Interleukin-7 induces differential lymphokine-activated killer cell activity against human melanoma cells, keratinocytes, and endothelial cells

Induction of T helper 17 cell response by interleukin-7 in patients with primary cutaneous melanoma

Interleukin (IL)-7 plays a vital role in proliferation and activation of T cells, however, its signaling through CD127 is impaired in T cells in cancers and chronic infections. The mechanisms underlying T helper 17 (Th17) cell responses by IL-7 in melanoma remain not fully understood. The aim of this study was to assess the effect of IL-7 signaling on Th17 responses in patients with primary cutaneous melanoma. Healthy and primary cutaneous melanoma donors were selected for this study of Th17 cell function. IL-17+CD4+ Th17 cells and CD127 expression on Th17 cells were determined by flow cytometry. Cytokine level was measured by ELISA. Peripheral and tissue-infiltrating CD4+ T cells were isolated using magnetic beads, and then stimulated with IL-7 and/or signal transducer and activator of transcription 5 inhibitor. Activated signaling molecules were analyzed by flow cytometry. Peripheral and tumor-infiltrating Th17 cells percentage was decreased, while peripheral IL-7 level was also reduced in melanoma patients. There was no significant difference of CD127 expression on Th17 cells between melanoma patients and controls. Antiapoptotic protein Bcl-2 was downregulated, whereas proapoptotic protein-activated caspase-3 was upregulated in peripheral and tissue-infiltrating Th17 cells in melanoma patients. Higher concentration of IL-7 (10 ng/mL), but not lower IL-7 concentration (1 ng/mL), promoted Bcl-2 expression and decreased caspase-3 expression in Th17 cells in melanoma patients. Inhibition of signal transducer and activator of transcription 5 resulted in the downregulation of Bcl-2 while upregulation of caspase-3 in Th17 cells. The present data suggested that reduced IL-7 responsiveness might be insufficient for Th17 activation in patients with primary cutaneous melanoma.

Unveil the mysterious mask of cytokine-based immunotherapy for melanoma

Melanoma is the leading cause of death among all skin cancers and its incidence continues to rise rapidly worldwide in the past decades. The available treatment options for melanoma remain limited despite extensive clinical research. Melanoma is an immunogenic tumor and great advances in immunology in recent decades allow for the development of immunotherapeutic agents against melanoma. In recent years, immunotherapy utilizing cytokines has been particularly successful in certain cancers and holds promise for patients with advanced melanoma. In this review, an overview of the current status and emerging perspectives on cytokine immunotherapy for melanoma are discussed in details. Such a study will be helpful to unveil the mysterious mask of cytokine-based immunotherapy for melanoma.

Functional CCR9 expression is associated with small intestinal metastasis

In general, metastases to the small intestine are rare, and mostly occur in melanoma. CCR9 has been shown to be the principal chemokine receptor for the thymus expressed chemokine (TECK), a chemokine selectively expressed in the small intestine and thymus. Here we show that CCR9 is highly expressed on melanoma cells and all melanoma cell lines isolated from small intestinal metastases, and on a proportion of cell lines from other sites. Only melanoma cells and cell lines from small intestinal metastases, however, were responsive to the CCR9 ligand TECK, as assessed by receptor downregulation and by actin polymerization. CCR9 expression was also found on the adenocarcinoma cell line CaCo-2 expressing characteristics of enterocytic differentiation, but not on any other cell line isolated from colorectal, breast, and lung cancer. Our data provide evidence that the aberrant functional cell surface expression of an organ-specific chemokine receptor is associated with metastasis to this site. The regulation of receptor function seems to be a critical step in the metastatic process.

Humoral immune response against melanoma antigens induced by vaccination with cytokine gene-modified autologous tumor cells

Although the existence of a humoral response against tumor-associated antigens is well appreciated, a systematic analysis of its possible induction by the tumor remains missing. We compared the specific IgG response of Stage IV melanoma patients during vaccination. Patients had been treated within 2 clinical trials with autologous tumor cells gene-modified for IL-7 or IL-12. A panel of 27 tumor-associated antigens (HD-MM-01 to HD-MM-27) was isolated by a SEREX screening of a testis cDNA library using a pool of 5 sera from patients after vaccination. All antigens were retested with individual sera of 12 patients both pre- and post-vaccination. A serological response was induced during vaccination against 18 antigens. Remarkably, induction was detected only in patients included in the screening pool. The low overlap between sero-reactivity of the 12 patients suggested a very individualized immunological reaction. Two of 5 sera included in the screening pool exhibited a high frequency of induced humoral responses. The same patients had been shown to have a high Karnovsky index and had generated lytic cytotoxic T cells against the tumor. Besides 2 known cancer-germline genes (SCP-1 and PLU-1), the other isolated antigens were expressed in a non-tumor-specific fashion as analyzed by virtual Northern blot or RT-PCR. The properties of homologues to several of the identified tumor-antigens, especially PLU-1, SCP-1, DNEL2, CLOCK, and PIASx-alpha, suggest further investigation of their possible function in malignant melanoma. We conclude that a strong humoral response against tumor-associated antigens is inducible by tumor cells and that this response is very individual.

