper (Th)1 clones. The IL-2R alpha expression of Th1 clones is known to be up-regulated by IL-12. Co-stimulation via CD28/CTLA-4 is also known to be important for efficient activation of CD4+ T cells. In the present experiments, IL-12-induced enhancement of IL-2R alpha expression of Th1 clones stimulated with B cells as antigen-presenting cells (APC) is suppressed by the addition of anti-B7-1. To analyze the mechanism, Th1 clones were stimulated with immobilized anti-CD3 plus IL-12 in the presence or absence of Chinese hamster ovary cells that express mouse B7-1 (B7-1CHO) and the enhancement of IL-2R alpha expression induced by the co-stimulation was analyzed. The results of these experiments indicate that B7-1 synergizes with IL-12 in IL-2R alpha expression of the Th1 clone stimulated with anti-CD3, although B7-1CHO alone did not enhance IL-2R alpha expression of the clones. B7-1 stimulation is not mediated by the enhancement of IL-2 production: B7-1 enhancement of IL-2R alpha expression was FK506 resistant, while the inclusion of FK506 abrogated IL-2 production of the Th1 cells. B7-1 co-stimulation did not stabilize IL-2E alpha mRNA, but did synergize with IL-12 to enhance IL-2R alpha mRNA transcription.

Animals↗
PubMed1996

Antigen-specific B cells are required for the secondary response of T cells but not for their priming.

We studied the potential role of B cells in T cell responses using severe-combined immunodeficient (SCID) mice grafted with the thymus from fetal C.B-17 mice (TG mice). These mice developed both CD4+ and CD8+ T cells, but not B cells within 2 months after transplantation. TG mice showed normal delayed-type hypersensitivity responses against the immunizing antigen ovalbumin (OVA). Lymph node (LN) cells of TG mice proliferated well in response to concanavalin A (Con A). Further, Con A stimulation induced the production of interleukin (IL)-2, IL-6 and interferon (IFN)-gamma and the expression of IL-4 mRNA. Thus, TG mice were reconstituted without remarkable immunodeficiency. However, these T cells failed to proliferate to OVA stimulation. Response to OVA was also inhibited in SCID mice grafted with fetal C.B-17 liver cells when B cells were depleted in the proliferation assay. Unresponsiveness against immunizing antigen was restored by the addition of antigen-primed B cells, but not by naive B cells, lipopolysaccharide-activated B cells or B cells primed with sheep red blood cells. Next, we examined whether antigen-primed B cells could induce T cell responses without professional antigen-presenting cells (APC). T and B cells were purified from OVA-immunized mice by cell sorter. These T cells proliferated in response to OVA and produced IFN-gamma in the absence of non-B APC. When anti-CD80 or anti-CD86 was added in the assay, proliferation and IFN-gamma production was inhibited. These results indicate that B cells activated specifically with antigen are required for the secondary response of T cells, but not for their priming.

Animals↗
PubMed1996

Effect of CD80 and CD86 blockade and anti-interleukin-12 treatment on mouse acute graft-versus-host disease.

We investigated the efficacy of a combination of anti-CD80 and CD86 (CD80 + 86) monoclonal antibodies (mAb), anti-interleukin (IL)-12 mAb, or both, for prophylaxis in a mouse acute graft-versus-host-disease (GVHD) model. The treatment with a combination of anti-CD80 + 86 mAb efficiently reduced the lethality of GVHD, whereas mAb against either CD80 or CD86 alone had an effect. A delay in lymphocyte reconstitution and GVHD-associated histological changes in organs was observed at 30 days post-bone marrow transplantation (BMT) even in the anti-CD80 + 86 mAb-treated mice, although these manifestations were resolved by 100 days. In vitro, host alloantigen-specific T cell proliferative responses and generation of CTL were significantly reduced by anti-CD80 + 86 treatment. Furthermore, anti-CD80 + 86 mAb preferentially inhibited the production of interferon (IFN)-gamma, but not IL-4 and IL-10, when cultures were assayed at 21 days. Although the anti-IL-12 mAb treatment alone inhibited the generation of cytotoxic T lymphocytes and IFN-gamma production in vitro, administration of anti-IL-12 mAb in vivo reversed the beneficial effects of anti-CD80 + 86 treatment on host survival post-BMT. The adverse effect of anti-IL-12 treatment seems to result from impairment of natural immunity and hematopoiesis, rather than as a consequence of an incomplete blockade of T helper (Th)1 responses. Our results suggest that the prevention of GVHD-induced death results from the efficient blockade of Th1 cell activation by the anti-CD80 + 86 treatment. However, further treatment is required for a complete prevention of GVHD, which seems to be partly mediated by Th2 cells.

