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Hans-Georg Rammensee

Publications and source records attributed to Hans-Georg Rammensee.

At least 19 recordsLinked to original sources
PubMed2026

A targetable dependency on nonsense-mediated decay for cellular homeostasis and immune control in small cell lung cancer.

Small cell lung cancer (SCLC) is one of the most aggressive malignancies, characterized by rapid metastatic dissemination and poor overall survival. Despite harboring excessive alterations, expectedly resulting in immunogenic neoantigens, patients with SCLC remain largely refractory to immunotherapy. We found abundant frameshift mutations in SCLC, regarded as highly immunogenic, counterbalanced by a hyperactive nonsense-mediated decay (NMD) pathway, responsible for frameshift-mRNA degradation. NMD activity correlated with tumor mutational burden (TMB) across cancers, suggesting that SCLC and other TMBhigh cancers may depend on NMD to limit the accumulation of mutation-derived byproducts in order to maintain cellular homeostasis and evade immune recognition. In TMBhigh SCLC models, inhibition of NMD impaired cell proliferation and induced ER stress-dependent apoptosis due to the accumulation of misfolded proteins. Genetic and pharmacological NMD inhibition in vivo effectively controlled TMBhigh tumor growth without overt toxicity. By integrating genome and transcriptome sequencing with MHC-I immunopeptidomics and functional in vitro and in vivo assays, we identified that NMD inhibition boosted neoantigen expression and presentation by tumor cells and increased T cell recognition, thus enhancing overall tumor immunogenicity and further improving immunotherapy efficacy in vivo. Our work shows that SCLC - as a TMBhigh cancer - relies on NMD for survival and immune escape, uncovering a novel TMB-dependent tractable vulnerability for this devastating disease.

Humans↗
PubMed2006

Identification of a highly immunogenic HLA-A*01-binding T cell epitope of WT1.

PURPOSE: The transcription factor Wilms tumor protein 1 (WT1) belongs to a new generation of tumor antigens, as it is essential for tumor cell proliferation and is highly expressed in various hematologic and solid malignancies. The aim of this study was to apply a modified reverse immunology strategy to identify immunogenic epitopes of WT1 which could be useful for immunotherapy. EXPERIMENTAL DESIGN: Potential HLA-A*01 epitopes predicted by a MHC binding algorithm were screened for recognition by peripheral blood mononuclear cells (PBMC) from patients with spontaneous T cell responses using intracellular cytokine cytometry. Epitope processing was shown by proteasomal cleavage. Epitope-specific T cells were generated from CD4+CD25+ regulatory T cell-depleted PBMC. RESULTS: One of five predicted HLA-A*01-binding candidate epitopes showed high immunogenicity as 5 of 14 patients with hematologic malignancies had WT1.317-327-reactive T cells ranging from 0.4% to 1.5% of CD3+CD8+ T cells. Proteasomal degradation assays indicated the cleavage of WT1.317-327. The depletion of regulatory T cells from PBMCs enabled the rapid expansion of WT1.317-327-specific CTL, whereas no CTL could be generated from unfractionated PBMC. WT1.317-327-specific CTL efficiently lysed an autologous WT1-expressing tumor cell line but not HLA-A*01-negative WT1-expressing tumor cells. Immunogenicity of the epitope across histologies was verified by the demonstration of spontaneous ex vivo WT1.317-327-specific T cell responses in two of six patients with HLA-A*01-positive melanoma or lung cancer. CONCLUSION: In this study, a modified reverse immunology strategy was employed to identify a first immunogenic HLA-A*01-restricted T cell epitope of the tumor antigen WT1, which is of considerable interest for use in vaccination trials.

Antigens, Neoplasm↗
PubMed2006

TLR2/TLR4-independent neutrophil activation and recruitment upon endocytosis of nucleosomes reveals a new pathway of innate immunity in systemic lupus erythematosus.

