Generation of in vitro B-CLL specific HLA class I restricted CTL responses using autologous dendritic cells pulsed with necrotic tumor lysate

Endothelial progenitor cell number and ERK phosphorylation serve as predictive and prognostic biomarkers in advanced hepatocellular carcinoma patients treated with sorafenib

Sorafenib is an oral anti-angiogenic multi-kinase inhibitor used for systemic therapy in patients with advanced hepatocellular carcinoma (HCC) who are not suitable candidates for surgery or liver transplantation. An earlier study conducted with HCC tumor tissue suggested that ERK phosphorylation (pERK), a downstream target of sorafenib, may serve as a potential biomarker for therapeutic efficacy of sorafenib. However, no study thus far has utilized a minimal invasive procedure to predict HCC patient responsiveness to sorafenib. We evaluated the biomarker utility of circulating endothelial progenitor cells (EPCs) frequency and intracellular pERK levels in EPCs in peripheral blood obtained pre- and post-sorafenib therapy or after transarterial chemoembolistaion (TACE). A statistically significant reduction in the level of ERK phosphorylation and in the absolute number of EPCs was detected following in vivo sorafenib treatment (p < 0 .01 for both). In contrast, the decrease in the level of ERK phosphorylation and EPC number was either marginally significant or insignificant in patients treated with TACE (p = 0.05 and 0.06, respectively). In vitro sorafenib treatment of pre- and post-samples from the same patient cohort inhibited ERK phosphorylation levels in EPCs and decreased the number of EPCs at all doses tested (p = 0.01). Our findings support that the evaluation of both the circulating EPC frequency and the level of ERK phosphorylation in EPCs may serve as potential non-invasive biomarkers of sorafenib efficacy, both as predictor of treatment outcome and efficacy during drug treatment.

Progress of dendritic cell-based cancer vaccines for patients with hematological malignancies

INTRODUCTION

Dendritic cells (DCs) are the most professional antigen-presenting cells eliciting cellular and humoral immune responses against cancer cells by expressing these antigens on MHC class I/II complexes to T cells. Therefore, they have been employed in many clinical trials as cancer vaccines for patients with cancer. This review focuses on the use of DCs in leukemia patients expressing leukemia-associated antigens (LAAs).

AREAS COVERED

The contribution of both stimulating vs. tolerogenic DCs as well as of other factors to the milieu of anti-leukemia immune responses are discussed. Several DC vaccination strategies like leukemia lysate, proteins and peptides have been developed. Next generation DC vaccines comprise transduction of DCs with retroviral vectors encoding for LAAs, cytokines and costimulatory molecules as well as transfection of DCs with naked RNA encoding for LAAs. Published as well as ongoing clinical trials are reported and critically reviewed.

EXPERT OPINION

Future results will demonstrate whether next-generation DCs are really superior to conventional pulsing with peptide, protein or tumor lysate. However, currently available methods based on nucleic acid transfection/transduction are tempting in terms of material production costs and time for clinical application according to good manufacturing practice (GMP).

T-regulatory cells and programmed death 1+ T cells contribute to effector T-cell dysfunction in patients with chronic obstructive pulmonary disease

RATIONALE

Previous studies from our laboratory have shown that peripheral blood mononuclear cells (PBMCs) from patients with chronic obstructive pulmonary disease (COPD) prone to exacerbations with nontypeable Haemophilus influenzae have impaired responses to lipoprotein P6. We hypothesized that an underlying immunosuppressive network could be responsible for the defective antibacterial immunity observed in these patients. We evaluated T regulatory cells (Tregs), myeloid-derived suppressor cells (MDSC), and exhausted T effector cells (programmed death 1 [PD-1](+)) in patients with COPD, because these cells are known to play a pivotal role in suppressing immune responses.

OBJECTIVES

We performed an in-depth characterization of Tregs, T effector cells, and MDSC in COPD and correlated their levels and function with disease severity.

