Morikazu Onji

Dendritic cells with immature phenotype and defective function in the peripheral blood from patients with hepatocellular carcinoma

BACKGROUND/AIMSnDefects and dysfunctions in antigen-presenting dendritic cells have been shown during carcinogenesis. The phenotype and function of dendritic cells have been studied in patients with hepatocellular carcinoma to explore the possibility of dendritic cell-based immune therapy in hepatocellular carcinoma.nnnMETHODSnThe stimulatory capacity of dendritic cells in allogenic mixed leukocytes reaction, the expression of surface makers on dendritic cells, the production of cytokines and nitric oxide by dendritic cells and the levels of maturation of dendritic cells from 17 patients with hepatocellular carcinoma, 10 patients with liver cirrhosis and 10 normal controls were compared.nnnRESULTnDendritic cells from hepatocellular carcinoma had significantly lower capacity to stimulate allogenic T cells in allogenic mixed leukocytes reaction compared with dendritic cells from liver cirrhosis and normal controls (p<0.05). Dendritic cells from hepatocellular carcinoma expressed significantly lower levels of HLA DR and induced decreased amounts of interleukin-12 compared with dendritic cells from normal controls (p<0.05). On the other hand, dendritic cells from hepatocellular carcinoma produced significantly higher levels of nitric oxide and tumor necrosis factor-a compared with dendritic cells from liver cirrhosis and normal controls (p<0.05). The uptake of fluorescein isothiocyanate-labeled dextran revealed an immature phenotype of dendritic cells from hepatocellular carcinoma compared with dendritic cells from liver cirrhosis (p<0.05).nnnCONCLUSIONnThe results of this study on the function of dendritic cells in hepatocellular carcinoma, and the prevalence of immature dendritic cells in hepatocellular carcinoma in the microenvironment of high levels of inflammatory cytokines indicate a specific defect of dendritic cell maturation during hepatocarcinogenesis. These data show that induction of dendritic cell maturation might be an approach to dendritic cell-based immune therapy during hepatocellular carcinoma.

Mechanism of action of vaccine therapy in murine hepatitis B virus carriers: vaccine-induced activation of antigen presenting dendritic cells

BACKGROUND/AIMSnVaccine therapy in which vaccine containing hepatitis B surface antigen (HBsAg) is injected has shown therapeutic activity (vaccine therapy) in some human and murine chronic hepatitis B virus (HBV)-carriers. Using HBV-transgenic mice (HBV-Tg), an animal model of the HBV-carrier state, the mechanism underlying the antiviral and immune modulatory capacity of vaccine therapy was studied.nnnMETHODSnPlacebo-controlled, double-blind trials of vaccine therapy were conducted in HBV-Tg; some HBV-Tg responded to the therapy, whereas others were non-responders. The titers of HBV-markers, the functions of lymphocytes and antigen presenting dendritic cells were compared between vaccine responders and vaccine non-responders.nnnRESULTSnThe prevaccinated titers of HBsAg, hepatitis B e-antigen (HBeAg), HBV DNA and the responses of lymphocytes to polyclonal mitogens were almost unchanged between responders and non-responders, but the levels of proliferation of HBsAg-specific lymphocytes from non-responders was significantly lower than responders (p<0.05). The capacity of dendritic cells to induce proliferation of T cells and production of antibody to HBsAg (anti-HBs) was significantly higher in responders compared with non-responders (p<0.05). Injection with HBsAg resulted in upregulation of MHC class II and CD86 antigens (p<0.05) on dendritic cells and increased production of IL-12, IL-2 and TNF-alpha in cultures (p<0.05) in vaccine responders but not in non-responders.nnnCONCLUSIONSnThe activation of dendritic cells following injection with vaccine containing HBsAg is the vital factor underlying the therapeutic potentiality of vaccine therapy in HBV carriers.

Macrophage migration inhibitory factor in hepatocellular carcinoma and liver cirrhosis; relevance to pathogenesis ☆

The levels of macrophage migration inhibitory factor (MIF), a proinflammatory and carcinogenic cytokine, were significantly higher in the sera from patients with hepatocellular carcinoma (HCC; 25.6+/-15.3 ng/ml, n=55) and liver cirrhosis (LC; 18.9+/-10.7 ng/ml, n=26) compared with sera from patients with gastrointestinal cancer (6.8+/-7.5 ng/ml, n=29) and normal controls (5.6+/-1.2 ng/ml, n=45; P<0.01). Hepatocytes from patients with LC and HCC, but not from chronic hepatitis, expressed very high levels of MIF. A possible association between overexpression of MIF and hepatocarcinogenesis is suggested.

Mechanism and therapeutic potential of DNA-based immunization against the envelope proteins of hepatitis B virus in normal and transgenic mice

Two plasmid DNA vectors, pCAGGS(S) encoding the genes of the major envelope protein of hepatitis B virus (HBV), and pCAGGS(Su2003+ preS2) encoding the genes of the middle envelope protein were used to study the mechanism and therapeutic potential of DNA‐based immunization. Injection of these plasmids into the regenerating bilateral tibialis anterior muscle (TA) of normal C57BL/6 mice induced hepatitis B surface antigen (HBsAg)‐specific humoral and cellular immune responses. Seventy‐two hours after injection of pCAGGS(S), infiltrating cells including antigen‐presenting dendritic cells (DC) were localized around the injection site and HBsAg was expressed by both muscle cells and infiltrating cells. Spleen DC from the mice were exposed to HBsAg for up to 32u2003weeks after a single injection of pCAGGS(S), because these DC induced the proliferation of HBsAg‐specific memory lymphocytes in culture without exogenous HBsAg. A single injection of pCAGGS(S) or pCAGGS(Su2003+u2003preS2) resulted in the clearance of HBsAg in 28 out of 30 HBV‐transgenic (Tg) mice. In contrast, more than 7u2003monthly injections of an HBsAg‐based vaccine were required for the clearance of HBsAg in 6 out of 29 HBV‐Tg mice. Infiltrating DC at the DNA vaccine injection site may have a role in initiating HBsAg‐specific immune response, whereas the persistence of HBsAg exposed spleen DC may contribute to long‐lasting immunity. This study also suggested that DNA‐based vaccines may be a potent tool for treating chronic HBV carriers.

