Biomedical subjects

Ena Wang

Publications and source records attributed to Ena Wang.

At least 55 records · Page 3Linked to original sources

PubMed2004

Gene expression profiling of anticancer immune responses.

Anticancer immune responses can be enhanced by immune manipulation, however, the biological mechanism responsible for these immune responses remains largely unexplained. Conventional immunology researchers have extensively studied specific interactions between immune and cancer cells, and additional investigations have identified co-factors that may enhance the effectiveness of such interactions. As the molecular understanding of individual interactions increases, it is becoming apparent that no single mechanism can explain the phenomenon of tumor rejection. The contribution of several components of the innate and adaptive immune response is likely to be required for successful tumor rejection. These components may be variably recruited and activated by molecules with immune modulatory properties being produced by tumor and bystander cells within the tumor micro-environment. Such complexity can only be appreciated and solved by high-throughput tools capable of providing a global view of biological processes as they occur. This review will present selected examples of how high-throughput gene expression profiling may contribute to the understanding of anticancer immune responses. As reviews on technological aspects of the genomic analysis of cancer are already available, this review will provide a speculative discussion about their potential usefulness.

Animals↗

PubMed2004

A global approach to tumor immunology.

Biological and clinical advances in the understanding of tumor immunology suggest that immune responsiveness of human tumors is a complex biological phenomenon that could be best studied by a real-time comparison of tumor/host interactions in the tumor microenvironment through a high-throughput discovery-driven approach. This conclusion is derived from our recognition that too many hypotheses or, in other words, no solid single hypothesis exist, based on experimental results, to further drive experimentation in human subjects. Functional genomic studies entertained during the last few years consolidated the belief that in humans the interactions between tumor and immune cells are too complex to be approached exclusively with a hypothesis driven method. We believe that immune cells suit cancer cells in a Yin and Yang balance by opposing and yet mutually depending on each other. Indeed, immune infiltration in tumors may play a dual role modulating in different circumstances cancer cell growth or destruction through a physiological modulation of inflammation. It is reasonable to question what induces inflammation at the tumor site. We hypothesize that inflammation is primarily driven by the phenotype of tumor cells that can modulate their microenvironment through cell-to-cell interactions or the secretion of soluble factors. Thus, in analogy the observation of immune cells within tumors parallels the presence of paramedics, police and firemen at the scene of an accident, which is reactive to and not causative of the occurrence. In this review we will explore this hypothesis by reporting and summarizing most of our recent work in the frame of available literature on the subject.

Adjuvants, Immunologic↗

PubMed2003

Polymorphism in clinical immunology - From HLA typing to immunogenetic profiling.

The pathology of humans, in contrast to that of inbred laboratory animals faces the challenge of diversity addressed in genetic terms as polymorphism. Thus, unsurprisingly, treatment modalities that successfully can be applied to carefully-selected pre-clinical models only sporadically succeed in the clinical arena. Indeed, pre-fabricated experimental models purposefully avoid the basic essence of human pathology: the uncontrollable complexity of disease heterogeneity and the intrinsic diversity of human beings. Far from pontificating on this obvious point, this review presents emerging evidence that the study of complex system such as the cytokine network is further complicated by inter-individual differences dictated by increasingly recognized polymorphisms. Polymorphism appears widespread among genes of the immune system possibly resulting from an evolutionary adaptation of the organism facing an ever evolving environment. We will refer to this high variability of immune-related genes as immune polymorphism. In this review we will briefly highlight the possible clinical relevance of immune polymorphism and suggest a change in the approach to the study of human pathology, from the targeted study of individual systems to a broader view of the organism as a whole through immunogenetic profiling.

Journal Article↗

PubMed2003

A strategy for detection of known and unknown SNP using a minimum number of oligonucleotides applicable in the clinical settings.