METHODS

Treg, effector T cell, and MDSC frequency from patients with COPD and healthy subjects' PBMCs were analyzed by flow cytometry. Treg immunosuppressive capacity was measured by in vitro suppression assay. The frequency of interferon-γ producing T cells and T-cell proliferation were measured after blocking CTLA-4 and PD-1. Plasma proinflammatory and immunosuppressive cytokine levels were measured.

MEASUREMENTS AND MAIN RESULTS

Significantly increased levels of Tregs, MDSC, and PD-1(+) exhausted effector T cells were present in patients with COPD compared with healthy subjects. Tregs from patients with COPD suppressed P6-specific T-cell proliferation to a greater extent than Tregs from healthy subjects. Plasma levels of Treg-generated cytokines, IL-10, and transforming growth factor-β were elevated. Blockade of CTLA-4 resulted in significant augmentation of T-cell IFN-γ production in patients with COPD.

CONCLUSIONS

Functionally suppressive Tregs, MDSCs, and exhausted PD-1(+) T cells contribute to effector T-cell dysfunction in COPD.

Dendritic cell vaccines for leukemia patients

Dendritic cells are the most professional antigen-presenting cells to elicit T-cellular responses toward microbial agents and cancer cells. The graft-versus-leukemia effect observed after allogeneic stem cell transplantation strongly suggests that T lymphocytes play a major role in the rejection of leukemic cells. This graft-versus-leukemia effect might be enhanced through dendritic cell vaccination. The characterization of leukemia-specific antigens eliciting immune responses in the autologous host has prompted researchers and clinicians to broaden the spectrum of dendritic cell vaccines to hematological malignancies. Recently, the focus is on acute myeloid leukemia and chronic lymphocytic leukemia. This review summarizes data on the administration of autologous and allogeneic dendritic cells to leukemia patients as an interesting approach in cellular therapy of leukemias.

Higher frequencies of GARP(+)CTLA-4(+)Foxp3(+) T regulatory cells and myeloid-derived suppressor cells in hepatocellular carcinoma patients are associated with impaired T-cell functionality

The extent to which T-cell-mediated immune surveillance is impaired in human cancer remains a question of major importance, given its potential impact on the development of generalized treatments of advanced disease where the highest degree of heterogeneity exists. Here, we report the first global analysis of immune dysfunction in patients with advanced hepatocellular carcinoma (HCC). Using multi-parameter fluorescence-activated cell sorting analysis, we quantified the cumulative frequency of regulatory T cells (Treg), exhausted CD4(+) helper T cells, and myeloid-derived suppressor cells (MDSC) to gain concurrent views on the overall level of immune dysfunction in these inoperable patients. We documented augmented numbers of Tregs, MDSC, PD-1(+)-exhausted T cells, and increased levels of immunosuppressive cytokines in patients with HCC, compared with normal controls, revealing a network of potential mechanisms of immune dysregulation in patients with HCC. In dampening T-cell-mediated antitumor immunity, we hypothesized that these processes may facilitate HCC progression and thwart the efficacy of immunotherapeutic interventions. In testing this hypothesis, we showed that combined regimens to deplete Tregs, MDSC, and PD-1(+) T cells in patients with advanced HCC restored production of granzyme B by CD8(+) T cells, reaching levels observed in normal controls and also modestly increased the number of IFN-γ producing CD4(+) T cells. These clinical findings encourage efforts to restore T-cell function in patients with advanced stage disease by highlighting combined approaches to deplete endogenous suppressor cell populations that can also expand effector T-cell populations.

