Phenotypic analysis of circulating and intrahepatic dendritic cell subsets in patients with chronic liver diseases

Decrease in Circulating Myeloid Dendritic Cell Precursors in Coronary Artery Disease

OBJECTIVES

We analyzed the frequency of myeloid dendritic cell (mDC) and plasmacytoid dendritic cell (pDC) precursors in blood of patients with coronary artery disease (CAD) and in atherosclerotic carotid plaques of patients with cerebrovascular disease (CVD).

BACKGROUND

Circulating DC precursors are reduced in several autoimmune diseases. Atherosclerosis has features of an autoimmune disease, such as the presence of autoantibodies or autoreactive T cells. Tissue-resident DCs were previously described in atheromata, and it is assumed that they are important for the activation of T cells against autoantigens there.

METHODS

Circulating mDC and pDC precursors were flow cytometrically detected in healthy controls (n = 19), CAD patients with stable (n = 20) and unstable angina pectoris (n = 19), and acute myocardial infarction (n = 17). In human carotid plaques (n = 65), mDC and pDC precursors were identified immunohistochemically.

RESULTS

Circulating mDC precursors were significantly reduced in patients with stable angina pectoris (0.19%, p = 0.04), unstable angina pectoris (0.16%, p = 0.004), and acute myocardial infarction (0.08%, p < 0.001) compared with control patients (0.22% of peripheral blood mononuclear cells). In contrast, pDC numbers were not significantly altered. Circulating mDC precursors inversely correlated with high-sensitivity C-reactive protein (r = -0.38, p = 0.001) or interleukin-6 (r = -0.42, p < 0.001). In contrast to pDC, significantly more mDC precursors were observed in vulnerable carotid plaques (24, 0.25 mm2; n = 31; p = 0.003) than in stable ones (6.4, 0.25 mm2; n = 34).

CONCLUSIONS

Similar to autoimmune diseases, circulating mDC precursors were significantly reduced in patients with CAD. The emergence of mDC precursors in vulnerable plaques suggests their recruitment into atheromata as a possible reason for their decrease in blood. In contrast, no significant association of circulating pDC precursors with atherosclerosis was observed.

In vitro effects of lamivudine on function of dendritic cells derived from patients with chronic hepatitis B infection

AIM: To investigate the effects of lamivudine on the function of dendritic cells derived from patients with chronic hepatitis B (CHB) in vitro.

METHODS: Dentritic cells (DCs) derived from the monocytes of CHB patients were cultured with interleukin-4 (IL-4) plus granulocyte-macrophage colony-stimulating factor (GM-CSF). Three days after being cultured, the cells were divided group A and B. Group A was treated with different concentrations of lamivudine (0, 0.125, 0.25, 0.5, 1, 2 mmol/L), while group B served as the control. Cell morphology was observed under light microscope and cell surface molecules including HLA-DR, CD80, CD83, and CD1a were assayed by flow cytometry. The concentrations of IL-6 and IL-12 in the supernatant were measured by enzyme-linked immunosorbent assay (ELISA). T cell proliferation induced by DC was detected by methyl thiazolyl tetrazolium (MTT).

RESULTS: The cells treated with 0.5 mmol/L lamivudine had the highest expression of CD1a, CD83 and HLA-DR, and the expression of CD80 was not significantly different between the cells with and without lamivudine treatment. After treatment with 0.5 mmol/L lamivudine, the expression of CD1a, CD83 and HLA-DR were significantly higher than those of DCs without lamivudine treatment (CD1a: 54.0 ± 9.2 vs 33.6 ± 10.1, P < 0.05; CD83: 20.3 ± 6.1 vs 11.8 ± 6.2, P < 0.05; HLA-DR: 74.5 ± 7.1 vs 52.9 ± 7.7, P < 0.05); the secretion of IL-12 was significantly increased in comparison with that of the control group (810.0 ± 91.5 ng/L vs 268.0 ± 34.3 ng/L, P < 0.05), while the level of IL-6 was lowered markedly (28.1 ± 2.6 ng/L vs 55.3 ± 7.4 ng/L, P < 0. 05); the stimulatory capacity of DCs in the allogeneic mixed leukocyte reaction was markedly enhanced as compared with that of the control group (stimulatory index: 1.9 ± 0.6 vs 1.2 ± 0.5, P < 0.05).

CONCLUSION: Pulsed with lamivudine in certain concentration, the biological activity of DCs derived from CHB patients can be efficiently enhanced.

