American journal of reproductive immunology (New York, N.Y. : 1989), Jan 9, 2016
Human leukocyte antigen-G (HLA-G) expression is related to 14-bp insertion/deletion polymorphism ... more Human leukocyte antigen-G (HLA-G) expression is related to 14-bp insertion/deletion polymorphism at the 3'UTR of the HLA-G gene. Soluble forms of HLA-G are released as free molecules or via extracellular vesicles (EVs). Due to the crucial role of HLA-G during pregnancy, we analyzed the 14-bp polymorphism and the two secreted forms in implantation failure women (IF) and in fertile women (FW). For the genetic analysis, 49 IF and 34 FW were genotyped. For sHLA-G quantification, serum samples from 35 IF and 23 FW were available. ExoQuick(™) kit was used for EVs precipitation. The total soluble HLA-G (sHLA-Gtot ) and vesicular sHLA-GEV were quantified by ELISA. The EVs size and concentration were determined by nanoparticle tracking analysis (NTA). An increased proportion of IF presented high levels of sHLA-Gtot (P = 0.02) and vesicular sHLA-GEV (P = 0.0003) compared to FW. The 14-bp deletion allele is more frequent in IF (P = 0.0002) and associated with high levels of sHLA-Gtot and v...
Most of the current hematopoietic stem cell (HSC) -directed gene therapy applications have focuse... more Most of the current hematopoietic stem cell (HSC) -directed gene therapy applications have focused on the replacement of defective or deficient genes in an autologous setting. More recently HSC gene therapy applications have also included the enhancement or improvement of HSC features. Allogeneic HSCs have been used to facilitate and improve allogeneic transplantation and to achieve tolerance to transplanted cells, tissues or organs. Different gene transfer approaches addressing a variety of immunomodulatory mediators contributing to graft tolerance or immunological ignorance may have a critical role in improving long-term graft survival. Allogeneic tissues are frequently recognized by allospecific T cells as foreign and are rapidly rejected in the absence of immunosuppression. The higher susceptibility to cancer and infectious diseases of immunosuppressed patients led to investigation of new therapies to induce graft-specific tolerance. Peripheral tolerance to allogeneic grafts can be achieved by a variety of mechanisms including clonal deletion, suppression caused by regulatory T cells and anergy induction associated with microchimerism effect. In the last decades, potential candidates to confer allograft protection were identified. In this review, we summarize ongoing strategies and developments in genetic manipulation of cells, tissues and organs for allogeneic transplantation including modulating the effector arm of the immune response.
A major goal in hematopoietic stem cell (HSC) research is to define conditions for the expansion ... more A major goal in hematopoietic stem cell (HSC) research is to define conditions for the expansion of HSCs or multipotent progenitor cells (MPPs). Since human HSCs/MPPs cannot be isolated, NOD/SCID repopulating cell (SRC) assays emerged as the standard for the quantification of very primitive hematopoietic cell. However, in addition to HSCs/MPPs, lympho-myeloid primed progenitors (LMPPs) were recently found to contain SRC activities, challenging this assay as clear HSC/MPP readout. Because our revised model of human hematopoiesis predicts that HSCs/MPPs can be identified as CD133(+)CD34(+) cells containing erythroid potentials, we investigated the potential of human mesenchymal and conventional murine stromal cells to support expansion of HSCs/MPPs. Even though all stromal cells supported expansion of CD133(+)CD34(+) progenitors with long-term myeloid and long-term lymphoid potentials, erythroid potentials were exclusively found within erythro-myeloid CD133(low)CD34(+) cell fractions....
Extracellular vesicles (EVs), such as exosomes and microvesicles, are released by different cell ... more Extracellular vesicles (EVs), such as exosomes and microvesicles, are released by different cell types and participate in physiological and pathophysiological processes. EVs mediate intercellular communication as cell-derived extracellular signalling organelles that transmit specific information from their cell of origin to their target cells. As a result of these properties, EVs of defined cell types may serve as novel tools for various therapeutic approaches, including (a) anti-tumour therapy, (b) pathogen vaccination, (c) immune-modulatory and regenerative therapies and (d) drug delivery. The translation of EVs into clinical therapies requires the categorization of EV-based therapeutics in compliance with existing regulatory frameworks. As the classification defines subsequent requirements for manufacturing, quality control and clinical investigation, it is of major importance to define whether EVs are considered the active drug components or primarily serve as drug delivery vehi...