Detection of unknown single nucleotide polymorphism (SNP) relies on large scale sequencing expeditions of genomic fragments or complex high-throughput chip technology. We describe a simplified strategy for fluorimetric detection of known and unknown SNP by proportional hybridization to oligonucleotide arrays based on optimization of the established principle of signal loss or gain that requires a drastically reduced number of matched or mismatched probes. The array consists of two sets of 18-mer oligonucleotide probes. One set includes overlapping oligos with 4-nucleotide tiling representing an arbitrarily selected "consensus" sequence (consensus-oligos), the other includes oligos specific for known SNP within the same genomic region (variant-oligos). Fluorescence-labeled DNA amplified from a homozygous source identical to the consensus represents the reference target and is co-hybridized with a differentially-labeled test sample. Lack of hybridization of the test sample to consensus- with simultaneous hybridization to variant-oligos designates a known allele. Lack of hybridization to consensus- and variant-oligos indicates a new allele. Detection of unknown variants in heterozygous samples depends upon fluorimetric analysis of signal intensity based on the principle that homozygous samples generate twice the amount of signal. This method can identify unknown SNP in heterozygous conditions with a sensitivity of 82% and specificity of 90%. This strategy should dramatically increase the efficiency of SNP detection throughout the human genome and will decrease the cost and complexity of applying genomic wide analysis in the context of clinical trials.

Journal Article↗

PubMed2003

Active-specific immunization against melanoma: is the problem at the receiving end?

The recent progress in tumor immunology is a striking example of the successful application of modern biotechnology to understand the complex phenomenon of immune-mediated cancer rejection. Tumor antigens were identified and successfully utilized in active immunization trials to induce tumor antigen-specific T cells. This achievement has left, however, clinicians and researchers perplexed by the paradoxical observation that immunization-induced T cells can recognize tumor cells in standard assays but cannot induce tumor regression. A closer look at T cell physiology and tumor biology suggests that this observation is not so surprising. Here, we argue that successful immunization is one of several steps required for tumor clearance while more needs to be understood about how T cells localize and are effective within a tumor microenvironment impervious to the execution of their effector function.

Antigens, Neoplasm↗

PubMed2003

The dual role of IL-10.

Classification of cytokines as pro-versus anti-inflammatory might not apply to the pleiotropic effects of interleukin-10 (IL-10). Several reports suggest that IL-10 enhances the function of natural killer cells, which leads, through pathogen destruction, to increased antigen availability. In addition, by inhibiting the maturation of antigen-presenting cells (APCs), IL-10 preserves their ability for antigen uptake while simultaneously hampering their migration to draining lymph nodes. This review suggests that this "antigen-loading" phase might constitute an important component of the innate immune reaction to a pathogen. Additional proinflammatory stimuli might subsequently lead to maturation of "loaded" APCs that could migrate to draining lymph nodes or recruit and activate adaptive immune effectors locally.

Animals↗

PubMed2003

Tumors as elusive targets of T-cell-based active immunotherapy.

The understanding of tumor-host interactions remains elusive despite significant progress in the identification of tumor antigens (TAs) recognized by autologous T cells. In particular, most human tumors do not regress and continue to grow in spite of spontaneous or immunization-induced immune responses demonstrated in circulating lymphocytes. Indeed, systemic immune responses might insufficiently address the complexity of tumor-host interactions because of factors, such as (1) the lack of productive T-cell receptor (TCR) engagement with epitope owing to qualitative and/or quantitative defects in the generation and maintenance of the immune response, (2) insufficient costimulation provided by the host, (3) the lack of localization of the immune response in target tissues and (4) the complexity of tumor-host interactions within the tumor microenvironment caused by temporal changes in tumor phenotypes and an array of immune mediators expressed in the tumor microenvironment. Here, we will review current knowledge of the different 'levels' of immune response that might be necessary for immunotherapy to be effective in the treatment of cancer. Furthermore, we will discuss the information still required in order to understand the mechanism(s) governing tumor rejection by the immune system in response to TA-specific immunization.

Animals↗

PubMed2002

Redirecting migration of T cells to chemokine secreted from tumors by genetic modification with CXCR2.

