Biomedical subjects

K Nomoto

Publications and source records attributed to K Nomoto.

At least 235 records · Page 13Linked to original sources

PubMed1995

The involvement of transforming growth factor beta in the impaired antitumor T-cell response at the gut-associated lymphoid tissue (GALT).

We studied the antitumor immune response in gut-associated lymphoid tissue (GALT), which is the tolerance-inducing site for numerous dietary antigens. The mice inoculated with colon 26 carcinoma (C-26) into the subserosal space of the cecum (i.c.) showed a more rapid tumor growth than did the mice inoculated s.c. with C-26 into the flank. In addition, the serum of the i.c. C-26-inoculated mice showed a more potent suppressive activity, and their plasma contained a higher level of transforming growth factor than the s.c. C-26-inoculated mice. We also evaluated the tumor-specific T-cell response in the GALT by utilizing B7-transfected P815 mastocytoma (B7/P815). The rejection of i.c. inoculated B7/P815 was delayed compared to that of the s.c. inoculated B7/P815. The draining axillary lymph node (LN) cells of the s.c. B7/P815-inoculated mice exhibited a CD4+ T-cell-dependent proliferative response to in vitro restimulation, whereas the draining mesenteric LN cells of the i.c. B7/P815-inoculated mice exhibited no apparent response even with the addition of interleukin 2. However, such draining mesenteric LN cells did produce higher levels of interleukin 2 and transforming growth factor beta than the draining axillary LN without any stimulation, and their production of such cytokines depend on the CD4+ and CD8+ cells, respectively. Collectively, our results suggest the possibility that the impaired antitumor T-cell response in the GALT may be attributed to "bystander suppression" by TGF-beta-producing CD8+ T cells.

Animals↗

PubMed1995

The GGNG peptides: novel myoactive peptides isolated from the gut and the whole body of the earthworms.

Three novel bioactive peptides, which were structurally related to each other, were purified and chemically identified from two species of the earthworms, Eisenia foetida and Pheretima vittata. One peptide was isolated from the gut tissue of E. foetida, and the other two were purified from the whole body of E. foetida and P. vittata, respectively. These peptides consisted of 17 or 18 amino acid residues and were named GGNG peptides after their unique, common structure of the C-termini. These GGNG peptides augmented both tension and frequency of spontaneous contractions of isolated gut preparations of E. foetida, and also elicited contractions of other annelidan tissues such as the polychaete esophagus and the leech vagina. However, they showed no activity on molluscan or arthropodan tissues, suggesting that GGNG peptides may be peculiar to annelids. No peptides homologous to GGNG peptides have been known so far in any living organisms.

Amino Acid Sequence↗

PubMed1995

Development of TCR-gamma delta CD4-CD8+ alpha alpha but not TCR-alpha beta CD4-CD8+ alpha alpha i-IEL is resistant to cyclosporin A.

Present evidence suggests that cyclosporin A (CSA) inhibits the development of both alpha beta and gamma delta T cells in the thymus. However, whether CSA can inhibit the development of murine intestinal intraepithelial lymphocytes (i-IEL) is unknown as most i-IEL are clearly derived from a different lineage than the conventional thymus-derived T cells found in the periphery. Using the adult thymectomized, lethally irradiated bone-marrow reconstituted chimera (ATXBM mice) as a model for the development of extrathymically derived i-IEL and the fetal thymus-grafted (FTG) nude mice as a model for the development of thymically derived i-IEL, we demonstrate that CSA nearly completely inhibited the development of extrathymically, and possibly thymically, derived TCR-alpha beta i-IEL. Most of the TCR-alpha beta i-IEL whose development was inhibited by CSA belonged to the CD4-CD8+ alpha alpha subset. In contrast, the development of extrathymically and thymically derived TCR-gamma delta i-IEL was completely resistant to CSA. The phenotype of CSA-resistant TCR-gamma delta i-IEL in these models was not different from those in control mice, and the TCR-gamma delta i-IEL in CSA-treated mice appear to be mature and activated as most were large, granular, and CD69+. Lastly, we demonstrate that CSA does not affect the extrathymic positive selection of V delta 4 i-IEL in C3H hosts. These results suggest that despite their similarity, the intracellular activation cascade involved after TCR stimulation between TCR-alpha beta CD4-CD8+ alpha alpha and TCR-gamma delta CD4-CD8+ alpha alpha i-IEL are markedly different.