IL-7 receptor is present on human microvascular endothelial cells

Interleukin-7 (IL-7) is a pleiotropic, non-redundant cytokine crucial for development of B and T lymphocytes. The cellular response to IL-7 is triggered by binding of the cytokine to its receptor, IL-7R. Until now the expression of the receptor was evidenced only in lymphoid and myeloid cell lineages. The receptor consists of two chains: IL-7 specific alpha chain (CD127) and the common gamma(c) chain (CD132) which is a component of several other cytokine receptors: IL-2, IL-4, IL-9 and IL-15. The former observation that exogenous IL-7 is biologically active towards murine endothelial cell lines from secondary lymphoid organs was the starting point of our studies. This observation has prompted us to search for the presence of IL-7 receptor in human microvascular endothelial cells. We used in our studies a set of human endothelial cell lines established from various organs. Our results demonstrate the presence of IL-7R in human microvascular endothelial cells, mainly in the mesenteric but also in the peripheral and to a lesser extent, in the mucosa-associated lymph node endothelial cells. On the basis of the RT-PCR reaction, molecular weight estimated in Western blot and IL-7 binding activity the identified endothelial IL-7 receptor was identical to the lymphocyte-type IL7-R.

Therapeutic vaccination against metastatic carcinoma by expression-modulated and immunomodified autologous tumor cells: a first clinical phase I/II trial

Therapeutic vaccination of tumor patients with cytokine gene-transfected tumor cells leads to tumor regression in animal models but has so far not resulted in significant clinical benefit. We and others demonstrated that tumor cells transfected to mediate overexpression of a cytokine gene activate immunologic effector cells for an improved proliferation rate and significantly higher antitumoral cytotoxic activity. Here, we performed a pilot study of therapeutic vaccination in patients with metastatic disease. Autologous tumor cells were simultaneously transfected with novel minimalistic, immunogenically defined, gene expression constructs (MIDGE) for overexpression of the two cytokines interleukin 7 (IL-7) and GM-CSF and newly designed double stem-loop immunomodulating oligodeoxyribonucleotides (d-SLIM) as a Th1-promoting and NK cell-stimulating adjuvant. Transfection was performed ex vivo by ballistomagnetic gene transfer. Patients received four subcutaneous injections of at least 1 x 10(6) of their expression-modulated and immunomodified autologous tumor cells. Ten patients have been enrolled in the study protocol. In all patients no adverse effects could be detected. IL-7 and interferon gamma levels were elevated in the serum of the patients after treatment. Interestingly, cytotoxicity of patient-derived PBLs increased significantly during treatment. All 10 patients had progressive disease when entering our protocol. One complete, one partial, and one mixed response with progression of abdominal metastases and regression of lung metastases were observed. Two patients showed a stable disease after treatment and five patients remained in progressive disease. Our observations confirm the capability of autologous expression-modified and immunomodulated tumor cell vaccines to stimulate a strong immune response in patients with metastatic cancer even in the presence of a large tumor burden.

Comparison of non-viral transfection methods in melanoma cell primary cultures

Melanoma primary cultures were transiently transfected via electroporation and lipofection for comparison. Transfection efficiency was superior with electroporation (58+/-9%) as compared to lipofection (23+/-9%) as determined by enhanced green fluorescent plasmid (EGFP) transfection. Secretion of IL-2 persisted for up to 3 weeks after electroporation. The increase in sensitivity against immunologic effector cells by transfection with IL-2 was not significant. Our results show the feasibility of a gene transfer into primary human melanoma cells, different from retroviral transduction.