Acute Disease↗
PubMed1996

Soluble Fas molecule in the serum of patients with systemic lupus erythematosus.

The serum level of soluble Fas (sFas) molecules in 35 patients with SLE was determined by enzyme-linked immunosorbent assay (ELISA) and its relation to other lymphocyte activation markers and clinical parameters was examined. The level of sFas increased significantly compared to that in normal subjects, consistent with previous reports. There was a significant correlation between the level of sFas and that of sCD4, suggesting some relation between sFas and activation of CD4+ T cell. Patients with lymphopenia tended to have low levels of sFas, making it possible to hypothesize that sFas protects against apoptosis. Although the change in the level of sFas protects steroid therapy was variable, some relation to the differential activation of T cell subsets was suggested.

CD4 Antigens↗
PubMed1996

Different signalling pathways involved in transforming growth factor-beta 1-induced morphological change and type IV collagen synthesis in simian virus-40-immortalized normal human salivary gland duct and myoepithelial cell clones.

To understand the specific cell type responsible for the synthesis of basement membrane components of the salivary gland, the effects of transforming growth factor (TGF)-beta 1 on morphological change, cellular proliferation and collagen synthesis were examined in these immortalized duct and myoepithelial cell clones, and the expression forms of their TGF-beta receptors analysed. When TGF-beta 1 was added to the cell clones in vitro, it induced a morphological alteration, with flattening in myoepithelial but not in duct cells. Although the growth of Mv1Lu mink lung epithelial cells was almost completely inhibited by TGF-beta 1, the duct and myoepithelial cells were partially resistant to such inhibition. By immunoblot analysis of immunoprecipitates, p53 was found bound to the simian virus-40 large T antigen, suggesting a functional loss of p53 in regulation of cell-cycle arrest. In the cloned myoepithelial cells but not the duct cells, TGF-beta 1 stimulated the production of type IV collagen. To attempt to understand the distinct responsiveness of cell clones to TGF-beta 1, the expression forms of TGF-beta receptors were examined by affinity cross-linking. Although the intensities of the cross-linked bands of the TGF-beta type II and type III receptors, particularly the type II, were weaker in the duct than the myoepithelial cell clones, the expression of the type II receptor mRNA was consistently detected in both clones. Accordingly, the reduction of TGF-beta 1 binding may have occurred at the post-transcriptional level. These findings imply that the cloned myoepithelial cells but not the cloned duct cells produce type IV collagen in response to TGF-beta 1 through the receptor-mediated signal transduction pathway, which is presumably disrupted in the cloned duct cells.

Animals↗
PubMed1996

Suppression of humoral immunity by monoclonal antibody to CD79b, an invariant component of antigen receptors on B lymphocytes.

CD79b is an invariant component of antigen receptors on B lymphocytes. Previous data have suggested that monoclonal antibody (mAb) to CD79b would introduce negative signals into B lymphocytes and suppress humoral immunity. We tested this hypothesis in this study using in vitro assay systems, and revealed that anti-CD79b mAb effectively suppressed the antibody response to a T-cell dependent antigen. The speculated mechanisms for this immunosuppression were: (i) down-modulation of antigen receptors, (ii) inhibition of B lymphocyte differentiation, and (iii) induction of B lymphocyte unresponsiveness. Of these three, we confirmed that the first two were actually induced by anti-CD79b mAb treatment, whereas the in vitro system could not induce the unresponsiveness of B lymphocytes.

Antibodies, Monoclonal↗
PubMed1996

Low-temperature resistance of higher plants is significantly enhanced by a nonspecific cyanobacterial desaturase.