Animals↗

PubMed1995

Isolation and characterization of opioid peptides in the avian brain.

Neuropeptides are supposed to be implicated in the regulation of hormone as well as nonhormone dependent behavioral processes in birds. Previous immunohistochemical studies have suggested that in birds opioid pentapeptides, Met- and Leu-enkephalins, may be present in the brain including the regions that regulate sex hormone dependent behaviors, such as reproductive behaviors. To determine biochemically the presence of opioid peptides in the avian brain, a study was conducted to isolate these peptides from Japanese quails and zebra finches. Acetic acid extracts of the quail and finch brains were respectively forced through disposable C-18 reversed-phase cartridges, and then the retained material was subjected to the cation-exchange and reversed-phase high performance liquid chromatographic (HPLC) purifications. All of the purified substances showed a single peak on the reversed-phase HPLC and these substances enhanced spontaneous contractions of the avian rectum. The purified bioactive substances were further subjected to amino acid sequence analysis and were characterized as peptides with the following sequences: Tyr-Gly-Gly-Phe-Met, Tyr-Gly-Gly-Phe-Leu, and Tyr-Gly-Gly-Phe-Met-Arg-Phe. These three peptides were identical with opioid pentapeptides, Met- and Leu-enkephalins, and a heptapeptide, Met-enkephalin-Arg6-Phe7, which had been previously isolated from mammalian species. This is the first direct demonstration of the presence of opioid peptides in the avian brain and confirms previous immunohistochemical findings suggesting a functional role for the opioid peptide in neural mechanisms of avian reproductive behavior.

Amino Acid Sequence↗

PubMed1995

Priming with donor spleen cells and activated B cells can induce prolonged survival of class I-disparate skin allografts in cyclophosphamide-treated mice.

We have previously reported a method for inducing tolerance using cyclophosphamide (CP) in a murine model, in which 200 mg/kg of CP is administered intraperitoneally 2 days after intravenous priming with donor spleen cells. The CP-induced tolerance method, however, cannot induce long-lasting skin allograft survival in an MHC class I-disparate combination. In this study, we tried to explain this phenomenon based on a costimulatory theory. That is, allo-class I-reactive host CD8+ helper T cells may receive insufficient costimulatory signals from donor spleen cells and, therefore, they are resistant to subsequently administered CP. We demonstrated that activated donor B cells, which can deliver sufficient costimulatory signals, induce a more efficient proliferation of allo-class I-reactive host CD8+ helper T cells than naive B cells in vitro. In addition, we also demonstrated that our idea can also be applied to the CP-induced skin allograft tolerance in an MHC class I-disparate combination.

Animals↗

PubMed1995

Bacterial infection of the testis leading to autoaggressive immunity triggers apparently opposed responses of alpha beta and gamma delta T cells.

The mechanisms that lead to the breakdown of self-tolerance and testis-specific immune reactivity in the murine orchitis model are understood only in part. We investigated the histopathologic and immunologic consequences of a unilateral bacterial (Listeria monocytogenes) infection of the testis. Both infected and contralateral sides of this bilateral organ suffered severe inflammatory responses despite a conspicuous absence of bacteria in the contralateral tissue. Also, in both testicles, T cell populations increased, involving both alpha beta and gamma delta T cell subsets. Concomitant with the bilateral orchitis, testis-specific delayed type hypersensitivity and Ab responses developed. Ab depletion experiments indicated that in this orchitis model, as in others, alpha beta T cells are initiators of the autoaggressive reactivity. In contrast, Ab depletion of gamma delta T cells accelerated the inflammatory response in both testicles, suggesting a regulatory role for this type of T cells in both infection-induced and autoimmune orchitis.

Animals↗

PubMed1995

Biosynthesis of phytosiderophores, mugineic acids, associated with methionine cycling.

