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T Yokoo

Publications and source records attributed to T Yokoo.

36 records · Page 2Linked to original sources
PubMed1996

Gene transfer of interleukin-1 receptor antagonist into the renal glomerulus via a mesangial cell vector.

Towards gene transfer-based therapies of renal glomerulonephritis, this study examines the feasibility of using a mesangial cell vector (J. Clin. Invest. 94, 497-505, 1994) engineered to secrete interleukin-1 receptor antagonist (IL-1ra). IL-1ra cDNA was introduced into cultured rat mesangial cells, and stably transfected vector cells were established. Compared to mock transfectants, the vector cells showed blunted expression of gelatinase B, stromelysin and monocyte chemoattractant protein-1 in response to IL-1 beta. The attenuated responses were transferable to untransfected cells by cross-feeding with vector cell-conditioned media. The vector cells were then delivered into the glomeruli of rats via the renal circulation. Compared to either unmodified or mock cell-containing glomeruli, the glomeruli transferred with vector cells showed repressed expression of gelatinase B in response to IL-1 beta. Transfer of vector cells thus conferred insensitivity to IL-1 on the glomerulus. This result indicates the feasibility of modifying glomerular microenvironment against certain pathogenic mediators via the ex vivo transfer of therapeutically-relevant genes to the glomerulus.

Animals↗
PubMed1996

Transforming growth factor-beta 1 is the predominant paracrine inhibitor of macrophage cytokine synthesis produced by glomerular mesangial cells .

Cross-communication between glomerular cells and infiltrating mononuclear cells plays an important role in the generation of or recovery from glomerular diseases. We found that cultured mesangial cells secrete a factor that inhibits production of proinflammatory cytokines by activated macrophages. Treatment of J774.2 macrophages with conditioned media from rat mesangial cells blunted the transcriptional induction of IL-1 beta, IL-6, and TNF-alpha by LPS. None of the media conditioned by other fibroblastic, epithelial, or endothelial cell lines exhibited the inhibitory effect. Media conditioned by normal rat glomeruli contained a similar inhibitory activity, which was enhanced in an acute model of mesangial proliferative glomerulonephritis. To identify the active component involved, we examined the expression of known macrophage deactivators IL-10, IL-13, and TGF-beta 1 in mesangial cells. Under the basal culture conditions, strong expression of TGF-beta 1 mRNA was observed, whereas expression of neither IL-10 nor IL-13 was detected. Immunoblot analysis and a specific bioassay detected the active form of TGF-beta 1 exclusively in the mesangial cell conditioned media. The inhibitory activity was enhanced by heat treatment, consistent with the known property of TGF-beta. A specific anti-TGF-beta 1 neutralizing Ab abolished the inhibitory effect exerted by the mesangial cell media, and exogenously added TGF-beta1 suppressed macrophage cytokine expression in a dose-dependent manner. These findings demonstrate that mesangial cells and isolated glomeruli secrete a factor which suppresses cytokine expression by activated macrophages, the active entity being identified as TGF-beta 1.

Animals↗
PubMed1996

Opposite, binary regulatory pathways involved in IL-1-mediated stromelysin gene expression in rat mesangial cells.

Glomerular mesangial cells express matrix metalloproteinase sromelysin in response to the proinflammatory cytokine IL-1 beta. The present study was conducted to identify intracellular machinery involved in this IL-1 action, especially focusing on the role of the TPA response element (TRE) located in the 5'-flanking region of the stromelysin gene. Using transient transfection with a pTRE-LacZ reporter plasmid, we detected no obvious up-regulation of TRE activity in rat mesangial cells following the IL-1 stimulation. However, the basal activity of TRE was found to be essential to the stromelysin induction, since (i) mesangial cells stably expressing a transdominant negative mutant of c-Jun, which effectively suppressed both basal and inducible TRE activity, exhibited the blunted expression of stromelysin in response to IL-1 beta, whereas (ii) transfection with a c-fos antisense gene, which suppressed only the inducible TRE activity, did not affect the stromelysin induction. To seek cooperative pathways required for the IL-1 action, we next focused on protein kinases, the potential regulators of the stromelysin gene. Stimulation of mesangial cells with a protein kinase C (PKC) activator, phorbol 12-myristate 13-acetate (PMA), induced the stromelysin transcript without affecting TRE activity. Depletion of intracellular PKC by high-dose PMA or inhibition of PKC activity with calphostin C suppressed the stromelysin induction by IL-1 beta, suggesting the crucial contribution of a PKC-mediated, but TRE-independent pathway. In contrast, either cAMP inducer forskolin or dibutyryl cAMP suppressed the IL-1-mediated stromelysin expression. An inhibitor of cAMP-dependent protein kinase A (PKA), HA1004, enhanced the IL-1 effect in a dose-dependent manner. Unexpectedly, the inhibitory action of PKA was not through cAMP response element (CRE) but through TRE, because (i) activation of CRE was not induced by IL-1 beta, and (ii) cAMP-mediated activation of PKA suppressed the basal TRE activity. These findings elucidated the unique, binary regulation of stromelysin by IL-1 beta; that is, IL-1 up-regulated the transcript via the PKC-dependent pathway under the cooperation with constitutively active TRE, and this stimulatory effect was in part counterbalanced by the IL-1-inducible PKA which down-regulated the basal TRE activity.