A broad-specificity delta 9 desaturase gene was cloned from the cyanobacterium Anacystis nidulans. The enzyme introduces a cis-double bond at the delta 9 position of both 16 and 18 carbon saturated fatty acids linked to many kinds of membrane lipids. The gene was stably introduced into tobacco plants under transcriptional control of the cauliflower mosaic virus 35S promoter, and the enzyme was targeted into plastids by the transit peptide of the pea RuBisCO small subunit. The transgenic plants had a highly reduced level of saturated fatty acid content in most membrane lipids and exhibited a significant increase in chilling resistance.

Adaptation, Physiological↗
PubMed1996

Preferential elimination of CD28+ T cells in systemic lupus erythematosus (SLE) and the relation with activation-induced apoptosis.

CD28 on T cells provides a potent costimulatory signal for T cell activation. Down-regulation of CD28 on peripheral T cells has been reported in certain clinical conditions, but full studies on the mechanism and biological significance have not been performed. Our extensive phenotype analysis of peripheral blood lymphocytes (PBL) from SLE patients revealed that the absolute number of CD28+ T cells of both CD4 and CD8 phenotypes was selectively decreased, while that of CD28- T cells was maintained. CD28+ T cells from SLE patients exhibited mostly normal proliferative responses to both CD28-dependent and -independent stimulations. In contrast, CD28- T cells were hyporesponsive to anti-CD3 stimulation in both SLE and normal controls. These results implied that the selective decrease of CD28+ T cells in SLE does not result from a hyporesponsiveness of CD28+ T cells. To investigate the reason for the selective loss of CD28+ T cells, we determined the appearance of apoptotic cells in culture with or without anti-CD3 stimulation. Apoptotic cells defined by merocyanine (MC)540 were gradually increased from 12 h to 24 h. Anti-CD3-induced apoptosis of CD28+ T cells was significantly accelerated in SLE, whereas apoptosis of CD28- T cells was hardly detected in both SLE and normal controls. Comparative analysis between CD28+ and CD28- T cells on CD95 (Fas) and Bcl-2 expression, which are related to activation-induced cell death (AICD), did not show a major difference, although CTLA4, which has been demonstrated to transmit an apoptosis-inducing signal, was expressed only on CD28+ T cells. Our results suggest that CD28-mediated costimulation influences T cell susceptibility to AICD and may be involved in T cell lymphopenia in SLE.

Adolescent↗
PubMed1996

Changes in serum fibrogenesis markers during interferon therapy for chronic hepatitis type C.

We serially measured the levels of serum N-terminal peptide of type III procollagen (PIIINP), the 7S domain of type IV collagen (IV-7S), and hyaluronate (HA) before (0 month), at the end (6 months), and 24 weeks after the end of interferon therapy (12 months) in patients with chronic hepatitis type C to estimate the effects of interferon alfa (IFN-alpha) on serum levels of hepatic fibrogenesis markers. One hundred twenty-one patients with chronic hepatitis type C received intramuscular injection of 6 million U of natural IFN-alpha for 24 weeks. Patients were divided into three groups: sustained complete response (CR-S), complete response with rebound (CR-R), and nonresponse (NR). Serum PIIINP, IV-7S, and HA levels were significantly decreased and reached normal levels at 12 months in CR-S; only IV-7S levels were significantly decreased at 12 months in CR-R, whereas these levels remained abnormally high in the NR. These results suggest that IFN-alpha therapy could lower the levels of serum hepatic fibrogenesis markers along with improvements in hepatic inflammation.

Adult↗
PubMed1996

The differential role of CD86 and CD80 co-stimulatory molecules in the induction and the effector phases of contact hypersensitivity.