Optical nanomanipulations of malignant cells: controlled cell damage and fusion

Specifically targeting and manipulating living cells is a key challenge in biomedicine and in cancer research in particular. Several studies have shown that nanoparticles irradiated by intense lasers are capable of conveying damage to nearby cells for various therapeutic and biological applications. In this work ultrashort laser pulses and gold nanospheres are used for the generation of localized, nanometric disruptions on the membranes of specifically targeted cells. The high structural stability of the nanospheres and the resonance pulse irradiation allow effective means for controlling the induced nanometric effects. The technique is demonstrated by inducing desired death mechanisms in epidermoid carcinoma and Burkitt lymphoma cells, and initiating efficient cell fusion between various cell types. Main advantages of the presented approach include low toxicity, high specificity, and high flexibility in the regulation of cell damage and cell fusion, which would allow it to play an important role in various future clinical and scientific applications.

TLR2 may influence the behavior of the malignant clone in B-CLL

B-cell receptor (BCR) and Toll-like receptor (TLR) stimulation and integration with signals from the pathogen or immune cells and their products determine the B-cell antibody response. Low expression of BCR is the hallmark of B lymphocytes in CLL, however little is known about the expression and function of TLR in B-CLL. We studied TLR2, TLR4, IL-6 and mIL-6Rα expression on mRNA and protein level in CD19(+) subpopulation of normal lymphocytes and the CD19(+)CD5(+) subpopulation from B-CLL. Experiments were performed on unstimulated and stimulated lymphocytes [Staphylococcus aureus Cowan I (SAC) and lipopolysaccharide (LPS) from Escherichia coli - TLR2- and TLR4-specific agonists, respectively]. We showed undetectable or low IL-6 expression, which seems to be specific for B-CLL lymphocytes. Induction of TLR4 mRNA upon LPS stimulation affected the expression of IL-6, but not of mIL-6Rα. Increased expression of TLR2 (MFI) after LPS and SAC stimulation did not correlate with mIL-6Rα receptor expression. B-CLL CD19(+)CD5(+) lymphocytes showed a significant increase in TLR2 expression at the protein level after stimulation with SAC and LPS compared to normal CD19(+) lymphocytes. TLR2 may influence the behaviour of the malignant clone in B-CLL.

Tumour-loaded α-type 1-polarized dendritic cells from patients with chronic lymphocytic leukaemia produce a superior NK-, NKT- and CD8+ T cell-attracting chemokine profile

Tumour-loaded dendritic cells (DCs) from patients with chronic lymphocytic leukaemia (CLL) matured using an α-type 1-polarized DC cocktail (IL-1β/TNF-α/IFN-α/IFN-γ/poly-I:C;αDC1) were recently shown to induce more functional CD8(+) T cells against autologous tumour cells in vitro than DCs matured with the 'standard' cocktail (IL-1β/TNF-α/IL-6/PGE(2) ;PGE(2) DCs). However, the ability of vaccine DCs to induce a type 1-polarized immune response in vivo probably relies on additional features, including their ability to induce a CXCR3-dependent recruitment of NK cells into vaccine-draining lymph nodes. Moreover, their guiding of rare tumour-specific CD8(+) T cells to sites of DC-CD4(+) T cell interactions by secretion of CCL3 and CCL4 is needed. We therefore analysed the chemokine profile and the lymphocyte-attracting ability in vitro of monocyte-derived PGE(2) DCs and αDC1s from patients with CLL. αDC1s produced much higher levels of CXCR3 ligands (CXCL9/CXCL10/CXCL11) than PGE(2) DCs. Functional studies further demonstrated that αDC1s were superior recruiters of both NK and NKT cells. Moreover, αDC1s produced higher levels of CCL3/CCL4 upon CD40 ligation. These findings suggest that functional αDC1s, derived from patients with CLL, produce a desirable NK-, NKT- and CD8(+) T cell-attracting chemokine profile which may favour a guided and Th1-deviated priming of CD8(+) T cells, supporting the idea that αDC1-based vaccines have a higher immunotherapeutic potential than PGE(2) DCs.

