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Biomedical subjects

Gerold Schuler

Publications and source records attributed to Gerold Schuler.

At least 19 recordsLinked to original sources
PubMed2006

An improved method for RNA isolation and removal of melanin contamination from melanoma tissue: implications for tumor antigen detection and amplification.

Several kits are available to isolate RNA(1) from tissues. However, melanoma tissue is often rich in melanin that co-purifies with DNA/RNA and inhibits subsequent PCR reactions, hampering tumor antigen detection and amplification. This problem has not yet been addressed systematically. Here we generated a photometric protocol to determine both the melanin and RNA concentration by correcting the latter for the absorption coefficient of melanin at 260 nm. Subsequently, different combinations of silica-based RNA-binding, size-exclusion, and ion-exchange columns were used in 8 protocols for isolation of RNA from melanoma tissue to compare efficacy of melanin removal and yield of RNA. Furthermore, the capability of the different RNA preparations to function as template in RT-PCRs with products of different length, i.e. GAP-DH, tyrosinase, and gp100, was tested. We found that the combination of silica-based RNA-binding and size-exclusion columns was not sufficient to remove melanin from highly contaminated tumor samples, and subsequent RT-PCR failed to give larger products. However, protocols including ion-exchange columns resulted in efficient removal of melanin, while retaining reasonable RNA yields in samples from highly pigmented melanomas. Efficient RT-PCR of larger products turned out to be inversely correlated to the melanin contamination. This RNA-purification method will help scientists to isolate polynucleotides from melanin-containing tumor samples, which subsequently can be used in antigen detection assays and vaccination strategies using amplified total tumor RNA.

Antigens, Neoplasm↗
PubMed2006

Inhibition of the transcription factor Foxp3 converts desmoglein 3-specific type 1 regulatory T cells into Th2-like cells.

Pemphigus vulgaris (PV) is a severe autoimmune bullous skin disorder and is associated with autoantibodies against desmoglein (Dsg)3 that are regulated by Th2 cells. Recently, Dsg3-specific type 1 regulatory T cells (Tr1) were identified that are presumably critical for the maintenance of tolerance against Dsg3 because there is a much lower Dsg3-specific Tr1:Th2 ratio in the PV patients than in healthy individuals. The aim of this study was to down-regulate the transcription factor Foxp3 in Dsg3-specific Tr1 using antisense oligonucleotides because Foxp3 is constitutively expressed by the Dsg3-specific Tr1. Antisense-treated Dsg3-specific Tr1 clones lost expression of Foxp3, glucocorticoid-induced TNFR family-related receptor, and CTLA-4, and started to secrete IL-2, whereas the secretion of IL-5, TGF-beta, and IL-10 remained unchanged. Moreover, antisense treatment induced a proliferative response to Dsg3 of the formerly anergic Tr1 and abrogated their suppressor activity on Dsg3-specific Th2 cell clones. Thus, inhibition of Foxp3 mRNA expression in the Tr1 induced a Th2-like phenotype. In conclusion, Foxp3 expression is inherent to Tr1 function, and modulation of Foxp3 expression in autoaggressive Th2 cells may provide a novel therapeutic approach aimed at restoring tolerance against Dsg3 in PV.

Cell Differentiation↗
PubMed2006

Autoreactive T and B cells from bullous pemphigoid (BP) patients recognize epitopes clustered in distinct regions of BP180 and BP230.

Bullous pemphigoid (BP) is a well-characterized model of autoantibody-mediated autoimmunity, which presumably depends on autoreactive Th cells that promote the activation of autoreactive B cells. The two major autoantigens of BP are BP180 and BP230, two components of dermoepidermal adhesion complexes. Both, autoreactive Th cell responses and autoantibody profiles were characterized in 35 patients with acute onset BP using BP180 and BP230 proteins. Our findings indicate the following: 1) autoreactive Th cells recognized epitopes within the NH2-terminal (77.1%), COOH-terminal (65.7%), and central portion (57.1%) of the BP180 ectodomain; 2) IgG autoantibodies were found to exhibit similar or identical reactivity against the NH2-terminal (82.8%), COOH-terminal (77.1%), and central portion (37.1%) of the BP180 ectodomain; 3) T and B cell reactivity with the NH2-terminal portion of the BP180 ectodomain was associated with extensive BP, whereas the central portion was more frequently recognized in limited BP; 4) only 7 of 16 (43.7%) and 6 of 16 (37.5%) BP patients showed a Th cellular response against the COOH- and NH2-terminal regions of BP230, respectively, whereas 5) IgG reactivity against the COOH- and NH2-termini of BP230 was detected in 5 of 16 (31.3%) and 6 of 16 (37.5%) patients, respectively. These results demonstrate that Th and B cell reactivities against BP180, are, in contrast to BP230 reactivity, almost constantly detectable in BP patients, and differential epitope recognition of BP180 seems to be associated with distinct clinical severity. These observations support the concept that BP180, but not BP230, is the primary autoantigen of BP critical for disease development.

