IntroductionMetastatic renal cell cancer (RCC) has a very poor prognosis with a median survival of only 6 to 12 months from the time of diagnosis. 1,2 Historically, there were no established effective treatment approaches for metastatic RCC because of its resistance to radiation and chemotherapy. 3 Until recently, cytokine-based immunotherapy using interferon-␣ (IFN-␣) and/or interleukin-2 (IL-2) was the only effective treatment resulting in response rates of 10% to 20%. 4 The understanding of RCC pathogenesis and identification of molecular mechanisms responsible for the malignant transformation and metastatic spread led to the development of drugs that target cancer-specific pathways, such as the PI3K/AKT and Ras/Raf/MAPK pathways. 5 RCC is often associated with up-regulated Raf1, EGFR, and VEGFR activity. 5,6 Furthermore, in a high proportion of RCC, mutational aberrations of the von Hippel-Lindau (VHL) gene were identified. The loss-of-function of this tumor suppressor gene results in an accumulation of hypoxia inducible factor (HIF)-␣ subunits and stimulation of angiogenesis via VEGF-and PDGF-receptors.Consequently, 2 novel tyrosine kinase inhibitors, sorafenib (Bayer HealthCare, Leverkusen, Germany) 5 and sunitinib (Pfizer, New York, NY), were introduced in the treatment of RCC patients.Sorafenib is a multikinase inhibitor initially developed to inhibit the Raf1-kinase pathway. 2 However, besides the RAF/MEK/ERK pathway, sorafenib targets receptor tyrosine kinases (RTKs), such as VEGFR-2 and -3, PDGFR-␤, Flt-3, and c-KIT. 2,7 In several clinical and preclinical trials, sorafenib was revealed to be a promising anticancer therapeutic, which negatively regulates tumor growth, cell proliferation, and angiogenesis 8,9 and additionally induces apoptosis in tumor cells. 10 In December 2005, sorafenib was approved by the FDA for treatment of patients with advanced/ metastatic RCC. In a randomized trial, sorafenib doubled the median duration of progression-free survival up to 24 weeks in patients refractory to or relapsed during cytokine treatment. 2,11,12 Sunitinib inhibits multiple split kinase domain RTKs, including VEGFR-1 and -2, PDGFR-␣ and -␤, c- 7,13 In 2 phase 2 studies, application of sunitinib resulted in response rates up to 40% and in a randomized phase 3 trial it showed an improved response rate and progression-free survival in comparison to 14,15 However, until now the effects of sorafenib and sunitinib on development and function of normal nonmalignant hematopoetic cells have not been evaluated in detail. It is known that PBLs isolated from patients receiving clinically relevant doses of sorafenib show inhibition of ERK phosphorylation on ex vivo PMA stimulation. 16 We therefore analyzed the immunomodulatory functions of these compounds using T cells and monocyte-derived dendritic cells (MDDCs), which were activated with ligands for TLR3 or 4. We found that sorafenib, but not sunitinib, has a detrimental effect on DC phenotype and inhibits cytokine secretion, migration ability, and T-cell stimulator...

