Publications by authors named "Duco Kramer"

21 Publications

  • Page 1 of 1

Gain-of-function mutation in ubiquitin-ligase KLHL24 causes desmin degradation and dilatation in hiPSC-derived engineered heart tissues.

J Clin Invest 2021 Jul 22. Epub 2021 Jul 22.

Department of Cardiology, University Medical Center Groningen, Groningen, Netherlands.

The start codon c.1A>G mutation in KLHL24, encoding ubiquitin-ligase KLHL24, results in the loss of 28 N-terminal amino acids (KLHL24-ΔN28) by skipping the initial start codon. In skin, KLHL24-ΔN28 leads to gain of function, excessively targeting intermediate filament keratin-14 for proteasomal degradation, ultimately causing epidermolysis bullosa simplex (EBS). The majority of these EBS-patients are also diagnosed with dilated cardiomyopathy (DCM), but the pathological mechanism in the heart is unknown. As desmin is the cardiac homologue of keratin-14, we hypothesized that KLHL24-ΔN28 leads to excessive degradation of desmin, resulting in DCM. Dynamically loaded engineered heart tissues (dyn-EHTs) were generated from human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes from two patients and three (non)familial controls. Ten-fold lower desmin protein levels were observed in patient-derived dyn-EHTs, in line with diminished desmin levels detected in patients' explanted heart. This was accompanied by tissue dilatation, impaired mitochondrial function, decreased force values and increased cardiomyocyte stress. HEK293 transfection studies confirmed KLHL24-mediated desmin degradation. KLHL24 RNA interference or direct desmin overexpression recovered desmin protein levels, restoring morphology and function in patient-derived dyn-EHTs. To conclude, presence of KLHL24-ΔN28 in cardiomyocytes leads to excessive degradation of desmin, affecting tissue morphology and function, that can be prevented by restoring desmin protein levels.
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http://dx.doi.org/10.1172/JCI140615DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8409593PMC
July 2021

Dynamic loading of human engineered heart tissue enhances contractile function and drives a desmosome-linked disease phenotype.

Sci Transl Med 2021 07;13(603)

Regenerative Biomaterials and Therapeutics Group, Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA.

The role that mechanical forces play in shaping the structure and function of the heart is critical to understanding heart formation and the etiology of disease but is challenging to study in patients. Engineered heart tissues (EHTs) incorporating human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes have the potential to provide insight into these adaptive and maladaptive changes. However, most EHT systems cannot model both preload (stretch during chamber filling) and afterload (pressure the heart must work against to eject blood). Here, we have developed a new dynamic EHT (dyn-EHT) model that enables us to tune preload and have unconstrained contractile shortening of >10%. To do this, three-dimensional (3D) EHTs were integrated with an elastic polydimethylsiloxane strip providing mechanical preload and afterload in addition to enabling contractile force measurements based on strip bending. Our results demonstrated that dynamic loading improves the function of wild-type EHTs on the basis of the magnitude of the applied force, leading to improved alignment, conduction velocity, and contractility. For disease modeling, we used hiPSC-derived cardiomyocytes from a patient with arrhythmogenic cardiomyopathy due to mutations in the desmoplakin gene. We demonstrated that manifestation of this desmosome-linked disease state required dyn-EHT conditioning and that it could not be induced using 2D or standard 3D EHT approaches. Thus, a dynamic loading strategy is necessary to provoke the disease phenotype of diastolic lengthening, reduction of desmosome counts, and reduced contractility, which are related to primary end points of clinical disease, such as chamber thinning and reduced cardiac output.
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http://dx.doi.org/10.1126/scitranslmed.abd1817DOI Listing
July 2021

The expression pattern of N-acetyltransferase 1 in healthy human skin.

Contact Dermatitis 2021 Jul 22;85(1):1-6. Epub 2021 Mar 22.

Department of Dermatology, University Medical Centre Groningen, University of Groningen, Groningen, The Netherlands.

Background: N-acetyltransferase 1 (NAT1) is an enzyme expressed among others in keratinocytes in human skin. NAT1 is important in the biotransformation of aromatic amines, an important example being p-phenylenediamine (PPD), a hair dye molecule. Unoxidized PPD penetrates the skin and is N-acetylated by NAT1.

Objectives: To investigate in detail the expression pattern of NAT1 in human skin.

Materials And Methods: Cryosections obtained from healthy human skin were stained for NAT1 and expression patterns were observed. NAT1 double stainings were performed with antibodies against different cellular organelles to determine expression patterns.

