Hepatitis: Imawari M

Imawari M. · No affiliation provided · J Gastroenterol Hepatol. · Pubmed #18699978 No free full text.

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Imawari M. · No affiliation provided · J Gastroenterol. · Pubmed #15565418 No free full text.

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Imawari M. · No affiliation provided · J Gastroenterol. · Pubmed #11063227 No free full text.

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Imawari M. · No affiliation provided · J Gastroenterol. · Pubmed #10213136 No free full text.

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Hiroishi K, Ito T, Imawari M. · Department of Gastroenterology, Showa University School of Medicine, Tokyo, Japan. · J Gastroenterol Hepatol. · Pubmed #18761560 No free full text.

Abstract: Immune responses against hepatitis C virus (HCV) play a crucial role in the pathogenesis of chronic hepatitis C. HCV infection often persists and leads to chronic hepatitis and eventually cirrhosis. Accumulated data suggest that HCV proteins suppress host immune responses through the suppression of functions of immune cells, such as cytotoxic T lymphocytes, natural killer cells, and dendritic cells. They also suppress the type 1 interferon signaling system. The resulting insufficient immune responses against HCV lead to the sustained infection. The appropriate control of immune responses would contribute to the eradication of HCV and the improvement of hepatitis, but there are still many issues to be clarified. This review describes the scientific evidence to support these emerging concepts, and will touch on the implications for improving antiviral therapy.

Nakamura I, Ochiai K, Imawari M. · Division of Gastroenterology, Omiya Medical Center, Jichi Medical School. · Nippon Rinsho. · Pubmed #15453297 No free full text.

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Nakamura I, Ochiai K, Imawari M. · Division of Gastroenterology, Omiya Medical Center, Jichi Medical School. · Nippon Rinsho. · Pubmed #15359829 No free full text.

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Hiroishi K, Matsumura T, Imawari M. · Second Department of Internal Medicine, Showa University School of Medicine. · Nippon Rinsho. · Pubmed #15359785 No free full text.

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Morita H, Imawari M. · Division of Gastroenterology, Omiya Medical Center, Jichi Medical School. · Nippon Rinsho. · Pubmed #15359784 No free full text.

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Imawari M. · Omiya Medical Center, Jichi Medical School, 1-847 Amanuma-cho, Saitama, Saitama 330-8503. · Uirusu. · Pubmed #12227166 No free full text.

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Imawari M. · No affiliation provided · Nippon Naika Gakkai Zasshi. · Pubmed #11681070 No free full text.

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Nakamura I, Imawari M. · Division of Gastroenterology and Hepatology, Omiya Medical Center, Jichi Medical School, Japan. · J Gastroenterol. · Pubmed #11573723 No free full text.

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Nakamura I, Imawari M. · Division of Gastroenterology and Hepatology, Jichi Medical School. · Nippon Rinsho. · Pubmed #11494538 No free full text.

Abstract: Patients with hepatitis C virus(HCV) responding differently to interferon(IFN) therapy were speculated to have different incidence of disease progression to cirrhosis and of the development of hepatocellular carcinoma(HCC). However, the background and prognosis of the patients with sustained biochemical response without eradication of HCV (BR) (asymptomatic HCV carrier) has not been revealed so far. Review of recent studies suggest that the characteristics of the patients with BR are lower HCV RNA load, higher rate of HCV subtype-2 and lower score of liver fibrosis when compared with those with NR. The IFN therapy in patients who have not cleared HCV and showed normal ALT retards progression of fibrosis and reduces the incidence of cirrhosis and HCC.

Fujiwara T, Imawari M. · Department of Integrated Medicine, Omiya Medical Center, Jichi Medical School. · Ryoikibetsu Shokogun Shirizu. · Pubmed #11212752 No free full text.

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Izumi N, Kumada H, Hashimoto N, Harada H, Imawari M, Zeniya M, Toda G. · Division of Gastroenterology and Hepatology, Musashino Red-cross Hospital, Tokyo, Japan. · Dig Dis Sci. · Pubmed #11318525 No free full text.