The biosynthesis of 2'-deoxymugineic acid, a key phytosiderophore, was examined in association with the putative methionine recycling pathway in the roots of wheat using labeling experiments and structural analysis. Feeding with D-[1-13C]ribose did not result in 13C enrichment of 2'-deoxymugineic acid, while D-[2-13C]ribose resulted in 13C enrichment at the C-4", -1, -4' positions, and D-[5-13C]ribose did in C-1', -4, and -1" positions of 2'-deoxymugineic acid, respectively. Furthermore, two isotope-labeled intermediates of the methionine recycling pathway, 5-[5-2H2]methylthioribose and 2-[1-13C]keto-4-methylthiobutyric acid, were synthesized, and their incorporation into 2'-deoxymugineic acids was investigated. Six deuterium atoms at the C-4, -1', and -1" positions of 2'-deoxymugineic acid were observed after feeding with 5-[5-2H2]methylthioribose. Feeding with 2-[1-13C]keto-4-methylthiobutyric acid yielded 2'-deoxymugineic acid enriched with 13C at the C-4', -1, and -4" positions. These results demonstrated for the first time that the biosynthesis of 2'-deoxymugineic acid is associated with the methionine recycling pathway. This association system functions to recycle methionine required for continued synthesis of mugineic acids in the roots of gramineous plants.

Azetidinecarboxylic Acid↗

PubMed1995

Effects of annetocin, an oxytocin-related peptide isolated from the earthworm Eisenia foetida, and some putative neurotransmitters on gut motility of the earthworm.

Annetocin, an oxytocin-related peptide recently isolated from the lumbricid earthworm Eisenia foetida, and putative transmitter substances were examined for their effects on rhythmic, spontaneous contractions of isolated gut preparations of the earthworm. Significant, dose-dependent effects of the following substances were observed: acetylcholine (ACh), gamma-aminobutyric acid (GABA), and dopamine were excitatory, while serotonin (5-HT) and octopamine were inhibitory. Annetocin, oxytocin, and vasotocin stimulated spontaneous contraction of the earthworm gut, annetocin being approximately 10-fold more potent than oxytocin or vasotocin. However, arginine-vasopressin (Arg-vasopressin), lysine-vasopressin (Lys-vasopressin), tocinoic acid (N-terminal hexapeptide fragment of oxytocin), and MSH release-inhibiting factor (MIF; C-terminal tripeptide fragment of oxytocin) did not show any effect on the earthworm gut motility. On the other hand, oxytocin, vasotocin, Arg-vasopressin, Lys-vasopressin, and tocinoic acid caused spontaneous contractions of isolated rat uterine preparations, where the potency was in this order, while annetocin and MIF exerted no oxytocic activity on the uterus. Dose-response relationship of the effects of annetocin and its related peptides on the annelid and mammalian systems shows that amino acid residue at the third position of these peptides is important for exertion of excitatory action on the smooth muscle systems. The results in the present study suggest that receptors for annetocin and for GABA on the earthworm gut, unlike those for ACh, desensitize during continuous exposure to these substances.

Amino Acid Sequence↗

PubMed1995

Generation of T cells with differential responses to alloantigens in CD45 exon 6-deficient mice.

We characterized the CD45+ population in the CD45 exon 6-deficient mice and addressed a question as to whether the T cells keep responsive properties to alloantigens. The peripheral CD45+ T cells from the untreated knockout mice showed a decreased expression level of CD45 but increased expression levels of LFA-1 alpha and CD44, indicating that the T cells are possibly in an activation state. The CD45 exon 6-deficient mice could readily reject fully allogeneic skin grafts but not non-MHC-disparate skin grafts. The skin allograft-rejected CD45 exon 6-deficient mice showed an increased number of peripheral CD8+ T cells expressing an isoform of CD45RB (CD45 zeta). In vitro assays including mixed lymphocyte reaction, CTL, and cytokine productions were consistent to the in vivo results. Furthermore, the effector cells shown in these assays were CD45+CD8+ T cells expressing a CD45RB isoform, CD45 zeta. Moreover, the CD45+ T cells had an abnormal regulation of CD45 expression level, as they could not increase their CD45 expression level after in vitro allogeneic stimulation. These results indicate that abnormal mature T cells in the periphery of CD45 exon 6-deficient mice cannot respond to nominal Ags presented by MHC but can react to allo-MHC. The reason that such functionally impaired T cells can be generated in the mice is still unknown but these results imply that there is differential requirement of CD45 function for alloreactive T cells in a thymic selection(s) and in effector functions.

