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Biomedical subjects

D Mizuno

Publications and source records attributed to D Mizuno.

261 records · Page 15Linked to original sources
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Expression of tumor necrosis factor-alpha and -beta transcripts in embryonal carcinoma and trophoblast cell lines: inflammation-like state as possible regulatory mechanism for ontogenesis.

TNF-alpha and TNF-beta are both involved in inflammation which regulates homeostasis in adults. We examined the mRNA expression of TNF-alpha and TNF-beta in murine embryonal carcinoma (EC) cell lines (PCC3, PCC4, ECA2 and F9) and trophoblast cell line (PL/B6) using a combined system of reverse transcription and polymerase chain reaction. Four lines of EC cells and PL/B6 expressed mRNA of both TNFs. Moreover, mRNA expression of two types of TNF-receptor and transcription factor NF-kappa B, both of which mediate a part of the biological function of TNFs, were also detected in EC and trophoblast cells. In order to clarify whether other cytokines may form a network during embryonal development, we also examined the expression of transcripts of inflammatory cytokines produced by activated macrophages (IL-1 alpha, IL-1 beta and G-CSF) or by T lymphocytes (IL-3 and IFN-gamma) in adult. We found that no IL-1 alpha transcript was expressed in any of the cell lines examined whether differentiated or not. Contrary to this, the transcript of G-CSF was continuously expressed in all cell lines, and those of IL-1 beta, IL-3 and IFN-gamma were slightly expressed in some cell lines.

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Early embryonic cells activate the alternative complement system.

Murine embryonic stem cells, embryonic carcinoma cells and pre-implantation embryos were found to be extremely sensitive to cytolysis by normal human serum as compared to matured cells. The cytolytic activity to embryonic cells was not removed by pre-absorption of serum with spleen lymphocytes. Conditions which block both complement activation pathways or, selectively, the alternative pathway completely abrogated the activity of human serum against embryonic cells whereas the activity was retained under conditions which block the classical complement pathway, indicating that embryonic cells activate the alternative complement system (ACS). The cytotoxic effect to murine embryonic cells was reproduced using syngeneic murine serum. Concerning the mechanism of ACS-activation, the expression of regulators of complement activation and of membrane bound sialic acid was analysed. Embryonic cells express mRNA for Crry similarly to other cells but additionally express Cr2-transcripts not found in most adult cells. Embryonic cells have strikingly low levels of membrane-bound sialic acid compared to adult cells.

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Induction of differentiation in embryonic stem cells by 26-kD membrane-bound tumor necrosis factor (TNF) and 17-kD free TNF.

The biological activity of 26-kD membrane-bound tumor necrosis factor (TNF)-a in embryonal development was examined in an in vitro system using embryonic stem (ES) cells. ES cells were seeded on NIH3T3 feeder cells transformed with mouse precursor TNF-a gene to express membrane-bound TNF-a on their cell surface. The proliferation of the ES cells was reduced and differentiation was accelerated. The same effects were also observed when 17-kD free TNF-a was added to the culture medium of the ES cells. Since free TNF-a is not present during embryogenesis, these results suggest that membrane-bound TNF-a may play an important role in embryonal development through cell-cell contact.

3T3 Cells↗
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Selective lysis of early embryonic cells by the alternative pathway of complement--a possible mechanism for programmed cell death in embryogenesis.

Early embryonic cells and early mouse embryos were shown to activate the alternative pathway of complement, and to be highly sensitive to complement-mediated cytolysis (Kircheis et al, In Vivo 9: 85-98, 1995). Under further development embryonic cells become resistant. The induction of resistance to the alternative pathway of complement correlates with: a) altered splicing of Cr2-transcript and b) changes in the acidic glycolipids under differentiation. Early embryonic cells have low amounts of sialic acid-containing glycolipids or express mainly GM3. The induction of differentiation changes the glycolipid pattern leading to an increase in membrane-bound sialic acid. The importance of membrane-bound sialic acid in the restriction of complement activation is demonstrated by increased sensitivity to complement after pre-treatment of cells with neuraminidase. The results indicate that there is target-specific lysis of early embryonic cells by the alternative pathway of complement. Early embryonic cells activate the alternative pathway of complement by expressing activators and low levels of membrane-bound sialic acid. Induction of differentiation changes the glycolipid pattern, leading to an increase in membrane-bound sialic acid sufficient to restrict complement-activation on the cell surface.

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Bidirectional feedback regulation on 17 kD tumor necrosis factor (TNF) production by 26 kD membrane-bound TNF precursor.