Restoration in vitro of impaired T-cell responses in patients with chronic hepatitis B by autologous dendritic cells loaded with hepatitis B virus proteins (R2)

BACKGROUND

The purpose of the present paper was to investigate dendritic cell (DC) and T-cell functions in patients with chronic hepatitis B (CHB) and determine whether therapeutic DC vaccines could restore T-cell function in those patients in vitro.

METHODS

Twelve patients with CHB and 10 normal control subjects with positivity for antibodies to hepatitis B surface and core antigens (anti-HBs and anti-HBc positivity) were enrolled in the present study. Phenotype analysis and allogeneic mixed lymphocyte reaction assay of DC from CHB patients and normal controls were made in the absence or presence of a cocktail of cytokines: interleukin-1beta (IL-1beta), prostaglandin E(2) (PGE(2)), IL-6 and tumor necrosis factor-alpha (TNF-alpha). Autologous T-cell proliferation assays and the enzyme-linked immunospot (ELISPOT) method for detecting interferon-gamma (IFN-gamma)-producing CD8(+) T cells were used to evaluate the efficacy of DC loaded in vitro with HBsAg or HBcAg.

RESULTS

The DC from CHB patients had a lower expression of costimulatory molecules CD80, CD86 and impaired allogeneic mixed lymphocyte reaction capacity compared to those from normal controls. However, the impaired DC function could be restored partially by cytokine cocktail supplemented in vitro. Mature DC loaded with HBsAg or HBcAg showed a greater capacity for autologous T-cell proliferation and antigen-specific IFN-gamma production than immature DC. Moreover, as a DC -loading antigen, HBcAg was more immunogenic than HBsAg.

CONCLUSIONS

The impaired function of DC in patients with CHB may be restored by supplementation in vitro with a cocktail of cytokines, and therapeutic DC vaccines might be effective to treat CHB infection in humans.

Aberrant composition of the dendritic cell population in hepatic lymph nodes of patients with hepatocellular carcinoma

Patients with hepatocellular carcinoma (HCC) are characterized by a weak T-cell response to their tumor, and chronic carriers of hepatitis B virus or hepatitis C virus have a poor T-cell response against the virus. These inadequate T-cell responses may be due to insufficient activation of the T cells by dendritic cells (DCs). Because lymph nodes (LNs) are the primary site of antigen-specific T-cell activation, we hypothesized that hepatic LNs of patients with HCC and/or chronic viral hepatitis might have aberrant compositions of their DC populations. To address this hypothesis, we enumerated mature myeloid DCs (MDCs) and plasmacytoid DCs (PDCs) in hepatic LNs by quantitative immunohistochemistry. Patients with HCC and chronic viral hepatitis and patients with chronic viral hepatitis without HCC were compared with patients with liver inflammation of nonviral etiology and with organ donors with healthy livers. The numbers of PDCs and mature MDCs in hepatic LNs of patients with chronic viral hepatitis did not differ from those of patients with liver inflammation of nonviral etiology nor from individuals with healthy livers. However, hepatic LNs of patients with HBV or HCV infection complicated by HCC showed a 1.5-fold reduction in numbers of mature MDCs and a 4-fold increase in numbers of PDCs in their T-cell areas compared with those of patients with viral hepatitis only (P <.01). In conclusion, patients with HCC have an aberrant composition of the DC population in their hepatic LNs. This may be one of the causes of the inadequate T-cell response against HCC in these patients.

Expression of ICAM-1, HLA-DR, and CD80 on peripheral circulating CD1 α DCs induced in vivo by IFN-α in patients with chronic hepatitis B

AIM: To explore the effects of interferon-α (IFN-α) application on peripheral circulating CD1α dendritic cells (DCs) in patients with chronic hepatitis B, and the expression of HLA-DR, CD80, and ICAM-1 on CD1α DCs in order to explore the mechanism of immune modulation of IFN-α.

METHODS: By flow cytometry technique, changes of CD1α DCs were monitored in 22 patients with chronic hepatitis B treated with IFN-α and in 16 such patients not treated with IFN-α within three months. Meanwhile, the expression of HLA-DR, CD80, and ICAM-1 on CD1α DCs was detected.

RESULTS: In the group of IFN-α treatment, the percentage of CD1α DCs in peripheral blood mononuclear cells was increased after three months of therapy. In patients who became negative for HBV-DNA after IFN-α treatment, the increase of DCs was more prominent, while in control, these changes were not observed. Increased expression of HLA-DR, CD80, and ICAM-1 on CD1α DCs was also observed.

CONCLUSION: CD1α DCs can be induced by IFN-α in vivo, and the immune related molecules such as HLA-DR, CD80, and ICAM-1 are up-regulated to some degree. This might be an important immune related mechanism of IFN-α treatment for chronic hepatitis B.

