Radek Spisek

Human Tumor Cells Killed by Anthracyclines Induce a Tumor-Specific Immune Response

Immunogenic cell death is characterized by the early surface exposure of chaperones including calreticulin and HSPs, which affect dendritic cell (DC) maturation and the uptake and presentation of tumor antigens. It has also been shown that it is characterized by the late release of high mobility group box 1 (HMGB1), which acts through Toll-like receptor 4 (TLR4) and augments the presentation of antigens from dying tumor cells to DCs. Most of the data on immunogenic tumor cell death were obtained using mouse models. In this study, we investigated the capacity of clinically used chemotherapeutics to induce immunogenic cell death in human tumor cell lines and primary tumor cells. We found that only anthracyclines induced a rapid translocation of calreticulin, HSP70, and HSP90 to the cell surface and the release of HMGB1 12 hours after the treatment. The interaction of immature DCs with immunogenic tumor cells led to an increased tumor cell uptake and induces moderate phenotypic maturation of DCs. Killed tumor cell-loaded DCs efficiently stimulated tumor-specific IFN-γ-producing T cells. DCs pulsed with killed immunogenic tumor cells also induced significantly lower numbers of regulatory T cells than those pulsed with nonimmunogenic tumor cells. These data indicate that human prostate cancer, ovarian cancer, and acute lymphoblastic leukemia cells share the key features of immunogenic cell death with mice tumor cells. These data also identify anthracyclines as anticancer drugs capable of inducing immunogenic cell death in sensitive human tumor cells.

Frequent and specific immunity to the embryonal stem cell–associated antigen SOX2 in patients with monoclonal gammopathy

Specific targets of cellular immunity in human premalignancy are largely unknown. Monoclonal gammopathy of undetermined significance (MGUS) represents a precursor lesion to myeloma (MM). We show that antigenic targets of spontaneous immunity in MGUS differ from MM. MGUS patients frequently mount a humoral and cellular immune response against SOX2, a gene critical for self-renewal in embryonal stem cells. Intranuclear expression of SOX2 marks the clonogenic CD138− compartment in MGUS. SOX2 expression is also detected in a proportion of CD138+ cells in MM patients. However, these patients lack anti-SOX2 immunity. Cellular immunity to SOX2 inhibits the clonogenic growth of MGUS cells in vitro. Detection of anti-SOX2 T cells predicts favorable clinical outcome in patients with asymptomatic plasmaproliferative disorders. Harnessing immunity to antigens expressed by tumor progenitor cells may be critical for prevention and therapy of human cancer.

Inflammation-associated lysophospholipids as ligands for CD1d-restricted T cells in human cancer

CD1d-restricted T cells have been implicated in the pathogenesis of several chronic inflammatory states. However, the nature of the specific ligands recognized by these cells in vivo in patients with inflammatory or malignant diseases remains unknown. We took a biochemical approach to directly isolate and characterize the nature of CD1d-binding ligands from the plasma of myeloma patients. Characterization of these ligands revealed several lysophosphatidylcholine (LPC) species. Human LPC-CD1d dimer binding cells are T-cell receptoralphabeta(+) T cells but predominantly Valpha24(-)Vbeta11(-). Cytokine secretion by LPC-specific T cells is skewed toward IL-13 secretion, and the frequencies of these cells are increased in myeloma patients relative to healthy donors. These data identify a distinct population of human CD1d-restricted T cells specific for inflammation-associated lysolipids and suggest a novel mechanism for inflammation mediated immune regulation in human cancer.

Gliadin fragments induce phenotypic and functional maturation of human dendritic cells.

Celiac disease is a chronic inflammatory disease developing in genetically predisposed individuals. Ingested gliadin, the triggering agent of the disease, can cross the epithelial barrier and elicit a harmful T cell-mediated immune response. Dendritic cells (DC) are supposed to play a pivotal role in shaping the immune response. The direction of the immune response toward immunity or tolerance depends on the stage of maturation and the functional properties of the DC. DC become fully functional APC upon maturation by various stimuli. We investigated the effect of a peptic digest of gliadin on the maturation of human monocyte-derived DC. Stimulation of cells with gliadin, in contrast with other tested food proteins, led to enhanced expression of maturation markers (CD80, CD83, CD86, and HLA-DR molecules) and increased secretion of chemokines and cytokines (mainly of IL-6, IL-8, IL-10, TNF-α, growth-related oncogene, MCP-1, MCP-2, macrophage-derived chemokine, and RANTES). Maturation was accompanied by a greater capacity to stimulate proliferation of allogeneic T cells and significantly reduced endocytic activity. Furthermore, gliadin-induced phosphorylation of members of three MAPK families (ERK1/2, JNK, and p38 MAPK) was demonstrated. The largest contribution of p38 MAPK was confirmed using its inhibitor SB203580, which markedly down-regulated the gliadin-triggered up-regulation of maturation markers and cytokine production. Gliadin treatment also resulted in increased NF-κB/DNA binding activity of p50 and p65 subunits. Taken together, gliadin peptides can contribute to overcoming the stage of unresponsiveness of immature DC by inducing phenotypic and functional DC maturation, resulting in more efficient processing and presentation of gliadin peptides to specific T lymphocytes.