Contact hypersensitivity (CH) has served as a useful model for investigating the allergen-specific immune responses of T cells and skin-associated antigen-presenting cells. We examined the distinct role between CD80 and CD86 on hapten-induced CH in both an induction and an effector phase. Intraperitoneal injection of mAb against CD86, but not CD80, 2 h before sensitization with epicutaneous application of dinitrofluorobenzene led to an almost complete inhibition of ear swelling, and histologically a marked reduction of edema, inflammatory polymorphonuclear cells and lymphocyte infiltration in the dermis. In contrast, the administration with either anti-CD80 or CD86 mAb 2 h before challenge partially inhibited CH reactions and a combination of both mAb did not improve the inhibitory effect. Although Langerhans cells (LC) expressing MHC class II were observed in both the epidermis and dermis 24 h after primary sensitization, CD86(+) LC were observed only in the subepidermal regions and CD80-bearing cells were not detected. Dendritic cells (DC) expressing both CD80 and CD86 were preferentially observed in the T cell areas of draining lymph nodes 24 h after challenge. The administration of anti-CD86 mAb in the induction phase prominently reduced the up-regulation of CD80 and CD86 on DC in the lymph nodes. The predominant role of CD86 was further supported by a marked reduction in proliferation of lymph node T cells against the sensitized hapten after the anti-CD86 treatment. These results suggest that CD86 plays a critical role in the initiation of primary immune responses in the skin, while CD80 and CD86 are not essential in the effector phase of CH reactions.

Animals↗
PubMed1996

The effects of sevoflurane on contractile and electrophysiologic properties in isolated guinea pig papillary muscles.

We examined, in guinea pig papillary muscles, whether the negative inotropic effect of sevoflurane is due to the depression of the influx of extracellular Ca2+ or to inhibition of the availability of intracellularly stored Ca2+. Sevoflurane decreased action potential duration and contractile force in a concentration-dependent fashion in normally polarized guinea pig papillary muscles. Sevoflurane produced a depression of contractile force with different rates or patterns of stimulation in the rested state and at low stimulation frequencies. In a potentiated state, sevoflurane did not depress contractile forces. Although sevoflurane decreased action potential duration and contractile force in a concentration-dependent fashion in normal Tyrode's solution, in high K+ Tyrode's solution, it caused a depression of contractile force without a shortening of action potential duration. Sevoflurane also depressed contractile force in normal and high K+ Tyrode's solution with ryanodine 1 microM. Our results suggest that in myocardial contractile force the negative inotropic effect of sevoflurane might be caused by depression of transsarcolemmal Ca2+ influx, accompanied by shortening of the action potential duration.

Action Potentials↗
PubMed1996

Functional CD86 (B7-2/B70) on cultured human Langerhans cells.

CD86 (B70/B7-2) has recently been identified as an alternative CD28/CTLA-4 ligand on activated B cells. CD86 has also been demonstrated as possibly serving as a primary costimulatory molecule in the initial immune response. Since the human Langerhans cell is one of the most potent antigen-presenting cells, we examined whether CD86 expression and function are found on organ-cultured skin, freshly isolated Langerhans cells, and cultured Langerhans cells in normal human epidermis. Immunohistochemical study in situ revealed that CD86 was expressed on dendritic cells with CD1a antigen in organ-cultured but not fresh skin. Fluorescence-activated cell sorter analysis revealed that no staining for either CD80 or CD86 was observed in freshly isolated Langerhans cells but that both CD80 and CD86 were expressed on cultured Langerhans cells. The actual expression of CD86 on cultured Langerhans cells was further confirmed by the detection of 70-kDa glycoprotein on Western blot analysis. Analysis of polymerase chain reaction demonstrated that both CD80 and CD86 were specifically amplified from purified cultured and freshly isolated Langerhans cells but not from Langerhans cell-depleted epidermal cells, indicating that both CD80 and CD86 genes were expressed by Langerhans cells. The functional importance of CD86 on Langerhans cells was confirmed by the allogeneic CD4 T cell proliferative responses with enriched Langerhans cells. A monoclonal antibody against CD86 caused 81% inhibition in contrast with 29% inhibition produced by anti-CD80 monoclonal antibody. This inhibitory effect was enhanced to 85.3% inhibition when a combination of anti-CD86 and anti-CD80 was administered. These results indicate that CD86 is predominantly expressed on the surface of cultured Langerhans cells and may transduce a primordial costimulatory signal in the interaction of Langerhans cells and T cells.

Antibodies, Monoclonal↗
PubMed1996

Biochemical characterization of alpha-fetoprotein and other serum proteins produced by a uterine endometrial adenocarcinoma.