The nonclassical HLA-G molecule is a trophoblast-specific molecule present in almost every pregna... more The nonclassical HLA-G molecule is a trophoblast-specific molecule present in almost every pregnancy. It differs from classical HLA class I molecules by the low degree of allelic variants and the high diversity of protein structures. HLA-G is reported to be a tolerogenic molecule that acts on cells of both innate and adaptive immunity. At the maternal-fetal interface HLA-G seems to be responsible largely for the reprogramming of local maternal immune response. This review will focus on the HLA-G gene expression profile in pregnancy, in preimplantation embryos, and in human embryonic stem cells with emphasis on the structural diversity of the HLA-G protein and its potential functional and diagnostic implications.
This report describes how donor- and recipient-derived immunity was influenced by immunosuppressi... more This report describes how donor- and recipient-derived immunity was influenced by immunosuppressive treatment of ABO incompatibility (rituximab and immunoadsorption/plasmaphereses) in the long-term. We present an 8-year course of Hepatitis B virus (HBV) immunity, isohemagglutinins and B cell numbers. Whereas cellular HBV immunity was transferred from the HBV vaccinated donor (blood group A1) to the HBV naïve recipient (blood group 0), humoral HBV specific immune transfer was lacking. Starting at month 17 after transplantation, the recipient was vaccinated six times against HBV. Anti-HBs did not appear until the sixth vaccination at month 44. Immunoadsorption prior to transplantation reduced anti-A1 IgG titers from 256 to 2. Titers after transplantation remained low (⩽64). B cell numbers were below standard values up to month 26, then normalized and exceeded normal values from year 7 to 8 post transplantation. In conclusion, donor-derived B cell immunity was lost but recipient-derive...
: Although the initial concepts of stem cell therapy aimed at replacing lost tissue, more recent ... more : Although the initial concepts of stem cell therapy aimed at replacing lost tissue, more recent evidence has suggested that stem and progenitor cells alike promote postischemic neurological recovery by secreted factors that restore the injured brain's capacity to reshape. Specifically, extracellular vesicles (EVs) derived from stem cells such as exosomes have recently been suggested to mediate restorative stem cell effects. In order to define whether EVs indeed improve postischemic neurological impairment and brain remodeling, we systematically compared the effects of mesenchymal stem cell (MSC)-derived EVs (MSC-EVs) with MSCs that were i.v. delivered to mice on days 1, 3, and 5 (MSC-EVs) or on day 1 (MSCs) after focal cerebral ischemia in C57BL6 mice. For as long as 28 days after stroke, motor coordination deficits, histological brain injury, immune responses in the peripheral blood and brain, and cerebral angiogenesis and neurogenesis were analyzed. Improved neurological impairment and long-term neuroprotection associated with enhanced angioneurogenesis were noticed in stroke mice receiving EVs from two different bone marrow-derived MSC lineages. MSC-EV administration closely resembled responses to MSCs and persisted throughout the observation period. Although cerebral immune cell infiltration was not affected by MSC-EVs, postischemic immunosuppression (i.e., B-cell, natural killer cell, and T-cell lymphopenia) was attenuated in the peripheral blood at 6 days after ischemia, providing an appropriate external milieu for successful brain remodeling. Because MSC-EVs have recently been shown to be apparently safe in humans, the present study provides clinically relevant evidence warranting rapid proof-of-concept studies in stroke patients. Transplantation of mesenchymal stem cells (MSCs) offers an interesting adjuvant approach next to thrombolysis for treatment of ischemic stroke. However, MSCs are not integrated into residing neural networks but act indirectly, inducing neuroprotection and promoting neuroregeneration. Although the mechanisms by which MSCs act are still elusive, recent evidence has suggested that extracellular vesicles (EVs) might be responsible for MSC-induced effects under physiological and pathological conditions. The present study has demonstrated that EVs are not inferior to MSCs in a rodent stroke model. EVs induce long-term neuroprotection, promote neuroregeneration and neurological recovery, and modulate peripheral post-stroke immune responses. Also, because EVs are well-tolerated in humans, as previously reported, the administration of EVs under clinical settings might set the path for a novel and innovative therapeutic stroke concept without the putative side effects attached to stem cell transplantation.