The nucleosome is a major autoantigen in systemic lupus erythematosus (SLE); it can be detected as a circulating complex in the serum, and nucleosomes have been suggested to play a key role in disease development. In the present study, we show for the first time that physiological concentrations of purified nucleosomes trigger innate immunity. The nucleosomes are endocytosed and induce the direct activation of human neutrophils (polymorphonuclear leukocytes (PMN)) as revealed by CD11b/CD66b up-regulation, IL-8 secretion, and increased phagocytic activity. IL-8 is a neutrophil chemoattractant detected in high concentrations in the sera of patients, and IL-8 secretion might thus result in enhanced inflammation, as observed in lupus patients, via an amplification loop. Nucleosomes act as free complexes requiring no immune complex formation and independently of the presence of unmethylated CpG DNA motifs. Both normal and lupus neutrophils are sensitive to nucleosome-induced activation, and activation is not due to endotoxin or high-mobility group box 1 contamination. In mice, i.p. injection of purified nucleosomes induces neutrophil activation and recruitment in a TLR2/TLR4-independent manner. Importantly, neutrophils have been suggested to link innate and adaptive immunity. Thus, nucleosomes trigger a previously unknown pathway of innate immunity, which may partially explain why peripheral tolerance is broken in SLE patients.

Animals↗
PubMed2006

Distorted relation between mRNA copy number and corresponding major histocompatibility complex ligand density on the cell surface.

The major histocompatibility complex (MHC) presents peptides derived from degraded cellular proteins to T-cells and is thus crucial for triggering specific immune responses against viral infections or cancer. Up to now, there has been no evidence for a correlation between levels of mRNA (the "transcriptome") and the density of MHC-peptide complexes (the "MHC ligandome") on cells. Because such dependences are of intrinsic importance for the detailed understanding of translation efficiency and protein turnover and thus for systems biology in general and for tumor immunotherapy in practical application, we quantitatively analyzed the levels of mRNA and corresponding MHC ligand densities in samples of renal cell carcinomas and their autologous normal kidney tissues. Relative quantification was carried out by gene chip analysis and by stable isotope peptide labeling, respectively. In comparing more than 270 pairs of gene expression and corresponding peptide presentation ratios, we demonstrate that there is no clear correlation (r = 0.32) between mRNA levels and corresponding MHC peptide levels in renal cell carcinoma. A significant number of peptides presented predominantly on tumor or normal tissue showed no or only minor changes in mRNA expression levels. In several cases, peptides could even be identified despite the virtual absence of the respective mRNA. Thus we conclude that a majority of epitopes from tumor-associated antigens will not be found in approaches based mainly on mRNA expression studies as mRNA expression reflects a distorted picture of the situation on the cell surface as visible for T-cells.

Amino Acid Sequence↗
PubMed2006

Unexpected abundance of HLA class II presented peptides in primary renal cell carcinomas.

PURPOSE: To elicit a long-lasting antitumor immune response, CD8+ and CD4+ T cells should be activated. We attempted to isolate HLA-DR-presented peptides directly from dissected solid tumors, in particular from renal cell carcinoma, to identify MHC class II ligands from tumor-associated antigens (TAA) for their use in peptide-based immunotherapy. EXPERIMENTAL DESIGN: Tumor specimens were analyzed by immunohistochemical staining for their HLA class II expression. HLA class II peptides were subsequently isolated and identified by mass spectrometry. Gene expression analysis was done to detect genes overexpressed in tumor tissue. Peptides from identified TAAs were used to induce peptide-specific CD4+ T-cell responses in healthy donors and in tumor patients. RESULTS: In the absence of inflammation, expression of MHC class II molecules is mainly restricted to cells of the immune system. To our surprise, we were able to isolate and characterize hundreds of class II peptides directly from primary dissected solid tumors, especially from renal cell carcinomas, and from colorectal carcinomas and transitional cell carcinomas. Infiltrating leukocytes expressed MHC class II molecules and tumor cells, very likely under the influence of IFNgamma. Our list of identified peptides contains ligands from several TAAs, including insulin-like growth factor binding protein 3 and matrix metalloproteinase 7. The latter bound promiscuously to HLA-DR molecules and were able to elicit CD4+ T-cell responses. CONCLUSIONS: Thus, our direct approach will rapidly expand the limited number of T-helper epitopes from TAAs for their use in clinical vaccination protocols.