Animals↗
PubMed1996

Macrophage-colony stimulating factor (M-CSF) enhances proteinuria and recruitment of macrophages into the glomerulus in experimental murine nephritis.

In this study, we examined the effects of macrophage-colony stimulating factor (M-CSF) on glomerular macrophages in lipopolysaccharide (LPS)-induced murine nephritis. Mice injected intraperitoneally with either M-CSF plus LPS, LPS alone, M-CSF alone or saline every day for 8 days were examined for the degree of urine albumin excretion and lymphocyte-function associated antigen-1-positive (LFA-1+) cells in peripheral blood as well as renal pathology. From our results, LPS or M-CSF combined with LPS emphasized the degree of proteinuria, glomerular deposition of immunoglobulins and mesangial proliferation, associated with accumulation of macrophages in the glomeruli. However, in immunohistological examination of kidneys from these nephritic mice, neither intercellular adhesion molecule-1 (ICAM-1), which may play an important role in the recruitment of macrophages into glomeruli, M-CSF receptor nor the number of LFA-1+ cells in peripheral blood was enhanced by M-CSF. On the other hand, M-CSF alone induced neither proteinuria nor any pathological changes and did not increase the number of glomerular Mac-1+ cells above that in saline-treated controls. These results indicate that M-CSF does not directly cause glomerulonephritis but might participate in accelerating the glomerular inflammatory process by stimulating a potent chemoattractant to recruit monocytes-macrophages into the glomeruli.

Animals↗
PubMed1996

Dual regulation of IL-1 beta-mediated matrix metalloproteinase-9 expression in mesangial cells by NF-kappa B and AP-1.

Glomerular mesangial cells express matrix metalloproteinase-9 (MMP-9) in response to the proinflammatory cytokine interleukin-1 beta (IL-1 beta). To elucidate the signal transduction systems involved, we focused on the role of nuclear factor-kappa B (NF-kappa B) and activator protein-1 (AP-1), since the 5'-flanking region of MMP-9 gene contains binding sequences for these transacting molecules. In rat mesangial cells treated with an inhibitor of NF-kappa B, pyrrolidine dithiocarbamate, induction of MMP-9 by IL-1 beta was suppressed at both mRNA and protein levels. Mesangial cells stably transfected with a transdominant negative mutant of NF-kappa B also showed blunted induction of MMP-9. Transient transfection study with a kappa B reporter plasmid revealed that IL-1 beta indeed activated the kappa B site and that pyrrolidine dithiocarbamate abolished this activation. These results suggest that IL-1 beta induced MMP-9 via the stimulation of NF-kappa B pathway. to examine whether tyrosine kinase is involved in this pathway, mesangial cells were stimulated by IL-1 beta in the presence of a tyrosine kinase inhibitor genistein. This inhibitor dose dependently suppressed the expression of MMP-9, as well as the activation of the kappa B site by IL-1 beta, indicating the involvement of tyrosine kinase in the stimulation of NF-kappa B. Because mesangial cells stimulated by IL-1 beta transiently expressed c-fos and c-jun nRNAs prior to the expression of MMP-9, the role of these genes in mediating the IL-1 beta response was further examined. Transfection of mesangial cells with a c-jun antisense cDNA and treatment with a pharmacological inhibitor of c-Jun/ AP-1, curcumin, revealed that the induction of c-Jun/AP-1 is essential for the expression of MMP-9 by IL-1 beta. Although protein kinase C (PKC) is regarded as a potential inducer of AP-1, stimulation of mesangial cells with phorbol 12-myristate 13-acetate failed to induce MMP-9. Similarly, depletion of intracellular PKC did not obviously affect the induction of MMP-9 by IL-1 beta. These findings demonstrate that dual operation of tyrosine kinase-mediated NF-kappa B stimulation and c-Jun/AP-1 activation is essential to the induction of MMP-9 by IL-1 beta in cultured mesangial cells.

