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Toshihiro Okamoto

Publications and source records attributed to Toshihiro Okamoto.

9 recordsLinked to original sources
PubMed2003

Regulatory roles of IL-2 and IL-4 in H4/inducible costimulator expression on activated CD4+ T cells during Th cell development.

We found a tight correlation among the levels of H4/inducible costimulator (ICOS) expression, IL-4 production, and GATA-3 induction, using activated CD4(+) T cells obtained from six different murine strains. BALB/c-activated CD4(+) T cells expressed approximately 10-fold more H4/ICOS on their surfaces and produced approximately 10-fold more IL-4 upon restimulation than C57BL/6-activated CD4(+) T cells. BALB/c naive CD4(+) T cells were shown to produce much higher amounts of IL-2 and IL-4 upon primary stimulation than C57BL/6 naive CD4(+) T cells. Neutralization of IL-4 with mAbs in culture of BALB/c naive CD4(+) T cells strongly down-regulated both H4/ICOS expression on activated CD4(+) T cells and IL-4 production upon subsequent restimulation. Conversely, exogenous IL-4 added to the culture of BALB/c or C57BL/6 naive CD4(+) T cells up-regulated H4/ICOS expression and IL-4 production upon restimulation. In addition, retroviral expression of GATA-3 during the stimulation of naive CD4(+) T cells from C57BL/6 or IL-4(-/-) mice increased H4/ICOS expression on activated CD4(+) T cells. A similar effect of IL-2 in the primary culture of BALB/c naive CD4(+) T cells appeared to be mediated by IL-4, the production of which was regulated by IL-2. These data suggest that IL-4 induced by IL-2 is critical to the maintenance of high H4/ICOS expression on BALB/c-activated CD4(+) T cells.

Animals↗
PubMed2003

Osthole prevents anti-Fas antibody-induced hepatitis in mice by affecting the caspase-3-mediated apoptotic pathway.

Fas (Apo-1/CD95) ligand, which is a type II membrane protein, is a major inducer of apoptosis. Osthole is a coumarin derivative present in medicinal plants. The effect of osthole on hepatitis induced by anti-Fas antibody in mice was studied. Pretreatment of mice with osthole (10, 50, and 100 mg/kg, i.p.) prevented the elevation of plasma alanine aminotransferase (ALT) caused by anti-Fas antibody (175 microg/kg, i.v.). Administration of osthole to mice even at a dose of 10 mg/kg significantly inhibited of anti-Fas antibody-induced elevation of plasma ALT. Capase-3 is a cysteine protease, and treatment of mice with anti-Fas antibody caused an elevation of caspase-3 activity at 3.5 and 6 hr. Pretreatment of mice with osthole (100 mg/kg, i.p.) inhibited the elevation of caspase-3 activity caused by anti-Fas antibody. However, the addition of osthole (up to 10(-4)M) to a liver cytosol fraction isolated from mice treated with anti-Fas antibody did not inhibit caspase-3 activity in vitro. Thus, treatment of mice with osthole inhibited caspase-3 activity by an effect upstream of caspase-3 activation. The livers of mice treated with anti-Fas antibody contained apoptotic and dead cells; osthole attenuated the development of this apoptosis and cell death. The present results show that osthole prevented anti-Fas antibody-induced hepatitis by inhibiting the Fas-mediated apoptotic pathway.

Alanine Transaminase↗
PubMed2003

Down-regulation of cyclooxygenase-2 expression but up-regulation of cyclooxygenase-1 in renal carcinomas of the Eker (TSC2 gene mutant) rat model.

