evaluating-plasmonic-transport-in-current-carrying-silver-nanowires

Evaluating Plasmonic Transport in Current-carrying Silver Nanowires

Plasmonics is an emerging technology capable of simultaneously transporting a plasmonic signal and an electronic signal on the same information ...

In previous studies CD8+ T cells specific for melanocyte antigens have been frequently found in melanoma patients responding to interleukin-2 (IL-2)-based therapies. In our study we analyzed the suitability of using circulating T cells from melanoma patients with clinical response after IL-2-based therapy to identify novel T-cell epitopes from defined tumor antigens. Using unstimulated peripheral blood mononuclear cells and the interferon-gamma (IFN-gamma) ELISPOT assay, we studied CD8(+) T-cell responses against 5 peptides from the tumor antigen tyrosinase (Tyr) selected by epitope prediction using an HLA-A1-binding computer algorithm. T cells specifically secreting IFN-gamma in response to 3 of these 5 peptides, namely, Tyr (454-463), Tyr (146-156) and Tyr (243-251), could be detected in 4 of 4 HLA-A1-positive patients with clinical response. In contrast, no T-cell responses against these peptides were seen in 6 HLA-A1-positive melanoma patients with progressive disease and in 8 healthy subjects. We could generate specific cytotoxic T lymphocytes (CTL) against Tyr (454-463) using peptide-pulsed autologous dendritic cells as antigen-presenting cells. The induced CTLs efficiently killed melanoma cells that express HLA-A1 and tyrosinase. The peptides Tyr (146-156) and Tyr (243-251) had recently been identified as CTL epitopes by other groups. Further ex vivo characterization of the T cells reactive against the novel epitope Tyr (454-463) in 1 patient by multicolor flow cytometry showed specific CD3+/CD8+/IFN-gamma+ T cells with frequencies of up to 0.41% of the CD3+/CD8+ T-cell population. Most of this T-cell population also expressed granzyme B. Our data confirm that in patients with tumor regressions induced by immunotherapy or chemoimmunotherapy circulating T cells reactive with tyrosinase epitopes can frequently be detected. Peripheral blood T cells from such patients are a valuable source for screening peptides selected by epitope prediction This strategy facilitates the rapid identification of immunogenic T-cell epitopes that are probable targets of immune-mediated tumor rejection.

Identification of known and novel immunogenic T-cell epitopes from tumor antigens recognized by peripheral blood T cells from patients responding to IL-2-based treatment.

The proteasome system represents a major source of HLA class I- presented peptides exposed to CTLs. Stimulation of cells with IFN-gamma instantly induces the expression of the proteasome immunosubunits as well as the proteasome activator PA28. These proteins have been shown to optimize class I antigen presentation of several viral CTL epitopes; however, their contribution to tumor antigen processing remains poorly understood. Here, we analyzed the generation of an HLA-A*0201-presented epitope derived from the melanoma antigen tyrosinase-related protein 2 (TRP2). Melanoma cells that lacked the IFN-gamma-inducible proteasome activator PA28 and immunoproteasomes did not display the TRP2(360-368) epitope to specific CTLs. Our experiments demonstrate that epitope presentation correlated with the presence of PA28 and could be completely rescued by restoration of PA28 expression. In vitro digestion of TRP2 polypeptides with 20S proteasomes confirmed that PA28 is essential for epitope liberation. Thus, our experiments indicate that PA28 provides the threshold for CTL recognition of this epitope. Importantly, processing of a second TRP2-derived epitope, TRP2(288-296), was diminished in IFN-gamma-treated cells, even in the absence of immunoproteasome up-regulation. Therefore, the reported IFN-gamma-induced self-regulation of epitopes may not necessarily be a consequence of immunoproteasomes as suggested previously.

Expression of the proteasome activator PA28 rescues the presentation of a cytotoxic T lymphocyte epitope on melanoma cells.