Animals↗
PubMed1996

Antioxidant PDTC induces stromelysin expression in mesangial cells via a tyrosine kinase-AP-1 pathway.

We found that pyrrolidine dithiocarbamate (PDTC) induces the matrix metalloproteinase stromelysin in cultured glomerular mesangial cells. Although PDTC is a well-known inhibitor of nuclear factor-kappa B (NF-kappa B), this effect was independent of the NF-kappa B activity, since overexpression of a dominant negative mutant of p50 NF-kappa B subunit repressed activity of the kappa B site, whereas it failed to induce stromelysin. To elucidate the intracellular mechanisms involved, we focused on the role of activator protein 1 (AP-1), since its binding site, the 12-O-tetradecanoylphorbol 13-acetate (TPA) response element (TRE), is located in the 5'-flanking region of the stromelysin gene. Northern blot analysis revealed that PDTC upregulated expression of c-jun and c-fos before the expression of stromelysin. Transient transfection studies using a TRE-LacZ reporter plasmid elucidated that activity of AP-1 was significantly increased by PDTC. Stable transfection with a c-jun antisense cDNA or pretreatment with curcumin, a pharmacological inhibitor of c-Jun/AP-1, revealed that inactivation of AP-1 diminished the induction of stromelysin by PDTC. To identify the machinery involved upstream of AP-1 activation, the role of tyrosine kinases was investigated. Western blot analysis showed that PDTC induced phosphorylation of tyrosine kinases. Treatment of mesangial cells with tyrosine kinase inhibitors suppressed activation of AP-1 as well as induction of stromelysin by PDTC. These findings demonstrate that the antioxidant PDTC induces stromelysin expression via stimulation of the tyrosine kinase-AP-1 pathway independent of its suppressive action on NF-kappa B.

Animals↗
PubMed1994

Heparin selectively inhibits gene expression of matrix metalloproteinase transin in cultured mesangial cells.

The aim of this study is to examine the transcriptional regulation of matrix metalloproteinase transin in glomerular mesangial cells responding to inflammatory cytokines and heparin. Northern blot analysis revealed that IL-1 beta preferentially induced transin mRNA. The stimulatory effect was not specific to transin, and upregulation of procollagen alpha 1(IV), laminin B2 and tissue inhibitor of metalloproteinases-1 (TIMP-1) mRNAs was also observed. After IL-1 stimulation, expression of the transin transcript increased progressively for up to 48 hours, differing from the limited induction of procollagen alpha 1(IV) or TIMP-1. When mesangial cells were stimulated by IL-1 beta in the presence of heparin, transin expression was markedly suppressed in a dose-dependent manner. The inhibitory effect of heparin was specific to transin, and induction of procollagen alpha 1(IV), laminin B2 or TIMP-1 by IL-1 beta was not affected. These findings revealed the selective counter regulation by IL-1 beta and heparin of the transin expression in mesangial cells.

Animals↗
PubMed1993

[Clinical studies of S-1108, a new oral cephem, in pediatric patients].

Clinical studies of S-1108, a new oral cephem, in pediatric patients were conducted and results are summarized below. 1) Clinical effects of S-1108 against 18 cases of bacterial infections were excellent in 5 cases, good in 10 cases, fair in 1 case and poor in 2 cases, thus the clinical efficacy rates was 83.3%. 2) Bacteriological effects were evaluated in 16 strains. The elimination rate was 100%. 3) No adverse effects nor abnormal laboratory test results were observed in any of the cases.

Administration, Oral↗
PubMed1991

Oxidative metabolic products released from polymorphonuclear leukocytes in middle ear fluid during experimental pneumococcal otitis media.

To determine whether oxidative metabolic products of phagocytic cells are present in the middle ear during experimental pneumococcal otitis media, we measured the concentration of myeloperoxidase (MPO) in middle ear fluid (MEF) and the capacity of neutrophils isolated from MEF and peripheral blood to produce MPO and superoxide anion (O2-) after in vitro stimulation. Free MPO in MEF was significantly increased 24 and 48 h after either viable or nonviable pneumococci were inoculated into the middle ear. In vitro-stimulated production of MPO and O2- from middle ear neutrophils was significantly less than that from peripheral blood neutrophils 24 h after nonviable pneumococci were inoculated but similar to it after 48 h. Twenty-four hours after viable pneumococci were inoculated, middle ear neutrophils stimulated in vitro produced less MPO but the same amount of O2- as did blood neutrophils. Oxidative metabolic products, therefore, are released from phagocytic cells into the MEF during pneumococcal otitis media, and future studies will need to define the contribution of these products to acute and chronic middle ear tissue injury.