Result: A speckled, granular expression of NAT1 was seen predominantly in the stratum basale. NAT1 was expressed in a cytoplasmic pattern, perinuclear, and in the nucleus. No co-localisation was seen with the selected cellular organelles. Local differences in NAT1 expression patterns were observed between donors and between different biopsies obtained from the same donor.

Conclusions: NAT1 is expressed predominantly in the stratum basale and can be found in the cytoplasm, nucleus, and perinuclear in human skin. Further studies should be performed to investigate expression of NAT1 in a larger sample size.
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http://dx.doi.org/10.1111/cod.13821DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8252542PMC
July 2021

Endocytosis of IgG, Desmoglein 1, and Plakoglobin in Pemphigus Foliaceus Patient Skin.

Front Immunol 2019 12;10:2635. Epub 2019 Nov 12.

Department of Dermatology, Centre for Blistering Diseases, University Medical Centre Groningen, University of Groningen, Groningen, Netherlands.

Pemphigus foliaceus (PF) is one of the two main forms of pemphigus and is characterized by circulating IgG to the desmosomal cadherin desmoglein 1 (DSG1) and by subcorneal blistering of the skin. The pathomechanism of blister formation in PF is unknown. Previously we have shown that PF IgG induces aggregation of DSG1, plakoglobin (PG), and IgG outside of desmosomes, what in immunofluorescence of PF patient skin visualizes as a granular IgG deposition pattern with a limited number of coarse IgG aggregates between cells. Here we have investigated the fate of these aggregates in skin and found that these are cleared by endocytosis. We performed double immunofluorescence staining on snap-frozen skin biopsies of six PF patients for the following molecules: IgG, the desmosomal proteins DSG1 and DSG3, desmocollins 1 and 3, PG, desmoplakin and plakophilin 3, and for the endosomal marker early endosomal antigen 1 and the lysosomal markers cathepsin D and lysosomal-associated membrane protein 1. Endosomes were present in all cells but did not make contact with the aggregates in the basal and suprabasal layers. In the higher layers they moored to the aggregates, often symmetrically from two adjacent cells, and IgG, DSG1, and PG were taken up. Finally these endosomes became localized perinuclear. Endocytosis was only observed in perilesional or lesional skin but not in non-lesional skin. Older immunoelectron microscopic studies have suggested that in PF skin endocytosis of detached desmosomes takes place but we found no other desmosomal proteins to be present in these endosomes. Double staining with cathepsin D and LAMP-1 revealed no overlap with IgG, DSG1, or PG suggesting that lysosomes have no role in the clearing process. Collectively, our results show that endocytosis is part of the pathogenic process in PF but that no detached desmosomes are taken up but instead the deposited IgG is taken up together with DSG1 and PG.
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http://dx.doi.org/10.3389/fimmu.2019.02635DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6861377PMC
November 2020

Murine type VII collagen distorts outcome in human skin graft mouse model for dystrophic epidermolysis bullosa.

Exp Dermatol 2019 10 20;28(10):1153-1155. Epub 2018 Aug 20.

Department of Dermatology, Center of Expertise of Blistering Diseases, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.

Human skin graft mouse models are widely used to investigate and develop therapeutic strategies for the severe generalized form of recessive dystrophic epidermolysis bullosa (RDEB), which is caused by biallelic null mutations in COL7A1 and the complete absence of type VII collagen (C7). Most therapeutic approaches are focused on reintroducing C7. Therefore, C7 and anchoring fibrils are widely used as readouts in therapeutic research with skin graft models. In this study, we investigated the expression pattern of human and murine C7 in a grafting model, in which human skin is reconstituted out of in vitro cultured keratinocytes and fibroblasts. The model revealed that murine C7 was deposited in both human healthy control and RDEB skin grafts. Moreover, we found that murine C7 is able to form anchoring fibrils in human grafts. Therefore, we advocate the use of human-specific antibodies when assessing the reintroduction of C7 using RDEB skin graft mouse models.
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http://dx.doi.org/10.1111/exd.13744DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7380020PMC
October 2019

Development of a Full-Thickness Human Skin Equivalent In Vitro Model Derived from TERT-Immortalized Keratinocytes and Fibroblasts.

Tissue Eng Part A 2015 Sep 3;21(17-18):2448-59. Epub 2015 Aug 3.