Alterations in the surface expression of HLA class I molecules have been described as a strategy of tumors to evade recognition by cytotoxic T cells. We detected complete loss of HLA class I antigen presentation for 2 tumor cell lines from 1 melanoma patient, the first originated from a regional lymph node lesion diagnosed simultaneously with the primary tumor and the second established 8 months later from a metastatic pleural effusion sample. Antigen presentation was not inducible with IFN-gamma but could be restored after transfection of tumor cells with b2m cDNA, indicating a defect in b2m expression. Analysis of the nature of this defect revealed that it originated from at least 2 mutational events affecting both copies of the b2m gene: a microdeletion of 498 bp in one b2m gene, including its entire exon 1, and a macrodeletion involving the entire copy of the second b2m gene. Microsatellite analysis pointed to the macrodeletion by demonstrating LOH for several specific markers on the long arm (q) of chromosome 15. Structural imbalance of 15q was verified by FISH. FISH studies also indicated the coexistence of a structurally abnormal variant of chromosome 15q with 2 apparently entire chromosomes 15q harboring the homozygous b2m microdeletion. Block of b2m expression in tumor cells builds a barrier to immunotherapy of cancer patients, and its early incidence should be of major consideration in the development and design of immunotherapeutic strategies.

Complete loss of HLA class I antigen expression on melanoma cells: a result of successive mutational events.

Tyrosinase-related protein-2 (TRP-2) is a known target antigen of spontaneous cytotoxic T cell responses in melanoma patients. Its frequent expression in metastatic tumors suggests that it might be an ideal candidate antigen for T cell-based immunotherapy. To provide knowledge about TRP-2-derived T cell epitopes useful for immunotherapy we applied a "reverse immunology strategy" based on repeated in vitro peptide stimulation of peripheral blood lymphocytes (PBL) from normal donors with predicted HLA-A*01 ligands. This led to the identification of TRP-2(181-190) as the first HLA-A*01-presented TRP-2-derived epitope. T-cell lines specific for peptide TRP-2(181-190) could be established from PBL of 50% of the normal HLA-A*01(+) donors tested. Such T cells responded specifically to autologous dendritic cells transduced virally with TRP-2, as well as to HLA-A*01(+), TRP-2(+) melanoma cells, although tumor cells had to be pretreated with IFN-gamma to become susceptible to T cell recognition. Interestingly, short-term in vitro peptide stimulation of PBL from HLA-A*01(+) melanoma patients showed the presence of TRP-2(181-190)-reactive CD8(+) T cells in some donors, suggesting their in vivo sensitization. Because TRP-2(181-190) overlaps with the known HLA-A*0201-presented epitope TRP-2(180-188), an 11mer peptide encompassing both epitopes might be of specific value for vaccination of a broad population of melanoma patients.

Melanoma patients respond to a new HLA-A*01-presented antigenic ligand derived from a multi-epitope region of melanoma antigen TRP-2.

The frequently expressed differentiation antigen tyrosinase-related protein-2 (TRP-2) has repeatedly been described as a target of spontaneous cytotoxic T-cell responses in melanoma patients, suggesting that it might be an ideal candidate antigen for T cell-based immunotherapy. As a prerequisite for immunization, T-cell epitopes have to be identified. Whereas a number of HLA class I-presented TRP-2-derived epitopes are known, information about HLA class II-presented antigenic ligands recognized by CD4+ T helper (Th) cells is limited.

Detection of spontaneous CD4+ T-cell responses in melanoma patients against a tyrosinase-related protein-2-derived epitope identified in HLA-DRB1*0301 transgenic mice.

Antigen-specific cancer immunotherapy directed toward tumor-nourishing angiogenic blood vessels holds the promise of high efficacy, low toxicity, and ease of application. To evaluate whether the human angiogenic kinase insert domain-containing receptor (KDR) can serve as a target for cellular immunotherapy, 19 peptide sequences with HLA-A*0201 motifs were selected by computer-based algorithms. Five peptides (KDR82-90, KDR288-297, KDR766-774, KDR1093-1101, KDR1035-1044) stimulated specific cytotoxic T lymphocytes (CTLs) from peripheral-blood mononuclear cells (PBMCs) of 3 HLA-A*0201 donors. The decapeptide KDR288-297 was efficient in sensitizing target cells for recognition by a CTL clone at a concentration of 10 nM. More important, KDR288-297-specific CTLs lysed target cells transfected with HLA-A2/KDR cDNAs and a range of HLA-matched KDR+ angiogenic endothelial cells (aECs) and also recognized CD34+ endothelial progenitor cells. The specificity of CTLs was further confirmed by tetramer assay and cold-target inhibition assay. In addition, ex vivo exposure of aECs to the inflammatory cytokines enhanced CTL reactivity, which is in keeping with up-regulated KDR and HLA class 1 expression. In Matrigel assays, recognition of aECs by specific CTLs triggered an antivascular effect. These findings provide the first proof of the antigenic property of KDR protein and may be useful for devising new immunotherapeutic approaches to human cancers.