Abstract: Virological response to interferon (IFN) is poor in patients with plasma levels of HCV RNA higher than 1 Meq/ml and genotype 1b hepatitis C viral infection. In 60 patients, a randomized control study was conducted to compare 3 MU of IFN-beta twice daily for four weeks (group A) and 6 MU once a day for four weeks (group B) followed by a four-week administration of 6 MU once a day. The plasma levels of HCV RNA, determined by an amplicore-monitor method, for patients in group A were significantly lower than those for group B at the fourth and eighth day of IFN administration, and complete virological responses were noted in two patients from group A but none in group B. It is concluded that twice daily administration of 3 MU IFN-beta is more effective than once a day 6 MU in the early phase of IFN therapy.

Inokuchi M, Ito T, Uchikoshi M, Shimozuma Y, Morikawa K, Nozawa H, Shimazaki T, Hiroishi K, Miyakawa Y, Imawari M. · Department of Gastroenterology, Showa University School of Medicine, Tokyo, Japan. · J Med Virol. · Pubmed #19235854 No free full text.

Abstract: Infection with hepatitis C virus (HCV) is associated with lymphoproliferative disorders, represented by essential mixed cryoglobulinemia and B-cell non-Hodgkin's lymphoma, but the pathogenic mechanism remains obscure. HCV may infect B cells or interact with their cell surface receptors, and induce lymphoproliferation. The influence of HCV infection of B cells on the development of lymphoproliferative disorders was evaluated in 75 patients with persistent HCV infection. HCV infection was more prevalent (63% vs. 16%, 14%, or 17% P < 0.05 for each), and HCV RNA levels were higher (3.35 +/- 3.85 vs. 1.75 +/- 2.52, 2.15 +/- 2.94 or 2.10 +/- 2.90 log copies/100 ng, P < 0.01 for each) in B cells than CD4(+), CD8(+) T cells or other cells. Negative-strand HCV RNA, as a marker of viral replication, was detected in B cells from four of the 75 (5%) patients. Markers for lymphoproliferative disorders were more frequent in the 50 patients with chronic hepatitis C than the 32 with chronic hepatitis B, including cryoglobulinemia (26% vs. 0%, P < 0.001), low CH(50) levels (48% vs. 3%, P = 0.012), and the clonality of B cells (12% vs. 0%, P < 0.01). By multivariate analysis, HCV RNA in B cells was an independent factor associated with the presence of at least one marker for lymphoproliferation (odds ratio: 1.98 [95% confidence interval: 1.36-7.24], P = 0.027). Based on the results obtained, the infection of B cells with HCV would play an important role in the development of lymphoproliferative disorders.

Ito H, Ando K, Ishikawa T, Saito K, Takemura M, Imawari M, Moriwaki H, Seishima M. · Department of Informative Clinical Medicine, Gifu University Graduate School of Medicine, Gifu City, Japan. · J Immunol. · Pubmed #19109170 No free full text.

Abstract: In previous studies, the mechanisms of acute liver injury and virus exclusion have been examined using a model wherein HBsAg-specific CTL are injected into HBsAg transgenic (Tg) mice. The importance of the role of TNF-alpha in virus exclusion was shown, but its role in liver injury was unclear. We crossed the TNF-alpha knockout mouse and HBsAg-Tg mouse to establish the HBsAg-Tg/TNF-alpha KO mouse, and examined the influence of TNF-alpha on liver injury. The severity of liver damage, as determined by serum alanine aminotransferase activity, was approximately 100 times greater in HBsAg-Tg/TNF-alpha(+/+) than in HBsAg-Tg/TNF-alpha(-/-) mice after i.v. administration of 5 x 10(6) CTLs. This liver damage reached the peak of its severity within 24-48 h, and was restored 7 days later. Histopathological examination showed hepatocellular necrosis and inflammatory cell infiltrate 24 h after the CTL injection in HBsAg-Tg/TNF-alpha(+/+) mice but not in HBsAg-Tg/TNF-alpha(-/-) mice. The liver damage was fatal for all HBsAg-Tg/TNF-alpha(+/+) mice that received 1.5 x 10(7) CTLs. In contrast, 1.5 x 10(7) CTLs could not kill the HBsAg-Tg/TNF-alpha(-/-) mice. The TNF-alpha production level was enhanced after the CTL injection in not only intrahepatic macrophages but also other types of mononuclear cells from non-HBsAg-Tg/TNF-alpha(+/+) mice. An adoptive transfer examination revealed that severe liver damage occurred in HBsAg-Tg/TNF-alpha(-/-) mice that had received mononuclear cells from TNF-alpha(+/+) mice. In conclusion, the present study provides evidence that TNF-alpha produced by intrahepatic non-Ag-specific inflammatory cells is critical in the development of lethal necroinflammatory liver disease.