The success of haematopoietic stem cell (HSC) transplantation largely depends on numbers of trans... more The success of haematopoietic stem cell (HSC) transplantation largely depends on numbers of transplanted HSCs, which reside in the CD34(+) populations of bone marrow (BM), peripheral blood stem cells (PBSC) and umbilical cord blood (UCB). More specifically HSCs reside in the CD38(low/-) subpopulation, which cannot be objectively discriminated from mature CD34(+) CD38(+) progenitors. Thus, better marker combinations for the quantification of more primitive haematopoietic stem and progenitor cells in transplants are required. Recently, by combining CD34 and CD133 we could clearly distinguish CD133(+) CD34(+) multipotent and lympho-myeloid from CD133(low) CD34(+) erythro-myeloid progenitors in UCB samples. To qualify the assessment of CD133 for routine quality control of adult HSC sources, we analysed the developmental potentials of CD133(+) and CD133(low) subpopulations in BM and PBSC. Similar to UCB, CD133 expression objectively discriminated functionally distinct subpopulations i...
Cell, tissue, and organ transplants are commonly performed for the treatment of different disease... more Cell, tissue, and organ transplants are commonly performed for the treatment of different diseases. However, major histocompatibility complex (MHC) diversity often prevents complete donor-recipient matching, resulting in graft rejection. This study evaluates in a preclinical model the capacity of MHC class I-silenced cells to engraft and grow upon allogeneic transplantation. Short hairpin RNA targeting β2-microglobulin (RN_shβ2m) was delivered into fibroblasts derived from LEW/Ztm (RT1(l)) (RT1-A(l)) rats using a lentiviral-based vector. MHC class I (RT1-A-) expressing and -silenced cells were injected subcutaneously in LEW rats (RT1(l)) and MHC-congenic LEW.1W rats (RT1(u)), respectively. Cell engraftment and the status of the immune response were monitored for eight weeks after transplantation. In contrast to RT1-A-expressing cells, RT1-A-silenced fibroblasts became engrafted and were still detectable eight weeks after allogeneic transplantation. Plasma levels of proinflammatory c...
Clinical cancer research : an official journal of the American Association for Cancer Research, Jan 15, 2014
CD8(+) T lymphocytes can kill autologous melanoma cells, but their activity is impaired when poor... more CD8(+) T lymphocytes can kill autologous melanoma cells, but their activity is impaired when poorly immunogenic tumor phenotypes evolve in the course of disease progression. Here, we analyzed three consecutive melanoma lesions obtained within one year of developing stage IV disease for their recognition by autologous T cells. One skin (Ma-Mel-48a) and two lymph node (Ma-Mel-48b, Ma-Mel-48c) metastases were analyzed for T-cell infiltration. Melanoma cell lines established from the respective lesions were characterized, determining the T-cell-stimulatory capacity, expression of surface molecules involved in T-cell activation, and specific genetic alterations affecting the tumor-T-cell interaction. Metastases Ma-Mel-48a and Ma-Mel-48b, in contrast with Ma-Mel-48c, were infiltrated by T cells. The T-cell-stimulatory capacity was found to be strong for Ma-Mel-48a, lower for Ma-Mel-48b, and completely abrogated for Ma-Mel-48c cells. The latter proved to be HLA class I-negative due to an i...
The goal of the StemNet Project (http://www.stemnet.de) is to develop a knowledge management syst... more The goal of the StemNet Project (http://www.stemnet.de) is to develop a knowledge management system for Hematopoietic Stem Cell Transplantation and Immunogenetics [1] in order to assist biomedical researchers and practitioners in finding relevant information. The evolving knowledge service goes beyond tradtional approaches in that enables a targeted and fine-grained search for relevant biomedical entities (e.g. various protein functions, different types of immune cells, various sorts of antigens, blood diseases, clinical outcomes, etc.) in unstructured biomedical free text, in particular PubMed abstracts. At the same time, this information is linked to relevant biological database and ontology entries, such as UniProt, Entrez Gene, dbSNP, the Gene Ontology, the Sequence Ontology, and the Cell Ontology (see http://obo.sourceforge.net). Thus, StemNet enables the linking of heterogenuous knowledge sources to which the user only had separate access before.
