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Biomedical subjects

Takao Koike

Publications and source records attributed to Takao Koike.

At least 37 records · Page 2Linked to original sources
PubMed2005

CD25(+)CD4(+) regulatory T cells exert in vitro suppressive activity independent of CTLA-4.

Cytotoxic T lymphocyte antigen-4 (CTLA-4) is constitutively expressed on CD25(+)CD4(+) regulatory T cells (Treg) and is suggested to play a role in Treg-mediated suppression. However, the results of analysis with anti-CTLA-4 have been controversial. We addressed this issue by analyzing mice over-expressing or deficient in CTLA-4. For over-expression, CTLA-4 transgenic mice expressing a full-length (FL) or a truncated (TL) mutant of CTLA-4 were analyzed. FL T cells expressed similar levels of CTLA-4 to Treg, whereas TL T cells expressed much higher levels on the cell surface. The number of Treg in both mice was decreased, although Foxp3 expression was not altered. Treg from both mice exerted suppressive activity, whereas CD25(-) T cells from FL mice showed no suppression. Furthermore, CD25(+)CD4 thymocytes from young CTLA-4-deficient mice were analyzed and found to exhibit suppressive activity. These results indicate that Treg exert in vitro suppressive activity independent of CTLA-4 expression.

Animals↗
PubMed2005

Significance of valine/leucine247 polymorphism of beta2-glycoprotein I in antiphospholipid syndrome: increased reactivity of anti-beta2-glycoprotein I autoantibodies to the valine247 beta2-glycoprotein I variant.

OBJECTIVE: To clarify the consequences of the valine/leucine polymorphism at position 247 of the beta(2)-glycoprotein I (beta(2)GPI) gene in patients with antiphospholipid syndrome (APS), by investigating the correlation between genotypes and the presence of anti-beta(2)GPI antibody. The reactivity of anti-beta(2)GPI antibodies was characterized using recombinant Val(247) and Leu(247) beta(2)GPI. METHODS: Sixty-five Japanese patients with APS and/or systemic lupus erythematosus who were positive for antiphospholipid antibodies and 61 controls were analyzed for the presence of the Val/Leu(247) polymorphism of beta(2)GPI. Polymorphism assignment was determined by polymerase chain reaction followed by restriction enzyme digestion. Recombinant Val(247) and Leu(247) beta(2)GPI were established to compare the reactivity of anti-beta(2)GPI antibodies to beta(2)GPI between these variants. The variants were prepared on polyoxygenated plates or cardiolipin-coated plates, and the reactivity of a series of anti-beta(2)GPI antibodies (immunized anti-human beta(2)GPI monoclonal antibodies [Cof-19-21] and autoimmune anti-beta(2)GPI monoclonal antibodies [EY1C8, EY2C9, and TM1G2]) and IgGs purified from patient sera was investigated. RESULTS: A positive correlation between the Val(247) allele and the presence of anti-beta(2)GPI antibodies was observed in the patient group. Human monoclonal/polyclonal anti-beta(2)GPI autoantibodies showed higher binding to recombinant Val(247) beta(2)GPI than to Leu(247) beta(2)GPI, although no difference in the reactivity of the immunized anti-beta(2)GPI between these variants was observed. Conformational optimization showed that the replacement of Leu(247) by Val(247) led to a significant alteration in the tertiary structure of domain V and/or the domain IV-V interaction. CONCLUSION: The Val(247) beta(2)GPI allele was associated with both a high frequency of anti-beta(2)GPI antibodies and stronger reactivity with anti-beta(2)GPI antibodies compared with the Leu(247) beta(2)GPI allele, suggesting that the Val(247) beta(2)GPI allele may be one of the genetic risk factors for development of APS.

Adult↗
PubMed2005

Butyrate suppresses tumor necrosis factor alpha production by regulating specific messenger RNA degradation mediated through a cis-acting AU-rich element.