Doi H, Hiroishi K, Shimazaki T, Eguchi J, Baba T, Ito T, Matsumura T, Nozawa H, Morikawa K, Ishii S, Hiraide A, Sakaki M, Imawari M. · Department of Gastroenterology, Showa University School of Medicine, Tokyo, Japan. · Hepatol Res. · Pubmed #19054151 No free full text.

Abstract: Aim: We investigated the relationship between the magnitude of comprehensive hepatitis C virus (HCV)-specific CD8(+) T-cell responses and the clinical course of acute HCV infection. Methods: Six consecutive patients with acute HCV infection were studied. Analysis of HCV-specific CD8(+) T-cell responses was performed using an interferon-gamma-based enzyme-linked immunospot assay using peripheral CD8(+) T-cells, monocytes and 297 20-mer synthetic peptides overlapping by 10 residues and spanning the entire HCV sequence of genotype 1b. Results: Five patients presented detectable HCV-specific CD8(+) T-cell responses against a single and different peptide, whereas 1 patient showed responses against three different peptides. Neither the magnitude of HCV-specific CD8(+) T-cell responses nor the severity of hepatitis predicts the outcome of acute hepatitis. The maximum number of HCV-specific CD8(+) T-cells correlated with maximum serum alanine aminotransferase level during the course (r = 0.841, P = 0.036). Conclusions: HCV-specific CD8(+) T-cell responses were detectable in all 6 patients with acute HCV infection, and 6 novel HCV-specific CTL epitopes were identified. Acute HCV infection can resolve with detectable HCV-specific CD8(+) T-cell responses, but without development of antibody against HCV.

Ito H, Ando K, Ishikawa T, Nakayama T, Taniguchi M, Saito K, Imawari M, Moriwaki H, Yokochi T, Kakumu S, Seishima M. · Department of Informative Clinical Medicine, Gifu University Graduate School of Medicine, 1-1 Yanagido, Gifu 501-1194, Japan. · Int Immunol. · Pubmed #18487227 No free full text.

Abstract: CTLs are thought to be major effectors for clearing viruses in acute infections including hepatitis B virus (HBV). Persistent HBV infection is characterized by a lack of or a weak CTL response to HBV, which is thought to reflect tolerance to HBV antigens. In the present study, we found that alpha-galactosylceramide (alpha-GalCer), a ligand for Valpha14-positive NKT cells, strongly enhanced the induction and proliferation of HBV-specific CTLs by HBsAg. In HBsAg transgenic mice, which are thought to be tolerant to HBV-encoded antigens, administration of HBsAg or alpha-GalCer alone failed to induce HBsAg-specific CTLs, but they were induced by co-administration of both compounds. Furthermore, by limiting dilution analysis, we confirmed the existence of HBsAg-specific CTL precursors in the HBsAg transgenic mice immunized with HBsAg and alpha-GalCer. A blocking experiment using antibodies to cytokines and CD40 ligand showed that IL-2 and CD40-CD40L interaction mediate the enhancement of CTL induction caused by alpha-GalCer through NKT cell activation. Our results may open up a new method for clearing the virus from patients with persistent HBV infection.

Iwamoto N, Ito H, Ando K, Ishikawa T, Hara A, Taguchi A, Saito K, Takemura M, Imawari M, Moriwaki H, Seishima M. · Department of Informative Clinical Medicine, Gifu University Graduate School of Medicine, Gifu, Japan. · Liver Int. · Pubmed #18397228 No free full text.