1 Department of Dermatology, VU University Medical Centre , Amsterdam, The Netherlands .

Currently, human skin equivalents (HSEs) used for in vitro assays (e.g., for wound healing) make use of primary human skin cells. Limitations of primary keratinocytes and fibroblasts include availability of donor skin and donor variation. The use of physiologically relevant cell lines could solve these limitations. The aim was to develop a fully differentiated HSE constructed entirely from human skin cell lines, which could be applied for in vitro wound-healing assays. Skin equivalents were constructed from human TERT-immortalized keratinocytes and fibroblasts (TERT-HSE) and compared with native skin and primary HSEs. HSEs were characterized by hematoxylin-eosin and immunohistochemical stainings with markers for epidermal proliferation and differentiation, basement membrane (BM), fibroblasts, and the extracellular matrix (ECM). Ultrastructure was determined with electron microscopy. To test the functionality of the TERT-HSE, burn and cold injuries were applied, followed by immunohistochemical stainings, measurement of reepithelialization, and determination of secreted wound-healing mediators. The TERT-HSE was composed of a fully differentiated epidermis and a fibroblast-populated dermis comparable to native skin and primary HSE. The epidermis consisted of proliferating keratinocytes within the basal layer, followed by multiple spinous layers, a granular layer, and cornified layers. Within the TERT-HSE, the membrane junctions such as corneosomes, desmosomes, and hemidesmosomes were well developed as shown by ultrastructure pictures. Furthermore, the BM consisted of a lamina lucida and lamina densa comparable to native skin. The dermal matrix of the TERT-HSE was more similar to native skin than the primary construct, since collagen III, an ECM marker, was present in TERT-HSEs and absent in primary HSEs. After wounding, the TERT-HSE was able to reepithelialize and secrete inflammatory wound-healing mediators. In conclusion, the novel TERT-HSE, constructed entirely from human cell lines, provides an excellent opportunity to study in vitro skin biology and can also be used for drug targeting and testing new therapeutics, and ultimately, for incorporating into skin-on-a chip in the future.
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http://dx.doi.org/10.1089/ten.TEA.2015.0139DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4554934PMC
September 2015

Large-Scale Electron Microscopy Maps of Patient Skin and Mucosa Provide Insight into Pathogenesis of Blistering Diseases.

J Invest Dermatol 2015 Jul 19;135(7):1763-1770. Epub 2015 Mar 19.

Department of Cell Biology, University Medical Centre Groningen, University of Groningen, Groningen, The Netherlands. Electronic address:

Large-scale electron microscopy ("nanotomy") allows straight forward ultrastructural examination of tissue, cells, organelles, and macromolecules in a single data set. Such data set equals thousands of conventional electron microscopy images and is freely accessible (www.nanotomy.org). The software allows zooming in and out of the image from total overview to nanometer scale resolution in a 'Google Earth' approach. We studied the life-threatening human autoimmune blistering disease pemphigus, using nanotomy. The pathomechanism of cell-cell separation (acantholysis) that underlies the blistering is poorly understood. Ultrastructural examination of pemphigus tissue revealed previously unreported findings: (i) the presence of double-membrane structures between cells in all pemphigus types; (ii) the absence of desmosomes around spontaneous blisters in pemphigus foliaceus (PF); (iii) lower level blistering in PF when force induced; and (iv) intercellular widening at non-acantholytic cell layers. Thus, nanotomy delivers open-source electron microscopic maps of patient tissue, which can be analyzed for additional anomalies from any computer by experts from different fields.
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http://dx.doi.org/10.1038/jid.2015.109DOI Listing
July 2015

Smaller desmosomes are seen in the skin of pemphigus patients with anti-desmoglein 1 antibodies but not in patients with anti-desmoglein 3 antibodies.

J Invest Dermatol 2014 Aug 12;134(8):2287-2290. Epub 2014 Mar 12.

Center for Blistering Diseases, Department of Dermatology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.

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http://dx.doi.org/10.1038/jid.2014.140DOI Listing
August 2014

Differential in vitro immortalization capacity of eleven (probable) [corrected] high-risk human papillomavirus types.

J Virol 2014 Feb 20;88(3):1714-24. Epub 2013 Nov 20.

Department of Pathology, Unit of Molecular Pathology, VU University Medical Center, Amsterdam, The Netherlands.

