Human slan (6-sulfo LacNAc) dendritic cells are inflammatory dermal dendritic cells in psoriasis and drive strong TH17/TH1 T-cell responses.

BACKGROUND: Psoriasis is a chronic inflammatory skin disease that is considered to result from activated T cells stimulated by a population of inflammatory dermal dendritic cells (DCs). The origin and identity of these inflammatory dermal DCs are largely unknown. OBJECTIVE: We previously identified slanDCs (6-sulfo LacNAc) DCs as a rich source of TNF-α and as the early major source of IL-12. Here we studied the relevance of slanDCs as inflammatory dermal DCs in psoriasis. METHODS: Psoriasis skin samples were stained for the presence of activated slanDCs. Functional studies were carried out to determine the cytokine production of slanDCs, their T(h)17/T(h)1 T-cell programming, and their migration behavior. RESULTS: Large numbers of IL-23, TNF-α, and inducible nitric oxide synthase expressing slanDCs were found in psoriatic skin samples, which can be recruited by C5a, CX3CL1, and CXCL12. SlanDCs isolated from blood produced high levels of IL-1ß, IL-23, IL-12, and IL-6. Compared with classic CD1c(+) DCs, slanDCs were far more powerful in programming T(h)17/T(h)1 T cells that secrete IL-17, IL-22, TNF-α, and IFN-γ, yet CD1c(+) DCs induced a higher IL-10 production of T cells. Self-nucleic acids complexed to cathelicidin LL37 trigger endosomal Toll-like receptor (TLR) signaling (TLR7, TLR8, TLR9) and are key factors for the activation of DCs in psoriasis. We show that slanDCs respond particularly well to complexes formed of self-RNA and LL37. Similarly, slanDCs stimulated with a synthetic TLR7/8 ligand produced high levels of proinflammatory cytokines. CONCLUSION: Our study defines slanDCs as inflammatory dermal DCs in psoriasis and identifies their strong capacity to induce T(h)17/T(h)1 responses.

Dendritic cell-based immunotherapy for prostate cancer.

Dendritic cells (DCs) are professional antigen-presenting cells (APCs), which display an extraordinary capacity to induce, sustain, and regulate T-cell responses providing the opportunity of DC-based cancer vaccination strategies. Thus, clinical trials enrolling prostate cancer patients were conducted, which were based on the administration of DCs loaded with tumor-associated antigens. These clinical trials revealed that DC-based immunotherapeutic strategies represent safe and feasible concepts for the induction of immunological and clinical responses in prostate cancer patients. In this context, the administration of the vaccine sipuleucel-T consisting of autologous peripheral blood mononuclear cells including APCs, which were pre-exposed in vitro to the fusion protein PA2024, resulted in a prolonged overall survival among patients with metastatic castration-resistant prostate cancer. In April 2010, sipuleucel-T was approved by the United States Food and Drug Administration for prostate cancer therapy.

GD3-7-aldehyde is an apoptosis inducer and interacts with adenine nucleotide translocase.

We prepared GD3-7-aldehyde (GD3-7) and determined its apoptotic potential. GD3-7 proved to be more efficient to induce pro-apoptotic mitochondrial alterations than GD3 when tested on mouse liver mitochondria. GD3-7-induced mitochondrial swelling and depolarization was blocked by cyclosporin A (CsA) supporting a critical role of the permeability transition pore complex (PTPC) during GD3-7-mediated apoptosis. In contrast to GD3, GD3-7 was able to induce channel formation in proteoliposomes containing adenine nucleotide translocase (ANT). This suggests that ANT is the molecular target of GD3-7. Using a specific antiserum, GD3-7 was detected in the lipid extract of the myeloid tumor cell line HL-60 after apoptosis induction, but not in living cells. Therefore, GD3-7 might be a novel mediator of PTPC-dependent apoptosis in cancer cells.

Extracorporeal photopheresis efficiently impairs the proinflammatory capacity of human 6-sulfo LacNAc dendritic cells.

BACKGROUND: Extracorporeal photopheresis (ECP) emerged as a promising treatment modality for steroid-refractory graft-versus-host disease (GVHD), which represents a major complication of allogeneic hematopoietic stem-cell transplantation. Dendritic cells (DCs) display an extraordinary capacity to induce T-cell responses and play a crucial role in the initiation and maintainance of GVHD. This study evaluated the direct impact of ECP on the proinflammatory capacity of 6-sulfo LacNAc (slan) DCs, representing a major subpopulation of human blood DCs. METHODS: SlanDCs were isolated from ECP-treated or untreated blood of healthy donors or GVHD patients by immunomagnetic isolation. The maturation of slanDC was determined by flow cytometry. Cytokine production of slanDCs was measured by enzyme-linked immunosorbent assay. SlanDC-mediated T-cell proliferation was evaluated by H-thymidine incorporation. SlanDC-mediated T-cell programming was determined by flow cytometry. RESULTS: ECP efficiently impairs the spontaneous maturation and secretion of proinflammatory tumor necrosis factor-alpha, interleukin-1beta, and interleukin-12 by slanDCs. Furthermore, ECP markedly inhibits slanDC-induced proliferation of CD4 and CD8 T cells and polarization of naïve CD4 T lymphocytes into Th1 cells. CONCLUSIONS: These novel findings indicate that ECP efficiently impairs the proinflammatory capacity of slanDCs, which may represent an important mechanism for the therapeutic efficiency of ECP in GVHD.