Phenotypic and functional characteristics of dendritic cells derived from human peripheral blood monocytes

OBJECTIVE

This study is aimed at developing a simple and easy way to generate dendritic cells (DCs) from human peripheral blood monocytes (PBMCs) in vitro.

METHODS

PBMCs were isolated directly from white blood cell rather than whole blood and purified by patching methods (collecting the attached cell and removing the suspension cell). DCs were then generated by culturing PBMCs for six days with 30 ng/ml recombinant human granulocyte-macrophage stimulating factor (rhGM-CSF) and 20 ng/ml recombinant human interleukin-4 (rhIL-4) in vitro. On the sixth day, TNF-alpha (TNFalpha) 30 ng/ml was added into some DC cultures, which were then incubated for two additional days. The morphology was monitored by light microscopy and transmission electronic microscopy, and the phenotypes were determined by flow cytometry. Autologous mixed leukocyte reactions (MLR) were used to characterize DC function after TNFalpha or lipopolysaccharide (LPS) stimulations for 24 h.

RESULTS

After six days of culture, the monocytes developed significant dendritic morphology and a portion of cells expressed CD1a, CD80 and CD86, features of DCs. TNFalpha treatment induced DCs maturation and up-regulation of CD80, CD86 and CD83. Autologous MLR demonstrated that these DCs possess potent T-cell stimulatory capacity.

CONCLUSION

This study developed a simple and easy way to generate DCs from PBMCs exposed to rhGM-CSF and rhIL-4. The DCs produced by this method acquired morphologic and antigenic characteristics of DCs.

Activation of dendritic cells by local ablation of hepatocellular carcinoma

BACKGROUND/AIMS

Local ablation methods are an effective treatment for hepatocellular carcinoma (HCC). The rate of recurrence or development of intra-hepatic metastases may be lowered by antitumoral immune responses. Since HCCs are in general only weakly immunogenic, cell injury induced by local tumor ablation (PEI/RFTA) may increase HCC immunogenicity and may release endogenous adjuvants that activate dendritic cells (DC). The aim of the study, therefore, was the analysis whether PEI or RFTA induced injury results in an adjuvant effect for immune responses to HCCs.

METHODS

Eight HCC patients were treated with PEI or RFTA and serially analyzed for 4 weeks. Plasmocytoid (PDC) and myeloid dendritic cells (MDC) were analyzed directly ex vivo and in vitro using FACS and proliferation assays.

RESULTS

HCC ablation induced a functional transient activation of MDC but not of PDC associated with increased serum levels of TNF-alpha and IL-1beta.

CONCLUSIONS

These findings suggest that the combination of PEI or RFTA and active antigen specific immunotherapeutic approaches using DCs is a promising approach for the induction of sustained antitumoral immune responses aiming at the reduction of tumor recurrence and metastases in HCC patients.

Antiviral treatment with alpha interferon up-regulates CD14 on liver macrophages and its soluble form in patients with chronic hepatitis B

To investigate whether therapy with alpha interferon (IFN-alpha) induces changes in intrahepatic antigen-presenting cells (APCs), we obtained liver biopsy specimens before, during, and after therapy with IFN-alpha from chronic hepatitis B patients whose viral load had already been reduced by at least 8 weeks of treatment with lamivudine. HLA-DR, CD1a, and CD83 were not modified by the therapy. The intralobular expression of CD68 on Kupffer cells remained stable, denoting no changes in the number of resident macrophages during IFN-alpha treatment. In contrast, CD14 was weakly expressed in the absence of IFN-alpha and was significantly up-regulated during therapy. At the same time, the levels of soluble CD14 and interleukin-10 in plasma increased significantly. In vitro, monocytes maintained in the presence of IFN-alpha differentiated into macrophages or dendritic cells with higher levels of expression of CD14 than that for the control cultures. During therapy with IFN-alpha, T-cell infiltration in the portal spaces was reduced, mainly due to a significant decrease in the number of CD8(+) T cells. These findings show that IFN-alpha is biologically active on APCs in vivo and in vitro and suggest that this newly described regulatory function, together with the already known inhibitory effects on lymphocytes, may cooperate to reduce inflammation and consequent tissue damage in patients with chronic viral hepatitis.

