Sk. Md. Fazle Akbar

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

BACKGROUND/AIMS Defects 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. METHODS The 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. RESULT Dendritic 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). CONCLUSION The 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.

Soluble CD163 in patients with liver diseases: very high levels of soluble CD163 in patients with fulminant hepatic failure

BackgroundThe levels of several cytokines and chemokines are elevated in various liver diseases, especially in fulminant hepatic failure (FHF). Activated macrophages may have a role in the production of these immune modulators. CD163 is a member of a scavenger receptor family and is expressed mainly on activated macrophages, and a soluble form of CD163 (sCD163) is released from activated macrophages. The aim of this study was to assess sCD163 levels in patients with FHF and to evaluate their clinical significance.MethodsThe levels of sCD163 in the sera were measured in 21 patients with FHF, 17 patients with acute hepatitis (AH), 22 patients with chronic hepatitis (CH), and 14 normal healthy controls (NC), by an enzyme-linked immunosorbent assay. The levels of sCD163 were observed serially in patients with FHF and AH.ResultsThe levels of sCD163 in the sera from patients with FHF were significantly higher than those in patients with AH and CH and the NC group (P < 0.0001). There was a good correlation between serum levels of sCD163 and prothrombin time (r = −0.677; P < 0.0001). A kinetic study revealed that the levels of sCD163 decreased in patients with AH and in survivors of FHF, whereas the levels of sCD163 progressively increased in nonsurvivors of FHF.ConclusionsThis study shows that the products of activated macrophages may be involved in the pathogenesis of FHF. This study also inspires optimism that sCD163 may possess prognostic importance in FHF.

Macrophage migration inhibitory factor in the sera and at the colonic mucosa in patients with ulcerative colitis: clinical implications and pathogenic significance.

Background Inflammatory cytokines produced by activated macrophages are implicated in the pathogenesis of ulcerative colitis (UC). With the theory that macrophage migration inhibitory factor (MIF) may have a role in the accumulation of macrophages, we studied MIF in UC.

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

BACKGROUND/AIMS Vaccine 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. METHODS Placebo-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. RESULTS The 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. CONCLUSIONS The activation of dendritic cells following injection with vaccine containing HBsAg is the vital factor underlying the therapeutic potentiality of vaccine therapy in HBV carriers.

Infection and dysfunction of circulating blood dendritic cells and their subsets in chronic hepatitis C virus infection.

BackgroundTo understand interactions between dendritic cells (DCs) and viruses, in vitro-cultured monocyte-derived DCs are usually used for functional analyses. However, several recent studies indicate that circulating blood DCs are different from monocyte-derived DCs, both phenotypically and functionally. Indeed, circulating DCs act as functional antigen-presenting cells in vivo. This study was conducted to evaluate the function of circulating blood DCs in patients with chronic hepatitis C and to examine whether circulating DCs from these patients were infected by hepatitis C virus (HCV).MethodsThe phenotypes and biological functions of circulating DCs from patients with chronic hepatitis C (n = 27), patients with non-HCV chronic liver disease (n = 7), and normal volunteers (n = 13) were analyzed. The presence of the HCV genome sequence in circulating blood DCs and in subsets of circulating DCs (myeloid DCs and plasmacytoid DCs) in patients with chronic hepatitis C was assessed.ResultsThe stimulatory capacity of circulating DCs was significantly reduced in patients with chronic hepatitis C compared to patients with non-HCV chronic liver diseases and normal controls (P < 0.01). HCV RNA was identified in the overall population of circulating DCs, and in myeloid DCs and plasmacytoid DCs. Nucleotide sequences of the 5′ non-coding region of HCV RNA showed marked differences between paired samples of circulating DCs and sera from the same patients.ConclusionsOur results indicate the dysfunction and infection of circulatory blood DCs in chronic HCV infection. This may compromise the capacity of patients with hepatitis C to induce an effective antiviral immune response.