Adolescent↗
PubMed2006

In vivo magnetic resonance imaging of dendritic cell migration into the draining lymph nodes of mice.

Dendritic cell (DC) migration into the draining lymph nodes is critical for T cell priming. Here, we show that magnetic resonance imaging (MRI) can be used to visualize DC migration in vivo. We combined clinically approved small particles of iron oxide (SPIO) with protamine sulfate to achieve efficient uptake by murine bone marrow-derived DC. SPIO-DC were largely unaltered and after injection into the footpads of mice, they migrated into the T cell areas of the draining lymph nodes, which could be visualized by MRI. Distinct MRI signal reduction patterns correlated with the detection of SPIO-DC mainly within Thy-1.2+ B220- T cell areas, as confirmed by iron staining and immunohistology. Clear signal reduction patterns could still be observed with 1x10(6) injected SPIO-DC at high resolution, resulting in the detection of about 2000 DC. Control injections of homing-incompetent SPIO-DC derived from CCR7-/- mice or SPIO alone did not reach the T cell areas. Taken together, the results demonstrate that clinically approved contrast agents allow the non-invasive visualization of DC migration into the draining lymph node by MRI in vivo at high resolution. This protocol therefore also allows dynamic imaging of immune responses and MRI-based tracking of human DC in patients.

Animals↗
PubMed2006

Mature monocyte-derived dendritic cells respond more strongly to CCL19 than to CXCL12: consequences for directional migration.

The chemokine receptor CCR7 is crucial for migration of mature dendritic cells (DC) directed toward secondary lymphoid organs; however, there is little knowledge about the function of the homeostatic chemokine receptor CXCR4 in DC and its contribution to directional migration of DC during inflammation. By comparing the impact of chemokine receptor engagement on mature DC we found that the CCR7 ligand CCL19 holds a stronger chemotactic potency than the CXCR4 ligand CXCL12. Moreover, CCL19 elicited rapid, steep and long-lasting mobilization of intracellular calcium in individual cells and induced intense phosphorylation of extracellular signal-regulated kinase 1/2 and protein kinase B, while the intracellular signals elicited by CXCL12 were in part distinct and significantly weaker. Analysis of chemokine receptor expression revealed that although CCR7 and CXCR4 were expressed by a similar percentage of DC, the mean fluorescence intensity of CCR7 was up to six times higher, suggesting a higher receptor density. Based on these correlations we propose that the type of chemokine signal in conjunction with the expression and functional activity of the respective chemokine receptor is also determining the migration rate and potency of a chemotactic response in mature DC. In conclusion, our data support the fundamental role of CCR7 for rapidly guiding DC toward secondary lymphoid organs at an extra- and intracellular molecular level and on the contrary render CXCR4 a weaker contributor to directional migration of DC during inflammation.

Calcium↗
PubMed2006

[Immunotherapy of malignant melanoma--basic principles and novel therapeutic approaches].

Immunotherapy has assumed increasing importance in the therapy of malignant melanoma. The main reason is the high immunogenicity of the tumor itself, so that an immune response against the tumor often exists even without immune stimulation. The goal of modern immunotherapeutic approaches is to augment these anti-tumoral immune reactions to fight the tumor. Despite multiple successes, the ultimate breakthrough in the therapy of malignant melanoma has not yet been achieved. This overview summarizes the reasons for this lack of success and highlights future strategies for more successful therapy of malignant melanoma.

Cancer Vaccines↗
PubMed2006

Prolonged clinical remission of patients with severe pemphigus upon rapid removal of desmoglein-reactive autoantibodies by immunoadsorption.