Hepatitis B virus (HBV)-transgenic mice as an investigative tool to study immunopathology during HBV infection

An overview is given regarding the use of hepatitis B virus (HBV) transgenic mice as an animal model of the HBV‐carrier state. Initially, we show how HBV‐transgenic mice have contributed insights into the immunopathobiological processes during HBV infection and later, we show how this new information from the experiments with HBV‐transgenic mice could be used to develop new methods to combat HBV infection.

Induction of cytokine production and proliferation of memory lymphocytes by murine liver dendritic cell progenitors: role of these progenitors as immunogenic resident antigen-presenting cells in the liver

BACKGROUND/AIMSnMany pathogenic organisms, including hepatotrophic viruses enter the liver and induce an immune response, but there is little information about the immunogenic resident antigen-presenting cells. The aim of this study was to determine whether dendritic cells in the liver are immunogenic antigen-presenting cells.nnnMETHODSnLiver dendritic cell progenitors were enriched from normal C57BL/6 mice by culturing non-parenchymal cells with granulocyte-macrophage colony stimulating factor for 7 days. Then the surface antigen (MHC class II, CD86) expression, endocytic capacity, ability to induce cytokines, and the proliferation of memory lymphocytes were investigated.nnnRESULTSnFreshly enriched liver dendritic cell progenitors exhibited an immature phenotype and failed to stimulate allogenic T cells. However, the progenitors underwent maturation following exposure to antigens such as hepatitis B surface antigen and keyhole limpet hemocyanin. The progenitors then became strong stimulators of allogenic T cells, supported the production of interleukin-12 and interferon-gamma, and induced the proliferation of antigen-specific memory lymphocytes.nnnCONCLUSIONSnDendritic cell progenitors are immunogenic resident antigen-presenting cells in the liver. Simultaneous investigation of both tolerogenic and immunogenic resident antigen-presenting cells may provide insights into the pathogenesis of persistent infection and autoimmmune diseases of the liver.

Immunohistochemical Localization of Antigen Presenting Cells in Liver from Patients with Primary Biliary Cirrhosis; Highly Restricted Distribution of CD83-positive Activated Dendritic Cells

In order to have insights into the abnormal immune regulation in primary biliary cirrhosis (PBC), different types of antigen presenting cells (APC) were localized immunohistochemically in liver specimens from 26 patients with PBC and compared with the distributions of APC from 11 and 10 patients with chronic hepatitis C (CH-C) and large bile duct obstruction, respectively. In all diagnostic conditions, 30-90% of the infiltrating cells were positive for HLA DR. In PBC, the numbers of interdigitating cells (IDC) were significantly higher than the numbers of CD83-positive dendritic cells (DC) (34.0 +/- 38.8 vs. 5.5 +/- 7.1/specimen, mean +/- SD, p < 0.05). On the other hand, the numbers of IDC (14.2 +/- 20.0/specimen) and CD83-positive DC (7.9 +/- 8.7/specimen) were almost similar in CH-C (p > 0.05). Positive stainings for IDC and CD83-positive DC were rarely seen in large bile duct obstruction. This is the first report on the existence of activated CD83-positive DC in PBC. The significantly increased numbers of IDC and the highly restricted distributions of CD83-positive DC in PBC indicate that activated DC may play a role in the abnormal immune pathogenesis of PBC.

Peripheral blood T‐cell responses to pyruvate dehydrogenase complex in primary biliary cirrhosis: role of antigen‐presenting dendritic cells

Patients with primary biliary cirrhosis (PBC) are usually characterized by the presence of antibody to pyruvate dehydrogenase complex (PDC) in the sera and PDC‐specific T cells in the liver. However, most of the patients with PBC do not show peripheral blood T cells response to PDC. In this study, we re‐evaluated the peripheral blood T cell responses to PDC in PBC using antigen‐presenting dendritic cells (DCs).

Antigen-presenting cells at the liver tissue in patients with chronic viral liver diseases: CD83-positive mature dendritic cells at the vicinity of focal and confluent necrosis

Although defective functions of peripheral blood or splenic antigen-presenting cells (APCs) are implicated in the pathogenesis of persistent infection in murine and human hepatitis B virus (HBV) and hepatitis C virus (HCV)-carriers, little is known regarding liver-infiltrating APCs in patients with chronic liver diseases. Using immunohistochemical methodology and antigen retrieval technique, we have detected APCs such as HLA DR-positive cells, interdigitating cells (IDCs) and CD83-positive mature and activated dendritic cells (DCs) at the liver specimens from 39 patients with chronic hepatitis (CH) and 10 patients with liver cirrhosis (LC). All 3 types of APCs were detected at the portal areas in both CH and LC, the most abundant being the HLA DR-positive APCs. CD83-positive, mature and activated DCs were detected in patients with CH around the areas of focal and confluent necrosis at the liver parenchyma in close association with T cells. The localization of CD83-positive mature and activated DCs at the liver tissues from patients with CH warrants further study about the role of these DCs in the induction of hepatocellular damage. This may also help to design DC-based therapy for patients with chronic liver diseases.