Based on the hypothesis that 26 kD membrane-bound rumor necrosis factor precursor (proTNF) may act as a principle regulator to maintain homeostasis in an adult, we tried to examine whether proTNF shows bidirectional regulation in specific cellular response. We focused on production of 17 kD mature TNF by acute monocytic leukemia cells THP-1 after stimulation by lipopolysaccharide. ProTNF of primed THP-1 cells had been shown to act as a positive regulator for production of mature TNF by homologous cells (primed THP-1) after LPS stimulation, whereas when THP-1 cells were co-cultivated with NIH3T3 which expressed pro-TNF, production of mature TNF by THP-1 by LPS was significantly suppressed. These results suggested that pro-TNF was really involved in bidirectional feedback regulation for TNF production by THP-1 cells themselves through cell to cell contact.

3T3 Cells↗
PubMedDate not supplied

Augmentation of antitumor effect of endogenously induced tumor necrosis factor by cyclophosphamide.

The antitumor effect of endogenous tumor necrosis factor (en-TNF) with cyclophosphamide (CY) was analyzed using the murine Meth A tumor model. En-TNF was induced by the administration of interferon-gamma (4 micrograms/kg: 1 x 10(4) units/ mouse) as a primer and Streptococcus preparation OK-432 (100 KE/kg) as a trigger. Seven days after inoculation of Meth A tumor in BALB/c mice, about one third of LD50 of CY or five other chemotherapeutic agents (actinomycin D, mitomycin C, tegaful, adriamycin and puromycin) was injected intravenously. En-TNF was induced 7 days after administration of these agents. A combination therapy of en-TNF with CY showed the strongest antitumor effect among several combinations and caused complete tumor regression (40-70%), while none of the combinations with the other chemotherapeutics did so. The optimal time interval to obtain this antitumor effect with CY and en-TNF induction was 7 days. The amount of en-TNF induced around a tumor lesion with CY was two fold higher than that without CY. En-TNF was observed to be induced in tumor lesion solely by CY injection. All these results suggest that the antitumor effect of en-TNF can be augmented by addition of a chemotherapeutic agent such as CY.

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Antitumor mechanism of intradermal administration of lipopolysaccharide.

We earlier demonstrated that 50% of the lethal dose of lipopolysaccharide (LPS) from Pantoea agglomerans given by the intradermal (i.d.) route is about 300 times greater than that given by the intravenous (i.v.) route, and that 400 micrograms/kg of LPS administered i.d. significantly suppressed metastasis whereas administered i.v., it did not. To learn the specific mechanism involved in this i.d. administration, the fate of LPS at the skin following administration and the concurrent production of endogenous tumor necrosis factor (TNF) in serum was examined. Histological observation following the i.d. administration of LPS (40 micrograms/kg) revealed neutrophiles in the skin 6 hours later. After 24 or 48 hours inflammatory cells were assembled at the site of injection. Endogenous TNF activity was found in the skin 24 hours after the injection and was significantly detectable even after 48 hours. Endogenous TNF was induced around tumor lesions of Meth A fibrosarcoma, MH134 hepatoma and Lewis lung carcinoma by treatment of LPS administered i.d. Taken together, these findings suggest that the antitumor activity of i.d. administered LPS results from the continuous supply of a small amount of this substance producing free TNF and activating inflammatory cells such as macrophages having membrane bound proTNF on their surface from the injected site to the tumor lesion for more than 48 hours.

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PubMedDate not supplied

Anti-tumor effect of lipopolysaccharide by intradermal administration as a novel drug delivery system.

We examined the antitumor effect of lipopolysaccharide extracted from Pantoea agglomerans, a Gram-negative bacterium, using intradermal administration on murine syngeneic tumors, Meth A fibrosarcoma, MH134 hepatoma and Lewis lung (LL) carcinoma. The latter two tumors are known to be relatively low in immunogenicity, highly metastatic and to have low sensitivity to biological response modifiers. Although the intradermal administration of LPSp had a significantly suppressive effect on the growth of all tumors, including seventy-five percent of complete regression of mice bearing Meth A tumor, no complete regression was observed in MH134 or LL tumors. In combination with cyclophosphamide given once prior to the administration of LPS, however, the antitumor effects by intradermal administration of LPS were significantly augmented and there was complete regression in all types of tumors. Pretreatment by anti-tumor necrosis factor antibody reduced the effect exerted by LPS, suggesting that induced tumor necrosis factor might have a crucial role. Toxicity of intradermal administration of LPS was 230-380 times less than that by the intravenous route. Thus clinical application of LPS administered intradermally in combination with chemotherapeutics such as cyclophosphamide appears promising in terms of its antitumor effect as well as toxicity.

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