Epidemiological studies identified 12 high-risk HPV (hrHPV) types and 8 probable/possible hrHPV types that display different cancer risks. Functional studies on transforming properties of hrHPV are mainly limited to HPV16 and -18, which induce immortalization of human foreskin keratinocytes (HFKs) by successive bypass of two proliferative life span barriers, senescence and crisis. Here, we systematically compared the in vitro immortalization capacities, as well as influences on p53, pRb, hTERT, growth behavior, and differentiation capacity, of nine hrHPV types (HPV16, -18, -31, -33, -35, -45, -51, -52, and -59), and two probable hrHPV types (HPV66 and -70). By retroviral transduction, the respective E6/E7 coding sequences were expressed in HFKs from two or three independent donors. Reduced p53 levels and low-level hTERT expression in early-passage cells, as seen in HPV16-, -31-, -33-, and -35-, and to a lesser extent HPV18-transduced HFKs, was associated with continuous growth and an increased immortalization capacity. Less frequent immortalization by HPV45 and -51 and immortalization by HPV66 and -70 was preceded by an intervening period of strongly reduced growth (crisis) without prior increase in hTERT expression. Immortalization by HPV59 was also preceded by a period crisis, despite the onset of low hTERT expression at early passage. HPV52 triggered an extended life span but failed to induce immortality. Variations in p53 and pRb levels were not correlated with differences in alternative E6/E7 mRNA splicing in all hrHPV-transduced HFKs. On collagen rafts, transductants showed disturbed differentiation reminiscent of precancerous lesions. In conclusion, in vitro oncogenic capacities differ between the established hrHPV types, and both some established and probable hrHPV types display weak or moderate immortalization potential.
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http://dx.doi.org/10.1128/JVI.02859-13DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3911618PMC
February 2014

The IgG "lupus-band" deposition pattern of pemphigus erythematosus: association with the desmoglein 1 ectodomain as revealed by 3 cases.

Arch Dermatol 2012 Oct;148(10):1173-8

Center for Blistering Diseases, Department of Dermatology, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands.

Background: Pemphigus foliaceus is an autoimmune skin disease characterized by subcorneal blistering and IgG antibodies directed against desmoglein 1. In the skin, these antibodies deposit intraepidermally. On rare occasions,an additional “lupus band” of granular depositions of IgG and complement is seen along the epidermal basement membrane zone. This combined pattern has been connected with a variant of pemphigus foliaceus named pemphigus erythematosus.

Observations: We describe 3 pemphigus foliaceus cases in which phototherapy was administered after a misdiagnosis of psoriasis. This treatment resulted in a flare of skin lesions. Direct immunofluorescence of skin biopsy specimens that were obtained several weeks later demonstrated intraepidermal and granular basement membrane zone depositions. The basement membrane zone depositions consisted of IgG, complement, and the ectodomain of desmoglein 1 and were located below the lamina densa.

Conclusions: High doses of UV light are likely to induce the cleaving of the desmoglein 1 ectodomain. In patients with pemphigus foliaceus, the circulating anti–desmoglein 1 antibodies precipitate this cleaved-off ectodomain along the basement membrane zone, resulting in a lupus band–like appearance. In pemphigus erythematosus, a similar mechanism may be active, which might explain the lupus-band phenomenon.
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http://dx.doi.org/10.1001/archdermatol.2012.1896DOI Listing
October 2012

Promiscuous behavior of HPV16E6 specific T cell receptor beta chains hampers functional expression in TCR transgenic T cells, which can be restored in part by genetic modification.

Cell Oncol 2010 ;32(1-2):43-56

Department of Pathology, VU University Medical Center, Amsterdam, The Netherlands.

Background: T cell receptor gene transfer is a promising strategy to treat patients suffering from HPV induced malignancies. Therefore we isolated the TCRalphabeta open reading frames of an HPV16E6 specific CTL clone and generated TCR transgenic T cells. In general low level expression of the transgenic TCR in recipient human T cells is observed as well as the formation of mixed TCRs dimers. Here we addressed both issues employing three different expression platforms.

Methods: We isolated the HVP16E6 specific TCRalpha and TCRbeta open reading frames and retrovirally transduced human T cells with either wild-type (wt), or codon-modified (cm) chains to achieve enhanced TCR expression levels, or used codon-modification in combination with cysteinization (cmCys) of TCRs to facilitate preferential pairing of the introduced TCRalpha and TCRbeta chains.

Results: Careful analysis of recipient T cells carrying the HPV16E6 TCRbeta and endogenous TCR chains revealed the transgenic TCRbeta chain to behave very promiscuously. Further analysis showed that the percentage of tetramer positive T cells in codon-modified/cysteinized TCR transgenic T cells was four-fold higher compared to wild-type and two-fold higher compared to codon-modification only. Functional activity, as determined by IFN-gamma production, was high in cmCysTCR transgenic T cells, where it was low in cm and wt TCR transgenic T cells. Recognition of endogenously processed HPV16E6 antigen by cmCysTCR transgenic T cells was confirmed in a cytotoxicity assay.