Clinical characteristics of autoimmune hepatitis with histological features of acute hepatitis

The number of patients with autoimmune hepatitis with histological features of acute hepatitis (AIH-AH) has been increasing recently. Here, the clinical features of patients with AIH-AH have been compared with those of patients with AIH with histological findings of chronic hepatitis (AIH-CH) and liver cirrhosis (AIH-LC). The levels of total serum bilirubin (P<0.05) and serum transaminases (P<0.05) were significantly higher in patients with AIH-AH than in patients with AIH-CH and AIH-LC. However, the serum levels of gamma-globulin (P<0.05) and immunoglobulin G (P<0.05) were significantly lower in AIH-AH than in patients with AIH-CH and AIH-LC. The aggregate score according to the criteria of the International Autoimmune Hepatitis Group in 1999 was also significantly lower in AIH-AH patients than in patients with AIH-CH and AIH-LC (P<0.05). Eleven patients with AIH-AH were treated with corticosteroids, however, the clinical response was insignificant in three patients. In summary, it is difficult to diagnose of patients with AIH-AH using the criteria of the International AIH scoring system. We wish that this scoring system would be modified in the near future.

Dendritic Cells and Chronic Hepatitis Virus Carriers

Many individuals infected with hepatitis B virus (HBV) and hepatitis C virus (HCV) are unable to clear these viruses following an acute infection and become chronically infected. There are more than 400 million HBV and HCV carriers in the world and a considerable number of these patients would eventually develop more severe complications like liver cirrhosis and hepatocellular carcinoma. It is not clearly known how an individual develops a chronic hepatitis virus carrier state; however, a defective immune response of the host is thought to play a critical role in the underlying pathogenetic mechanism. On the other hand, dendritic cells (DCs), the most potent antigen-presenting cells, are widely distributed in both lymphoid and nonlymphoid tissues. Recognition of the microbes or microbial antigens by DCs is one of critical events for the initiation of an immune response. DCs also play a cardinal role during the progression and termination of an immune response. The aim of this overview is to provide information regarding the role of DCs in the pathogenesis of chronic hepatitis due to HBV and HCV in humans and in animal models of HBV and HCV carrier states. First, we summarize our current understanding of the pathogenesis of hepatitis virus carrier states and also of general properties of DCs. Next, we discuss the data on the phenotypes and functions of DCs in both human and murine HBV and HCV carriers. We also discuss vaccine therapy in murine HBV carriers because activation of DCs due to vaccination-initiated HBsAg-specific immune responses in HBV transgenic mice (HBV-Tg), which in turn resulted in complete clearance of hepatitis B surface antigen and hepatitis B e antigen and decreased levels of HBV DNA in some HBV-Tg. Finally, we discuss the extracted questions and future research directions.

Production of antibody to hepatitis B surface antigen (anti-HBs) by murine hepatitis B virus carriers : neonatal tolerance versus antigen presentation by dendritic cells

The inability of hepatitis B virus (HBV) transgenic mice, which express abundant hepatitis B surface antigen (HBsAg) in sera from the neonatal period onwards, to produce antibody to HBsAg (anti‐HBs) is considered to be due to defective function of lymphocytes. The defective function is thought to result from neonatal tolerance because antigenic challenge during the neonatal period is considered to be a tolerogenic event rather than an immunogenic one. However, a series of mixed culture experiments in vitro showed that lymphocytes taken from transgenic mice that had been injected with HBsAg in complete Freund’s adjuvant (CFA) constitutively produced anti‐HBs when cultured with dendritic cells from age‐, sex‐ and major histocompatibility complex (MHC)‐matched normal mice, but not when cultured with dendritic cells from transgenic mice. The expression of major histocompatibility complex (MHC) class II and B 7.2 (CD86) antigens on dendritic cells was significantly lower in transgenic mice compared with the same from the normal mice (P<0·05). Treatment of transgenic mice with interferon‐γ (IFN‐γ) resulted in up‐regulation of MHC class II on dendritic cells, and lymphocytes from HBsAg‐injected transgenic mice produced anti‐HBs in vitro when cultured with dendritic cells from IFN‐γ‐treated transgenic mice, but not when cultured with the dendritic cells from untreated transgenic mice. These experiments have shown that defective function of antigen‐presenting cells (APC), not immunogenic tolerance, is responsible for the inability of murine HBV‐carriers to produce anti‐HBs. Production of anti‐HBs by lymphocytes from HBsAg‐injected transgenic mice in the presence of dendritic cells that express higher levels of MHC class II and CD86 antigens has inspired optimism that a more effective vaccine therapy can be developed for chronic HBV‐carriers, injecting vaccine containing HBsAg with modulator(s) of APC function of dendritic cells.

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/AIMS Many 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. METHODS Liver 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. RESULTS Freshly 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. CONCLUSIONS Dendritic 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.