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Biomedical subjects

Michio Imawari

Publications and source records attributed to Michio Imawari.

At least 19 recordsLinked to original sources
PubMed2006

Identification of novel hepatitis C virus-specific cytotoxic T lymphocyte epiotpe in NS3 region.

Hepatitis C virus (HCV)-specific cytotoxic T lymphocytes (CTL) are thought to be effective in limiting viral spread and in clearing virus during infection. Therefore, we attempted to establish HCV-specific CTL and identify novel HCV-specific CTL epitopes in a patient with acute hepatitis C by a novel screening method using recombinant vaccinia viruses (rVV) and synthetic peptides. CD8(+)CD45RA(-) T cells (memory T cells) were isolated from peripheral blood mononuclear cells (PBMC) of a patient with acute hepatitis C. HCV-specific CTL were cloned at limited dilutions and tested for HCV-specific CTL activity using a standard (51)Cr release assay. CTL assay was performed using rVV expressing regions of HCV-J, and overlapping and truncated synthetic peptides from HCV-J. CTL recognizing the NS3 region were isolated by (51)Cr release assay with rVV-HCV. Isolated CTL were restricted by HLA class I molecules B(*)5603. We confirmed that isolated CTL recognized 8-mer amino acids in the NS3 region of HCV-J by (51)Cr release assay with overlapping and truncated synthetic peptides. In conclusion, we isolated HCV-specific CTL restricted by HLA-B(*)5603 and identified a novel HCV-specific CTL epitope (IPFYGKAI, amino acids 1373-1380) in the NS3 region. The identified HCV-specific CTL epitope might be useful for HCV therapy.

Journal Article↗
PubMed2006

Immune responses of liver-infiltrating lymphocytes and peripheral blood mononuclear cells to hepatitis C virus core and NS3 antigens.

BACKGROUND AND AIM: Th1/Th2 cytokine balance is thought to play an important role in antiviral immunity and pathogenesis in viral infection. Ex vivo hepatitis C virus (HCV) antigen-specific T-cell responses were investigated. METHODS: Using enzyme-linked immunospot assay, HCV core and NS3 antigen-specific interferon-gamma-, interleukin-4- and interleukin-10-secreting cells were enumerated in peripheral blood mononuclear cells (PBMCs) from 30 chronic hepatitis C patients and 16 healthy controls, and in liver-infiltrating lymphocytes (LILs) from 17 of the 30 patients. RESULTS: IFN-gamma- and IL-10-secreting cells in response to stimulation with HCV core and NS3 antigen were detectable in both PBMCs and LILs from patients with chronic hepatitis C, although frequencies of the cytokine-secreting cells were much higher in LILs than PBMCs. They were not detectable in PBMCs of healthy controls except for IL-10-secreting cells in response to HCV NS3 antigen stimulation. IL-4-secreting cells were hardly detectable in both PBMC and LIL in both the patients and the healthy controls. Frequencies of HCV NS3 antigen-specific IFN-gamma- and IL-10-secreting cells in PBMCs correlated with those in LILs (rho=0.599, p=0.044 and rho=0.716, p=0.004, respectively). CONCLUSIONS: These data provide further evidence of the immunomodulatory role of the CD4(+)CD25(+) regulatory T lymphocytes in chronic HCV infection.

Journal Article↗
PubMed2006

Late toxicity in complete response cases after definitive chemoradiotherapy for esophageal squamous cell carcinoma.

BACKGROUND: We retrospectively investigated long-term toxicity after concurrent chemoradiotherapy (CRT) for patients with esophageal squamous cell carcinoma (ESCC). METHODS: Concurrent chemoradiotherapy was performed in 110 patients with T1 to T4 disease containing M1 lymph node (LYM) disease. Chemotherapy consisted of protracted infusion of 5-fluorouracil 400 mg/m(2) per 24 h on days 1 to 5 and 8 to 12, combined with 2-h infusion of cisplatin 40 mg/m(2) on days 1 and 8. Radiation treatment of the mediastinum at a dose of 30 Gy in 15 fractions was administered concomitantly with chemotherapy. A course schedule with a 3-week treatment and a 2-week break was applied twice, with a total radiation dose of 60 Gy. For the assessment of toxicity, the Radiation Therapy Oncology Group/European Organization for Research and Treatment of Cancer late radiation morbidity scoring schema was adopted. RESULTS: A total of 81 patients were recruited in patients with stage I to IVA. Of 34 patients with complete response, 1 patient died as a result of acute myocardial infarction. Grade 2, 3, and 4 late toxicities occurred with the following incidences: pericarditis in 3 patients, 1 patient, and 2 patients, respectively; heart failure in 0, 0, and 3 patients; pleural effusion in 2, 3, and 0 patients; and radiation pneumonitis in 0, 0, and 1 patient, respectively. CONCLUSIONS: Definitive chemoradiotherapy for ESCC is effective with substantial toxicities. Further investigation is warranted to minimize the normal tissue toxicities.

Aged↗
PubMed2005

Translational enhancement of HCV RNA genotype 1b by 3'-untranslated and envelope 2 protein-coding sequences.