Maturation state of dendritic cells during the extracorporeal photopheresis and its relevance for the treatment of chronic graft-versus-host disease

BACKGROUND:  Chronic graft‐versus‐host disease (cGVHD) represents a major cause of morbidity and mortality after allogeneic bone marrow transplantation (BMT). Extracorporeal photochemotherapy (ECP), a technique used in the treatment of cutaneous T‐cell lymphoma, has also shown clinical efficacy in the treatment of refractory cGVHD.

Towards a Better Way to Die with Chemotherapy: Role of Heat Shock Protein Exposure on Dying Tumor Cells

The ultimate goal of most anti-tumor therapies is to kill tumor cells. While most of the attention in cancer therapy has been towards enhancing the death of tumor cells, the effect of dying tumors on the immune system has been less studied. Recent studies have suggested that cell death induced by different agents may have distinct consequences for the immune system. One of the immunogenic signals may be the expression of heat shock proteins on dying tumor cells under certain settings. For example, bortezomib (a proteasome inhibitor) induces the expression of heat shock protein 90 (hsp90) on the surface of dying human myeloma tumor cells. Recognition of such tumor cells by antigen presenting dendritic cells leads to the generation of anti-tumor T cells. Harnessing the properties of some anti-tumor agents to induce immunogenic death of tumor cells may facilitate the recruitment of adaptive immunity and promote the durability of anti-tumor effects.

Role of Teichoic Acid Choline Moieties in the Virulence of Streptococcus pneumoniae

ABSTRACT In recent reports it was shown that genetically modified choline-free strains of Streptococcus pneumoniae (D39Cho−licA64 and D39ChiplicB31) expressing the type II capsular polysaccharide were virtually avirulent in the murine sepsis model, in sharp contrast to the isogenic and highly virulent strains D39Cho− and D39Chip, which have retained the choline residues at their surface. We now demonstrate that this choline-associated virulence is independent of Toll-like receptor 2 recognition. Also, despite the lack of virulence, choline-free strains of S. pneumoniae were able to activate splenic dendritic cells, induce secretion of proinflammatory cytokines, and produce specific protective immunity against subsequent challenge. However, after this transient engagement of the immune system the choline-free bacteria were rapidly cleared from the blood, while the isogenic virulent strain D39Cho− continued to grow, accompanied by prolonged expression of cytokines, eventually killing the experimental animals. The critical contribution of choline residues to the virulence potential of pneumococci appears to be the role that these amino alcohol residues play in a pneumococcal immune evasion strategy, the mechanism of which is unknown at the present time.

Immunoprevention of cancer: time to reconsider timing of vaccination against cancer

Expert Rev. Anticancer Ther. 6(12), 1689–1691 (2006) The immune system has the ability to remember an encounter with an antigen for decades or even a lifetime. Exploration of this property and the induction of a longterm, pathogen-specific immune response led to the phenomenal success of vaccination programs against infectious diseases that still represent some of the most impressive triumphs of modern medicine and immunology. The immune system also plays a crucial role in the control of tumor development, as now convincingly documented by studies carried out on immunodeficient mice. Thus there is a hope that similar to the success of vaccination against infections, immune responses could also be harnessed to protect against cancer. This enthusiasm has been further fueled by recent advances in our understanding of the mechanisms controling activation of the immune system, together with the progress in laboratory techniques that allows manipulation of components of the immune system in vitro and the generation of increasingly sophisticated vaccines. Some of the important findings relevant to the development of tumor immunotherapeutic strategies include:

Clinical relevance of regulatory T cells monitoring in the peripheral blood of ovarian cancer patients.

BACKGROUND Tregs play a suppressive role in the control of antitumour immunity. In this study we evaluated the relevance of prospective monitoring of peripheral blood regulatory T cells (Tregs) as a potential prognostic marker of future outcome of epithelial ovarian cancer in patients with or without a metronomic chemotherapy. METHODS 46 patients diagnosed with the ovarian cancer were enrolled in the study and divided into groups according to the stage of the disease, outcome of the surgery and treatment received. Proportions of Tregs in the peripheral blood samples were evaluated using flow cytometry. RESULTS We show that the early stage of the disease and absence of the tumor residuum after radical surgery are the most important factors predicting a favourable clinical outcome in the ovarian cancer. We did not show any significant effect of consolidation chemotherapy with metronomic doses of etoposide or cyclophosphamide on the peripheral blood Tregs and on the clinical outcome. The slope of the Tregs trend line was a significant predictor of an early relapse, even after controlling for stage and tumor residuum after the surgical debulking by using the Cox proportional hazard model. CONCLUSIONS This study shows that the faster kinetics of Tregs increase in the peripheral blood, expressed as the slope of the Tregs trend line, is a significant predictor of ovarian cancer early relapse hazard. However, due to its relatively low specificity, the informative value of regular monitoring of Tregs kinetics in the peripheral blood for the subsequent clinical outcome is limited.

Autologous dendritic cell immunotherapy (DCVAC/PCa) added to docetaxel chemotherapy in a Phase III trial (viable) in men with advanced (mCRPC) prostate cancer

Meeting abstracts Prostate cancer (PCa) is the second most common cancer, and the fifth leading cause of cancer related death among men worldwide. Immunotherapy designed to induce tumor cell specific immune responses capable of destroying tumor cells has emerged as a promising treatment modality in