Conclusion: Promiscuous behavior of the HPV16E6 specific TCRbeta chain can in part be forced back into specific action in TCR transgenic T cells by codon modification in combination with the inclusion of an extra cysteine in the TCR chains.
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http://dx.doi.org/10.3233/CLO-2009-0493DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4619291PMC
June 2010

IFN-gamma-producing human invariant NKT cells promote tumor-associated antigen-specific cytotoxic T cell responses.

J Immunol 2008 Aug;181(4):2446-54

Department of Pathology, VU University Medical Center, Cancer Center Amsterdam, Amsterdam, The Netherlands.

CD1d-restricted invariant NKT (iNKT) cells can enhance immunity to cancer or prevent autoimmunity, depending on the cytokine profile secreted. Antitumor effects of the iNKT cell ligand alpha-galactosylceramide (alphaGC) and iNKT cell adoptive transfer have been demonstrated in various tumor models. Together with reduced numbers of iNKT cells in cancer patients, which have been linked to poor clinical outcome, these data suggest that cancer patients may benefit from therapy aiming at iNKT cell proliferation and activation. Herein we present results of investigations on the effects of human iNKT cells on Ag-specific CTL responses. iNKT cells were expanded using alphaGC-pulsed allogeneic DC derived from the acute myeloid leukemia cell line MUTZ-3, transduced with CD1d to enhance iNKT cell stimulation, and with IL-12 to stimulate type 1 cytokine production. Enhanced activation and increased IFN-gamma production was observed in iNKT cells, irrespective of CD4 expression, upon stimulation with IL-12-overexpressing dendritic cells. IL-12-stimulated iNKT cells strongly enhanced the MART-1 (melanoma Ag recognized by T cell 1)-specific CD8(+) CTL response, which was dependent on iNKT cell-derived IFN-gamma. Furthermore, autologous IL-12-overexpressing dendritic cells, loaded with Ag as well as alphaGC, was superior in stimulating both iNKT cells and Ag-specific CTL. This study shows that IL-12-overexpressing allogeneic dendritic cells expand IFN-gamma-producing iNKT cells, which may be more effective against tumors in vivo. Furthermore, the efficacy of autologous Ag-loaded DC vaccines may well be enhanced by IL-12 overexpression and loading with alphaGC.
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http://dx.doi.org/10.4049/jimmunol.181.4.2446DOI Listing
August 2008

Tumor associated antigen and interleukin-12 mRNA transfected dendritic cells enhance effector function of natural killer cells and antigen specific T-cells.

Clin Immunol 2008 Jun 21;127(3):375-84. Epub 2008 Mar 21.

VU University Medical Center, Department of Pathology, Amsterdam, The Netherlands.

Immunotherapy aiming at the combined activation of tumor associated antigen (TAA) specific cytotoxic T lymphocytes (CTL) and Natural Killer (NK) cells may be crucial to eradicate both MHC-I positive and negative tumors. Vaccination with mature dendritic cells (DC) transfected with mRNA encoding for TAA and the pro-inflammatory cytokines interleukin (IL)-12 and IL-18 may increase NK cell and TAA specific CTL activity. We demonstrate here that IL-12 over-expressing human DC induces increased NK cell activation and effector function and confirm the increase in TAA specific CTL by TAA/IL-12 double transfected DC. The effects of IL-18 transfection were limited to phenotypic activation and down-regulation of tissue homing receptors and did not add to the effect of IL-12 on NK cell effector function. In conclusion, co-transfection of TAA and IL-12 mRNA into mature DCs offers a vaccine for the induction of an anti-tumor immune response mediated by CTL and NK effector cells.
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http://dx.doi.org/10.1016/j.clim.2008.02.001DOI Listing
June 2008

Interleukin-12 increases proliferation and interferon-gamma production but not cytolytic activity of human antigen-specific effector memory cytotoxic T lymphocytes: power of the effect depends on the functional avidity of the T cell and the antigen concentration.

Hum Immunol 2005 Nov 3;66(11):1137-45. Epub 2006 Mar 3.

Department of Pathology, VU University Medical Center, Amsterdam, The Netherlands.