Purpose: Histone deacetylases (HDAC) modulate gene transcription and chromatin assembly by modifying histones at the posttranscriptional level. HDAC inhibitors have promising antitumor activity and are presently explored in clinical studies. Cumulating evidence in animal models of immune disorders also suggests immunosuppressive properties for these small molecules, although the underlying mechanisms remain at present poorly understood. Here, we have evaluated the effects of two HDAC inhibitors currently in clinical use, sodium valproate and MS-275, on human monocyte-derived DCs. Experimental Design: DCs were generated from monocytes through incubation with granulocyte macrophage colony-stimulating factor and interleukin-4. DC maturation was induced by addition of polyinosinic-polycytidylic acid. DC phenotype, immunostimulatory capacity, cytokine secretion, and migratory capacity were determined by flow cytometry, mixed leukocyte reaction, ELISA, and Transwell migration assay, respectively. Nuclear translocation of RelB, IFN regulatory factor (IRF)-3, and IRF-8 were determined by immunoblotting. Results: HDAC inhibition skews DC differentiation by preventing the acquisition of the DC hallmark CD1a and by affecting the expression of costimulation and adhesion molecules. In addition, macrophage inflammatory protein-3h/chemokine, motif CC, ligand 19^induced migration, immunostimulatory capacity, and cytokine secretion by DCs are also profoundly impaired. The observed defects in DC function on exposure to HDAC inhibitors seem to reflect the obstruction of signaling through nuclear factor-nB, IRF-3, and IRF-8. Conclusions: HDAC inhibitors exhibit strong immunomodulatory properties in human DCs. Our results support the evaluation of HDAC inhibitors in inflammatory and autoimmune disorders.

IntroductionDendritic cells (DCs) are recognized as the most efficient antigenpresenting cells that initiate antigen-specific immune responses. They reside in an immature state in peripheral tissues, where they sense their environment and take up antigens. Upon activation through inflammatory mediators or pathogen-derived products, they change their expression pattern of various cell-surface molecules and secreted mediators like cytokines and chemokines. These alterations enable DCs to migrate to lymphoid tissues, where they present antigens and induce differentiation of both naive CD4 ϩ and CD8 ϩ T lymphocytes. These functional changes are accompanied with a lower capacity to take up soluble and cellular antigens by phagocytosis or pinocytosis by mature DCs and an increased ability to stimulate T-cell responses. 1,2 Usually, antigens from exogenous sources are taken up by DCs, become processed, and are presented to CD4 ϩ T lymphocytes on MHC class II molecules while intracellular-derived peptides are loaded onto MHC class I molecules where they stimulate antigenspecific CD8 ϩ T lymphocytes. 3 However, DCs are able to present antigens taken up from their environment on MHC class I molecules in a process called cross-presentation. This mechanism enables these cells to raise immune responses against tumor cells or pathogens like viruses that do not infect themselves. [4][5][6][7][8] DCs employ various molecules to sense their environment for pathogen-associated molecular patterns (PAMPs), microbial elementary components that are not or only minimal subjected to host adaptation. The most prominent of these receptors resembles the Toll-like receptor (TLR) family. TLR family members recognize microbial components such as lipopolysaccharide (LPS), flagellin, lipopeptides, or nucleic acids, and therefore initiate specific signaling pathways that lead to distinct immune responses. 9 In our study, we analyzed the effects of TLR-mediated DC activation on uptake of cellular antigens and their crosspresentation on MHC class I molecules. We show that TLR3 or TLR4 but not TLR2 or TLR7/8 matured DCs are impaired in the phagocytosis of cellular material and subsequent cross-presentation of antigens on MHC class I molecules. Materials and methodsApproval was obtained from the ethics committee of the University of Tübingen for these studies. In our study we used buffy coats provided by the local blood bank. Informed consent was provided according to the Declaration of Helsinki. CellsHEK-293 cells (embryonal kidney; DSMZ, Braunschweig, Germany) were cultured in RP10 medium (RPMI 1640 with glutamax I, supplemented with 10% inactivated fetal calf serum [FCS] and antibiotics; Invitrogen, Karlsruhe, Germany). Generation of DCsDCs were generated from peripheral blood monocytes by magnetic cell sorting as described previously. 10 In brief, peripheral blood mononuclear cells were isolated by Ficoll/Paque (Biochrom, Berlin, Germany) density gradient centrifugation of blood obtained from buffy coats of healthy volunteers from the blood ba...

Human Dectin-1 (hDectin-1) is a member of the C-type lectin-like receptor family that was shown to be the major receptor for fungal beta-glucans and to play an important role in the cellular responses mediated by these carbohydrates. In this study, we demonstrate that hDectin-1 is involved in

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