Animals↗
PubMed1990

A case of pyloric atresia associated with junctional epidermolysis bullosa.

We describe an infant with congenital pyloric atresia associated with junctional epidermolysis bullosa, which is now recognized as an autosomal recessive syndrome. Laparotomy revealed a membrane in the pyloric antrum. Clinical manifestations included intractable diarrhoea and malnutrition due to protein-losing gastroenteropathy. A satisfactory nutritional state could not be obtained during the clinical course and the child died.

Epidermolysis Bullosa↗
PubMed1990

Aleukemic leukemia cutis.

A 39-year-old man had multiple nodules on the skin. The appearance of atypical monocytes in a skin biopsy specimen preceded the onset of overt acute monocytic leukemia by 14 months.

Adolescent↗
PubMed1990

Effect of continuous LDL apheresis with dextran-sulfate cellulose column system on a child with homozygous familial hypercholesterolemia.

A new system for selective low density lipoprotein apheresis with an automated regenerating column using dextran-sulfate (DS) as ligand was evaluated for six months in a 13-year-old boy homozygous for familial hypercholesterolemia. Two columns each containing 150 ml of DS cellulose were alternately used after rinsing with a regenerating solution. The patient could well tolerate the volume in the system. The values of plasma total cholesterol decreased by 79.4 +/- 4.9% of the pretreatment levels after a total of 5l plasma apheresis, while those of high density lipoprotein cholesterol did not change. Although the values of CH50 decreased, no adverse reaction was seen during the period of treatment. It was concluded that the present apheresis system was highly efficacious and safe for children homozygous for the mutant LDL receptor gene.

Adolescent↗
PubMed1988

Neonatal onset of medium-chain acyl-CoA dehydrogenase deficiency in two siblings.

Two male siblings with medium-chain acyl-CoA dehydrogenase deficiency were reported, in whom the enzyme activity was essentially undetectable and the symptoms and signs, including cyanosis, apnea, low body temperature, hypoglycemia and hyperammonemia, appeared within 48 hours of life. Muscle weakness and cardiomegaly in association with morphological abnormalities of mitochondria in skeletal and cardiac muscles, respectively, were found on electron microscopic examination in one of them. These observations suggest that the patients suffered from the most severe form of the disease, which has not been described in the literature.

Acyl-CoA Dehydrogenases↗
PubMed1986

Ultrastructure of insulin secretory granules and insulin content of fetal pancreas exposed to ethanol in utero in the rat.

Fetal rat pancreata exposed to ethanol in utero were examined for morphometric analysis of insulin secretory granules and insulin content. The beta-cells contained both dark and light granules, and their volume density was unaltered by maternal ethanol ingestion during pregnancy. The insulin content of pancreata of newborn rats was nearly equal in control and experimental animals. The study indicates no adverse effect of maternal ethanol ingestion on fetal pancreatic insulin concentration and insulin secretory granules.

Animals↗
PubMedDate not supplied

Gene delivery into the renal glomerulus by transfer of genetically engineered, autologous mesangial cells.

To obviate the problem of rejection in situations where cells are used as vectors for gene delivery, the feasibility of using autologous mesangial cells cultured from renal biopsy specimens was studied for the purpose of gene transfer into the glomerulus. Using the calcium-phosphate co-precipitation method, a reporter gene which encodes bacterial beta-galactosidase was introduced into cultured mesangial cells derived from renal biopsy tissue of rats. Stable transfectants were established in the presence of a selection drug and then transferred back into the contralateral kidneys of the same animals via renal artery injection. Among 5 rats tested, expression of beta-galactosidase was detected in the isolated glomeruli from 4 injected kidneys. One week after cell injection, 31 +/- 13% of the glomeruli showed positive X-gal (5-bromo-4-chloro-3-indolyl beta- D-galactopyranoside) staining, indicating expression of the transferred gene. The use of autologous mesangial cells from biopsy specimens is thus realistic and would be useful to obviate the risk of rejection in the mesangial cell vector system.

Animals↗