OBJECTIVE: To study the capacity of butyrate to inhibit production of tumor necrosis factor alpha (TNFalpha) in macrophage-like synoviocytes (MLS) from patients with rheumatoid arthritis (RA), in human peripheral monocytes, and in murine RAW264.7 macrophages. METHODS: The concentrations of TNFalpha in culture supernatants of these cells were measured using enzyme-linked immunosorbent assay. The expression levels of various messenger RNAs (mRNA), such as those for TNFalpha, the mRNA-binding protein TIS11B, and luciferase, were measured using real-time quantitative polymerase chain reaction. The in vitro effects of butyrate on transcriptional regulation were evaluated by transfection with various reporter plasmids in RAW264.7 macrophages. The effects of TIS11B on TNFalpha expression were examined using an overexpression model of TIS11B in RAW264.7 cells. RESULTS: Butyrate suppressed TNFalpha protein and mRNA production in MLS and monocytes, but paradoxically enhanced transactivation of the TNFalpha promoter. Expression of the AU-rich element (ARE)-binding protein TIS11B was up-regulated by butyrate. Induction of TNFalpha mRNA by lipopolysaccharide was significantly inhibited when TIS11B was overexpressed. Butyrate facilitated the degradation of luciferase transcripts containing the 3'-untranslated region (3'-UTR) of TNFalpha, and this effect was dependent on the ARE in the 3'-UTR that is known to be involved in the regulation of mRNA degradation. CONCLUSION: These results indicate that butyrate suppresses TNFalpha expression by facilitating mRNA degradation mediated through a cis-acting ARE. Butyrate has the ability to regulate TNFalpha at the mRNA level and is therefore a potential therapeutic drug for RA patients.

3' Untranslated Regions↗
PubMed2005

Research around beta 2-glycoprotein I: a major target for antiphospholipid antibodies.

Beta2-glycoprotein I (beta2GPI), a phospholipid-binding protein, is one of the major target antigens for antiphospholipid antibodies (aPL) found in patients with antiphospholipid syndrome (APS). Thrombophilic disorders in APS patients are strongly associated with aPL, and their pathogenic properties depend on the presence of beta2GPI. Procoagulant cell stimulation by aPL, via beta2GPI, is one of the most plausible mechanisms of thrombosis in APS, and p38 mitogen activated protein kinase (MAPK) pathway plays a crucial role in such activation. beta2GPI is proteolytically cleaved in domain V by activated factor X or plasmin, leading to the generation of the nicked form of beta2GPI. Recently, increasing attention is focused on the role of nicked-beta2GPI as a regulator of extrinsic fibrinolysis pathway.

Amino Acid Sequence↗
PubMed2005

Antiprothrombin antibodies detected in two different assay systems. Prevalence and clinical significance in systemic lupus erythematosus.

We evaluated the clinical significance of aPT and aPS-PT by testing for the presence of these antibodies in 212 SLE patients and in 100 healthy individuals. Results show that anti-prothrombin antibodies were found in 47% of the patients (aPT in 31% and aPS-PT in 31%). Their presence did not correlate with that of aCL, anti-beta2GPI, LA and/or anti-protein S. IgG but not IgM aPT were more frequently found in patients with thrombosis than in those without. IgG and IgM aPS-PT were also more frequent in patients with thrombosis (venous and/or arterial) than in those without. Levels of IgG aPT and IgG and IgM aPS-PT were higher in patients with thrombosis than in those without. Although aPT and aPS-PT were more frequently found in women with adverse obstetric history than in those without, the differences were not statistically significant. More significantly, 48% of the patients with aPL-related clinical features who were negative for standard tests had antiprothrombin antibodies. We can conclude that aPT and aPS-PT are frequently found in SLE. Their presence is associated with thrombosis, making these antibodies potential markers for the APS. Testing for these antibodies could be of clinical benefit in patients who are negative for the routinely used tests.

Adult↗
PubMed2005

Protein C Sapporo (protein C Glu 25 --> Lys): a heterozygous missense mutation in the Gla domain provides new insight into the interaction between protein C and endothelial protein C receptor.

Interaction of the gamma-carboxyglutamic acid (Gla) domain of protein C with endothelial protein C receptor (EPCR) is a critical step for efficient activation of protein C, though interactions by mutants in the Gla domain of protein C with EPCR have been rarely evaluated. We identified a 44-year-old Japanese woman with a history of recurrent thromboembolism as an inherited missense mutation, the first such case reported in Japan, which involved a protein C Gla 25 mutation. Total protein C antigen and Gla protein C antigen levels in the proband were normal. Protein C activity measured with an anticoagulant assay was reduced, whereas that measured with an amidolytic assay was normal. She was therefore phenotypically diagnosed as type IIb protein C deficiency. Direct sequencing of the PCR fragments revealed a heterozygous G to A transition at nucleotide position 1462 in exon 3, which predicted an amino acid substitution of Glu 25 by Lys. Her mother and one son were also heterozygous for this mutation. A molecular dynamics simulation of Gla 25-->Lys/EPCR complex in water suggested that the affinity between the molecules was decreased compared to the wild type Gla domain/EPCR complex. Since Gla 25 has been shown to play an important role in protein C function, not only in membrane phospholipid binding but also in binding to EPCR, our findings provide new insight into the mechanism by which the Glu 25-->Lys mutation induces type IIb protein C deficiency in individuals.

Adult↗
PubMed2005

Cat-eye syndrome with isolated idiopathic hypogonadotropic hypogonadism.