Animals↗

PubMed1995

Dibutyryl cyclic AMP protects Corynebacterium parvum-treated mice against lipopolysaccharide-induced lethal toxicity.

The effects of dibutyryl cyclic AMP (DBcAMP) on the lethal toxicity of lipopolysaccharide (LPS) were investigated in mice made hypersensitive to LPS by administration with Corynebacterium parvum (C. parvum). The peritoneal macrophages in C. parvum-treated mice released a conspicuous level of TNF alpha in response to LPS in vitro. These macrophages exhibited much higher susceptibility to LPS-induced cytotoxicity than with resident or peptone-induced macrophages. Pretreatment of the C. parvum-induced macrophages with DBcAMP significantly inhibited the TNF alpha production in response to LPS and decreased the susceptibility to LPS-induced cytotoxicity in vitro. Similar to the findings seen in in vitro experiments, in vivo administration with DBcAMP significantly inhibited the TNF alpha release in the sera of C. parvum-treated mice after LPS challenge and consequently decreased the susceptibility to LPS-induced shock. These results suggest that raising level of intracellular cAMP protects C. parvum-treated mice from hypersensitivity to lethal toxicity of LPS through downregulating TNF alpha synthesis.

Animals↗

PubMed1995

Tolerance induction in a fully allogeneic combination using anti-T cell receptor-alpha beta monoclonal antibody, low dose irradiation, and donor bone marrow transfusion.

In a murine strain combination disparate in both H-2 antigens and minor histocompatibility antigens consisting of C57BL/6 (B6; H-2b, Mls-1b) mice as recipients and AKR/J (AKR; H-2k, Mls-1a) mice as donors, we reported that the administration of anti-TCR-alpha beta mAb nonspecifically suppresses the ability to reject allografts. However, such an effect was only temporary and all grafts were eventually rejected within 40 days in the anti-TCR-alpha beta mAb-treated mice. In this study, to induce donor-specific tolerance, the transfer of donor bone marrow cells was added to the administration of anti-TCR-alpha beta mAb but donor bone marrow cells were rejected and failed to cause donor-specific unresponsiveness. After donor bone marrow cell transfer in the anti-TCR-alpha beta mAb-treated mice, the B cells of the recipients were observed along with the production of antidonor antibody. To abolish the residual lymphocyte populations, low dose irradiation was also added. A long-lasting skin allograft tolerance can be achieved by the tolerance system, in which low dose irradiation was added to the combined treatment with anti-TCR-alpha beta mAb and transfer of donor bone marrow cells. Such a protocol also established central and peripheral chimerism, which suggests that hematopoietic chimerism is necessary to maintain the tolerance. B cells were completely abolished in recipients given this combined treatment and their antibody production against donor antigens after the transfer of donor bone marrow cells was also completely suppressed. A possible role of B cells in the rejection of donor bone marrow cells before the establishment of chimerism is discussed.

Animals↗

PubMed1995

Early appearance of T cell receptor alpha beta + CD4- CD8- T cells with a skewed variable region repertoire after infection with Listeria monocytogenes.

We found that the number of T cell receptor (TCR) alpha beta + CD4- CD8- T cells increased in the peritoneal cavity on day 5 after an intraperitoneal infection with Listeria monocytogenes strain EGD together with TCR gamma delta + CD4- CD8- T cells. Thereafter, the TCR alpha beta + CD4- CD8- T cells decreased to a normal level by day 14. The TCR alpha beta + CD4- CD8- T cells showed an activated T cell phenotype (L-selectin CD44 +) and expressed CD45/B220 and interleukin-2 receptor beta, but did not express heat stable antigen, which is expressed by the immature CD4- CD8- thymocytes. Furthermore, 20-30% of the TCR alpha beta + CD4- CD8- T cells expressed the NK1.1 natural killer cell marker. Analysis of the TCR V region repertoire of the TCR alpha beta + CD4- CD8- T cells induced by L. monocytogenes infection showed that more than 80% of the TCR alpha beta + CD4- CD8- T cells expressed TCR V beta 8 detected by anti-TCR V beta 8.1 and 8.2 mAb, and a reverse transcription-polymerase chain reaction analysis of V alpha 14 relative to V alpha 11 expression revealed that the TCR alpha beta + CD4- CD8- T cells expressed a higher level of V alpha 14, which was reported to be preferentially expressed by TCR alpha beta + CD4- CD8- thymocytes rather than conventional CD4+ T cells. The TCR alpha beta + CD4- CD8-T cells showed a proliferative response to anti-TCR alpha beta mAb stimulation. In contrast, they showed no response to stimulation with either Listeria antigen or 65-kDa heat shock protein of Mycobacterium bovis, which do stimulate the Listeria-specific TCR alpha beta + CD4- CD8- T cells and the Listeria-induced TCR gamma delta + T cells, respectively. These results suggest that the TCR alpha beta + CD4- CD8- T cells may recognize a restricted set of self antigens induced by L. monocytogenes infection, and that they contribute to host protection at an early stage of infection.