BACKGROUND: In pemphigus, loss of epidermal adhesion is induced by binding of circulating autoantibodies to the desmosomal cadherins desmoglein 3 (Dsg3) in pemphigus vulgaris (PV) and desmoglein 1 (Dsg1) in pemphigus foliaceus (PF), respectively. Therapeutic removal of Dsg-reactive autoantibodies by immunoadsorption (IA) has been demonstrated to exert clinical remission of the disease. OBJECTIVES: The aim of this intervention study was to evaluate the efficacy and safety of the peptide-based Globaffin adsorber system in the treatment of severe pemphigus cases. PATIENTS AND METHODS: We applied IA in 4 PV and 2 PF patients with severe chronic disease resistant to conventional immunosuppressive therapy. IA was performed on 4 consecutive days, representing 1 treatment cycle, followed by a 4-week treatment-free interval. Serum samples for determining serum IgG and anti-Dsg1/Dsg3 IgG autoantibodies were drawn daily before and after IA, respectively. During follow-up, patients were examined carefully, and laboratory parameters were controlled monthly for up to 1 year. RESULTS: IA led to excellent clinical responses. Skin and mucosal lesions cleared almost completely within weeks. One IA cycle reduced anti-Dsg1 and anti-Dsg3 autoantibodies by an average of 50-70% as determined by ELISA. CONCLUSIONS: Using the Globaffin adsorber system, IA represents an effective and safe treatment opportunity in severe and therapy-resistant pemphigus.

Adult↗
PubMed2005

A new way to generate cytolytic tumor-specific T cells: electroporation of RNA coding for a T cell receptor into T lymphocytes.

Effective T cell receptor (TCR) transfer until now required stable retroviral transduction. However, retroviral transduction poses the threat of irreversible genetic manipulation of autologous cells. We, therefore, used optimized RNA transfection for transient manipulation. The transfection efficiency, using EGFP RNA, was >90%. The electroporation of primary T cells, isolated from blood, with TCR-coding RNA resulted in functional cytotoxic T lymphocytes (CTLs) (>60% killing at an effector to target ratio of 20:1) with the same HLA-A2/gp100-specificity as the parental CTL clone. The TCR-transfected T cells specifically recognized peptide-pulsed T2 cells, or dendritic cells electroporated with gp100-coding RNA, in an IFNgamma-secretion assay and retained this ability, even after cryopreservation, over 3 days. Most importantly, we show here for the first time that the electroporated T cells also displayed cytotoxicity, and specifically lysed peptide-loaded T2 cells and HLA-A2+/gp100+ melanoma cells over a period of at least 72 h. Peptide-titration studies showed that the lytic efficiency of the RNA-transfected T cells was similar to that of retrovirally transduced T cells, and approximated that of the parental CTL clone. Functional TCR transfer by RNA electroporation is now possible without the disadvantages of retroviral transduction, and forms a new strategy for the immunotherapy of cancer.

Apoptosis↗
PubMed2005

Differences in phenotype and function between spontaneously occurring melan-A-, tyrosinase- and influenza matrix peptide-specific CTL in HLA-A*0201 melanoma patients.

Melanoma-specific T cells can occur spontaneously or in response to vaccination or other therapies, but the frequency is much lower than observed in viral infections. The presence of tumor-specific T cells does not necessarily translate into clinical regressions for a variety of reasons such as an insufficient frequency, activation state or homing capacity of the T cells or escape strategies of the tumor. Having screened melanoma patients prior to inclusion in vaccination trials for spontaneous tumor-specific T cells either by Elispot or tetramer-staining, we have identified 3 patients with sufficient numbers of tumor-reactive T cells to more than 1 TAA and at least 1 virus-antigen to perform phenotypic and functional analysis directly ex vivo. These stage IV melanoma patients showed specific CTL against melan-A.A2, tyrosinase.A2 and influenza matrix peptide (IMP).A2 readily detectable in peripheral blood. T-cell receptor (TCR) staining using the tetramer technology was combined with phenotypic characterization and functional assays. In contrast to IMP-specific CTL, melanoma-specific CTL were predominantly terminally differentiated effector cells. However, analysis of melan-A- and tyrosinase-specific T-cell lines showed that only a part of the melanoma-specific CTL were able to lyse peptide-loaded target cells. Interestingly, the described phenotypic and functional differences of melan-A- and tyrosinase-specific CTL appeared not only between patients but were also evident within patients, suggesting that the immune response against various tumor antigens is regulated independently.