T-cell-based immunotherapies provide a promising means of cancer treatment although durable antitumor responses are infrequent. A potential reason for these shortcomings may lie in the observed lack of trafficking of specific T cells to tumor. Our increasing knowledge of the process of trafficking involving adhesion molecules and chemokines affords us the opportunity to intervene and correct deficiencies in this process. Chemokines can be expressed by a range of tumors and may serve as suitable targets for directing specific T cells toward tumor. We initially sought to identify which chemokines were produced by a range of human tumor cell lines, and which chemokines and chemokine receptors were expressed by cultured T cells. We identified two chemokines: Growth-Regulated Oncogene-alpha (Gro-alpha; CXCL1) and Regulated on Activation Normal T Cell-Expressed and Secreted (RANTES; CCL5), to be secreted by several human tumor cell lines. Expression was also detected in fine-needle aspirates of melanoma from patients. In addition, we determined the expression of several chemokine receptors on cultured human T cells including CCR1, CCR2, CCR4, CCR5, CXCR3, and CXCR4. Cultured, activated human T cells expressed the chemokines lymphotactin (XCL1), RANTES, macrophage inflammatory protein-1 alpha (MIP-1 alpha; CCL3) and MIP-1 beta (CCL4), but no appreciable Gro-alpha. In a strategy to direct T cells toward chemokines expressed by tumors we chose Gro-alpha as the target chemokine because it was produced by tumor and not by T cells themselves. However, T cells did not express the receptor for Gro-alpha, CXCR2, and therefore, T cells were transduced with a retroviral vector encoding CXCR2. Calcium ion mobilization, an important first step in chemokine receptor signaling, was subsequently demonstrated in transduced T cells in response to Gro-alpha. In addition, Gro-alpha was chemotactic for T cells expressing CXCR2 in vitro toward both recombinant protein and tumor-derived chemokine. Interestingly we demonstrate, for the first time, that Gro-alpha was able to induce interferon-gamma (IFN-gamma) secretion from transduced T cells, thereby extending our knowledge of other potential functions of CXCR2. This study demonstrates the feasibility of redirecting the migration properties of T cells toward chemokines secreted by tumors.

Calcium↗

PubMed2002

Prospective molecular profiling of melanoma metastases suggests classifiers of immune responsiveness.

We amplified RNAs from 63 fine needle aspiration (FNA) samples from 37 s.c. melanoma metastases from 25 patients undergoing immunotherapy for hybridization to a 6108-gene human cDNA chip. By prospectively following the history of the lesions, we could correlate transcript patterns with clinical outcome. Cluster analysis revealed a tight relationship among autologous synchronously sampled tumors compared with unrelated lesions (average Pearson's r = 0.83 and 0.7, respectively, P < 0.0003). As reported previously, two subgroups of metastatic melanoma lesions were identified that, however, had no predictive correlation with clinical outcome. Ranking of gene expression data from pretreatment samples identified approximately 30 genes predictive of clinical response (P < 0.001). Analysis of their annotations denoted that approximately half of them were related to T-cell regulation, suggesting that immune responsiveness might be predetermined by a tumor microenvironment conducive to immune recognition.

Adult↗

PubMed2002

Gene-expression profiling of the response of peripheral blood mononuclear cells and melanoma metastases to systemic IL-2 administration.

BACKGROUND: Interleukin-2 (IL-2) has direct pluripotent effects on cells with immune and inflammatory function. Which of these effects has a critical role in mediating tumor regression remains enigmatic. In this study, we compared early changes in transcriptional profiles of circulating mononuclear cells with those occurring within the microenvironment of melanoma metastases following systemic IL-2 administration. RESULTS: The results suggest that the immediate effects of IL-2 administration on the tumor microenvironment is transcriptional activation of genes predominantly associated with monocyte cell function; minimal effects were noted on migration, activation and proliferation of T cells. However, production of chemokines and markers of adhesion and migration within few hours of IL-2 administration may be responsible for a secondary recruitment of immune cells to the tumor site later. CONCLUSIONS: Our results suggest that IL-2 induces inflammation at tumor sites with three predominant secondary effects: activation of antigen-presenting monocytes; massive production of chemoattractants that may recruit other immune cells to the tumor (including MIG and PARC, which are specific for T cells); and activation of cytolytic mechanisms in monocytes (calgranulin, grancalcin) and NK cells (NKG5, NK4).