Animals↗

PubMed1995

Precursor cells to CD3-intermediate (CD3int) liver mononuclear cells in the adult liver: further evidence for the extrathymic development of CD3int liver mononuclear cells.

Liver mononuclear cells (LMNC) can be divided into CD3-high positive (CD3hi), CD3-intermediate positive (CD3int) and CD3- populations. CD3int LMNC, but not CD3hi LMNC, are considered to be extrathymically derived because they are found in the liver of nude mice and adult thymectomized lethally irradiated bone marrow chimeras. CD3int LMNC express NK1.1 and show a skewed T cell receptor (TCR) V region repertoire with relatively high levels of V beta 8 and V alpha 14 expression, further suggesting that they belong to a different lineage from conventional T cells, which lack NK1.1 expression and V region skewing. Since the liver has been proposed to be a site of extrathymic T cell differentiation in adult mice, we analyzed LMNC for the presence of T cell precursors. CD3- LMNC contained CD4- CD8- cells and CD4lo CD8- cells. Reverse transcription-polymerase chain reaction analysis showed both CD3- populations express the recombination-activating gene -1, which is indispensable in gene rearrangement of TCR and expressed by thymic T cell precursors. Furthermore, when electronically sorted CD3- LMNC were cultured in medium without any feeder cells or exogenously added cytokines for 24 h, CD3int cells, but not CD3hi cells, appeared. These results suggest that the adult liver contains T cell precursors that lack the expression of the CD3/TCR complex, but are strongly committed to differentiate into extrathymic liver CD3int T cells.

Animals↗

PubMed1995

Differential requirements of CD45 for lymphocyte development and function.

CD45 exon 6-deficient mice show a profound block of thymocyte development at a transitional differentiation step from immature CD4+ CD8+ to mature single-positive cells. Only a few T lymphocytes are observed in the periphery of such animals, but B cell development is not affected. We investigated whether mature B lymphocytes in CD45 exon 6-deficient mice have normal functions in the absence of CD45 expression and show here that CD45-defective B lymphocytes from CD45 exon 6-deficient mice have intact B lymphocyte functions, including T-dependent and T-independent antigen-specific antibody production and class switching in vivo if normal CD4+ T lymphocytes were adoptively transferred into the mutant mice. From these results, we conclude that CD45 expression on B lymphocytes is not essential for B cell responses following antigen stimulation in vivo. However, CD4+ T helper function was severely diminished in CD45 exon 6-deficient mice, suggesting that the requirements of CD45 molecules in antigen-specific response and development are different between T and B lymphocytes.

Animals↗

PubMed1995

Expression of phospholipases gamma 1, beta 1, and delta 1 in primary human colon carcinomas and colon carcinoma cell lines.

The levels of expression of phosphoinositide-specific phospholipase Cs (PLCs) were examined in a series of primary human colon carcinomas and in eight colon carcinoma cell lines by using monoclonal antibodies and cDNA probes for PLC gamma 1, PLC beta 1, and PLC delta 1. Western and northern blot analyses of PLC gamma 1 revealed elevated expression of this isozyme at both the protein and mRNA levels in most tumors when compared with paired adjacent normal mucosa samples (in 11 of 13 pairs in the western blots and 8 of 9 pairs in the northern blots). On the other hand, decreased levels of the PLC delta 1 protein were seen in most colon carcinomas (12 of 13 paired samples). The levels of PLC beta 1 protein were too low to detect possible differences between the carcinoma and normal mucosa samples. Relatively high expression of PLC gamma 1 was found in almost all of the eight human colon carcinoma cell lines at both the protein and mRNA levels. Only weak expression of PLC beta 1 was detected in these cell lines, by both western and northern blot analyses, and PLC delta 1 protein was not detected in any of the carcinoma cell lines. These findings provide evidence that colon carcinomas display altered expression of individual isoforms of PLCs and suggest that increased expression of PLC gamma 1 may play an important role in colon carcinogenesis.