Cytotoxic T lymphocytes (CTLs) play an important role in the defense against viral infections and malignant diseases. Interleukin (IL)-12 plays a crucial role in induction of antigen-specific primary CTL responses and enhances proliferation, interferon-gamma (IFN-gamma) production, and cytolytic activity of mitogen-stimulated T cells. However, the effects of IL-12 on proliferation and effector functions of previously in vitro or in vivo primed antigen-specific CTLs are less clear. Our results show that IL-12 induces an increase in proliferation of and IFN-gamma production by influenza peptide-specific CTLs, but no increase in cytolytic activity on a per cell basis was observed in bulk cultures. Stimulation of a CTL clone confirmed these results; IL-12 supported an increase in IFN-gamma production, but did not increase cytolytic activity. The extent of the effect of IL-12 on IFN-gamma production differs per CTL clone and depends on the avidity of the clone and the peptide concentration on its target. Our data suggest that IL-12 is a good adjuvant for boosting CTL responses, in terms of proliferation and IFN-gamma production, the latter particularly for CTLs with low to intermediate avidity, such as tumor-associated self-antigen-specific CTLs.
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http://dx.doi.org/10.1016/j.humimm.2006.02.002DOI Listing
November 2005

Constitutively active STAT5b induces cytokine-independent growth of the acute myeloid leukemia-derived MUTZ-3 cell line and accelerates its differentiation into mature dendritic cells.

J Immunother 2006 Mar-Apr;29(2):188-200

Department of Pathology, Vrije Universiteit University Medical Center, Amsterdam, The Netherlands.

The CD34(+) human acute myeloid leukemia-derived cell line MUTZ-3 is dependent on hematopoietic growth factors for its proliferation and is able to differentiate into dendritic cells (DCs) in response to the combination of granulocyte-macrophage colony-stimulating factor, interleukin-4, and tumor necrosis factor-alpha. This cell line carries human leukocyte antigen (HLA)-A2.1, HLA-A3, and HLA-B44, which cover most of the caucasian population, and it could therefore be used as an off-the-shelf allogeneic DC-based vaccine. Signal transduction and activation of transcription (STAT) 5b is involved in cytokine signal transduction, particularly of cytokines involved in DC precursor growth and differentiation. The constitutively active form of STAT5b induced cytokine-independent growth of MUTZ-3 cells. Furthermore, STAT5b-transduced cells differentiated into mature DCs in 3 to 4 days after stimulation with DC differentiation-inducing cytokines, reducing the culture period to obtain mature DCs with 5 days compared with unmodified MUTZ-3-derived mature DC cultures. Both DC types expressed DC maturation markers and were equally effective in inducing primary T-cell responses. DCs derived from the STAT5b-transduced cells had a more stable mature phenotype after cytokine deprivation, which was reflected in a better performance in functional assays. In conclusion, these results show that STAT5b-transduced MUTZ-3 can be propagated in cytokine-free medium and rapidly differentiated into functional mature DCs that sustain a mature phenotype over a period of 3 to 5 days in the absence of differentiation-inducing cytokines. The simplified propagation and rapid differentiation into mature DCs may facilitate clinical application of this cell line as an allogeneic DC-based vaccine.
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http://dx.doi.org/10.1097/01.cji.0000197095.00359.67DOI Listing
May 2006

Codon modification of T cell receptors allows enhanced functional expression in transgenic human T cells.

Clin Immunol 2006 May 2;119(2):135-45. Epub 2006 Feb 2.

Department of Pathology, VU University Medical Center, de Boelelaan 1117, NL-1081 HV Amsterdam, The Netherlands.

Expression of native transgenic T cell receptors in recipient human T cells is often insufficient to achieve highly reactive T cell bulks. Here we show that codon modification of an HPV16E7-specific T cell receptor (TCR), together with omission of mRNA instability motifs and (cryptic) splice sites, leads to a dramatic increase in the expression levels of the transgenic TCRs in human CD8+ T cells. The codon-modified TCRs have been tested in three different configurations in the retroviral vector LZRS: (1) TCRalpha-IRES-GFP in combination with TCRbeta-IRES-NGFR, (2) TCRalpha-IRES-TCRbeta, and (3) TCRalpha-2A-TCRbeta. T cells carrying the codon-modified TCRs are functionally active against target cells loaded with relevant peptide, model tumor cells expressing the specific epitope as well as cervical carcinoma cells. The significant improvements we report here in the functional expression of specific human TCRs will hopefully expedite clinical application of TCR transfer-based immunotherapy.
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http://dx.doi.org/10.1016/j.clim.2005.12.009DOI Listing
May 2006

Antigen gene transfer to human plasmacytoid dendritic cells using recombinant adenovirus and vaccinia virus vectors.