Antigens, Neoplasm↗
PubMed2006

Interaction of TLR2 and TLR4 ligands with the N-terminal domain of Gp96 amplifies innate and adaptive immune responses.

Activation of dendritic cells by ligands for Toll-like receptors (TLR) is a crucial event in the initiation of innate and adaptive immune responses. Several classes of TLR ligands have been identified that interact with distinct members of the TLR-family. TLR4 ligands include lipopolysaccharide derived from different Gram-negative bacteria and viral proteins. Recent reports have demonstrated the TLR-mediated activation of dendritic cells by heat shock proteins (HSPs). However, doubts were raised as to what extent this effect was due to lipopolysaccharide contaminations of the HSP preparations. We re-examined this phenomenon using Gp96 or its N-terminal domain, nominally endotoxin-free (<0.5 enzyme units/mg). As described previously, innate immune cells are activated by Gp96 at high concentrations (> or =50 microg/ml) but not at lower concentrations. However, preincubation of low amounts of Gp96 with TLR2 and TLR4 ligands at concentrations unable to activate dendritic cells by themselves results in the production of high levels of proinflammatory cytokines, up-regulation of activation markers, and amplification of T cell activation. Our results provide significant new insights into the mechanism of HSP-mediated dendritic cell activation and present a new function of HSPs in the amplification of dendritic cell activation by bacterial products and induction of adaptive immune responses.

Animals↗
PubMed2006

Comparative analysis of volatile constituents from mice and their urine.

We report the volatile composition of the body scent of male C57BL/6J mice in comparison to the volatile composition of their urine. From a total of 67 components, nitromethane, propanoic acid, dimethyldisulfide, 1-octene, 1-hexanol, hexanoic acid, indole, alpha- and beta-farnesene, and one unidentified component were observed only in the volatiles from the body of mice. On the other hand, 3-penten-2-one, 3-methyl-2-buten-1-ol, 3-methyl-cyclopentanone, p-xylene, 3-hepten-2-one, 2,3-dehydro-exo-brevicomin, benzylmethylketone, and 13 unidentified components were only found in urine volatiles. All other substances were present in the volatiles of both mice and their urine. Aliphatic aldehydes from pentanal to decanal were prominent mouse odor components. Because receptors for these aldehydes have been extensively characterized in the main olfactory organ, these components may be important for mice in recognizing their conspecifics.

Animals↗
PubMed2006

Characterization of the ribonuclease activity on the skin surface.

The rapid degradation of ribonucleic acids (RNA) by ubiquitous ribonucleases limits the efficacy of new therapies based on RNA molecules. Therefore, our aim was to characterize the natural ribonuclease activities on the skin and in blood plasma i.e. at sites where many drugs in development are applied. On the skin surfaces of Homo sapiens and Mus musculus we observed dominant pyrimidine-specific ribonuclease activity. This activity is not prevented by a cap structure at the 5'-end of messenger RNA (mRNA) and is not primarily of a 5'- or 3'-exonuclease type. Moreover, the ribonuclease activity on the skin or in blood plasma is not inhibited by chemical modifications introduced at the 2'OH group of cytidine or uridine residues. It is, however, inhibited by the ribonuclease inhibitor RNasin although not by the ribonuclease inhibitor SUPERase* In. The application of our findings in the field of medical science may result in an improved efficiency of RNA-based therapies that are currently in development.

Journal Article↗
PubMed2006

Immunotherapy of renal cell carcinoma.