Reciprocal activating interaction between 6-sulfo LacNAc+ dendritic cells and NK cells.

Dendritic cells (DCs) display an extraordinary capacity to induce T-cell responses providing the opportunity of DC-based cancer vaccination strategies. Additional findings indicate that DCs may also play a crucial role for the activation of natural killer (NK) cells, which are important effectors in innate antitumor immunity. However, studies investigating the interaction between native human DCs and NK cells are limited. Recently, we defined 6-sulfo LacNAc (slan) DCs as a major subpopulation of myeloid human blood DCs, which represent principal producers of the proinflammatory cytokines tumor necrosis factor-alpha and interleukin (IL)-12. Functional data revealed that slanDCs efficiently induce neoantigen-specific CD4+ T cells and activate tumor-reactive cytotoxic T cells. When evaluating the crosstalk between slanDCs and NK cells in this study, we found that lipopolysaccharide (LPS)-activated slanDCs efficiently enhance NK cell CD69 expression and interferon (IFN)-gamma secretion. NK cell-mediated tumor-directed cytotoxicity was significantly improved by slanDCs. NK cell activation induced by slanDCs was critically dependent on IL-12. When investigating the impact of NK cells on the immunostimulatory capacity of slanDCs, we observed that they promote DC maturation. In addition, NK cells strongly enhanced the secretion of immunomodulatory IL-12 and reduced the release of immunosuppressive IL-10 by slanDCs. IFN-gamma and cell-to-cell contact contributed to these effects. Furthermore, data revealed that DC-NK cell crosstalk improves slanDC-mediated differentiation of naïve CD4+ T lymphocytes into IFN-gamma-producing Th1 cells. In conclusion, we demonstrate a reciprocal activating interaction between slanDCs and NK cells, which may play a pivotal role in the regulation of antitumor immunity.

Adoptive transfer of cytotoxic T-cells for treatment of residual disease after irradiation.

PURPOSE: To evaluate whether immunotherapy based on adoptively transferred cytotoxic T-cells (CTL) can improve the antitumour efficacy of irradiation. MATERIAL AND METHODS: The experiments were performed using the human squamous cell carcinoma line UT-SCC-15, which expresses human leukocyte antigen (HLA)-A2. The UT-SCC-15 cell-mediated activation of JB4 CTL in terms of interferon (IFN)-gamma secretion and cytotoxic potential was determined by enzyme-linked immunosorbent assay and chromium release assay, the perforin content of JB4 cells by flow cytometry. In vivo, tumours were irradiated with 14 Gy. Subsequently, JB4 CTL were injected intra- and peritumourally. Volume doubling times were calculated as a marker of tumour growth delay. RESULTS: UT-SCC-15 tumour cells were well recognized by JB4 CTL in vitro, as indicated by profound IFN-gamma secretion and tumour cell lysis. This response was completely abrogated in the presence of an anti-HLA-A2 antibody. In vivo, adoptive transfer of JB4 CTL after irradiation did not delay tumour growth in comparison to irradiation alone. As a possible underlying mechanism, a loss of perforin content and cytolytic function of the CTL in the absence of interleukin (IL)- 2 or IL-15 was found in vitro. CONCLUSION: HLA-A2-alloreactive JB4 cells efficiently recognize and destroy UT-SCC-15 tumour cells in vitro. However, the intratumoural application of JB4 cells after irradiation does not enhance the in vivo effect of radiotherapy alone, which might be caused by the reduced cytotoxic potential of JB4 cells in the absence of IL-2 or IL-15. Thus, co-administration of these cytokines might improve the efficacy of combined irradiation and CTL treatment.

Targeting of tumor cells expressing the prostate stem cell antigen (PSCA) using genetically engineered T-cells.