Immunologic abnormalities exhibited in IL-7 transgenic mice with dermatitis

Interleukin (IL)-7 transgenic mice, which we established previously, developed severe dermatitis characterized by massive infiltration of gammadelta T cells in the dermal lesion. To fully understand the pathology of this intriguing skin disease, we examined several immunologic features of dermis infiltrating lymphocytes from the lesional skin of IL-7 transgenic mice. We observed a moderate response to mitogens, a poor response to alloantigens, and the absence of cytotoxic activities to several tumor cell lines and skin derived cells regardless of the presence of IL-2 or IL-7. On the other hand, dermis infiltrating lymphocytes could proliferate with exogenous IL-2 and IL-7. Moreover, reverse transcriptase polymerase chain reaction and fluorescence activated cell sorter analysis revealed that dermis infiltrating lymphocytes expressed various cytokines including IL-4 and IL-7, and several activation markers for T cells (CD44, CD69, IL-2R alpha), in addition to IL-7R alpha. In the sera of the affected mice, hyper epsilon-globulinemia was observed. These findings suggested that dermis infiltrating lymphocytes proliferated in an activated state in the skin lesion in an autocrine and/or paracrine manner and produced Th2 type cytokines that might evoke immunologic abnormalities. This study and previous findings suggest that IL-7 transgenic mouse with dermatitis offer the potential of serving as a useful tool for investigating the immunologic role of cutaneous gammadelta T cells, especially their participation in IgE production in vivo.

Human small intestinal epithelial cells secrete interleukin-7 and differentially express two different interleukin-7 mRNA Transcripts: implications for extrathymic T-cell differentiation

The small intestinal epithelium, composed of epithelial cells (EC) and intraepithelial T lymphocytes, is exposed to numerous ingested antigens. Small intestinal EC may act as accessory and/or antigen presenting cells for intestinal T cells, some of which may mature extrathymically and regulate local immunity and tolerance. Since interleukin-7 (IL-7) plays an essential role in T cell maturation and activation, we examined its expression by human small intestinal EC. IL-7 was detected by ELISA in supernatants from 4 of 4 epithelial layer (EpL) cultures. Using RT-PCR, IL-7 mRNA was detected in 4 EpL studied, and two distinct IL-7 transcripts were identified in 3 of the 4. The ratios of the intensities of the larger to the smaller bands varied amongst individuals. Furthermore, the intensity ratios were higher in whole-thickness intestine and lamina propria preparations than in their corresponding EpL. This is the first report of the expression of two IL-7 transcripts in human intestine and of IL-7 secretion by human small intestinal EpL cells. This supports the hypothesis that small intestinal EC may influence differentiation and/or activation of neighboring T cells. The differential expression of the two transcripts may have important implications for immune regulation in the intestinal epithelium.

Cytokine-induced cytotoxic function expressed by lymphocytes of the innate immune system: distinguishing characteristics of NK and LAK based on functional and molecular markers

Several molecular events are now identifiable during the activation, recognition, and killing by natural killer (NK) cells that are distinct from those differentiated in response to cytokines during the generation of lymphokine-activated killer (LAK) cells or during lymphocyte proliferation. Because LAK and MHC-unrestricted killing activities also include the prototypic NK targets as part of their broad recognition spectra, accurate identification of the complete function being studied is critical. In many publications, past and present, only NK-sensitive target cells were used (K562, Molt-4, others), and, therefore, the results do not necessarily indicate whether the effectors are NK or have differentiated into LAK cells. Such a consideration becomes critical when the effectors are grown in interleukin-2 (IL-2), and an attempt is made to define receptor recognition, signal transduction pathways, and specificity at the molecular level. In some instances, effector cells are likely to have stopped, therefore merely expressing NK activity, and have also acquired LAK function. The identified receptors may not have been unique to NK cells or NK function. Not until the targets employed are also confirmed to be NK sensitive, and the effectors do not kill NK-resistant targets can the results of molecular studies be proposed to represent aspects unique to NK. Reports of the use of IL-2-expanded NK clones are most likely providing data concerning the biology of LAK and not of classic NK. The classic NK activity surveying our blood apparently performs an important function, including the ability to respond rapidly to certain cytokines and to acquire additional functions and receptors for use in destroying a vast array of target cells. It is critical for scientists to appreciate the functional distinctions and to identify the molecules and pathways unique to each of these curious cytolytic systems.