Carcinomas of the kidney generally have a poor prognosis and respond minimally to classical radiotherapy or chemotherapy. Immunotherapy constitutes an interesting alternative to these established forms of treatment, and indeed, cytokine-based therapies have been used for many years, leading to favorable clinical responses in a small subset of patients. During the past few years, immunotherapeutical trials targeting renal cell tumor-associated antigens have also been reported, with diverse passive or active approaches using antibodies or aimed at activating tumor-directed T lymphocytes. The following review presents the results and the progress made in the field, including classical cytokine treatments, non-myeloablative stem cell transplantation and antigen specific-based trials, with special focus on T-cell studies. In consideration of the few specific molecular targets described so far for this tumor entity, current strategies which can lead to the identification of new relevant antigens will be discussed. Hopefully these will very soon contribute to an improvement in renal cell carcinoma specific immunotherapy and its evaluation.

Antigens, Neoplasm↗
PubMed2006

Proteasomes shape the repertoire of T cells participating in antigen-specific immune responses.

Differences in the cleavage specificities of constitutive proteasomes and immunoproteasomes significantly affect the generation of MHC class I ligands and therefore the activation of CD8-positive T cells. Based on these findings, we investigated whether proteasomal specificity also influences CD8-positive T cells during thymic selection by peptides derived from self proteins. We find that one of the self peptides responsible for positive selection of ovalbumin-specific OT-1 T cells, which is derived from the f-actin capping protein (Cpalpha1), is efficiently generated only by immunoproteasomes. Furthermore, OT-1 mice backcrossed onto low molecular mass protein 7 (LMP7)-deficient mice show a 50% reduction of OT-1 cells. This deficiency is also observed after transfer of BM from OT-1 mice in LMP7-deficient mice and can be corrected by the injection of the Cpalpha1 peptide. Interestingly, WT and LMP7-deficient mice mount comparable immune responses to the ovalbumin-derived epitope SIINFEKL. However, their cytotoxic T lymphocytes (CTL) differ in the use of T cell receptor Vbeta genes. CTL derived from WT mice use Vbeta8 or Vbeta5 (the latter is also used by OT-1 cells), whereas SIINFEKL-specific CTL from LMP7-deficient mice are exclusively Vbeta8-positive. Taken together, our experiments provide strong evidence that proteasomal specificity shapes the repertoire of T cells participating in antigen-specific immune responses.

Actin Capping Proteins↗
PubMed2006

Monocyte-derived dendritic cells over-express CD86 in patients with systemic lupus erythematosus.

OBJECTIVES: Dendritic cells (DCs) play a key role in regulating immune responses, especially in priming naïve T-cells. Recently, DCs have been suggested to be involved in systemic lupus erythematosus (SLE) development by activating autoreactive T-helper lymphocytes. As a consequence, we compared the activation state of human monocyte-derived DCs (MDDCs) obtained from lupus patients and normal individuals. METHODS: The MDDCs were generated in vitro from blood from healthy donors and lupus patients. Immature and mature MDDCs were analysed by flow cytometry for several cell surface molecules. In parallel, cytokine secretion was determined by ELISA before and after MDDC activation. In each experiment, lupus DCs were compared with normal DCs. RESULTS: Here, we show for the first time that lupus MDDCs spontaneously over-express CD86 in the absence of any DC activation signal as compared with normal MDDCs (P = 0.025). Moreover, activation-induced IL-6 secretion was increased in lupus DCs with high CD86 over-expression as compared with normal DCs (P = 0.010). Interestingly, the percentage of MDDCs in lupus preparations is negatively correlated with disease activity scores (SLEDAI; P = 0.031). CONCLUSIONS: Lupus MDDCs are pre-activated suggesting that they might be more efficient antigen-presenting cells. This result might partly explain how the peripheral tolerance is broken in SLE.

Adult↗
PubMed2006

Therapeutic anti-tumor immunity triggered by injections of immunostimulating single-stranded RNA.