Antineoplastic Agents↗

PubMed2002

Functional heterogeneity of vaccine-induced CD8(+) T cells.

The functional status of circulating vaccine-induced, tumor-specific T cells has been questioned to explain their paradoxical inability to inhibit tumor growth. We enumerated with HLA-A*0201/peptide tetramers (tHLA) vaccine-elicited CD8(+) T cell precursor frequency among PBMC in 13 patients with melanoma undergoing vaccination with the HLA-A*0201-associated gp100:209-217(210 M) epitope. T cell precursor frequency increased from undetectable to 12,400 +/- 3,600 x 10(6) CD8(+) T cells after vaccination and appeared heterogeneous according to previously described functional subtypes: CD45RA(+)CD27(+) (14 +/- 2.6% of tHLA-staining T cells), naive; CD45RA(-)CD27(+) (14 +/- 3.2%), memory; CD45RA(+)CD27(-) (43 +/- 6%), effector; and CD45RA(-)CD27(-) (30 +/- 4.1%), memory/effector. The majority of tHLA(+)CD8(+) T cells displayed an effector, CD27(-) phenotype (73%). However, few expressed perforin (17%). Epitope-specific in vitro stimulation (IVS) followed by 10-day expansion in IL-2 reversed this phenotype by increasing the number of perforin(+) (84 +/- 3.6%; by paired t test, p < 0.001) and CD27(+) (from 28 to 67%; by paired t test, p = 0.01) tHLA(+) T cells. This conversion probably represented a change in the functional status of tHLA(+) T cells rather than a preferential expansion of a CD27(+) (naive and/or memory) PBMC, because it was reproduced after IVS of a T cell clone bearing a classic effector phenotype (CD45RA(+)CD27(-)). These findings suggest that circulating vaccine-elicited T cells are not as functionally active as inferred by characterization of IVS-induced CTL. In addition, CD45RA/CD27 expression may be more informative about the status of activation of circulating T cells than their status of differentiation.

CD8-Positive T-Lymphocytes↗

PubMed2002

Interferon-gamma reduces melanosomal antigen expression and recognition of melanoma cells by cytotoxic T cells.

In malignant melanoma, tumor-infiltrating lymphocytes are frequently reactive with melanosomal antigens. Achieving complete remissions by peptide therapy is frequently hampered by metastases evading immune recognition. The tumor microenvironment seems to favor reduced expression of target antigens by melanoma cells. Among candidate factors, interferon-gamma (IFN-gamma) (10(2) to 10(3) U/ml) suppressed expression of antigens MART-1, TRP-1, and gp100 by M14 melanoma cells as shown by immunohistology and fluorescence-activated cell sorting analysis, reducing MART-1 expression by >65%. Northern blot analysis revealed that reduced expression was regulated at the transcriptional level, demonstrating a 79% reduction in MART-1 transcript abundance after 32 hours of IFN-gamma treatment. To evaluate consequences of IFN-gamma exposure for immune recognition, MART-1-responsive T cells were reacted with pretreated HLA-matched melanoma cells. Cytotoxicity was reduced up to 78% by IFN-gamma pretreatment, and was restored by addition of MART-1 peptide AAGIGILTV for 2 hours. Examination of melanoma lesions by quantitative reverse transcriptase-polymerase chain reaction revealed up to 188-fold more abundant IFN-gamma transcripts when compared to control skin. Laser capture microdissection and immunohistology localized most IFN-gamma-producing T cells to the tumor stroma. Reduced MART-1 expression was frequently observed in adjacent tumor cells. Consequently, IFN-gamma may enhance inflammatory responses yet hamper effective recognition of melanoma cells.

Antigens, Neoplasm↗

PubMed2002

The role of quantitative PCR for the immune monitoring of cancer patients.