Interleukin-7. Biology and implications for dermatology

In recent years, it has become apparent that IL-7, originally characterized as a growth factor for pre-B lymphocytes, also has important implications for the skin. Keratinocytes have been shown to produce IL-7. which in turn can elicit a variety of biological responses on several cell types residing in the skin. IL-7 has been demonstrated to augment the cytolytic activity of cytotoxic T cells (CTL) and natural killer (NK) cells against various neoplastic targets including melanoma cells. Proliferation and long-term survival of murine dendritic epidermal T lymphocytes (DETC) in vitro is supported by IL-7. IL-7 also induces secretion of inflammatory cytokines by monocytes/macrophages and renders these cells to become tumoricidal against melanoma cells. Normal and malignant melanocytes respond to IL-7 with increased expression of intercellular adhesion molecule (ICAM-1). In addition, IL-7 has been shown to act as growth factor for Sezary cells, suggesting a role of keratinocyte-derived IL-7 in the pathogenesis of cutaneous T cell lymphoma. Because of the potent in vitro immunomodulatory effects of IL-7 which have been confirmed in mouse tumor models, IL-7 may become a valuable additional agent to immunotherapeutical regimens currently studied in patients with advanced melanoma. This review summarizes our present knowledge about the molecular and immunological properties of IL7 with emphasis on the effects of that cytokine within the cutaneous compartment and the potential clinical utility in dermatology.

Dendritic cells generated from peripheral blood transfected with human tyrosinase induce specific T cell activation

Peptides of melanosomal proteins have recently been shown to be recognized in an HLA-restricted mode by specific cytolytic T lymphocytes in melanoma patients. Dendritic antigen-presenting cells (DC) are considered to be the most effective stimulators of T cell responses, and the use of these cells has therefore been proposed to generate therapeutic responses to tumor antigens in cancer patients. We, therefore, generated DC from peripheral blood of normal donors in the presence of granulocyte/macrophage colony-stimulating factor and interleukin-4. Flow cytometric analysis of the cells during a 2-week culture revealed a loss of CD14 and CD34 expression, a concomittent increase of CD1a, CD11a,b and c, CD44, CD45, CD54, HLA-class I and II, and intermediate levels of CD26, CD80 and CD86. Cultured DC stimulated proliferation of allogeneic T cells and induced a marked, up to 20-fold, stimulation of T cell proliferation after pulsing with tetanus toxoid. To achieve independence of already-identified antigenic peptides presented in HLA class I-restricted fashion, which limits the general applicability of such peptides for vaccination of melanoma patients, we tested whether DC are transfectable with eukaryotic expression plasmids. DC transfected with two reporter genes (CAT, beta-galactosidase) using a liposome-based transfection technique, exhibited only low levels of enzymatically active proteins, but were able to degrade rapidly intracellular proteins and to process peptides efficiently. Chloramphenicol acetyltransferase as well as tyrosinase mRNA were detectable after transfection by reverse-transcriptase-polymerase chain reaction, and enzyme activities became measurable. Furthermore, DC transfected with the tyrosinase gene were able to induce specific T cell activation in vitro, indicating appropriate peptide processing and presentation in DC after transfection. These data suggest new approaches to future tumor vaccination strategies.

Effects of various synthetic retinoids on proliferation and immunophenotype of human melanoma cells in vitro

Since response rates in human melanoma are low with currently available therapeutic modalities, we have reevaluated the potential usefulness of retinoids as new alternatives for therapy of metastatic melanoma. Nine synthetic retinoids with high affinity and/or selectivity for the retinoic acid receptors (RAR) alpha, beta, and gamma were studied in comparison to all-trans retinoic acid (RA) for their in vitro effects on melanoma cell proliferation and for their immunomodulating capacities using four human melanoma cell lines. Eight out of ten retinoids tested had no effect on melanoma cell growth, whereas the remaining two compounds with high RAR-gamma selectivity (CD437 and CD2325) showed a dose-dependent antiproliferative effect on all melanoma cell lines with IC50 (concentration inhibiting response by 50%) values between 10(-6) and 10(-7)M. Further analyses showed that paracrine-mediated tumor cell growth inhibition such as induction of transforming growth factor (TGF)-beta described as one mechanism of retinoid action and enzyme systems such as tyrosinase and monoamine oxidase were not involved in mediating the antiproliferative effects exerted by the two retinoids. Four of nine retinoids modulated HLA-DR expression on human melanoma cells, and expression levels of intercellular adhesion molecule 1 (ICAM-1) was increased by another subset of compounds. These effects were, however, not correlated to the receptor selectivity of the retinoids. The potent growth inhibitory effect of the RAR-gamma-selective retinoids and the immunomodulating capacities of the retinoids open an interesting alternative for new antiproliferative and immunomodulatory strategies in the treatment of metastatic melanoma.