Although it is generally accepted that cyclooxygenase (Cox)-2 is overexpressed in carcinomas, few studies have examined Cox-2 expression in renal carcinoma (RC). The Eker rat RC is an example of a Mendelian dominantly inherited carcinoma, and in the present study, expression of Cox-2 in the Eker rat RC was examined. Reverse transcription polymerase chain reaction indicated constitutive expression of Cox-2 mRNA in the normal control kidney and non-tumor part of Eker rat kidney. Unexpectedly, expression of Cox-2 mRNA was down-regulated in four Eker RCs from two Eker rats, and in the cell line Lk9ds. Immunohistochemical analysis failed to reveal Cox-2 protein staining in Eker RCs. As a control to Cox-2 expression, Cox-1 expression was examined. Interestingly, in contrast to the down-regulated Cox-2 expression, Cox-1 mRNA expression was induced in these four Eker RCs and cell lines. Cox-2 and Cox-1 expression were further examined in six additional Eker RCs. In total, Cox-2 mRNA expression was down-regulated in eight out of ten Eker RCs and cell lines, while Cox-1 mRNA expression was up-regulated in nine out of ten Eker RCs and cell lines.

Animals↗
PubMed2003

Requirement of drug development for chronic renal disease: Other strategies than blockade of the renin-angiotensin system.

The number of patients with chronic renal disease is increasing, hypertension and diabetes being major causes of it. Chronic renal disease progresses to the end-stage, of which a patient requires dialysis or transplantation, and thus prevention of progression of renal disease to the end-stage is a very important issue. Accumulating data indicate that angiotensin-converting enzyme (ACE) inhibitor is more effective than other antihypertensive drugs for treating chronic renal disease, since in addition to an antihypertensive effect, ACE inhibitor has a renoprotective effect. Although ACE inhibitor is more effective than other antihypertensive drugs, it only prevents the progression of chronic renal disease by less than 50%. Thus, in addition to blockers of the renin-angiotensin system, other types of drugs are required. Chronic renal disease progresses through a common pathway, regardless of the type of initial insult. This common pathway includes direct hemodynamic actions, modulation of glomerular cell injury, growth factor actions and induction of apoptosis. Blockade of this common pathway is one of the drug development strategies for chronic renal disease.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed2003

Expression and function of the co-stimulator H4/ICOS on activated T cells of patients with rheumatoid arthritis.

OBJECTIVE: To investigate the expression and function of the inducible co-stimulator H4/ICOS in rheumatoid arthritis (RA) patients. H4/ICOS is the newest member of the CD28/CTLA-4 family to have been found to be expressed on activated T cells, and it participates in a variety of important immunoregulatory functions. METHODS: The levels of H4/ICOS expression on T cells among peripheral blood mononuclear cells (PBMC) and synovial fluid mononuclear cells (SFMC) from 28 patients with RA were analyzed by flow cytometry. To explore the role of H4/ICOS function in the inflammation of rheumatoid joints, lymphokine production by SF CD4+ T cells co-stimulated by H4/ICOS was assayed. Expression of H4/ICOS ligand (B7RP-1) mRNA in synovial tissues from patients with RA was examined by reverse transcription polymerase chain reaction (RT-PCR). RESULTS: H4/ICOS-positive cells were increased significantly in whole, CD4+, and CD8+ T-cell fractions of SFMC compared with control PBMC. Comparison between control PB and PB from patients with active RA showed that H4/ICOS-positive whole and CD8+ T-cell fractions were increased significantly in the PB of RA patients. H4/ICOS costimulation clearly increased interferon-g, interleukin 4 (IL-4), and IL-10 production by SF CD4+ T cells. By RT-PCR, RA synovial tissue was shown to express mRNA of B7RP-1. CONCLUSION: Our results suggest that local immune responses may be modulated by H4/ICOS expressed on T cells in the joints of patients with RA, and thus H4/ICOS may be involved in the pathogenetic mechanism of RA.

Adult↗
PubMed2002

A co-stimulatory molecule on activated T cells, H4/ICOS, delivers specific signals in T(h) cells and regulates their responses.