Abstract: BACKGROUND/AIMS: Indoleamine-2,3-dioxygenase (IDO) is a tryptophan-catabolizing enzyme inducing suppression of T-cell function and immune tolerance. In hepatitis B virus (HBV) transgenic (Tg) mice, the adoptive transfer of HBV-specific cytotoxic T lymphocytes (CTL) causes a necroinflammatory liver disease that is histologically similar to acute viral hepatitis in man. The present study aimed to determine IDO expression in the liver and hepatocytes during an acute hepatitis model. METHODS: Serum l-kynurenine (l-Kyn) concentration in HBV Tg mice administered with HBV-specific CTL was measured over time, together with serum levels of alanine aminotransferase (ALT). Furthermore, we examined the expression of IDO in the total liver and isolated hepatocytes of HBV Tg mice after CTL injection using immunohistochemical analysis and reverse-transcription polymerase chain reaction (PCR). RESULTS: In HBV Tg mice, HBV-specific CTL induced, over the course of several days, a chronic increase in serum l-Kyn levels, which was associated with a sustained enhancement of liver IDO activity. In particular, IDO expression was enhanced in the liver parenchymal cells (hepatocytes) after HBV-specific CTL injection both in immunohistochemical analysis and in reverse-transcription PCR. Moreover, murine recombinant interferon-gamma (IFN-gamma) directly increased the IDO expression in primary hepatocytes in vitro. CONCLUSIONS: Cytotoxic T lymphocytes transduction results in the upregulation of IDO, which might downregulate T-cell responsiveness. Our findings provide evidence that hepatocyte itself expresses IDO and increases levels of l-Kyn in the blood in acute lethal hepatitis of mice. These data indicate that HBV infection facilitates the induction of IDO in response to proinflammatory cytokines, particularly IFN-gamma.

Sakaki M, Hiroishi K, Baba T, Ito T, Hirayama Y, Saito K, Tonoike T, Kushima M, Imawari M. · Second Department of Internal Medicine, Showa University School of Medicine, Tokyo, Japan. · Hepatol Res. · Pubmed #18021223 No free full text.

Abstract: Aim: Regulatory T cells (Tregs) maintain immunological tolerance and suppress autoreactive immune responses. We evaluated the intrahepatic status of Tregs in patients with autoimmune hepatitis (AIH), primary biliary cirrhosis (PBC), chronic hepatitis C (CH-C), or chronic hepatitis B (CH-B). Methods: We analyzed 85 patients (20 AIH, 22 PBC, 27 CH-C, and 16 CH-B) and 14 controls. Using liver tissue samples obtained by needle biopsy or from marginal parts of resected metastatic liver tumors in the controls, immunohistochemical analyses of forkhead box P3(+), which is a specific marker for Tregs, CD4(+), and CD8(+) cells were performed. Results: Intrahepatic Tregs were significantly more infiltrated in patients with liver diseases than in the controls. There were significantly fewer intrahepatic Tregs in the AIH patients than in the PBC patients (P = 0.037). Patients with alow frequency of intrahepatic Tregs were detected significantly more in the AIH and CH-B groups than in the PBC and CH-C groups (P < 0.05). In addition, the frequency of Tregs decreased in the liver of PBC patients as the pathological stage of the disease advanced. We found significantly less infiltration of CD4(+) T cells in AIH than in other diseases (P < 0.05). Liver-infiltrating CD8(+) T cells were detected more frequently in the CH-B group than in other groups (P < 0.003). Conclusion: Intrahepatic Tregs were increased in both patients with autoimmune liver diseases and those with viral hepatitis. In autoimmune liver diseases, intrahepatic Tregs were fewer in the AIH patients than in the PBC patients.

Ito K, Shiraki K, Funatsuki K, Ishiko H, Sugimoto K, Murata K, Nakano T, Imawari M. · First Department of Internal Medicine, Mie University School of Medicine, 2-174 Edobashi, Tsu, Mie 514-8507, Japan. · Hepatol Res. · Pubmed #16996788 No free full text.

Abstract: 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.

Tajimi M, Ugajin T, Ota M, Hiroishi K, Nakamura I, Imawari M. · Division of Gastroenterology, Omiya Medical Center, Jichi Medical School, Japan. · Hepatol Res. · Pubmed #16765635 No free full text.

Abstract: 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.

Morikawa K, Ito T, Nozawa H, Inokuchi M, Uchikoshi M, Saito T, Mitamura K, Imawari M. · The Second Department of Internal Medicine, Showa University School of Medicine, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo 142-8666, Japan. · Virology. · Pubmed #16289655 No free full text.

Abstract: 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.

Nakao K, Tsunoda A, Shimizu Y, Takenaka K, Morohara K, Suzuki N, Yamazaki K, Aoki T, Hoshino M, Kusano M, Kitadai E, Kurihara T, Takeuchi Y, Imawari M. · Second Department of Surgery, Showa University School of Medicine, 1-5-8 Hatanodai, Tokyo 146-8666, Japan. · Int J Clin Oncol. · Pubmed #16136376 No free full text.

Abstract: 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.