Adult↗
PubMed2005

Optimizing the exogenous antigen loading of monocyte-derived dendritic cells.

Dendritic cell (DC) vaccination, i.e. the adoptive transfer of antigen-loaded DC, is still at an early stage and requires standardization. In this study, we investigated the exogenous loading of monocyte-derived DCs with HLA class I- and II-restricted peptides, as despite widespread use, little effort has been put into its pre-clinical validation. We found that only mature DCs (m-DC) but not immature DCs (im-DC) could be sufficiently loaded with exogenous class I-restricted peptides and were by far superior in expanding CD8(+) primary (Melan-A.A2 peptide-specific) and recall [Influenza matrix peptide (IMP) A2-specific] T cell responses. Primary stimulation with peptide-loaded im-DCs even down-regulated antigen-specific T cell responses. Our results indicate that stimulation with m-DCs is superior in terms of quantity and quality compared with im-DCs, supporting their preferred use in clinical DC trials. Loading of m-DCs with high (10 microM) concentrations generated clearly more Melan-A effectors than loading with 1 or 0.1 microM without any negative effect on the quality (affinity) of the resulting T cells. In contrast to the findings with the Melan-A peptide loading with 10 microM IMP was counter-productive, induced apoptosis and yielded fewer specific T cells of inferior affinity as compared with loading with 1 or 0.1 microM. In sharp contrast to the situation for HLA class I, much higher levels and longer half-lives of peptide-HLA class II complexes were obtainable upon loading of im-DCs with exogenous peptide, but m-DCs were functionally preferable to induce T(h)1 responses in vitro. Another surprising finding was that, while presentation to T cells upon simultaneous loading of several peptides with highly varying affinities and competing for the same class I or II molecule was possible, in priming experiments peptide competition clearly inhibited T cell induction. Although peptides will obviously vary in their individual properties, our study clearly points to some important principles that should be taken into account.

Antibodies↗
PubMed2005

Generation of an optimized polyvalent monocyte-derived dendritic cell vaccine by transfecting defined RNAs after rather than before maturation.

Transfection with RNA is an attractive method of Ag delivery to dendritic cells (DCs), but has not yet been standardized. We describe in this study the methods to efficiently generate an optimized mature monocyte-derived DC vaccine at clinical scale based on the electroporation of several RNAs either into immature DC followed by maturation or, alternatively, directly into mature DCs, which has not been possible so far with such high efficiency. Electroporation of DCs resulted in high yield, high transfection efficiency (>90%), and high migration capacity. Intracellular staining allowed the study of the expression kinetics of Ags encoded by the transfected RNAs (MelanA, MAGE-3, and survivin) and a validation of the vaccine (>/=90% transfection efficiency). Expression of all three Ags peaked 3-4 h after electroporation in DC transfected either before or after maturation, but decreased differently. The DC vaccine can also be cryopreserved and nevertheless retains its viability, stimulatory capacity as well as migratory activity. In addition, we uncover that DC transfected after rather than before maturation appear to be preferable vaccines not only from a production point of view but also because they appear to be immunologically superior for CTL induction in sharp contrast to common belief. DCs transfected after maturation not only more effectively generate and present the Mage-3.A1 and MelanA.A2.1 epitopes to T cell clones, but they even are superior in priming to the standard proteasome-dependent MelanA.A2.1 wild-type prototype tumor epitope, both in terms of T cell expansion and effector function on a per cell basis.

Antigen Presentation↗
PubMed2005

A polyclonal anti-vaccine CD4 T cell response detected with HLA-DP4 multimers in a melanoma patient vaccinated with MAGE-3.DP4-peptide-pulsed dendritic cells.