A 34-year-old Japanese man diagnosed as having cat-eye syndrome (CES) with isolated idiopathic hypogonadotropic hypogonadism (IHH) was treated at our university. He showed preauricular pits/tags, downward slanting palpebral fissures, ocular hypertelorism, and strabismus. However, ocular coloboma and anal atresia, major characteristic features of CES, were negative. Chromosomal analysis revealed malformation in chromosome 22 and eunuchoid features and a low grade development of secondary sexual characteristics were also evident. Endocrinological examinations revealed that this patient was in a state of isolated IHH. Although CES with IHH is extremely rare, endocrine disorders should be given due attention.

Adult↗
PubMed2005

Expression of inducible 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase/PFKFB3 isoforms in adipocytes and their potential role in glycolytic regulation.

6-Phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFK-2/FBPase) catalyzes the synthesis and degradation of fructose 2,6-bisphosphate (F2,6BP), which is a powerful activator of 6-phosphofructo-1-kinase, the rate-limiting enzyme of glycolysis. Four genes encode PFK-2/FBPase (PFKFB1-4), and an inducible isoform (iPFK-2/PFKFB3) has been found to mediate F2,6BP production in proliferating cells. We have investigated the role of iPFK-2/PFKFB3 and related isoforms in the regulation of glycolysis in adipocytes. Human visceral fat cells express PFKFB3 mRNA, and three alternatively spliced isoforms of iPFK-2/PFKFB3 are expressed in the epididymal fat pad of the mouse. Forced expression of the iPFK-2/PFKFB3 in COS-7 cells resulted in increased glucose uptake and cellular F2,6BP content. Prolonged insulin treatment of 3T3-L1 adipocytes led to reduced PFKFB3 mRNA expression, and epididymal fat pads from db/db mice also showed decreased expression of PFKFB3 mRNA. Finally, anti-phospho-iPFK-2(Ser461) Western blotting revealed strong reactivity in insulin-treated 3T3-L1 adipocyte, suggesting that insulin induces the phosphorylation of PFKFB3 protein. These data expand the role of these structurally unique iPFK-2/PFKFB3 isoforms in the metabolic regulation of adipocytes.

3T3 Cells↗
PubMed2005

Aberrant expression of HOX genes in human invasive breast carcinoma.

HOX genes are known not only as master genes that control the morphogenesis, but also as regulator genes that maintain tissue or organ specificity in the adult body. We hypothesized that dysregulated expression of HOX genes was associated with tumor development and malignant progression such as invasion and metastasis. In this study, we analyzed the expression patterns of 39 HOX genes in human invasive ductal breast cancer tissues and normal tissues by the real-time RT-PCR method. We found 11 HOX genes (HOXA1, A2, A3, A5, A9, C11, D3, D4, D8, D9 and D10) expression levels of which were significantly different between cancerous and normal tissues. All 10 genes except HOXC11 were expressed at lower levels in cancerous tissues than normal tissues. Comparing expression levels of each HOX gene among the different types of cancer tissues, the expression level of HOXB7 was lower in lymph node metastasis-positive cancer tissues than negative cancer tissues; those of HOXD12 and D13 were higher in progesterone receptor-positive cancer tissues than negative cancer tissues; and the expression level of HOXC5 was lower in cancerous tissues with mutated-type p53 than in normal and cancerous tissues with wild-type p53. These results suggest that the aberrant expression of HOX genes is related to the development of breast cancer and malignant behavior of cancer cells.

Adult↗
PubMed2005

[Treatment with phosphate binder (sevelamer hydrochloride, calcium carbonate) based on PTH].

When sevelamer hydrochloride is used as a phosphate binder instead of the more common calcium carbonate, the PTH rises. This has been observed in many cases and makes it more difficult for practical use. However, considering the calcium load, the excessive dosing of calcium carbonate must be avoided. With that in mind, we divided the i-PTH in groups of 100 pg/mL and tested the changes in i-PTH value, P value, the adjusted Ca value, and the product of Ca and P before and after a dosage of sevelamer hydrochloride. When the average i-PTH was under 100mg/mL 6 months before dosing, the sevelamer hydrochloride single dosage group showed an early rise in i-PTH after dosing, maintaining a higher level than the calcium carbonate combined dosage group. Therefore, it was concluded that the use of sevelamer hydrochloride alone as a phosphate binder is best. On the other hand, the group with an average i-PTH over 100 pg/mL 6 months before dosing showed a rise of i-PTH that went over the K/DOQI guideline with a single dosing of sevelamer hydrochloride. Therefore, we concluded that using both sevelamer hydrochloride and calcium carbonate for phosphate binder is best.

