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Toru Kita

Publications and source records attributed to Toru Kita.

At least 145 records · Page 8Linked to original sources
PubMed2003

A coordinated cytotoxic effect of IFN-gamma and cross-reactive antibodies in the pathogenesis of Helicobacter pylori gastritis.

BACKGROUND: Helicobacter pylori (H. pylori) infection is associated with chronic infiltration into the stomach by T cells and plasma cells producing IFN-gamma and antibodies of various specificities, respectively. It is unknown whether these lymphocyte-products may play coordinated roles in the gastric pathology of this infection. AIMS: To know how IFN-gamma may relate to anti-H. pylori antibodies in their roles in pathogenesis, we determined the isotype subclass of those antibodies as well as their cross-reactivity and cytotoxicity to gastric epithelium. METHODS AND RESULTS: We infected BALB/c mice with H. pylori (SS1, Sydney Strain 1) and generated monoclonal antibodies, which were comprised of 240 independent clones secreting immunoglobulin and included 80 clones reactive to SS1. Ninety percent of the SS1-reactive clones had IgG2a isotype. Two clones, 2B10 and 1A9, were cross reactive to cell surface antigens in H. pylori and to antigens of 28 KDa and 42 KDa, respectively, which were present on the cell surface of and shared by both mouse and human gastric epithelial cells. The antigens recognized by these monoclonal antibodies localized a distinctive area in the gastric glands. In the presence of complement, 2B10 showed cytotoxicity to gastric epithelial cells. The effect was dose dependant and augmented by IFN-gamma. Finally, administration of 2B10 to mice with SS1 infection aggravated gastritis by increasing cellular infiltration. CONCLUSION: IFN-gamma by gastric T cells may participate in pathogenesis of the H. pylori infected stomach by directing an isotype-switch of anti-H. pylori antibodies to complement-binding subclass and by augmenting cytotoxic activity of a certain autoantibody. This may explain a host-dependent diversity in gastric pathology of the patients with H. pylori infection.

Animals↗
PubMed2003

A liver tolerates a portal antigen by generating CD11c+ cells, which select Fas ligand+ Th2 cells via apoptosis.

Administration of an antigen (Ag) per oral route leads to apoptosis of Ag-specific CD4(+) T cells and to development of Th2 cells expressing Fas ligand (FasL) in the liver. We determined whether presentation of an ingested Ag in the liver alone was enough to select these FasL(+)Th2 cells and explored how this selection was achieved in the liver. Ovalbumin (OVA) administered orally was colocalized with class II(+) cells in the periportal and parenchymal area of the liver. On coculture with naive OVA-specific CD4(+) T cells, hepatic CD11c(+) cells from mice fed OVA generated Ag-specific Th2 cells. This was achieved by apoptosis of CD4(+) T cells, decrease of interleukin 12 (IL-12) secretion, and increase of IL-18 secretion by the CD11c(+) cells. Addition of IL-12 to this coculture prevented apoptosis of the CD4(+) T cells, which was associated with up-modulation of IL-2 receptor beta chain expression. Administration of IL-12 to mice fed OVA prevented apoptosis of OVA-specific CD4(+) T cells in the liver. Moreover, adoptive transfer of hepatic CD11c(+) cells from mice fed OVA together with OVA-specific CD4(+) T cells led to development of Th2 cells as well as apoptosis of the transferred CD4(+) T cells in the lymph nodes of the recipient mice on immunization with OVA. In conclusion, presentation of an ingested Ag by hepatic CD11c(+) cells selects Th2 cells resistant to apoptosis in the liver, which is mediated in part by down-regulation of IL-12 secretion by the former cells.

Adoptive Transfer↗
PubMed2003

Helper CD4+ T cells for IgE response to a dietary antigen develop in the liver.