We have recently shown that kidney transplant recipients with clinically stable condition can pro... more We have recently shown that kidney transplant recipients with clinically stable condition can produce almost normal antibody concentrations at month 1 after vaccination against Streptococcus pneumoniae. It was the aim of the present study to define the long-term efficacy of this vaccination in a similar cohort. Using Pneumovax 23, we immunized 49 kidney transplant recipients (21 women and 28 men, aged 29-74 years). Antibodies against 14 pneumococcal serotypes were determined before vaccination and at months 1 and 15 after vaccination by Luminex assay. The total antibody concentration (median [range]) increased from 18.2 mg/L (2.9-55.5 mg/L) before vaccination to 53.6 mg/L (4.5-132.4 mg/L) at month 1 and 41.3 mg/L (4.9-105.0 mg/L) at month 15 (P<0.0001 as compared with before vaccination). The antibody concentration at month 15 was 77% of the response at month 1. The number of pneumococcal serotypes recognized was 8 (0-13) before vaccination, 13 (0-14) at month 1, and 11 (0-14) at month 15. At month 15, the total antibody concentration and the number of serotypes with protective antibodies already displayed a significant decrease (P<0.0001 each) as compared with month 1. It could be shown that the decrease in antibody concentrations (months 1-15) was minor in younger patients, in women, in patients receiving cyclosporine A versus tacrolimus, and in patients with better kidney function. Our results demonstrate that, at month 15 after vaccination versus before vaccination, kidney transplant recipients with clinically stable condition still display higher antibody concentrations against pneumococci. Therefore, they should be partly protected against pneumococcal infection until month 15.
Mycophenolic acid (MPA) is the pharmacologically active compound of the immunosuppressive drug my... more Mycophenolic acid (MPA) is the pharmacologically active compound of the immunosuppressive drug mycophenolate mofetil. Dendritic cells (DC) are the key to initiating and priming the adaptive immune response leading to allograft rejection. We investigated the effects of MPA on human blood myeloid DC (MDC) homeostasis with a particular emphasis on their trafficking properties. Isolated peripheral blood mononuclear cells from healthy donors were cultured with MPA for 48 hr without the addition of exogenous growth factors. Flow cytometry was used for phenotypic and functional analysis of MDC within the cultured peripheral blood mononuclear cells population. Freshly isolated MDC were used for assessment of endocytotic and allostimulatory properties. Exposure to MPA decreased the expression of CC chemokine receptor (CCR)7 and increased the expression of CCR1 in MDC. In line with their CCR expression profile, MPA-treated MDC showed an enhanced migration toward inflammatory chemokines, whereas their migratory response toward lymph node chemokines decreased. MDC cultured with MPA exhibited an immature phenotype with higher endocytotic capacity, an impaired activation in response to toll-like receptor 3 ligation and loss of capacity to stimulate allogenic T cells in mixed lymphocyte reactions. MPA interferes with the initiation of acquired immunity and thus may promote allograft tolerance.
American journal of reproductive immunology (New York, N.Y. : 1989), Jan 9, 2016
Human leukocyte antigen-G (HLA-G) expression is related to 14-bp insertion/deletion polymorphism ... more Human leukocyte antigen-G (HLA-G) expression is related to 14-bp insertion/deletion polymorphism at the 3'UTR of the HLA-G gene. Soluble forms of HLA-G are released as free molecules or via extracellular vesicles (EVs). Due to the crucial role of HLA-G during pregnancy, we analyzed the 14-bp polymorphism and the two secreted forms in implantation failure women (IF) and in fertile women (FW). For the genetic analysis, 49 IF and 34 FW were genotyped. For sHLA-G quantification, serum samples from 35 IF and 23 FW were available. ExoQuick(™) kit was used for EVs precipitation. The total soluble HLA-G (sHLA-Gtot ) and vesicular sHLA-GEV were quantified by ELISA. The EVs size and concentration were determined by nanoparticle tracking analysis (NTA). An increased proportion of IF presented high levels of sHLA-Gtot (P = 0.02) and vesicular sHLA-GEV (P = 0.0003) compared to FW. The 14-bp deletion allele is more frequent in IF (P = 0.0002) and associated with high levels of sHLA-Gtot and v...
Most of the current hematopoietic stem cell (HSC) -directed gene therapy applications have focuse... more Most of the current hematopoietic stem cell (HSC) -directed gene therapy applications have focused on the replacement of defective or deficient genes in an autologous setting. More recently HSC gene therapy applications have also included the enhancement or improvement of HSC features. Allogeneic HSCs have been used to facilitate and improve allogeneic transplantation and to achieve tolerance to transplanted cells, tissues or organs. Different gene transfer approaches addressing a variety of immunomodulatory mediators contributing to graft tolerance or immunological ignorance may have a critical role in improving long-term graft survival. Allogeneic tissues are frequently recognized by allospecific T cells as foreign and are rapidly rejected in the absence of immunosuppression. The higher susceptibility to cancer and infectious diseases of immunosuppressed patients led to investigation of new therapies to induce graft-specific tolerance. Peripheral tolerance to allogeneic grafts can be achieved by a variety of mechanisms including clonal deletion, suppression caused by regulatory T cells and anergy induction associated with microchimerism effect. In the last decades, potential candidates to confer allograft protection were identified. In this review, we summarize ongoing strategies and developments in genetic manipulation of cells, tissues and organs for allogeneic transplantation including modulating the effector arm of the immune response.