Cell Oncol 2005 ;27(3):175-82

Department of Pathology, VU University Medical Center, 1081 HV Amsterdam, The Netherlands.

Recombinant adenoviruses (RAd) and recombinant vaccinia viruses (RVV) expressing tumour-associated antigens (TAA) are used as anti-tumour vaccines. It is important that these vaccines deliver the TAA to dendritic cells (DC) for the induction of a strong immune response. Infection of myeloid DC (MDC) with RAd alone is relatively inefficient but CD40 retargeting significantly increases transduction efficiency and DC maturation. Infection with RVV is efficient without DC maturation. Plasmacytoid dendritic cells (PDC) play a role in the innate immune response to viral infections through the secretion of IFNalpha but may also play a role in specific T-cell induction. The aim of our study was to investigate whether PDC are better targets for RAd and RVV based vaccines. RAd alone hardly infected PDC (2%) while CD40 retargeting did not improve transduction efficiency, but it did increase PDC maturation (25% CD83 positive cells). Accordingly, specific CTL activation by RAd infected PDC was limited (the number of IFNgamma producing CTL was reduced by 75% compared to stimulation with peptide loaded PDC). RVV infected PDC specifically stimulated CTL but PDC were not activated. These results indicate that PDC are not ideal targets for RAd and RVV based vaccines. However, PDC induced specific CTL activation after pulsing with recombinant protein, indicating that PDC can also cross-present antigens released from surrounding infected cells.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4617564PMC
http://dx.doi.org/10.1155/2005/753549DOI Listing
December 2005

Identification of a potential human telomerase reverse transcriptase-derived, HLA-A1-restricted cytotoxic T-lymphocyte epitope.

Cancer Immunol Immunother 2005 Jul 22;54(7):703-12. Epub 2005 Feb 22.

Department of Pathology, VU University Medical Center, de Boelelaan 1117, 1081 HV Amsterdam, The Netherlands.

The catalytic subunit of human telomerase reverse transcriptase (hTERT) is expressed in the majority of tumor cells of different histological origins as opposed to most normal somatic cells. This implicates hTERT as a widely expressed tumor-associated antigen and an attractive candidate for antigen-specific tumor immunotherapy. T lymphocytes specific for hTERT-derived epitopes have been isolated and shown reactive with hTERT-expressing tumor cells. To further increase the applicability of hTERT as a target antigen for immunotherapy, we set out to identify potential hTERT-derived, HLA-A1-restricted cytotoxic T-lymphocyte (CTL) epitopes. The "reverse immunology" approach, involving computer-assisted epitope prediction, in vitro CTL induction, and tetramer-guided CTL isolation, resulted in specific CTLs against hTERT-derived, HLA-A1-binding peptides. Intermediate- to low-avidity CTLs were induced against the hTERT325-333 peptide and recognized endogenously processed hTERT. Recognition of endogenous hTERT depended on an increase of hTERT expression above normal levels in tumor cells through hTERT transduction, most probably as a result of limited CTL avidity. The altered peptide ligand hTERT699T-707 was designed to increase HLA-A1-binding affinity of the hTERT699-707 peptide and was used to induce CTLs. However, these CTLs poorly cross-recognized native hTERT699-707 and failed to recognize endogenously processed hTERT. In conclusion, our study has identified the hTERT325-333 peptide as a potential hTERT-derived epitope that may prove useful for induction and monitoring of hTERT-specific, HLA-A1-restricted CTL responses.
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http://dx.doi.org/10.1007/s00262-004-0611-zDOI Listing
July 2005

Plasmacytoid dendritic cells are present in cervical carcinoma and become activated by human papillomavirus type 16 virus-like particles.

Gynecol Oncol 2005 Mar;96(3):897-901

Department of Pathology, VU University Medical Center, PO Box 7057, 1007 MB, Amsterdam, The Netherlands.

Objectives: Plasmacytoid dendritic cells (PDC) play an important role in the innate immune response to viral infections through the secretion of high levels of IFNalpha. We investigated whether PDC play a role in Human Papillomavirus (HPV) associated cervical carcinoma.

Methods: Frozen sections of 18 cervical carcinomas were analyzed for the presence of myeloid and plasmacytoid DC. To study whether the HPV virus can activate PDC, expression of putative VLP receptors (CD49f and CD16) was analyzed on PDC in peripheral blood mononuclear cells of healthy donors. Furthermore, CD83 induction and IFNalpha production by purified blood-derived PDC was measured after incubation with HPV 16 virus like particles (VLP).