BACKGROUND: Curative therapeutic options for minimal residual disease or advanced tumor stages in prostate cancer (PCa) are still missing. Adoptive transfer of cytotoxic T-cells that have been polyclonally rendered tumor-specific by genetic engineering appears to be a promising immunotherapeutic strategy. Among the numerous prostate tissue/tumor antigens identified during the last years, the "prostate stem cell antigen" (PSCA) is an attractive immunotherapeutic target. It is broadly expressed on the surface of primary PCa cells as well as on PCa metastases. METHODS: To generate a chimeric T-cell receptor (TCR) recognizing PSCA, a monoclonal anti-PSCA antibody was raised and a single-chain fragment (scFv) was prepared. The resulting anti-PSCA scFv 7F5 was fused to the beta2 constant region derived from the beta-chain of a TCR and to the CD3zeta-signaling domain. RESULTS: The chimeric alpha-PSCA-beta2/CD3zeta-TCR, expressed in Jurkat cells, was phosphorylated in the ITAMs of the CD3-zeta chain upon cross-linking by insolublized PSCA. When transduced into a mouse cytotoxic T-cell line, the chimeric receptor specifically activated cytotoxicity against PSCA-positive tumor cells. CONCLUSIONS: We developed a functional chimeric TCR against PSCA for treatment of PCa. The chimeric alpha-PSCA-beta2/CD3zeta-TCR might now be used for arming human cytotoxic T-cells for further studies towards a clinical treatment of PCa.

9-O-acetyl GD3 protects tumor cells from apoptosis.

The ganglioside GD3 (Neu5Ac alpha8Neu5Ac alpha3Gal beta4GlcCer) is an intracellular lipid messenger that induces apoptosis by targeting mitochondria in various cell types. GD3 can also promote apoptosis when externally added to cells. Previous studies showed that the proapoptotic effects of GD3 can be counteracted by 9-O-acetylation. To determine whether 9-O-acetyl GD3 (acGD3) has a general antiapoptotic potential, the apoptosis-sensitive Jurkat cell line and an apoptosis-sensitive variant of the cell line Molt-4 were preincubated with micromolar concentrations of acGD3 and then treated with inducers of apoptosis. A reduced apoptotic index and an increased cell viability were observed. On the other hand, when the Jurkat cells were treated with GD3 for extended periods of time, a population was selected that was resistant to apoptosis induction by N-acetyl sphingosine as well as by the anti-leukemic drug daunorubicin. Comparative analysis of gangliosides revealed the formation of acGD3 in the resistant Jurkat cells that was not found in the apoptosis-sensitive cells. Conversely, exposing the acGD3 positive and apoptosis-resistant cell line Molt-4 to the O-deacetylating activity of salicylate resulted in a complete disappearance of acGD3 and an enhanced sensitivity to N-acetyl sphingosine-mediated apoptosis. Formation of acGD3 might thus represent a new mechanism how tumor cells can escape apoptosis.

Promotion of cell adherence and spreading: a novel function of RAGE, the highly selective differentiation marker of human alveolar epithelial type I cells.

The receptor for advanced glycation endproducts (RAGE) is expressed under pathological conditions in many tissues and has been assigned many functions. We demonstrate, in normal human lung tissue, the preferential and highly abundant expression of RAGE by quantitative polymerase chain reaction. In addition, RAGE expression, as a specific differentiation marker of alveolar epithelial type I cells (AT I cells), and its localization to the basolateral plasma membrane have been confirmed by means of newly raised monoclonal antibodies. The physiological function of RAGE on AT I cells has previously remained elusive. By using HEK293 cells transfected with cDNA encoding for full-length RAGE, we show that RAGE enhances the adherence of epithelial cells to collagen-coated surfaces and has a striking capacity for inducing cell spreading. The preferential binding of RAGE to collagen has been confirmed by assaying the binding of soluble RAGE to various substrates. RAGE might thus assist AT I cells to acquire a spreading morphology, thereby ensuring effective gas exchange and alveolar stability.

Transcriptional activation of the type I collagen genes COL1A1 and COL1A2 in fibroblasts by interleukin-4: analysis of the functional collagen promoter sequences.

Pneumonitis followed by lung fibrosis is a frequent complication of radiation therapy of chest tumors. A hallmark of these fibrotic lesions is the excessive production and accumulation of extracellular matrix proteins such as type I collagen. In addition to TGF-beta1, IL-4 has been recognized as a potent inducer of collagen gene synthesis in fibroblasts. In this study, we analyzed the regulation of the alpha1(I) procollagen (COL1A1) promoter and the alpha2(I) procollagen (COL1A2) promoter by IL-4 in normal human lung fibroblasts. We provide evidence that the IL-4-induced transcriptional activator STAT6 binds to various sequences within the COL1A1 and COL1A2 promoter. The regulatory function of these regions was tested by reporter gene analysis using 5' deletions of the COL1A1 and COL1A2 promoter fused to the luciferase gene. Interleukin-4 treatment of human fibroblasts transiently transfected with COL1A1 promoter deletion constructs resulted in luciferase activity exceeding that of untreated fibroblasts by 25%, while luciferase activity driven by the COL1A2 promoter was enhanced by about 70% upon IL-4 treatment. A combined action of SP1, NFkappaB, and STAT6 essentially contributes to the IL-4 mediated COL1A2 gene activation. An AP2 site adjacent to the reverse orientated STAT6 consensus motif TTC N(3/4) GCT is located within 205 bases from the transcription start site and seems to support the moderate IL-4-induced COL1A1 gene activation. Interferon-gamma downregulation of transcription is mainly seen with the COL1A1 promoter.