Aged↗
PubMed2005

[Defining the role of sevelamer chloride as a therapeutic agent for management of phosphate in patient with hemodialysis].

It has been about 18 months after the commercial release of sevelamer hydrochloride. I examined the phosphorus management in patient with hemodialysis with the use sevelamer hydrochloride. The phosphorus reduction of sevelamer hydrochloride was weaker than the precipitated calcium carbonate. Patients on artificial dialysis must undergo dietary therapy for the sevelamer hydrochloride to be effective. However, by switching from precipitated calcium carbonate to sevelamer hydrochloride, the calcium level dropped, and as a result the intact PTH rose. It was possible to subdue the rise of intact PTH with vitamin D. The usefulness of vitamin D dramatically increased with the decrease and the eventual cancellation of precipitated calcium carbonate. Furthermore, the calcium load lightened and the product of calcium and phosphorus decreased. At this point, I do not expect substantial phosphorus reduction from sevelamer hydrochloride. It must be recognized that the basis of phosphorus management is proper diet. Only with that can sevelamer hydrochloride be used to its fullest potential.

Aged↗
PubMed2005

[Relationship between serum calcium level and PTH concentration proved with sevelamer hydrochloride].

About a dialysis patient's calcium-phosphate (Ca.P) metabolism, in general good control is obtained by use of sevelamer hydrochloride. As for this, what is significantly depended on not only lower P concentration but also lower Ca concentration by the change to sevelamer hydrochloride from calcium carbonate. However, by one side, much rises of i-PTH are observed by most patients with change to sevelamer hydrochloride. In this examination, Deltai-PTH was intentionally correlated with Delta calcium concentration but there was no correlation in i-PTH and Ca concentration.

Calcium↗
PubMed2004

Novel negative regulator of expression in Fas ligand (CD178) cytoplasmic tail: evidence for translational regulation and against Fas ligand retention in secretory lysosomes.

Fas ligand ((FasL) CD178), a type II transmembrane protein, induces apoptosis of cells expressing the Fas receptor. It possesses a unique cytoplasmic tail (FasLCyt) of 80 aa. As a type II transmembrane protein, the early synthesis of FasLCyt could affect FasL translation by impacting FasL endoplasmic reticulum translocation and/or endoplasmic reticulum retention. Previous studies suggest that the proline-rich domain (aa 43-70) in FasLCyt (FasLPRD) inhibits FasL membrane expression by retaining FasL in the secretory lysosomes. This report shows that deletion of aa 2-33 of FasLCyt dramatically increased total FasL levels and FasL cell surface expression. This negative regulator of FasL expression is dominant despite the presence of FasLPRD. In addition, retention of proline-rich domain-containing FasL in the cytoplasm was not observed. Moreover, we demonstrated that FasLCyt regulates FasL expression by controlling the rate of de novo synthesis of FasL. Our study demonstrated a novel negative regulator of FasL expression in the FasLCyt region and its mechanism of action.

Amino Acid Sequence↗
PubMed2004

The p38 mitogen-activated protein kinase (MAPK) pathway mediates induction of the tissue factor gene in monocytes stimulated with human monoclonal anti-beta2Glycoprotein I antibodies.

The anti-phospholipid syndrome (APS) is characterized by thrombosis and the presence of anti-phospholipid antibodies (aPL). Tissue factor (TF), the major initiator of the coagulation system, is induced on monocytes by aPL in vitro, explaining, in part, the pathophysiology in this syndrome. However, little is known regarding the nature of the aPL-induced signal transduction pathways leading to TF expression. In this study, we investigated aPL-inducible genes in PBMC using cDNA array system and real-time PCR. Our results indicated that the mitogen-activated protein kinase (MAPK) pathway was related to TF expression when PBMCs were treated, in the presence of beta(2)Glycoprotein I (beta(2)GPI), with human monoclonal anti-beta(2)GPI antibodies [beta(2)GPI-dependent anti-cardiolipin antibodies (aCL/beta(2)GPI)]. Western blotting studies using monocyte cell line (RAW264.7) demonstrated that p38 MAPK protein was phosphorylated with nuclear factor kappaB (NF-kappaB) activation by monoclonal aCL/beta(2)GPI treatment, and that SB203580, a specific p38 MAPK inhibitor, decreased the aCL/beta(2)GPI-induced TF mRNA expression. The p38 MAPK phosphorylation, NF-kappaB translocation and TF mRNA expression triggered by aCL/beta(2)GPI were abolished in the absence of beta(2)GPI. These results demonstrated that the p38 MAPK signaling pathway plays an important role in aPL-induced TF expression on monocytes and suggest that the p38 MAPK may be a possible therapeutic target to modify a pro-thrombotic state in patients with APS.

Antibodies, Monoclonal↗