BACKGROUND: Although T-cell responses to food antigens are normally inhibited either by deletion, active suppression, or both of antigen-specific T cells, T helper cells for IgE response to a food antigen still develop by unknown mechanisms in a genetically susceptible host. OBJECTIVE: We determined the site at which those IgE helper T cells develop. METHODS: We administered ovalbumin (OVA) orally to DO11.10 mice and studied CD4+ T cells in Peyer's patches, the spleen, and the liver. Helper activity for IgE response was assessed by adoptively transferring those CD4+ T cells to naive BALB/c mice, followed by systemic immunization with OVA. RESULTS: OVA-specific CD4+ T cells were deleted by cell death in the liver and Peyer's patches of DO11.10 mice fed OVA. OVA-specific CD4+ T cells that survived apoptosis in the liver expressed Fas ligand and secreted IL-4, IL-10, and transforming growth factor beta(1). CD4+ T cells producing IFN-gamma were deleted in the liver by repeated feeding of OVA. On transfer of CD4+ T cells to naive mice and systemic immunization with OVA, a marked increase in OVA-specific IgE response developed only in the mice that received hepatic CD4+ T cells from OVA-fed mice, the effect of which was not observed in the recipients of hepatic CD4+ T cells deficient in IL-4. In addition, significant suppression of delayed-type hypersensitivity and IgG(1)/IgG(2a) responses to OVA was observed in the recipients of hepatic CD4+ T cells, and this suppression required Fas/Fas ligand interaction. CONCLUSION: Together, these results suggested that a food antigen might negatively select helper T cells for IgE response to the antigen by preferential deletion of T(H)1 cells in the liver.

Administration, Oral↗
PubMed2003

Cardiac p300 is involved in myocyte growth with decompensated heart failure.

A variety of stresses on the heart initiate a number of subcellular signaling pathways, which finally reach the nuclei of cardiac myocytes and cause myocyte hypertrophy with heart failure. However, common nuclear pathways that lead to this state are unknown. A zinc finger protein, GATA-4, is one of the transcription factors that mediate changes in gene expression during myocardial-cell hypertrophy. p300 not only acts as a transcriptional coactivator of GATA-4, but also possesses an intrinsic histone acetyltransferase activity. In primary cardiac myocytes derived from neonatal rats, we show that stimulation with phenylephrine increased an acetylated form of GATA-4 and its DNA-binding activity, as well as expression of p300. A dominant-negative mutant of p300 suppressed phenylephrine-induced nuclear acetylation, activation of GATA-4-dependent endothelin-1 promoters, and hypertrophic responses, such as increase in cell size and sarcomere organization. In sharp contrast to the activation of cardiac MEK-1, which phosphorylates GATA-4 and causes compensated hypertrophy in vivo, p300-mediated acetylation of mouse cardiac nuclear proteins, including GATA-4, results in marked eccentric dilatation and systolic dysfunction. These findings suggest that p300-mediated nuclear acetylation plays a critical role in the development of myocyte hypertrophy and represents a pathway that leads to decompensated heart failure.

Animals↗
PubMed2003

Sustained reduction of serum cholesterol in low-dose 6-year simvastatin treatment with minimum side effects in 51,321 Japanese hypercholesterolemic patients.

The Japan Lipid Intervention Trial (J-LIT) study, a nationwide cohort study utilizing the clinical practice of general physicians, was designed to clarify the relationship between the incidence of coronary heart disease and serum lipid concentrations during simvastatin therapy, as well as the safety of the therapy, in a large number of Japanese hypercholesterolemic patients. All the enrolled patients were treated with simvastatin. The current study analyzed the lipid lowering effect and safety of the low-dose simvastatin therapy used in the J-LIT study. Open-labeled simvastatin was given to 51,321 patients at an initial dose of mostly 5 mg/day. After 6 months of the treatment, the average serum total cholesterol (TC) and low density lipoprotein-cholesterol concentrations in all the patients followed up were reduced by 18.3% and 26.0%, respectively, and that of high density lipoprotein-cholesterol increased 2.3% on average. These concentrations were well maintained throughout the 6-year treatment period. A minority of patients (1.4%) unexpectedly had a remarkable reduction in TC concentration by more than 40%. Hyper-responders, even to low-dose statin, were found for the first time in this large-scale and long-term investigation. Overall adverse drug reactions occurred in 3.3% of subjects during the 6-year treatment, the major events being hepatic and musculoskeletal disorders, of which the incidence was less than 1%. Low-dose simvastatin therapy of 5 mg/day effectively controlled the serum TC concentration by reducing it by approximately 20% on average in hypercholesterolemic Japanese patients, a reduction that corresponds to the effect of simvastatin 20 mg/day in Western studies. In addition, the low incidence of drug-related adverse events in this study may be also related to the low dosage of simvastatin.

Anticholesteremic Agents↗
PubMed2003

Life style and cardiovascular risk factors in the Japanese population--from an epidemiological survey on serum lipid levels in Japan 1990 part 1: influence of life style and excess body weight on HDL-cholesterol and other lipid parameters in men.