Adult↗

PubMed1995

Natural killer cells inhibit the development of autoantibody production in (C57BL/6 x DBA/2) F1 hybrid mice injected with DBA/2 spleen cells.

We investigated the role of natural killer (NK) cells in the development of autoantibody production in which (C57BL/6 x DBA/2) F1 (BDF1) hybrid mice were injected intravenously with spleen cells (SC) from parental DBA/2 mice (treated BDF1 mice). Treated BDF1 mice began to show an increase in serum anti-dsDNA antibody 2 weeks after injection, while the NK activity of their SC transiently increased initially in the first 1 to 2 weeks after injection, but subsequently decreased dramatically. Flow cytometric analysis suggested that this sequential change in NK activity correlated with the absolute number of host-derived NK1.1+ cells in SC from treated BDF1 mice. We demonstrated that the level of anti-dsDNA in serum is directly influenced by the level of NK activity in treated BDF1 mice. Depletion of NK cells by administration of anti-NK1.1 mAb accelerated the development of autoantibody production, whereas augmentation of NK activity by administration of poly-(I:C) inhibited the development of autoantibody production. This inhibitory effect of poly(I:C) was abolished by prior depletion of NK cells. Interestingly, suppression of autoantibody production was seen only when poly(I:C) was administrated within 1 week after injection of parental SC. Last, we demonstrate that adoptive transfer of interleukin-2 (IL-2)-activated NK cells had a protective effect against the development of autoantibody production. These findings imply that NK cells may have a protective role in lupus-like disease especially in its early stage. In addition, it opens up the possibility that adoptive immunotherapy with IL-2-activated NK cells can delay or even prevent the development of autoimmune disease.

Animals↗

PubMed1995

The antitumor activity induced by the in vivo administration of activated B cells bound to anti-CD3 monoclonal antibody.

We examined the immunotherapeutic ability of activated B cells which bound to anti-CD3 monoclonal antibody (mAb) to enhance antitumor T cell immunity in vivo. A flow cytometric analysis revealed that LPS (lipopolysaccharide)-activated B cells (LPS blasts) expressed Fc receptor (FcR) which can bind to anti-CD3 mAb. LPS blasts were also stained with CTLA-4Ig, which can bind to costimulation molecules with high affinity, which suggested that LPS blasts expressed costimulation molecules on their surface. In an in vitro assay, T cells remarkably proliferated in the presence of LPS blasts and soluble anti-CD3 mAb, whereas this proliferation was blocked by the addition of CTLA-4Ig. In a model of metastasis established by the intravenous inoculation of melanoma cells, the in vivo administration of LPS blasts incubated with anti-CD3 mAb and followed by treatment with polyethylene glycol, to reinforce the binding, induced a low but significant antitumor activity against melanoma. The antitumor activity induced by the in vivo administration of LPS blasts which bound to anti-CD3 mAb was also detected in the spontaneously established model of metastasis. These results therefore suggest that the in vivo administration of activated B cells which bound to anti-CD3 mAb was able to enhance the antitumor T cell response against metastatic melanoma.

Animals↗

PubMed1995

Effect of neonatal thymectomy on murine small intestinal intraepithelial lymphocytes expressing T cell receptor alpha beta and "clonally forbidden V beta s".

Neonatal thymectomy NTX performed on Day 3 of C3H mice causes over a 50% reduction in small intestinal intraepithelial lymphocytes (IEL) expressing the alpha beta T cell receptor (TCR) when analyzed at 10 weeks of age. Furthermore, this reduction is most notable in alpha beta TCR IEL expressing the CD8 alpha homodimer and no Thy 1 marker. This is in direct contradiction to the present theory that alpha beta TCR IEL expressing these markers are thymic independent. Evaluation of V beta expression shows a relative increase in V beta s which are clonally forbidden (V beta s 3, 5, 11), and which is consistent with the extrathymic origin of these particular IEL.

Animals↗