HCV RNA has a unique regulatory mechanism for translation. The X region of 3'-UTR and core-coding sequence regulate HCV translation. In this study, we clarified that the entire 3'-UTR also enhances HCV translation, and the envelope-coding sequence of HCV genotype 1b increases degree of this enhancement. In the luciferase reporter assay using rabbit reticulocyte lysates, translational enhancement by 3'-UTR with core to E2 regions was 25-fold higher when compared with control RNA lacking the 3'-UTR. Presence of the entire E2 sequence was important for this enhancement. This phenomenon was not due to transcript stability, and envelope protein alone did not affect translation. E2-coding sequence of genotype 1a had no effect on translation. We observed the same results in animal cell culture systems using bicistronic RNA. Structural protein-coding sequences and 3'-UTR of HCV RNA regulate viral translation, and a target for antiviral agents may be present in these regions.

3' Untranslated Regions↗
PubMed2005

Cholecystokinin stimulates the recruitment of the Src-RhoA-phosphoinositide 3-kinase pathway by Vav-2 downstream of G(alpha13) in pancreatic acini.

In isolated rat pancreatic acini, Src, RhoA, PI3-K, Vav-2, G(alpha12), and G(alpha13) were detected by immunoblotting. CCK enhanced the levels of these proteins, and the levels of Src and RhoA were reduced by the Src inhibitor herbimycin A and the Rho inhibitor pravastatin. The PI3-K inhibitor wortmannin reduced the level of PI3-K. These inhibitors also decreased amylase secretion in CCK-treated pancreatic acini without altering basal secretion. Immunoprecipitation studies indicated that CCK caused Src to associate with Vav-2, RhoA, and PI3-K and RhoA and Src to associate with Vav-2. Ras, RasGAP, and SOS did not coimmunoprecipitate with Vav-2, and RasGAP and SOS did not coimmunoprecipitate with RhoA. CCK also enhanced Vav-2 and RhoA to coimmunoprecipitate with G(alpha13). We conclude that CCK stimulates the recruitment of the Src-RhoA-PI3-K signaling pathway by Vav-2 downstream of G(alpha13) in pancreatic acini.

Amylases↗
PubMed2005

Development of hepatocellular carcinoma following treatment with 6-mercaptopurine for ulcerative colitis: investigation of chromosomal aberration by comparative genomic hybridization.

In a 64-year-old man who had been treated with prednisolone (PSL) and 6-mercaptopurine (6MP) for a long period, for ulcerative colitis (UC), hepatocellular carcinoma (HCC) was detected incidentally. The UC was in remission with these medications. After he had been taking these medications for about 8 years, HCC was detected by computed tomography (CT), done for the evaluation of an other disease. Blood chemistry examination results were normal, except that the protein induced by vitamin K antagonist (PIVKA)-II level was 7940 AU/ml. We performed resection of liver segment V. With comparative genomic hybridization, chromosomal aberrations were recognized; these were gains of 1q, 3ptel-21, 8p12, and 22q11.23-22q13.1. Generally, HCC is associated with hepatitis virus infection in most cases, but in this patient, the HCC was not related to hepatitis C virus (HCV) or HBV. It is presumed that this case was related to the immunosuppressive therapy for UC and was associated with the gains of 1q, 3p, and 8p.

Carcinoma, Hepatocellular↗
PubMed2005

Prevalence of hepatitis B and C virus infection in haematological malignancies and liver injury following chemotherapy.

The aim of this study was to determine the carrier rate of hepatitis virus in patients with haematological malignancies and the incidence of liver injury in these patients following chemotherapy. From January 1996 to September 2002, we studied 601 consecutive, unselected series of patients with haematological malignancies admitted in our hospital unit (Japan). They consisted of 246 cases of acute leukaemia, 218 non-Hodgkin's lymphoma (NHL), 13 adult T-cell leukaemia, and 124 multiple myeloma. Of these 601 patients, 373 were men and 228 were women; their mean age was 61 yr, with a range from 18 to 89 yr. The prevalences of hepatitis B virus (HBV) and hepatitis C virus (HCV) were 7.3% and 10.1%, respectively, in NHL, both higher than those in acute leukaemia (1.7% and 2.9%, P < 0.005) and in general Japanese population (1.2% and 2.6%). The incidence of post-chemotherapy liver injury in 25 HBV carriers (36.0%) was significantly higher than that in 539 non-hepatitis virus carriers (12.6%, P = 0.003) and 37 HCV carriers (10.8%, P = 0.026). Liver injury in HBV carriers was more often present in patients who had been treated with steroids than in those without steroids (72.7% and 0%, P = 0.013). After lamivudine became available in our institution, the incidence of liver injury in HBV carriers was reduced from 53.3% to 10.0% (P = 0.041). The therapeutic strategy for haematological malignancies in hepatitis virus carriers should be further investigated.

Adolescent↗
PubMed2004

Molecular differences between sporadic serrated and conventional colorectal adenomas.