Low HDL-cholesterol (HDL-C) has long been used as an important predictor of coronary artery disease (CAD), although HDL-C values themselves are influenced by various factors including serum triglyceride (TG) levels, obesity, and life style. In view of the importance of the metabolic syndrome as a risk factor of CAD, changes in HDL-C and other lipid parameters in the Japanese population associated with life style, especially in males, were analyzed in this study based on data obtained in an epidemiological survey carried out in 1990. Smokers had higher TG and lower HDL-C levels than non-smokers, while BMI and LDL-C were slightly decreased by smoking in middle-aged men (40-59 years old). Increases in both HDL-C and TG due to alcohol consumption were associated with an increase in BMI in younger men aged 20-39. In middle-aged men, significant increases in HDL-C were seen in every quintile of BMI, while the increase in TG levels due to alcohol was small. Middle-aged men engaged in occupations requiring greater physical activity also had higher HDL-C levels in every quintile of BMI. The influence of life style on serum lipid parameters appeared to be mostly expressed as a function of BMI in younger men, while it appeared to be independent of BMI in older men.

Adult↗
PubMed2003

Life style and cardiovascular risk factors in the Japanese population--from an epidemiological survey on serum lipid levels in Japan 1990 part 2: association of lipid parameters with hypertension.

The importance of metabolic syndrome as a risk factor of coronary artery disease (CAD) has recently become more and more recognized. In view of such a background, changes in cholesterol and other lipid parameters in the Japanese population associated with excess body weight and hypertension were analyzed in this study based on data obtained in an epidemiological survey carried out in 1990. Hypertension was closely associated with a higher body mass index (BMI). Among the lipid parameters, triglyceride (TG) and non-HDL-C (total cholesterol minus HDL-cholesterol) levels showed remarkable differences between hypertensive and normotensive subjects, with a greater statistical significance than LDL-cholesterol (LDL-C) levels. Changes in lipid parameters in the presence of hypertension were mostly associated with an increase in BMI in younger men aged 20-39, while increases in TG levels took place independently of excess body weight in middle-aged (40-59-year old) men. Considering that hypertension is a common and the greatest risk factor in the Japanese population, TG and non-HDL-C appear to be more important than LDL-C as major lipid parameters related to atherogenesis.

Adult↗
PubMed2003

RhoA expression is not a critical determinant in hypertension evolution in salt-sensitive Dahl rats.

BACKGROUND: The Rho/Rho kinase pathway plays an important role in regulation of vascular smooth muscle cell contraction and is involved in the pathogenesis of hypertension. However, little is known about the role of this pathway in the evolution of salt-sensitive hypertension and vascular remodeling. The aim of this study was to examine whether the age-dependent surge of blood pressure after exposure to a high salt-containing diet, which is well-established for Dahl salt-sensitive rats, is primarily regulated by the level of expression of RhoA in arterial vessels. MATERIAL/METHODS: We examined Dahl salt-sensitive rats at 3 weeks, 6 weeks, and 9 weeks of age (n=10, each). In each group, animals were switched to being fed a diet containing 8% NaCl from one containing 0.3% NaCl. After 7 days, mRNA and protein levels of RhoA from the thoracic aorta were quantified. RESULTS: At the time of examination, increases in systolic blood pressure were significantly different depending on the age at which the high salt diet was initiated. The % increases were 34+/-3% (3-weeks), 20+/-2% (6-weeks), and 13+/-2% (9-weeks). Despite these differing changes in blood pressure, mRNA and protein levels of RhoA in the arteries did not differ among the groups. CONCLUSIONS: RhoA expression and activity appear not to be the critical determinant of the surge in hypertension when Dahl salt-sensitive rats are exposed to salt-rich diets. Hence, the age-dependent salt-sensitivity must be mediated by alternative pathways.

Animals↗
PubMed2002

Involvement of nectin in the localization of junctional adhesion molecule at tight junctions.