During the last few years, HLA class I tetramers have been successfully used to demonstrate anti-vaccine CD8 CTL proliferation in cancer patients vaccinated with tumor antigens. Frequencies of CTL as low as 10(-6) among CD8 cells were observed even in patients showing tumor regression. Little is known about the role of tumor-antigen-specific CD4 T cells in the context of these anti-vaccine responses. Therefore, we developed a very sensitive approach using fluorescent class-II-peptide multimers to detect antigen-specific CD4 T cells in vaccinated cancer patients. We produced HLA-DP4 multimers loaded with the MAGE-3(243-258) peptide and used them to stain ex vivo PBL from melanoma patients injected with dendritic cells pulsed with several class I and class II tumor antigenic peptides, including the MAGE-3(243-258) peptide. The multimer(+) CD4 T cells were sorted and amplified in clonal conditions; specificity was assessed by their ability to secrete IFN-gamma upon contact with the MAGE-3 antigen. We detected frequencies of about 1x10(-6) anti-MAGE-3.DP4 cells among CD4 cells. A detailed analysis of one patient showed an anti-MAGE-3.DP4 CD4 T cell amplification of at least 3000-fold upon immunization. TCR analysis of the clones from this patient demonstrated a polyclonal response against the MAGE-3 peptide.

Antibodies, Neoplasm↗
PubMed2005

Infliximab in the treatment of moderate to severe atopic dermatitis.

BACKGROUND: Chronic use of standard therapies for atopic dermatitis (AD) is associated with variable efficacy and potential side effects. Targeted therapeutic approaches, such as the inhibition of tumor necrosis factor-alpha, may be a novel option. OBJECTIVE: This investigator-initiated, open, prospective, single-center, pilot study was conducted to evaluate the long-term efficacy and safety of infliximab in patients with AD. METHODS: Nine patients with moderate or severe AD were enrolled. AD in these patients was resistant to conventional therapy. Infliximab 5 mg/kg was administered by intravenous infusion at weeks 0, 2, 6, 14, 22, 30, and 38, and patients were followed for 46 weeks. RESULTS: Induction therapy with infliximab significantly improved all clinical parameters, but this improvement was not sustained through maintenance therapy. Only two patients with severe AD achieved an excellent clinical response by 46 weeks. CONCLUSIONS: Infliximab monotherapy may be an additional therapeutic option for the management of refractory severe AD.

Adult↗
PubMed2005

Efficient elutriation of monocytes within a closed system (Elutra) for clinical-scale generation of dendritic cells.

Dendritic cells (DC) are promising tools for the immunotherapy of cancer. The induction of tumor-specific T cells and clinical regressions have already been observed in early phase I/II vaccination trials. As DC vaccination is now facing trials with larger patient collectives it becomes increasingly important to obtain large numbers of cells suitable for therapeutic applications under labor- and cost-effective conditions. We describe here a procedure that uses a novel cell separator (Elutra, Gambro BCT) to enrich monocytes from an entire apheresis product within one hour. Cells are separated on the basis of size and to a lesser extent density, by elutriation in a 40-ml conical chamber. The total monocyte recovery following elutriation (n = 6) was 98.53% (+/-8.07%), the recovery in the monocyte-rich fraction 75.45% (+/-11.31%), and the mean purity 82.95% (+/-6.01%). These monocytes can be cultured either in conventional culture dishes or in closed cell culture bags and differentiated, by using GM-CSF+IL-4 followed by a maturation cocktail composed of IL-1beta+IL-6+TNF-alpha+PGE2, into fully mature DC. The Elutra separator allows for fast and easy enrichment of monocytes within a closed system. Subsequently, elutriated monocytes can be successfully cultured into phenotypically and functionally mature DC for immunotherapeutic approaches. The method neither requires a density gradient step to enrich PBMC from leucapheresis products nor does it apply (xenogeneic) antibodies to target monocytes. Isolation of monocytes with Elutra may greatly facilitate future DC-based vaccination approaches.

Cell Differentiation↗
PubMed2005

Detection of laminin 5-specific auto-antibodies in mucous membrane and bullous pemphigoid sera by ELISA.