Stabilized synthetic RNA oligonucleotides (ORN) and protected messenger RNA (mRNA) were recently discovered to possess an immunostimulatory capacity through their recognition by TLR 7 and 8. We wanted to find out whether this danger signal is capable of triggering anti-tumor immunity when injected locally into an established tumor. Using the mouse glioma tumor cell line SMA-560 in syngenic VM/Dk mice, we were able to show that intra-tumor injections of protamine-stabilized mRNA do indeed induce tumor regression and long-term anti-tumor immunity. Residual RNA-injected tumors show CD8 infiltration. Distant injections of protamine-protected mRNA and intra-tumor injection of naked mRNA also result in anti-tumor immunity. Although they are strong danger signals, RNA are labile molecules with a short half-life: they do not trigger side effects such as long-term, uncontrolled immunostimulation evidenced by splenomegaly in CpG DNA-treated mice. In conclusion, RNA molecules are potent and safe danger signals that are relevant for active immunotherapy strategies aimed at the eradication of solid tumors.

Animals↗
PubMed2006

Precursor frequency can compensate for lower TCR expression in T cell competition during priming in vivo.

The factors controlling clonal dominance of cytotoxic T lymphocyte (CTL) responses are currently not well understood. To study the functional impact of the strength of the interaction of a T cell with an antigen-presenting cell in this context, we established a new mouse model comprised of two T cell receptor (TCR)-transgenic strains expressing the identical TCR in differing amounts, hence providing two CTL clones with different avidities but identical specificity and affinity. Utilizing this new model, we show that upon antigen challenge higher-avidity CTL expand at the expense of moderate-avidity CTL in vivo if present in equal numbers. Beyond this, moderate-avidity T cells can also contribute to a CTL response when present in excess. These results suggest that in addition to a proposed affinity/avidity threshold, the precursor frequency is important in defining clonal dominance. A new model in which TCR density and precursor frequency define the outcome of a CTL response is discussed.

Adoptive Transfer↗
PubMed2006

Peptides made to order.

How loading of major histocompatibility complex (MHC) class I-specific peptides by conserved degradation machinery is performed economically has now been resolved by Kanaseki et al. (2006) in this issue of Immunity: The individual MHC molecule serves as a template for its own ligand.

Animals↗
PubMed2005

Supraagonistic, bispecific single-chain antibody purified from the serum of cloned, transgenic cows induces T-cell-mediated killing of glioblastoma cells in vitro and in vivo.

Here we characterize the antitumor activity of a recombinant bispecific single-chain antibody isolated from the serum of cloned transgenic cows. The antibody, termed r28M, is directed to a melanoma-associated proteoglycan, also expressed on glioblastoma cells, and to human CD28. Bound to tumor cells, r28M induced exceedingly efficient supraagonistic T-cell activation via the CD28 molecule without an additional stimulus via the TCR/CD3 complex. In vitro, T cells and NK cells contributed to tumor cell killing after r28M-mediated activation of peripheral blood mononuclear cells. However, NK activity depended on T-cell-derived cytokines. In vivo, r28M markedly inhibited the growth of human glioblastoma cells in nude mice. The serum half-life of the protein after i.v. injection was approximately 6 hr. Thus, r28M is unique not only in inducing supraagonistic CD28-mediated T-cell activation against tumor cells in vitro and in vivo, it also meets 2 additional requirements that are critical for clinical application: a relatively long serum half-life and the possibility of obtaining large amounts of active material from cloned transgenic livestock.

Animals↗
PubMed2005

SNEP: SNP-derived epitope prediction program for minor H antigens.

The single nucleotide polymorphism (SNP)-derived Epitope Prediction program (SNEP) is now available to the public. It predicts minor histocompatibility antigens (miHAgs), which are T-cell epitopes containing polymorphic spots, from proteins listed in the SWISS-PROT database. SNEP recognizes polymorphisms (termed VARIANT or CONFLICT in SWISS-PROT) and predicts potential T-cell epitopes within a chosen distance around the polymorphic residue. The prediction algorithm is based on the SYFPEITHI T-cell epitope prediction program. SNEP is able to search for proteins according to their accession numbers, sequence stretches or gene names, for example. The predictions are available for several human leucocyte antigen class I and class II allelic products, which allow for a rapid and precise evaluation of potential miHAgs within polymorphic antigens.

Amino Acid Sequence↗