Localization, dynamics, and function of survivin revealed by expression of functional survivinDsRed fusion proteins in the living cell.

Survivin, a member of the inhibitor of apoptosis protein family, has attracted growing attention due to its expression in various tumors and its potential application in tumor therapy. However, its subcellular localization and function have remained controversial: Recent studies revealed that survivin is localized at the mitotic spindle, binds caspases, and could thus protect cells from apoptosis. The cell cycle-dependent expression of survivin and its antiapoptotic function led to the hypothesis that survivin connects the cell cycle with apoptosis, thus providing a death switch for the termination of defective mitosis. In other studies, survivin was detected at kinetochores, cleavage furrow, and midbody, localizations being characteristic for chromosomal passenger proteins. These proteins are involved in cytokinesis as inferred from the observation that RNA interference and expression of mutant proteins led to cytokinesis defects without an increase in apoptosis. To remedy these discrepancies, we analyzed the localizations of a survivinDsRed fusion protein in HeLa cells by using confocal laser scanning microscopy and time-lapse video imaging. SurvivinDsRed was excluded from the interphase nucleus and was detected in centrosomes and at kinetochores. It dissociated from chromosomes at the anaphase/telophase transition and accumulated at the ends of polar microtubuli where it was immediately condensed to the midbody. Overexpression of both survivinDsRed and of a phosphorylation-defective mutant conferred resistance against apoptosis-inducing reagents, but only the overexpressed mutant protein caused an aberrant cytokinesis. These data characterize in detail the dynamics of survivin in vertebrate cells and confirm that survivin represents a chromosomal passenger protein.

Prostate stem cell antigen: Identification of immunogenic peptides and assessment of reactive CD8+ T cells in prostate cancer patients.

Identification of TAAs recognized by CD8(+) CTLs paved the way for new concepts in cancer therapy. In view of the heterogeneity of tumors and their diverse escape mechanisms, CTL-based cancer therapy largely depends on an appropriate number of TAAs. In prostate cancer, the number of antigens defined as suitable targets of CTLs remains rather limited. PSCA is widely distributed in prostate cancer. In this report, we define immunogenic peptides of PSCA which are recognized by circulating CD8(+) T cells from prostate cancer patients and able to activate CTLs in vitro. Screening the amino acid sequence of PSCA for peptides containing a binding motif for HLA-A*0201 resulted in 8 candidate peptides. Specificity and affinity of peptide binding were verified in a competition assay. Frequencies of CD8(+) T lymphocytes reactive against selected epitopes were determined in the blood of prostate cancer patients using the ELISPOT assay. Increased frequencies were revealed for CD8(+) T cells recognizing the peptides ALQPGTALL and AILALLPAL. CTLs from prostate cancer patients were raised against these 2 peptides in vitro when presented by autologous DCs. They specifically recognized peptide-pulsed T2 target cells and prostate cancer cells that were HLA-A*0201- and PSCA-positive, indicating that these peptides were naturally generated by tumor cells. These data suggest that PSCA is a promising target for the immunotherapy of prostate cancer.

Native human blood dendritic cells as potent effectors in antibody-dependent cellular cytotoxicity.

Functional studies on native human dendritic cells (DCs) are hampered by technical difficulties in preparing fresh DCs. Recently, with the help of the monoclonal antibody M-DC8, we succeeded in isolating a major subpopulation of human blood DCs by a one-step immunomagnetic separation procedure. These cells strongly express Fc gamma RIII (CD16) and Fc gamma RII (CD32) and are quite efficient in the antigen-specific activation of naive T cells. Because some Fc gamma receptor-bearing cell types are known as effector cells in antibody-dependent cellular cytotoxicity (ADCC), we investigated whether M-DC8(+) DCs are capable of effectuating ADCC. In this report we show that freshly prepared M-DC8(+) DCs efficiently mediate tumor-directed ADCC and that both types of Fc gamma receptors as well as tumor necrosis factor alpha essentially contribute to the cytotoxic activity. The results provide evidence that, in addition to their pivotal role in primary T-cell activation, a subset of blood DCs displays efficient cytotoxicity in ADCC.