Increased expression of urokinase plasminogen activator in Quebec platelet disorder is linked to megakaryocyte differentiation

Quebec platelet disorder (QPD) is an inherited bleeding disorder associated with increased urokinase plasminogen activator (uPA) in platelets but not in plasma, intraplatelet plasmin generation, and alpha-granule protein degradation. These abnormalities led us to investigate uPA expression by QPD CD34(+) progenitors, cultured megakaryocytes, and platelets, and whether uPA was stored in QPD alpha-granules. Although QPD CD34(+) progenitors expressed normal amounts of uPA, their differentiation into megakaryocytes abnormally increased expression of the uPA gene but not the flanking genes for vinculin or calcium/calmodulin-dependent protein kinase IIgamma on chromosome 10. The increased uPA production by cultured QPD megakaryocytes mirrored their production of alpha-granule proteins, which was normal. uPA was localized to QPD alpha-granules and it showed extensive colocalization with alpha-granule proteins in both cultured QPD megakaryocytes and platelets, and with plasminogen in QPD platelets. In QPD megakaryocytes, cultured without or with plasma as a source of plasminogen, alpha-granule proteins were stored undegraded and this was associated with much less uPA-plasminogen colocalization than in QPD platelets. Our studies indicate that the overexpression of uPA in QPD emerges with megakaryocyte differentiation, without altering the expression of flanking genes, and that uPA is costored with alpha-granule proteins prior to their proteolysis in QPD.

Type 1-polarized dendritic cells loaded with autologous tumor are a potent immunogen against chronic lymphocytic leukemia

Induction of active tumor-specific immunity in patients with chronic lymphocytic leukemia (CLL) and other hematologic malignancies is compromised by the deficit of endogenous dendritic cells (DCs). In attempt to develop improved vaccination strategies for patients with CLL and other tumors with poorly identified rejection antigens, we tested the ability of ex vivo-generated DCs to cross-present the antigens expressed by CLL cells and to induce CLL-specific, functional CTL responses. Monocyte-derived DCs from CLL patients were induced to mature using a "standard" cytokine cocktail (in IL-1beta, TNF-alpha, IL-6, and PGE2) or using an alpha-type 1-polarized DC (alphaDC1) cocktail (in IL-1beta, TNF-alpha, IFN-alpha, IFN-gamma, and polyinosinic:polycytidylic acid) and were loaded with gamma-irradiated, autologous CLL cells. alphaDC1 from CLL patients expressed substantially higher levels of multiple costimulatory molecules (CD83, CD86, CD80, CD11c, and CD40) than standard DCs (sDCs) and immature DCs, and their expression of CCR7 showed intermediate level. alphaDC1 secreted substantially higher (10-60 times) levels of IL-12p70 than sDCs. Although alphaDC1 and sDCs showed similar uptake of CLL cells, alphaDC1 induced much higher numbers (range, 2.4-38 times) of functional CD8+ T cells against CLL cells. The current demonstration that autologous tumor-loaded alphaDC1 are potent inducers of CLL-specific T cells helps to develop improved immunotherapies of CLL.

Immunity of unloaded dendritic cells in lung melanoma of mice

In order to investigate the immunity of unloaded dendritic cells (DCs) derived from murine bone marrow to preexisting lung melanoma metastases of mice, MO5 were intravenously injected to induce lung metastases in syngeneic C57BL/6 mice. Unloaded GM-CSF DCs, PBS and DCs+SIINFEKEL were subcutaneously injected into the mice, which were divided as experimental group, negative control group and positive control group respectively. Monoclonal antibody was used to deplete NK or T cells separately. The immunity-inhibitory effects on the lung melanoma were observed and the corresponding effector cells were examined. It was found that in the experimental and positive groups, the regression was induced in metastatic nodules in the lungs of tumor-bearing mice, but abrogated by treatment with anti-asialo-GM1 but not anti-CD8. It was concluded that the unloaded DCs could suppress the lung melanoma metastases to some extent, which was mediated by NK cells, and could be used as a potent therapeutic agents for lung tumor.