The kinase insert domain-containing receptor is an angiogenesis-associated antigen recognized by human cytotoxic T lymphocytes.

Cholesterol-binding cytolysins constitute an evolutionarily conserved family of pore-forming proteins expressed by different gram-positive pathogens. Listeriolysin O, one well-characterized member of the cytolysin family, is also known to induce specific CD4 and CD8 T cell responses upon infection of mice with Listeria monocytogenes. Here we describe an HLA-DRB1*0301-restricted listeriolysin O-derived T cell epitope that is conserved among several members of the cytolysin family. An HLA-DRB1*0301-restricted CD4+ T cell line, established from spleen lymphocytes of L. monocytogenes-infected HLA-DRB1*0301-transgenic mice, cross-reacted with a homologous peptide from perfringolysin O, a cytolysin expressed by Clostridium perfringens. Ex vivo analysis of infected mice revealed an even broader cross-reaction of T cells with homologous peptides derived from perfringolysin O, streptolysin O, and cereolysin O. Interestingly, a cross-reactive memory CD4+ T cell response against the homologous peptides derived from listeriolysin O and perfringolysin O could also be detected in the blood from healthy HLA-DRB1*0301+ human donors. Remarkably, this response was even present in donors who did not exhibit a memory T cell reactivity against a second, non-conserved HLA-DRB1*0301-restricted LLO-derived CD4 T cell epitope, suggesting that cytolysin-producing bacteria other than L. monocytogenes can stimulate a cross-reactive cytolysin-specific immunity.

Identification of a cross-reactive HLA-DRB1*0301-restricted CD4 T cell response directed against cholesterol-binding cytolysins from two different pathogens.

The clonotypic T-cell receptor (TCR) is a potential target antigen for specific immunotherapy of cutaneous T-cell lymphoma (CTCL). We identified T-cell epitopes from the rearranged TCR beta chain of the malignant T-cell population by the "reverse immunology" approach. Peptide-specific T-cell lines were generated against predicted epitopes and tested for the recognition of tumor cells and cells transfected with the full-length DNA coding for TCRV beta chain. Two peptides derived from the clonotypic TCRVbeta of a HLA-A2 positive patient could induce peptide-specific T cells from peripheral blood mononuclear cells of healthy donors and the patient as assessed by IFN-gamma ELISpot assay. Furthermore, the reactive CTLs efficiently recognized autologous Sézary tumor cells, as well as HLA-A2 positive 293 cells transfected with recombinant plasmid expressing the corresponding TCRVbeta29 protein. Similar results were obtained in a HLA-A3+ patient for TCRVbeta7-Jbeta2.7. In conclusion, our experiments show that the TCR beta chain harbors epitopes suitable as targets for specific vaccination which might be a promising approach for the specific immunotherapy of cutaneous T-cell lymphoma patients.

Identification of HLA class I dependent immunogenic peptides from clonotypic TCRbeta expressed in cutaneous T-cell lymphoma.

Given the multiple escape mechanisms of tumor cells, immunotherapy targeting tumor-dependent stroma may be an effective cancer treatment strategy. Animal models indicate that inducing immunity to tumor endothelia engenders potent antitumor effects without significant pathology. Recently, the first human tumor endothelial antigen vascular endothelial growth factor receptor-2 (VEGFR-2) recognized by HLA class I-restricted CD8(+) T cells has been characterized. In this study, we sought to investigate specific recognition of this molecule by human CD4(+) T cells.

Human CD4+ T lymphocytes recognize a vascular endothelial growth factor receptor-2-derived epitope in association with HLA-DR.

As tumor antigen-specific CD4+ T cells can mediate strong therapeutic anti-tumor responses in melanoma patients we set out to establish a comprehensive screening strategy for the identification of tumor-specific CD4+ T cell epitopes suitable for detection, isolation and expansion of tumor-reactive T cells from patients.

Screening of human tumor antigens for CD4 T cell epitopes by combination of HLA-transgenic mice, recombinant adenovirus and antigen peptide libraries.

Als Tumor Antigen-spezifische CD4 + T-Zellen starke therapeutische Anti-Tumor-Antworten bei Melanompatienten vermitteln k&ouml;nnen dargelegt wir, f&uuml;r die Identifizierung von Tumor-spezifischer CD4 + T Zelle Epitopes geeignet f&uuml;r Erkennung, Isolierung und Ausbau der Tumor-reaktive T-Zellen von Patienten eine umfassende &Uuml;berpr&uuml;fung festgelegt.