Plasmacytoid dendritic cells in acute and chronic hepatitis C virus infection

Chronic evolution of acute hepatitis C (aHC) occurs in more than 80% of patients but can frequently be prevented by early treatment with interferon (IFN)-alpha. Plasmacytoid dendritic cells (pDCs) are the major endogenous IFN-alpha producers, but their role in aHC is unknown. In this study, frequency, phenotype, and pDC function were analyzed in 13 patients with aHC and 32 patients with chronic hepatitis C (cHC) compared with 20 healthy controls, 33 sustained responders to antiviral treatment, 14 patients with acute hepatitis B (aHB), and 21 patients with nonviral inflammatory disease. In aHC, pDCs in the peripheral blood were significantly reduced compared with healthy controls (median, 0.1% vs. 0.36%, P < .0005) and were inversely correlated to alanine aminotransferase levels (r = -0.823; P < .005). Circulating pDCs in aHC were immature, as determined via reduced expression of HLA-DR and CCR7, and produced little amounts of IFN-alpha (median, 3.5 pg/50,000 peripheral blood mononuclear cells [PBMCs] vs. 498.4 pg/50,000 PBMCs in healthy controls; P < .0005). Less pronounced changes were present in cHC (median, 0.17%, 28.0 pg/50,000 PBMCs IFN-alpha, respectively). However, a significantly reduced frequency and IFN-alpha production was also found in self-limited aHB (median 0.1%, 8.6 pg/50,000 PBMCs) and in patients with nonviral inflammatory disease (median 0.19%, 7.5 pg/50,000 PBMCs). In conclusion, in aHC frequency and IFN-alpha-producing capacity of peripheral blood pDCs are dramatically reduced and inversely correlated with the degree of liver inflammation. In cHC there is incomplete recovery of pDC function, which, however, could be solely due to the chronic inflammatory state.

Decreased numbers and impaired function of circulating dendritic cell subsets in patients with chronic hepatitis B infection (R2)

BACKGROUND AND AIM

To investigate the frequencies, numbers and function of circulating dendritic cell (DC) subsets in patients with hepatitis B virus (HBV) infection, we assayed the circulating precursor DC subsets (including pDC1 and pDC2) and their ability in patients at various stages of HBV infection in vitro.

METHODS

Circulating pDC1 and pDC2 frequencies in peripheral blood mononuclear cells (PBMC) were analyzed by flow cytometric analysis. Costimulatory molecule expression and allostimulatory mixed lymphocyte reaction (AMLR) of DC1, cultured from PBMC in vitro, were detected in patients with chronic hepatitis B (CHB). On behalf of pDC2, interferon (IFN)-alpha production of PBMC was determined by the ELISA method in HBV-infected patients.

RESULTS

The number of circulating pDC1 decreased only in patients with liver cirrhosis (LC) compared with that in normal controls. However, pDC2 numbers decreased in both CHB and LC patients. DC1 from CHB patients showed lower expression of costimulatory molecules CD80, CD86 and impaired allostimulatory mixed lymphocyte reaction (AMLR) compared with those in normal controls. The ability of PBMC to secrete IFN-alpha also decreased significantly in patients with chronic HBV infection.

CONCLUSIONS

Our results suggest that patients with chronic HBV infection have a significantly lower expression of costimulatory molecules and impaired AMLR of pDC1, as well as decreased number and impaired function of circulating pDC2, which may be partially related to HBV disease progression in these patients.

Immunoregulation of dendritic and T cells by alpha-fetoprotein in patients with hepatocellular carcinoma

BACKGROUND/AIMS

Novel immunotherapeutic and other strategies are being explored for the treatment of hepatocellular carcinoma (HCC). Alpha-fetoprotein (AFP) may be a target antigen for immunotherapy. Little is known, however, about the immunobiology of AFP. Therefore, the impact of AFP on dendritic cells (DC), CD4+ and CD8+ T cells was studied in detail.

METHODS

Immune cells from peripheral blood of 27 HCC patients were studied using FACS, ELISPOT, and proliferation assays.

RESULTS

The in vitro generation, maturation, and T cell stimulatory capacity of DCs were not altered by AFP up to concentrations of 20 microg/ml. Higher AFP concentrations (> 20 microg/ml) resulted in phenotypic changes on DCs without impairing their capacity to stimulate CD4+ T cells. Frequencies and function of DCs and AFP specific T cells were not reduced in HCC patients independent on serum AFP levels. Finally, T lymphocytic infiltrations in the liver were not dependent on AFP serum levels.

CONCLUSIONS

These studies clearly demonstrate that (i) DC-based immunotherapeutic approaches are a promising approach for HCC treatment and (ii) AFP-reactive T cell clones have not been deleted from the human T cell repertoire establishing AFP as a potential target for T cell based immunotherapy of HCC.