Results: PDC were detected in 83% of the CxCa cases, primarily in the stroma. PDC express one of the putative VLP receptors (CD49f). IFNalpha production but no CD83 expression was induced in PDC upon incubation with VLP.

Conclusion: Our data suggest that PDC, which are at hand locally in the cervix, play a role in the natural immune response against HPV and identify PDC as possible targets for VLP-based vaccines.
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http://dx.doi.org/10.1016/j.ygyno.2004.10.040DOI Listing
March 2005

Preservation and redirection of HPV16E7-specific T cell receptors for immunotherapy of cervical cancer.

Clin Immunol 2005 Feb;114(2):119-29

Department of Pathology, VU University Medical Center, de Boelelaan 1117, 1081 HV Amsterdam, The Netherlands.

Human papilloma virus (HPV) type 16 infections of the genital tract are associated with the development of cervical cancer (CxCa) in women. HPV16-derived oncoproteins E6 and E7 are expressed constitutively in these lesions and might therefore be attractive candidates for T-cell-mediated adoptive immunotherapy. However, the low precursor frequency of HPV16E7-specific T cells in patients and healthy donors hampers routine isolation of these cells for adoptive transfer. To overcome this problem, we have isolated T cell receptor (TCR) genes from four different HPV16E7-specific healthy donor and patient-derived human cytotoxic T lymphocyte (CTL) clones. We examined whether genetic engineering of peripheral blood-derived CD8+ T cells in order to express HPV16E711-20-specific TCRs is feasible for adoptive transfer purposes. Reporter cells (Jurkat/MA) carrying a transgenic TCR were shown to bind relevant but not irrelevant tetramers. Moreover, these TCR-transgenic Jurkat/MA cells showed reactivity towards relevant target cells, indicating proper functional activity of the TCRs isolated from already available T cell clones. We next introduced an HPV16E711-20-specific TCR into blood-derived, CD8+ recipient T cells. Transgenic CTL clones stained positive for tetramers presenting the relevant HPV16E711-20 epitope and biological activity of the TCR in transduced CTL was confirmed by lytic activity and by interferon (IFN)-gamma secretion upon antigen-specific stimulation. Importantly, we show recognition of the endogenously processed and HLA-A2 presented HPV16E711-20 CTL epitope by A9-TCR-transgenic T cells. Collectively, our data indicate that HPV16E7 TCR gene transfer is feasible as an alternative strategy to generate human HPV16E7-specific T cells for the treatment of patients suffering from cervical cancer and other HPV16-induced malignancies.
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http://dx.doi.org/10.1016/j.clim.2004.11.005DOI Listing
February 2005

Different splice variants of filamin-B affect myogenesis, subcellular distribution, and determine binding to integrin [beta] subunits.

J Cell Biol 2002 Jan 21;156(2):361-76. Epub 2002 Jan 21.

Netherlands Cancer Institute, Division of Cell Biology, 1066 CX Amsterdams, Netherlands.

Integrins connect the extracellular matrix with the cell interior, and transduce signals through interactions of their cytoplasmic tails with cytoskeletal and signaling proteins. Using the yeast two-hybrid system, we isolated a novel splice variant (filamin-Bvar-1) of the filamentous actin cross-linking protein, filamin-B, that interacts with the cytoplasmic domain of the integrin beta1A and beta1D subunits. RT-PCR analysis showed weak, but wide, expression of filamin-Bvar-1 and a similar splice variant of filamin-A (filamin-Avar-1) in human tissues. Furthermore, alternative splice variants of filamin-B and filamin-C, from which the flexible hinge-1 region is deleted (DeltaH1), were induced during in vitro differentiation of C2C12 mouse myoblasts. We show that both filamin-Avar-1 and filamin-Bvar-1 bind more strongly than their wild-type isoforms to different integrin beta subunits. The mere presence of the high-affinity binding site for beta1A is not sufficient for targeting the filamin-Bvar-1 construct to focal contacts. Interestingly, the simultaneous deletion of the H1 region is required for the localization of filamin-B at the tips of actin stress fibers. When expressed in C2C12 cells, filamin-Bvar-1(DeltaH1) accelerates their differentiation into myotubes. Furthermore, filamin-B variants lacking the H1 region induce the formation of thinner myotubes than those in cells containing variants with this region. These findings suggest that specific combinations of filamin mRNA splicing events modulate the organization of the actin cytoskeleton and the binding affinity for integrins.
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http://dx.doi.org/10.1083/jcb.200103037DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2199218PMC
January 2002
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