Screening von menschlichen Tumor-Antigene f&uuml;r CD4 T-Zelle Epitopes durch Kombination von HLA-transgene M&auml;use, rekombinante Adenoviren und Antigen Peptid Bibliotheken.

Using dual-plane leakage radiation microscopy, we investigate plasmon propagation in individual penta-twinned crystalline silver nanowires. By measuring the wavevector content of the light emitted in the substrate, we unambiguously determine the effective index and the losses of the mode propagating in these structures. The experimental results, in particular, the unexpectedly low effective index, reveal the direct influence of the nanowire crystallinity and pentagonal structure on the observed plasmon modes. By analogy with molecular orbitals of similar symmetry, the plasmon modes are also determined numerically in good agreement with the observed values. We further investigate the effect of wire geometry (length, diameter) on the effective index and propagation loss. Our results show that, beyond dissipation concerns, the morphological and structural control obtained in crystalline colloidal plasmonic nanostructures can be exploited to finely tune their optical properties.

Imaging symmetry-selected corner plasmon modes in penta-twinned crystalline Ag nanowires.

Amplifying local electromagnetic fields by engineering optical interactions between individual constituents of an optical antenna is considered fundamental for efficient nonlinear wavelength conversion in nanometer-scale devices. In contrast to this general statement we show that high field enhancement does not necessarily lead to an optimized nonlinear activity. In particular, we demonstrate that second-harmonic responses generated at strongly interacting optical gap antennas can be significantly suppressed. Numerical simulations are confirming silencing of second-harmonic in these coupled systems despite the existence of local field amplification. We then propose a simple approach to restore and amplify the second-harmonic signal by changing the manner in which electrically-connected optical antennas are interacting in the charge-transfer plasmon regime. Our observations provide critical design rules for realizing optimal structures that are essential for a broad variety of nonlinear surface-enhanced characterizations and for realizing the next generation of electrically-driven optical antennas.

Article	Year
Identification of known and novel immunogenic T-cell epitopes from tumor antigens recognized by peripheral blood T cells from patients responding to IL-2-based treatment. International journal of cancer. Journal international du cancer\| PubMed ID: 11920592	2002
Expression of the proteasome activator PA28 rescues the presentation of a cytotoxic T lymphocyte epitope on melanoma cells. Cancer research\| PubMed ID: 12019167	2002
Complete loss of HLA class I antigen expression on melanoma cells: a result of successive mutational events. International journal of cancer. Journal international du cancer\| PubMed ID: 12516095	2003
Melanoma patients respond to a new HLA-A*01-presented antigenic ligand derived from a multi-epitope region of melanoma antigen TRP-2. International journal of cancer. Journal international du cancer\| PubMed ID: 15856458	2005
Detection of spontaneous CD4+ T-cell responses in melanoma patients against a tyrosinase-related protein-2-derived epitope identified in HLA-DRB1*0301 transgenic mice. Clinical cancer research : an official journal of the American Association for Cancer Research\| PubMed ID: 16033842	2005
The kinase insert domain-containing receptor is an angiogenesis-associated antigen recognized by human cytotoxic T lymphocytes. Blood\| PubMed ID: 16234362	2006
Identification of a cross-reactive HLA-DRB1*0301-restricted CD4 T cell response directed against cholesterol-binding cytolysins from two different pathogens. Microbes and infection / Institut Pasteur\| PubMed ID: 16798043	2006
Identification of HLA class I dependent immunogenic peptides from clonotypic TCRbeta expressed in cutaneous T-cell lymphoma. International journal of cancer. Journal international du cancer\| PubMed ID: 16858680	2006
Human CD4+ T lymphocytes recognize a vascular endothelial growth factor receptor-2-derived epitope in association with HLA-DR. Clinical cancer research : an official journal of the American Association for Cancer Research\| PubMed ID: 18594014	2008
Screening of human tumor antigens for CD4 T cell epitopes by combination of HLA-transgenic mice, recombinant adenovirus and antigen peptide libraries. PloS one\| PubMed ID: 21152437	2010
Imaging symmetry-selected corner plasmon modes in penta-twinned crystalline Ag nanowires. ACS nano\| PubMed ID: 21682318	2011
Silencing and enhancement of second-harmonic generation in optical gap antennas. Optics express\| PubMed ID: 22565675	2012

Mingxia Song

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