Alpha-fetoprotein impairs APC function and induces their apoptosis

alpha-Fetoprotein (AFP) is a tumor-associated Ag, and its serum level is elevated in patients with hepatocellular carcinoma (HCC). In vitro, AFP induces functional impairment of dendritic cells (DCs). This was demonstrated by the down-regulation of CD40 and CD86 molecules and the impairment of allostimulatory function. Also, AFP was found to induce significant apoptosis of DCs, and AFP-treated DCs produced low levels of IL-12 and TNF-alpha, a cytokine pattern that could hamper an efficient antitumor immune response. Ex vivo, APCs of patients with HCC and high levels of AFP produced lower levels of TNF-alpha than that of healthy individuals. In conclusion, these results illustrate that AFP induces dysfunction and apoptosis of APCs, thereby offering a mechanism by which HCC escapes immunological control.

Phenotype and function of monocyte derived dendritic cells in chronic hepatitis B virus infection

The antiviral T cell failure of patients with chronic hepatitis B virus (HBV) infection was suggested to be caused by a T cell stimulation defect of dendritic cells (DC). To address this hypothesis, monocyte derived DC (MDDC) of patients with chronic or resolved acute HBV infection and healthy controls were studied phenotypically by FACS analyses and functionally by mixed lymphocyte reaction, ELISA, ELISpot and proliferation assays of MDDC cultures or co-cultures with an allogeneic HBc-specific Th cell clone. HBV infection of MDDC was studied by quantitative PCR. MDDC from HBV patients seemed to be infected by the HBV, showed a reduced surface expression of HLA DR and CD40 and exhibited a reduced secretion of IL12p70 in response to HBcAg but not to LPS, as compared to control MDDC. However, after cytokine induced maturation, MDDC from HBV patients revealed an unimpaired phenotype. Moreover, the T cell stimulatory capacity of HBV-DC was intact, since (i) the induction of allospecific proliferative and IFN-gamma responses was not affected in HBV-MDDC, and (ii) HLA DR7 restricted stimulation of an allogeneic HBc-specific Th cell clone was not impaired by HBV-MDDC compared to control MDDC. It is hypothesized that HBV infection of DC might lead to minor phenotypic and functional alterations without significantly affecting their antiviral Th cell stimulatory capacity.

Autologous cytokine-induced killer cell therapy in clinical trial phase I is safe in patients with primary hepatocellular carcinoma

AIM: To investigate the influence of autologous cytokine-induced killer (CIK) cells on the phenotypes of CIK effector cells, peripheral T lymphocyte subsets and dendritic cell subsets in patients with primary hepatocellular carcinoma (HCC).

METHODS: Peripheral blood mononuclear cells (PBMC) were collected by a blood cell separator from 13 patients with HCC, then expanded by priming them with interferon-gamma (IFN-γ) followed by monoclonal antibody (mAb) against CD3 and interleukin-2 (IL-2) the next day. The phenotypic patterns of CIK cells were characterized by flow cytometry on d 0, 4, 7, 10, 13 and 15 of incubation, respectively. Then, 5 mL of venous blood was obtained from HCC patients before or 8-10 d after CIK cells were transfused into patients to assess the influence of CIK cells on the percentages of effector cells, and proportions of DC1 or DC2 in peripheral blood by flow cytometry.

RESULTS: After two weeks of in vitro incubation, the percentages of CD3⁺CD8⁺, CD3⁺CD56⁺, and CD25⁺ cells increased significantly from 33.5 ± 10.1%, 7.7 ± 2.8%, and 12.3 ± 4.5% to 36.6 ± 9.0% (P < 0.05), 18.9 ± 6.9% (P < 0.01), and 16.4 ± 5.9% (P < 0.05), respectively. However, the percentages of CD3⁺CD4⁺ and NK cells had no significant difference. The percentages of CD3⁺ and CD3⁺CD8⁺ cells were kept at high levels during the whole incubation period, but those of CD25⁺, and CD3⁺CD56⁺ cells began to decrease on d 7 and 13, respectively. The proportions of type I dendritic cell (DC1) and type II dendritic cell (DC2) subsets increased from 0.59 ± 0.23% and 0.26 ± 0.12% before CIK cell therapy to 0.85 ± 0.27% and 0.43 ± 0.19% (all P < 0.01) after CIK cell transfusion, respectively. The symptoms and characteristics of HCC patients were relieved without major side effects.

CONCLUSION: Our results indicated that autologous CIK cells can efficiently improve the immunological status in HCC patients, and may provide a potent approach for HCC patients as the adoptive immunotherapy.