Human tumour immunology is at a standstill whereas implemented cancer vaccines have shown effectiveness in inducing immune responses detectable in circulating lymphocytes. In most circumstances, however, such immune responses are not sufficient to induce cancer regression. This paradoxical observation could be explained in several ways depending upon the immunological endpoint used for immune monitoring. For instance, analysis of immune responses in circulating lymphocytes that address the presence of T cells bearing T-cell receptors specific for the epitope used for vaccination, can accurately enumerate the number of T cells elicited by the vaccines but does not yield information about their functional status. Other monitoring strategies may yield general information about the reactivity of various T cells in response to a relevant stimulus and, therefore, may provide information more relevant to the purpose of the immunisation. Furthermore, the material used to monitor immune responses may, in itself, determine the significance of the findings obtained. In the assessment of the therapeutic efficacy of specific cancer treatment, analysis of immune responses in circulating lymphocytes (systemic response) may not be as relevant as the analysis of the same effector populations within the tumour microenvironment (peripheral response). This review will describe a novel approach that allows extreme flexibility in the analysis of systemic and peripheral responses by accurately measuring the level of expression of relevant genes using quantitative real-time reverse transcriptase polymerase chain reaction.

Animals↗

PubMed2002

Transcriptional analysis of tumor-specific T-cell responses in cancer patients.

Over the last decade, tumor immunology in general and tumor immunotherapy in particular have made important progress. Thanks to the discovery of tumor-associated antigens (TAA), and the consequent development of active-specific immunization protocols, TAA-specific T-cell responses can now be induced reproducibly in cancer patients. However, clinical responses directly ascribable to TAA-specific T cells occur only occasionally. It is not clear why TAA-specific T cells do not eliminate tumor cells in vivo. This paradoxical coexistence of antigen-bearing tumor cells and antigen-specific T cells constitutes a critical point of current investigation. In recent years, protein-ligand interaction-based methods aimed at the identification and characterization of T cells using antibodies (cell surface phenotyping, intracellular and secreted cytokine detection), or HLA-peptide multimers, have significantly improved the analysis of TAA-specific T cells. These methods, however, seem to have reached the limit of their usefulness. Transcriptional analysis may add sensitivity and resolution and may provide global pictures of the multifactorial requirements for an efficient immune response against tumors. In this review, we describe the use of molecular genetic methods, such as real time qRT-PCR, cDNA microarrays, and TCR repertoire analysis. In addition, we describe techniques for high-fidelity messenger RNA amplification that allow high-throughput analysis of samples obtained from minimal sources, such as HLA/peptide tetramer sorted antigen-specific T cells, laser capture dissection, or fine needle aspirates. Recent work discussed in this review summarizes the complementarity of transcriptional analysis as an essential tool that, in addition to conventional methods, may deepen and broaden the characterization of tumor-specific T cells.

Gene Expression Profiling↗

PubMedDate not supplied

Characterization of CD8(-) HLA class I/epitope tetrameric complexes binding T cells.

Antigen-specific CD8-expressing T cells play a crucial role in the host's defense against viral disease and malignancy. Epitope-specific CD8(+)T cell responses to malignant and viral disease can be accurately measured using tetramers (tHLA) of HLA class I molecules loaded with antigenic peptides. In addition, tHLA have been used to evaluate immune responses to antigen-specific immunization. tHLA bind specifically to complementary T-cell receptor (TCR) structures on the surface of T cells expressing the CD8 coreceptor. Surprisingly, however, CD8(-) cells binding tHLA are often observed. This study uses four-color flow cytometry to show that HLA-A*0201-tHLA-stained CD8(-) cells can be divided into two subsets: 87% represent B-lymphocytes (CD19(+), CD45RA(+), HLA-DR(+), and CD20(+)), and 13% represent T-helper cells (CD3(+), CD4(+), CD45RA(+), and CD27(+)). This phenomenon is not HLA-restricted because it could be observed even in peripheral blood mononuclear cells (PBMC) from a non HLA-A*0201-expressing healthy donor. In addition, no T-cell receptor was detected on the B-lymphocytes. Retrospective enumeration of vaccine-induced CD8(-) tHLA cells in 243 PBMC samples from 36 patients with melanoma undergoing peptide vaccination revealed that tHLA staining is not dependent on immunization status or the presence of CD8(+) tHLA(+) T cells. These findings, suggest that the nonspecific binding of tHLA to non-TCR-expressing T cells requires a careful interpretation of results and further steps in preparation of sample for tHLA-based sorting of epitope specific T cells.