Junctional adhesion molecule (JAM) is a Ca2+-independent immunoglobulin-like cell-cell adhesion molecule which localizes at tight junctions (TJs). Claudin is a key cell-cell adhesion molecule that forms TJ strands at TJs. JAM is associated with claudin through their cytoplasmic tail-binding protein, ZO-1. JAM is furthermore associated with Par-3, a cell polarity protein which forms a ternary complex with Par-6 and atypical protein kinase C. Nectin is another Ca2+-independent immunoglobulin-like cell-cell adhesion molecule which localizes at adherens junctions (AJs). Nectin is associated with E-cadherin through their respective cytoplasmic tail-binding proteins, afadin and catenins, and involved in the formation of AJs cooperatively with E-cadherin. We show here that nectin is furthermore involved in the localization of JAM at TJs. During the formation of the junctional complex consisting of AJs and TJs in Madin-Darby canine kidney (MDCK) cells, JAM was recruited to the nectin-based cell-cell adhesion sites. This recruitment of JAM was inhibited by nectin inhibitors, which inhibited the trans-interaction of nectin. Microbeads coated with the extracellular fragment of nectin, that interacted with cellular nectin, also recruited JAM to the bead-MDCK cell contact sites. Furthermore, when cadherin-deficient L fibroblasts stably expressing both exogenous JAM and nectin (nectin-JAM-L cells) were co-cultured with L fibroblasts expressing only nectin (nectin-L cells), JAM was concentrated at the cell-cell adhesion sites between nectin-JAM-L and nectin-L cells without the trans-interaction of JAM. Analyses of the localization and immunoprecipitation of JAM revealed that it was associated with nectin through afadin and ZO-1. These results suggest that nectin has a role in the localization of JAM at TJs in the process of the formation of the junctional complex in epithelial cells.

Animals↗
PubMed2002

Administration of an antigen at a high dose generates regulatory CD4+ T cells expressing CD95 ligand and secreting IL-4 in the liver.

Ags administered orally at a high dose are absorbed in immunogenic forms and perfuse the liver, which raises a question regarding the relevance of hepatic lymphocyte activation to the systemic hyporesponsiveness against the ingested Ag. Oral administration of 100 mg of OVA to the mice led to massive cell death of OVA-specific (KJ1-26+)CD4+ T cells by Fas-Fas ligand (FasL)-mediated apoptosis in the liver, which was associated with the emergence of hepatic KJ1-26+CD4+ T cells expressing FasL. Hepatic CD4+ T cells in OVA-fed mice secreted large amounts of IL-4, IL-10, and TGF-beta(1) upon restimulation in vitro and inhibited T cell proliferation. Adoptive transfer of these hepatic CD4+ T cells to naive mice and subsequent antigenic challenge led to suppression of T cell proliferation as well as IgG Ab responses to OVA; this effect was mostly abrogated by a blocking Ab to FasL. i.p. administration of an Ag at a high dose also generated hepatic CD4+FasL+ T cells with similar cytokine profile as T cells activated by oral administration of Ags at a high dose. Finally, we did not see an increase in FasL+ cells in the hepatic CD4+Vbeta8+ T cell subset of MRL/lpr/lpr mice given staphylococcal enterotoxin B, indicating the requirement for Fas-mediated signals. These hepatic CD4+FasL+ regulatory cells may explain the tolerogenic property of the liver and play roles in systemic hyporesponsiveness induced by an Ag administered at a high dose.

Administration, Oral↗
PubMed2002

Lectin-like oxidized LDL receptor-1 (LOX-1) supports adhesion of mononuclear leukocytes and a monocyte-like cell line THP-1 cells under static and flow conditions.

Adhesion of mononuclear leukocytes to vascular endothelial cells appears one of the initial steps in the process of atherogenesis and inflammation. We examined if LOX-1, an endothelial scavenger receptor with C-type lectin-like structure, can support adhesion of mononuclear leukocytes. Under a static condition, CHO-K1 cells stably expressing LOX-1 showed more prominent adhesion of human peripheral blood mononuclear leukocytes and THP-1 cells than untransfected CHO-K1 cells, in a temperature-independent fashion. Mononuclear leukocytes also adhered to plastic plates precoated with recombinant soluble LOX-1 extracellular domain. A neutralizing anti-LOX-1 monoclonal antibody, as well as oxidized low-density lipoprotein, significantly blocked adhesion of THP-1 cells to CHO-K1 cells overexpressing LOX-1 and bovine aortic endothelial cells. Under a flow condition, increased numbers of THP-1 cells showed rolling with reduced velocities on LOX-1-expressing CHO-K1 cells, compared with those on untransfected CHO-K1 cells. Taken together, LOX-1 can work as a cell surface receptor for mononuclear leukocytes under both static and flow conditions.

Animals↗
PubMed2002

Blockade of platelet-derived growth factor receptor-beta pathway induces apoptosis of vascular endothelial cells and disrupts glomerular capillary formation in neonatal mice.