We examined the co-stimulatory activity of H4/ICOS on murine activated CD4(+) T cells and found that the cross-linking of H4/ICOS enhanced their proliferation, in addition to raising IFN-gamma, IL-4 and IL-10 production to levels comparable to those induced by CD28. However, IL-2 production was only marginally co-stimulated by H4/ICOS. This distinct pattern of lymphokine production appears to be induced by a specific intracellular signaling event. Compared with CD28, H4/ICOS dominantly elicited the Akt pathway via phosphatidylinositol 3-kinase. In addition, mitogen-activated protein kinase family kinases were activated in different ways by CD28 and H4/ICOS. The strong phosphorylation of p46 c-Jun N-terminal kinase was observed upon CD28 co-stimulation, but was less potently induced by H4/ICOS. The strain diversity in the induction of H4/ICOS was recognized. The expression of H4/ICOS on BALB/c activated CD4(+) T cells was >6-fold higher compared with C57BL/6 activated CD4(+) T cells. Furthermore, BALB/c activated CD4(+) T cells exhibited more T(h)2-deviated lymphokine production as compared with C57BL/6 activated CD4(+) T cells and signaling through H4/ICOS during the primary stimulation of naive CD4(+) T cells promoted the generation of T(h)2 cells. Thus, the difference in H4/ICOS expression on activated CD4(+) T cells, which is regulated among the mouse strains, may also regulate the polarization of T(h) cells.

Animals↗
PubMed2002

NSAID zaltoprofen improves the decrease in body weight in rodent sickness behavior models: proposed new applications of NSAIDs (Review).

In infectious diseases and during inflammation, anorexia, loss of body weight, malaise, fatigue and depression are induced. These symptoms are correctively called 'sickness behaviors', and the central actions of cytokines play a role in their induction. The loss of body weight in cancer cachexia is also a result of development of sickness behaviors. It has been reported that the administration of NSAID ibuprofen to patients with cancer cachexia improves the loss in body weight. We studied the effect of NSAID on the loss of body weight by using rodent sickness behavior models. We have reported that sickness behaviors such as anorexia, decrease in body weight, and loss of locomotor activity are induced in concanavalin A (Con A)-induced mouse hepatitis and carbon tetrachloride-induced rat hepatitis. Zaltoprofen is a non-steroidal anti-inflammatory drug (NSAID) causes potent inhibition of cyclooxygenase-2 with fewer side effects on the gastrointestinal tract. Zaltoprofen improves the loss in body weight in both Con A-treated mice and carbon tetrachloride-treated rats. These results suggest the possible application of zaltoprofen for the treatment of sickness behaviors including loss of body weight occurring in cancer cachexia.

Animals↗
PubMed2002

[Combination chemotherapy with nedaplatin (CDGP) and 5-FU for oral cancer].

Chemotherapy using CDGP plus 5-FU was evaluated in patients with oral cancer. The subjects were patients with squamous cell carcinoma of the oral cavity who had not received any therapy, comprising 7 patients with carcinoma of the tongue, 2 with buccal carcinoma, 2 with maxillary gingival carcinoma, and 1 with carcinoma of the oral floor. There were 4 patients in Stage II, 3 patients in Stage III and 5 patients in Stage IV. Patients with a PS < or = 1, WBC > or = 4,000/mm3, Hb > or = 10 g/dl, platelet count > or = 10 x 10/mm3, and normal liver, kidney, and heart function at baseline were selected for this study. In all patients, 5-FU was administered at a dose of 600 mg/m2/day for 5 days (day 1 to day 5) by continuous infusion, for a total dose of 3,000 mg/m2. CDGP was administered on day 1 at a dose of 80 mg/m2 in 8 patients and at 100 mg/m2 in 4 patients. This treatment was one course of therapy, and patients received 1 or 2 courses. Of 12 patients who were evaluable, there were 9 partial responses and 3 no changes, for a major response rate of 75%. Toxicities experienced by patients were mild (grade 2 or lower) gastrointestinal disorders (including nausea/vomiting) and renal impairment, while grade 3 leukopenia and thrombocytopenia developed in 1 patient each and grade 4 thrombocytopenia occurred in another patient. Thus, patients receiving CDGP + 5-FU therapy should be closely monitored for hematologic toxicity. Since CDGP + 5-FU therapy achieved a good response rate (75%) in the treatment of squamous cell carcinoma of the oral cavity, we plan to use this therapy in the future and assess its benefit in a larger number of patients.

Adult↗