A major goal in hematopoietic stem cell (HSC) research is to define conditions for the expansion ... more A major goal in hematopoietic stem cell (HSC) research is to define conditions for the expansion of HSCs or multipotent progenitor cells (MPPs). Since human HSCs/MPPs cannot be isolated, NOD/SCID repopulating cell (SRC) assays emerged as the standard for the quantification of very primitive hematopoietic cell. However, in addition to HSCs/MPPs, lympho-myeloid primed progenitors (LMPPs) were recently found to contain SRC activities, challenging this assay as clear HSC/MPP readout. Because our revised model of human hematopoiesis predicts that HSCs/MPPs can be identified as CD133(+)CD34(+) cells containing erythroid potentials, we investigated the potential of human mesenchymal and conventional murine stromal cells to support expansion of HSCs/MPPs. Even though all stromal cells supported expansion of CD133(+)CD34(+) progenitors with long-term myeloid and long-term lymphoid potentials, erythroid potentials were exclusively found within erythro-myeloid CD133(low)CD34(+) cell fractions....
Extracellular vesicles (EVs), such as exosomes and microvesicles, are released by different cell ... more Extracellular vesicles (EVs), such as exosomes and microvesicles, are released by different cell types and participate in physiological and pathophysiological processes. EVs mediate intercellular communication as cell-derived extracellular signalling organelles that transmit specific information from their cell of origin to their target cells. As a result of these properties, EVs of defined cell types may serve as novel tools for various therapeutic approaches, including (a) anti-tumour therapy, (b) pathogen vaccination, (c) immune-modulatory and regenerative therapies and (d) drug delivery. The translation of EVs into clinical therapies requires the categorization of EV-based therapeutics in compliance with existing regulatory frameworks. As the classification defines subsequent requirements for manufacturing, quality control and clinical investigation, it is of major importance to define whether EVs are considered the active drug components or primarily serve as drug delivery vehi...
The nonclassical HLA-G molecule is a trophoblast-specific molecule present in almost every pregna... more The nonclassical HLA-G molecule is a trophoblast-specific molecule present in almost every pregnancy. It differs from classical HLA class I molecules by the low degree of allelic variants and the high diversity of protein structures. HLA-G is reported to be a tolerogenic molecule that acts on cells of both innate and adaptive immunity. At the maternal-fetal interface HLA-G seems to be responsible largely for the reprogramming of local maternal immune response. This review will focus on the HLA-G gene expression profile in pregnancy, in preimplantation embryos, and in human embryonic stem cells with emphasis on the structural diversity of the HLA-G protein and its potential functional and diagnostic implications.
This report describes how donor- and recipient-derived immunity was influenced by immunosuppressi... more This report describes how donor- and recipient-derived immunity was influenced by immunosuppressive treatment of ABO incompatibility (rituximab and immunoadsorption/plasmaphereses) in the long-term. We present an 8-year course of Hepatitis B virus (HBV) immunity, isohemagglutinins and B cell numbers. Whereas cellular HBV immunity was transferred from the HBV vaccinated donor (blood group A1) to the HBV naïve recipient (blood group 0), humoral HBV specific immune transfer was lacking. Starting at month 17 after transplantation, the recipient was vaccinated six times against HBV. Anti-HBs did not appear until the sixth vaccination at month 44. Immunoadsorption prior to transplantation reduced anti-A1 IgG titers from 256 to 2. Titers after transplantation remained low (⩽64). B cell numbers were below standard values up to month 26, then normalized and exceeded normal values from year 7 to 8 post transplantation. In conclusion, donor-derived B cell immunity was lost but recipient-derive...