PURPOSE: The purpose is to compare the molecular characteristics of serrated adenomas (SAs) with those of conventional adenomas (CADs) and hyperplastic polyps (HPs). EXPERIMENTAL DESIGN: We evaluated the proliferative activity and molecular alterations in 47 SAs (25 pure-type and 22 mixed-type), 71 CADs, and 23 HPs. RESULTS: The proliferative activity of SAs, as evaluated by Ki-67 expression, was intermediate between CADs and HPs. There was no significant difference in the incidence of KRAS or p53 mutations between the three histological groups. In the microsatellite instability (MSI) analysis, 21% of SAs (9 of 43) showed MSI at two or more loci (MSI-H); corresponding values were 5% of CADs (3 of 64) and 8% of HPs (1 of 13; SAs versus CADs, P = 0.0125). MSI-H was more likely to be found in pure-type SAs (36%; 8 of 22) than in mixed-type SAs (5%; 1 of 21; P = 0.0212). Loss of hMLH-1 expression was found in 8 of 9 SAs with MSI-H. The incidence of BRAF or KRAS mutations was 36 and 15% of SAs, respectively; the combined incidence of BRAF and KRAS mutations occurred in 49% of SAs. However, there was no significant difference in the incidence of BRAF or KRAS mutations between SAs with and without MSI-H. CONCLUSIONS: Genetic instability is more frequently implicated in the tumorigenesis of SAs, especially pure-type SAs, than in that of CADs. In contrast, activation of the Ras/Raf/MEK/MAP kinase cascade by BRAF or KRAS mutation, independently of the genetic instability, may be associated with the progression of about half of SAs.

Adaptor Proteins, Signal Transducing↗
PubMed2004

Cellular immune response in primary biliary cirrhosis.

The generation of immune responsiveness to self-antigen can result in the pathogenic autoimmune damage of tissues mediated by both humoral and cellular immune responses. Primary biliary cirrhosis (PBC) constitutes a model of autoimmune disease reflective of other organ-specific autoimmune feature. Although the etiology of PBC remained elusive, growing data suggest the role of cell-mediated immune response in the pathogenesis of PBC. Indeed, autoreactive CD4 as well as CD8 T cells have been characterized and their epitopes defined. Molecular mimicry is implicated in the initiation of these autoreactive T cell responses. Moreover, selective enrichment of NKT cells in the liver of PBC is demonstrated using CD1d tetramer.In this review, we shall focus on the recent advance of cell-mediated immune responses in PBC, which may be directly associated with inflammatory response in PBC.

Journal Article↗
PubMed2004

Phagocytic function of neutrophils of patients with decompensated liver cirrhosis is restored by oral supplementation of branched-chain amino acids.

It has been reported that phagocytic function of neutrophils is impaired in cirrhotic patients. We examined the effects of oral supplementation of branched-chain amino acids (BCAA) on phagocytic function of neutrophils in peripheral blood of patients with decompensated cirrhosis. Five patients with decompensated cirrhosis received 12g of BCAA daily for 3 months. Phagocytic function of neutrophils and NK activities of lymphocytes in peripheral blood as well as serum albumin levels and Fisher's ratios were determined before and at 1 and 3 months of BCAA supplementation. Phagocytic function of neutrophils was significantly improved by 3-month BCAA oral supplementation. NK activity of lymphocytes was improved in four of five patients at 3 months of BCAA supplementation, although the changes were not statistically different. In conclusion, BCAA supplementation improved phagocytic function of neutrophils in cirrhotic patients. BCAA supplementation may reduce the risk of bacterial infection in patients with decompensated liver cirrhosis.

Journal Article↗
PubMed2004

Identification of novel hepatitis C virus-specific cytotoxic T lymphocyte epitopes by ELISpot assay using peptides with human leukocyte antigen-A*2402-binding motifs.

The human leukocyte antigen (HLA)-A*2402 is common in Asians. The authors attempted to identify epitopes for HLA-A*2402-restricted, hepatitis C virus (HCV)-specific CD8(+) T cells by an enzyme-linked immunospot (ELISpot) assay using peripheral blood CD8(+) T cells from HLA-A*2402-positive hepatitis C patients and synthetic HCV peptides based on HLA-A*2402-binding motifs and the amino acid sequence of type 1b HCV. Ten novel epitopes were identified in five of seven HLA-A*2402-positive patients with acute or short-term chronic HCV infection (<3 years), but in none of four with longer-term chronic infection (>10 years). Only one of the ten epitopes proved to be definitely HLA-A*2402-restricted. Another epitope was identified in one of two HLA-A*2402-negative acute hepatitis C patients. In two of the six patients with positive CD8(+) T cell responses, the targeted epitopes were multiple. The same epitope was targeted in two patients. When patients with unresolved acute HCV infection were treated with alpha interferon, peripheral blood HCV-specific CD8(+) T cells decreased with resolution of the hepatitis. In conclusion, CD8(+) T cell responses to HCV infection are heterogeneous. One definite HLA-A*2402-restricted and ten probably non-HLA-A*2402-restricted epitopes were identified. Patients with short-term HCV infection are suitable for searching for novel HCV epitopes, but peripheral blood HCV-specific CD8(+) T cells decrease markedly after loss of antigenic stimulation.

Binding Sites↗