Mucous membrane pemphigoid (MMP) is an autoimmune bullous disease that primarily affects mucous membranes leading to a scarring phenotype. MMP patients produce auto-antibodies (auto-ab) that preferentially recognize two components of the dermoepidermal basement membrane zone (BMZ): bullous pemphigoid (BP)180 and laminin 5 (LN5). Since detection of disease-specific auto-ab may be critical for diagnosis of MMP, we developed an ELISA with affinity-purified native human LN5. A total of 24 MMP, 72 BP, and 51 control sera were analyzed for LN5-specific auto-ab: 18/24 (75.0%) MMP and 29/72 (40.3%) BP sera were LN5 reactive. Sensitivity and specificity of the LN5 ELISA for MMP were 75% and 84.3%, respectively, and 40.3% and 88.2% for BP, respectively. The LN5 ELISA was more sensitive than a dot blot assay with native LN5, which detected LN5-reactive IgG in 14/24 (58.3%) MMP and 16/72 (22.2%) BP sera. In MMP, but not BP, levels of LN5-reactive IgG correlated with disease severity. Furthermore, IgG reactivity to LN5 of the MMP and BP sera was not significantly associated with IgG reactivity against other autoantigens of the BMZ, such as BP180 or BP230. Thus, the established LN5 ELISA holds great promise as a novel diagnostic and prognostic parameter for MMP.

Autoantibodies↗
PubMed2005

Ex vivo analysis of desmoglein 1-responsive T-helper (Th) 1 and Th2 cells in patients with pemphigus foliaceus and healthy individuals.

Pemphigus foliaceus (PF) is a severe autoimmune bullous disorder, characterized by autoantibodies (autoAb) against desmoglein 1 (Dsg1). As T cells may be critical in the pathology of PF, the aim of the present study was to identify and characterize autoaggressive T-helper cells reactive to Dsg1 in PF patients and healthy individuals. Eight patients with the clinical diagnosis of PF and six HLA class II-matched healthy individuals were examined. By magnetic cell-sorting (MACS) cytokine-secretion assay, Dsg1-responsive T-helper (Th) 1 and Th2 cells were isolated and cloned by limiting dilution. The generated T-cell clones (TCC) were characterized regarding proliferative response, TCR Vbeta-chain usage, and cytokine profile upon in vitro stimulation with Dsg1. Both Dsg1-reactive Th1 and Th2 cells were detected in PF patients and controls at similar frequencies. A total of 15 Th1 and Th2 clones were isolated from patients and 27 TCC from healthy controls. Analysis of TCR Vbeta-chain usage of autoreactive T cells from both groups revealed no predominance of a specific Vbeta chain. Noteworthy, the isolated TCC showed a polarized Th1- or Th2-like phenotype upon in vitro culture and stable expression of Th1 or Th2 cytokines during long-term in vitro culture. In summary, our data demonstrate that T-cell autoreactivity against Dsg1 is not restricted to patients with PF. Moreover, both Th1 and Th2 cells were present in patients and healthy donors, suggesting that the loss of B-cell tolerance against Dsg1 in PF is not exclusively determined by the presence of autoaggressive T cells.

B-Lymphocytes↗
PubMed2005

Activated CD4+ CD25+ T cells suppress antigen-specific CD4+ and CD8+ T cells but induce a suppressive phenotype only in CD4+ T cells.

CD4(+) CD25(+) regulatory T cells are increasingly recognized as central players in the regulation of immune responses. In vitro studies have mostly employed allogeneic or polyclonal responses to monitor suppression. Little is known about the ability of CD4(+) CD25(+) regulatory T cells to suppress antigen-specific immune responses in humans. It has been previously shown that CD4(+) CD25(+) regulatory T cells anergize CD4(+) T cells and turn them into suppressor T cells. In the present study we demonstrate for the first time in humans that CD4(+) CD25(+) T cells are able to inhibit the proliferation and cytokine production of antigen specific CD4(+) and CD8(+) T cells. This suppression only occurs when CD4(+) CD25(+) T cells are preactivated. Furthermore, we could demonstrate that CD4(+) T-cell clones stop secreting interferon-gamma (IFN-gamma), start to produce interleukin-10 and transforming growth factor-beta after coculture with preactivated CD4(+) CD25(+) T cells and become suppressive themselves. Surprisingly preactivated CD4(+) CD25(+) T cells affect CD8(+) T cells differently, leading to reduced proliferation and reduced production of IFN-gamma. This effect is sustained and cannot be reverted by exogenous interleukin-2. Yet CD8(+) T cells, unlike CD4(+) T cells do not start to produce immunoregulatory cytokines and do not become suppressive after coculture with CD4(+) CD25(+) T cells.

CD4-Positive T-Lymphocytes↗