A high serum alpha-fetoprotein (AFP) level was found in a patient with endometrial adenocarcinoma of the uterus, which appeared to be hepatoid on histological examination. The AFP of this unusual patient was purified by immunoaffinity chromatography and characterized. The electrophoretic profiles on sodium dodecyl sulfate-polyacrylamide get electrophoresis both before and after glycopeptidase F treatment were indistinguishable from those of a hepatoma AFP. This indicates that the patient's AFP was also composed of a single polypeptide chain of Mr 67,000 and an N-linked sugar chain of Mr 3,000. Amino acid sequence analyses of this AFP, and of AFP from hepatoma and umbilical cord serum indicated that the N-terminal sequences were essentially the same. The sequence, Arg-Thr-Leu-His-Arg-Asn-Glu-Tyr-Gly-Ile, was slightly different from previous reports, but matched that deduced from the cDNA sequence. AFP isoforms due to microheterogeneity of the sugar chain were analyzed by lectin affinity electrophoresis using a series of lectins. The AFP isoform profiles were distinct from those of proteins derived from cord serum, hepatoma, yolk sac tumor and gastric cancer. The reverse-transcription of RNA from the tumor tissue followed by a polymerase chain reaction using primers with AFP-specific sequences gave a product of the size and nucleotide sequence expected for AFP. mRNAs possessing the requisite sequences for albumin and transferrin syntheses were also detected in the tumor. The expression of these hepatocyte-specific proteins supported the hepatoid nature of this tumor.

Adenocarcinoma↗
PubMed1996

Increased matrix metalloproteinase-2 activity induced by TGF-beta 1 in duct cells of human salivary gland is associated with the development of cyst formation in vivo.

Proteolytic enzyme activity has been shown to be important for cyst formation. In this study, we constructed a cyst-like structure in vivo and analyzed molecular mechanisms involved in the development of the lesion. When SV40-immortalized duct cells of normal human salivary gland (NS-SV-DC) were treated with TGF-beta 1 at a concentration of 1 ng/ml or 5 ng/ml followed by co-inoculation with Matrigel into the backs of nude mice, they formed large cysts containing fluid when 5 ng/ml of TGF-beta 1 was used. Analysis of the fluid demonstrated high MMP activity. Immunohistochemical staining exhibited strong reactivity with anti-MMP-2 antibody in TGF-beta 1 (5 ng/ml)-treated NS-SV-DC. Northern blot analysis indicated that the expression of TGF-beta 1 and MMP-2 mRNAs in cells was greatly enhanced by treatment with 5 ng/ml TGF-beta 1. These findings suggest that the in vivo cyst formation by TGF-beta 1-treated cells is associated with continuous induction of MMP-2 activity.

Animals↗
PubMed1996

Analysis of phosphorylation pathways of antiherpesvirus nucleosides by varicella-zoster virus-specific enzymes.

The inhibitory activities of acyclovir (ACV), 1-beta-D-arabinofuranosyl-E-5-(2-bromovinyl)uracil (BV-araU), ganciclovir (GCV), 9-(2-deoxy-2-hydroxymethyl-beta-D-erythro-oxetanosyl)guanine (OXT-G), and (+)-9-[(1R,2R,3S)-2,3-bis(hydroxymethyl)Cyclobutyl]guanine (cOXT-G) on the replication of wild-type and thymidine kinase (TK)-negative strains of herpes simplex virus types 1 and 2 and varicella-zoster virus (VZV) and the wild-type strain of human cytomegalovirus were tested to clarity whether the phosphorylation of these compounds is catalyzed by viral TK or other enzymes. ACV and BV-araU had little effect on the replication of TK-negative virus strains. On the other hand, GCV, OXT-G, and cOXT-G inhibited the replication of TK-negative VZV at concentrations 10 times higher than those at which they inhibited wild-type VZV, indicating that a kinase other than TK phosphorylates GCV and OXT-G in VZV-infected cells. GCV phosphorylation activity was not detected in VZV-infected cell lysates; therefore, this activity was evaluated in COS 1 cells expressing viral TK and viral protein kinase (PK). The COS 1 cells expressing VZV TK were shown to be susceptible to all compounds tested. In contrast, VZV Pk-expressing COS 1 cells were susceptible to only GCV, OXT-G, and cOXT-G. These results suggest that VZV PK phosphorylates some nucleoside analogs, for example, GCV, OXT-G, and cOXT-G. This phosphorylation pathway may be important in the anti-VZV activities of some nucleoside analogs.

Acyclovir↗