Platelet-derived growth factor (PDGF), a potent chemotactic and proliferation factor for mesenchymal-derived cells, has been demonstrated to play critical roles in kidney development. Two receptors for PDGF, PDGFR-alpha and PDGFR-beta, have been identified and we previously analyzed the effects of blockade of PDGFR-alpha signal in neonatal mice. In the current study, we examined the role of PDGFR-beta in glomerular development by blocking PDGFR-beta signal in neonatal mice by administration of antagonistic anti-PDGFR-beta monoclonal antibody. Unlike the mice injected with anti-PDGFR-alpha antibody, the mice injected daily with anti-PDGFR-beta antibody could be kept alive at least for 2 weeks after birth but showed severe disruption of the glomerular structure, whereas no apparent deformation was observed in the collecting ducts. In the disrupted glomeruli, the number of the mesangial cells was reduced markedly. Electron microscopic analysis and immunohistochemical studies with terminal deoxynucleotidyl transferase nick-end labeling staining revealed that the capillary endothelial cells of the glomeruli in the outer cortex region underwent apoptosis. However, the glomeruli located near the medulla were less affected. Because PDGFR-beta is not expressed in the endothelial cells, the effects of the blockade of PDGFR-beta might have caused glomerular endothelial cell apoptosis by inducing the loss of mesangial cells and/or pericytes.

Animals↗
PubMed2002

Differential localization of colitogenic Th1 and Th2 cells monospecific to a microflora-associated antigen in mice.

BACKGROUND & AIMS: Clonal expansion of T cells is associated with inflammatory bowel diseases, which indicates antigenic activation of the T cells. We investigated whether the introduction of CD4 T cells specific to a microflora would initiate colitis and assessed the cytokine requirements for colitogenic CD4 T cells. METHODS: Severe combined immunodeficiency disease (SCID) mice were reconstituted with CD4 T cells, which were either deficient in interleukin (IL)-4/interferon (IFN)-gamma production or differentiated in vitro to T-helper (Th) 1/Th 2 and bearing a transgenic T-cell receptor (TCR) specific to ovalbumin (OVA), and then inoculated with an Escherichia coli-producing OVA (ECOVA). Clinical and histologic manifestations of colitis were assessed. RESULTS: Mice with ECOVA colonization and OVA-specific CD4 T cells developed colitis with histologic features of focal infiltration by mononuclear cells, destruction of crypts, and loss of goblet cells. Further, infiltration was initiated in pre-existing lymph follicles. Th1- and IL-4 deficient T cells were diffusely localized in the lamina propria and submucosa, whereas Th2- and IFN-gamma-deficient T cells were localized preferentially in lymph follicles. CONCLUSIONS: A microbe-associated antigen, non-cross-reactive to colonic tissue, can drive antigen-specific CD4 T cells to cause colitis in SCID mice. Although the presence of IFN-gamma and IL-4 in the effector CD4 T cells was not an absolute requirement for the development of colitis, they seemed to regulate it in part by modulating migration of the effector T cells.

Animals↗
PubMed2002

Regional cerebral blood flow abnormalities in nondemented patients with memory impairment.

BACKGROUND: Patients with objective evidence of memory impairment have been considered to be at risk for developing Alzheimer's disease (AD). However, little is known about patterns of regional cerebral blood flow abnormalities and their prognostic significance in these patients. METHODS: The authors retrospectively studied 28 nondemented subjects with memory loss and investigated patterns of blood flow abnormalities on single photon emission computed tomography (SPECT). RESULTS: The patients were followed up for more than 2 years; during follow-up, 14 patients (50%) developed AD. The onset of memory impairment in patients who progressed to AD was significantly earlier than in those who remained in a nondemented condition. SPECT data from the initial evaluation were analyzed by region of interest analysis and statistical parametric mapping. Interestingly, both groups of patients shared hypoperfusion in the medial temporal regions and the posterior cingulate. In addition to these regions, significant blood flow reduction in the parietal and anterior cingulate cortices was detected in patients who progressed to AD. CONCLUSIONS: These results demonstrate that (1) subjects with an earlier onset of memory loss have an increased risk for developing AD, (2) SPECT can be useful for distinguishing subjects with memory loss who will rapidly progress to AD from those who will not, and (3) perfusion impairment typical of AD was evident even in subjects with memory impairment who remained nondemented.

Aged↗