Cancer Vaccines↗

PubMedDate not supplied

Workshop on cancer biometrics: identifying biomarkers and surrogates of cancer in patients: a meeting held at the Masur Auditorium, National Institutes of Health.

The current excitement about molecular targeted therapies has driven much of the recent dialog in cancer diagnosis and treatment. Particularly in the biologic therapy of cancer, identifiable antigenic T-cell targets restricted by MHC molecules and the related novel stress molecules such as MICA/B and Letal allow a degree of precision previously unknown in cancer therapy. We have previously held workshops on immunologic monitoring and angiogenesis monitoring. This workshop was designed to discuss the state of the art in identification of biomarkers and surrogates of tumor in patients with cancer, with particular emphasis on assays within the blood and tumor. We distinguish this from immunologic monitoring in the sense that it is primarily a measure of the tumor burden as opposed to the immune response to it. Recommendations for intensive investigation and targeted funding to enable such strategies were developed in seven areas: genomic analysis; detection of molecular markers in peripheral blood and lymph node by tumor capture and RT-PCR; serum, plasma, and tumor proteomics; immune polymorphisms; high content screening using flow and imaging cytometry; immunohistochemistry and tissue microarrays; and assessment of immune infiltrate and necrosis in tumors. Concrete recommendations for current application and enabling further development in cancer biometrics are summarized. This will allow a more informed, rapid, and accurate assessment of novel cancer therapies.

Alternative Splicing↗

PubMedDate not supplied

Tumor microenvironment: what have we learned studying the immune response in this puzzling battlefield?

Recent developments hallmark the progress in the understanding of tumor immunology and related therapeutic strategies. The administration of interleukin-2 (IL-2) to patients with cancer has shown that immune manipulation can mediate the regression of established cancers. The identification of the genes encoding cancer antigens and the development of means for effectively immunizing against these antigens has opened new avenues for the development of active immunization of patients with cancer. However, an efficient immune response against tumor comprises an intricate molecular network still poorly understood. Only when the code governing immune responsiveness of cancer will be deciphered, new therapeutic strategies could be designed to fit biologically defined mechanisms of immune rejection of cancer. In this review, we propose that the mechanisms regulating tumor rejection in response to vaccination will be more efficiently identified by following the evolution of treatment induced events within the tumor microenvironment taking advantage of recently developed technological tools. As a model, we will discuss the observed immune response to tumor antigen -specific immunization and its relationship with the systemic administration of IL-2.

Animals↗

PubMedDate not supplied

Cytokines and Immune Response in the Tumor Microenvironment.

SUMMARY: Over the last few decades a wealth of evidence has been gathered on the potential role that the immune system (IS) can play in the fight against cancer. Together with cell surface adhesion molecules, cytokines (CKs) mediate the activities of IS cells. Therefore, CK kinetics may represent a mirror of the immunologic phenomena occurring in the tumor microenvironment, where immune and malignant cells interact. Yet, CKs are currently used in a clinical setting to polarize the immune response against cancer. Despite the large amount of information available on IS physiology, little is known about the role of CKs in modulating the effectiveness of immunotherapy clinical trials aimed at the treatment of patients with cancer. This underscores our relative ignorance about the complex cascade of events that lead to tumor rejection. Here, we review the properties of some CKs believed to be particularly relevant to tumor immunology (i.e., interleukin [IL]-10, transforming growth factor-beta, interferon-gamma, IL-2, IL-4, and IL-12). We summarized the experience gained with these CKs in vitro, in animal models, and in human beings to illustrate the achievements, the controversies, and the challenges that characterize this fascinating field of oncology. In addition, we added a short section in which a broad view of CKs released in the tumor microenvironment is proposed to underline the variety of factors that contribute to the complexity of tumor-IS interactions.

Journal Article↗