Yumiko Kamogawa

Cutting Edge: Chromatin Remodeling at the IL-4/IL-13 Intergenic Regulatory Region for Th2-Specific Cytokine Gene Cluster

During the differentiation of naive Th cells into Th2 effector cells, the entire IL-4/IL-13 locus is remodeled into an accessible chromatin conformation. Here we show that ectopic expression and activation of Stat6 or GATA-3 in Th cells developing under Th1-polarizing conditions lead to the induction of chromatin remodeling not only at the flanking regions of the IL-4 and IL-13 genes but also at the IL-4/IL-13 intergenic regulatory region for the IL-4/IL-13/IL-5 gene cluster. Furthermore, we demonstrate that GATA-3 and another Th2-specific, inducible protein complex interact with the IL-4/IL-13 intergenic DNase I hypersensitive region specifically in Th2 cells.

Significance of Fas antigen-mediated apoptosis in human fulminant hepatic failure

Abstract OBJECTIVE: The aim of this study was to elucidate the role of apoptosis in human fulminant hepatic failure. We studied the expression of Fas antigen on liver tissues, Fas ligand in lymphocytes, and soluble Fas ligand in patients’ serum. METHODS: On finding apoptotic cells in fulminant hepatic failure liver, we first examined them using the TUNEL method. Subsequently, the expression of Fas was studied by immunostaining. Simultaneously, Fas ligand presenting on both liver-infiltrated cells and peripheral lymphocytes was studied by reverse transcription-polymerase chain reaction, and soluble Fas ligand in sera was measured by ELISA. RESULTS: By using the TUNEL method, we first demonstrated that many apoptotic cells existed in fulminant hepatic failure but not in normal ones. Our immunohistochemistry study showed that many hepatocytes in fulminant hepatic failure strongly expressed Fas. In addition, Fas ligand on both liver-infiltrating lymphocytes and peripheral lymphocytes in fulminant hepatic failure patients was detected. The serum level of soluble Fas ligand was significantly increased in fulminant hepatic failure (mean value, 2.91 ng/ml in fulminant hepatic failure [n = 10], 1.62 ng/ml in acute hepatitis [n = 10], and 0.27 ng/ml in healthy controls [n = 10]). Furthermore, this serum level of sFas ligand was significantly associated with prothrombin time both in acute hepatitis and fulminant hepatic failure. CONCLUSIONS: The present results indicate that Fas-mediated apoptosis may be one of the triggers for the induction of fulminant hepatic failure.

Role of NFATx (NFAT4/NFATc3) in Expression of Immunoregulatory Genes in Murine Peripheral CD4+ T Cells

Ca2+-regulated NFAT family members are transcription factors crucial for the expression of various cytokine genes and other immunoregulatory genes. Analyses of mice defective in one or two NFAT family members have revealed functions specific to each NFAT gene. However, the redundant functions of several family members limit the usefulness of gene disruption analysis. For example, CD4+ T cells isolated from NFATx-disrupted mice do not show any modulation in cytokine gene expression, perhaps because other family members compensate for its absence. To analyze the role of NFATx in the regulation of immunoregulatory genes in T cells, we made a gain-of-function mutant by creating transgenic mice expressing a constitutively nuclear form of NFATx in T cell lineages. In naive CD4+ T cells, NFATx up-regulated the expression of several cytokine genes and activation markers and suppressed the expression of CD154. In Th1 cells, NFATx enhanced the expression of the Th1 cytokine genes, IFN-γ and TNF-α. In contrast, NFATx suppressed Th2 cytokine genes such as IL-4 and IL-5 in Th2 cells. It has been reported that both NFAT1 and NFATx are required to maintain the homeostasis of the immune system. Our results suggest that NFATx exerts this function by inhibiting the expression of some critical immunoregulatory genes.

In vitro binding of hepatitis C virus to CD81-positive and -negative human cell lines

Aim: The aim of the present study is to study the mechanism of entry of hepatitis C virus (HCV) into human cells. We examined the in vitro binding of HCV to various human cell lines with or without CD81 expression.

Hepatitis B virus-DNA transfected myeloma cell-specific cytotoxic T cells in chronic hepatitis B patients

To study the mechanisms of hepatitis B virus (HBV)-induced chronic hepatitis (B-CH), we took chronic hepatitis B patients peripheral blood lymphocytes (PBL) and examined their cytotoxic activities against human myeloma cells (ARH77) transfected by HBV-DNA. Two different transfected cells, one expressing HBV envelope antigens (S6) and the other expressing HBV core antigens (C4), were prepared and used as targets in the in vitro cytotoxic test. We found that PBL of B-CH patients had specific cytotoxic activity against these target cells (S6, 22.0 +/- 4.8%; C4, 21.6 +/- 4.8%), whereas no remarkable cytotoxic activity was observed in non-B chronic hepatitis patients as well as asymptomatic chronic HBV carriers. These specific cytotoxic activities were inhibited with anti-CD3 antibody, hence these killer cells belonged to T cells (cytotoxic T cells; CTL). The requirement of HLA class 1 antigens to exert these CTL activities was demonstrated by the absence of CTL activity with PBL obtained from HLA-nonidentical B-CH patients and by the inhibition of their activities with anti-HLA class 1 antibody. Thus, our results indicate that, at least two different CTL, one recognizing envelop antigen and the other recognizing core antigen, exist in chronic hepatitis B patients.

Effect of B7.1-transfected human colon cancer cells on the induction of autologous tumour-specific cytotoxic T cells

Background : The induction of tumour‐specific immunity is important for advanced cancer therapy. There are many molecules, including costimulatory molecules, that have been identified as the activator for tumour‐specific T cells.

Effect of α-interferon on hepatitis B virus-specific cytotoxic T cells

Abstract To study the mechanism of the effects of α‐interferon (α‐IFN) on chronic hepatitis B, we examined its effect on hepatitis B virus (HBV)‐specific cytotoxic T cells (CTL). Using two different HBV‐DNA transfected human myeloma cell lines, one expressing hepatitis B core antigen (HBcAg; C4) and the other expressing hepatitis B surface antigen (HBsAg; S6) as targets in cytotoxic tests in vitro, peripheral blood mononuclear cells obtained from chronic hepatitis B patients who were treated with α‐IFN were examined for their cytotoxic activity against these transfectants. During the treatment with α‐IFN, in association with a decline of serum alanine amino transferase levels, CTL activities were significantly reduced. An inhibition study in vitro revealed that α‐IFN did not directly inhibit these CTL activities, indicating that α‐IFN may inhibit the induction of CTL, and thereby may be related to the reduction of hepatocyte injury.

Cytokines, Extracellular Transport and Processing

The expression of various cytokines is regulated either transcriptionally or posttranscriptionally. In addition, for some cytokines, processing of cytokine proteins and releasing from cells are important steps for the regulation of their biological activities.