: Although the initial concepts of stem cell therapy aimed at replacing lost tissue, more recent ... more : Although the initial concepts of stem cell therapy aimed at replacing lost tissue, more recent evidence has suggested that stem and progenitor cells alike promote postischemic neurological recovery by secreted factors that restore the injured brain's capacity to reshape. Specifically, extracellular vesicles (EVs) derived from stem cells such as exosomes have recently been suggested to mediate restorative stem cell effects. In order to define whether EVs indeed improve postischemic neurological impairment and brain remodeling, we systematically compared the effects of mesenchymal stem cell (MSC)-derived EVs (MSC-EVs) with MSCs that were i.v. delivered to mice on days 1, 3, and 5 (MSC-EVs) or on day 1 (MSCs) after focal cerebral ischemia in C57BL6 mice. For as long as 28 days after stroke, motor coordination deficits, histological brain injury, immune responses in the peripheral blood and brain, and cerebral angiogenesis and neurogenesis were analyzed. Improved neurological impairment and long-term neuroprotection associated with enhanced angioneurogenesis were noticed in stroke mice receiving EVs from two different bone marrow-derived MSC lineages. MSC-EV administration closely resembled responses to MSCs and persisted throughout the observation period. Although cerebral immune cell infiltration was not affected by MSC-EVs, postischemic immunosuppression (i.e., B-cell, natural killer cell, and T-cell lymphopenia) was attenuated in the peripheral blood at 6 days after ischemia, providing an appropriate external milieu for successful brain remodeling. Because MSC-EVs have recently been shown to be apparently safe in humans, the present study provides clinically relevant evidence warranting rapid proof-of-concept studies in stroke patients. Transplantation of mesenchymal stem cells (MSCs) offers an interesting adjuvant approach next to thrombolysis for treatment of ischemic stroke. However, MSCs are not integrated into residing neural networks but act indirectly, inducing neuroprotection and promoting neuroregeneration. Although the mechanisms by which MSCs act are still elusive, recent evidence has suggested that extracellular vesicles (EVs) might be responsible for MSC-induced effects under physiological and pathological conditions. The present study has demonstrated that EVs are not inferior to MSCs in a rodent stroke model. EVs induce long-term neuroprotection, promote neuroregeneration and neurological recovery, and modulate peripheral post-stroke immune responses. Also, because EVs are well-tolerated in humans, as previously reported, the administration of EVs under clinical settings might set the path for a novel and innovative therapeutic stroke concept without the putative side effects attached to stem cell transplantation.
The success of haematopoietic stem cell (HSC) transplantation largely depends on numbers of trans... more The success of haematopoietic stem cell (HSC) transplantation largely depends on numbers of transplanted HSCs, which reside in the CD34(+) populations of bone marrow (BM), peripheral blood stem cells (PBSC) and umbilical cord blood (UCB). More specifically HSCs reside in the CD38(low/-) subpopulation, which cannot be objectively discriminated from mature CD34(+) CD38(+) progenitors. Thus, better marker combinations for the quantification of more primitive haematopoietic stem and progenitor cells in transplants are required. Recently, by combining CD34 and CD133 we could clearly distinguish CD133(+) CD34(+) multipotent and lympho-myeloid from CD133(low) CD34(+) erythro-myeloid progenitors in UCB samples. To qualify the assessment of CD133 for routine quality control of adult HSC sources, we analysed the developmental potentials of CD133(+) and CD133(low) subpopulations in BM and PBSC. Similar to UCB, CD133 expression objectively discriminated functionally distinct subpopulations i...
Cell, tissue, and organ transplants are commonly performed for the treatment of different disease... more Cell, tissue, and organ transplants are commonly performed for the treatment of different diseases. However, major histocompatibility complex (MHC) diversity often prevents complete donor-recipient matching, resulting in graft rejection. This study evaluates in a preclinical model the capacity of MHC class I-silenced cells to engraft and grow upon allogeneic transplantation. Short hairpin RNA targeting β2-microglobulin (RN_shβ2m) was delivered into fibroblasts derived from LEW/Ztm (RT1(l)) (RT1-A(l)) rats using a lentiviral-based vector. MHC class I (RT1-A-) expressing and -silenced cells were injected subcutaneously in LEW rats (RT1(l)) and MHC-congenic LEW.1W rats (RT1(u)), respectively. Cell engraftment and the status of the immune response were monitored for eight weeks after transplantation. In contrast to RT1-A-expressing cells, RT1-A-silenced fibroblasts became engrafted and were still detectable eight weeks after allogeneic transplantation. Plasma levels of proinflammatory c...
Clinical cancer research : an official journal of the American Association for Cancer Research, Jan 15, 2014
CD8(+) T lymphocytes can kill autologous melanoma cells, but their activity is impaired when poor... more CD8(+) T lymphocytes can kill autologous melanoma cells, but their activity is impaired when poorly immunogenic tumor phenotypes evolve in the course of disease progression. Here, we analyzed three consecutive melanoma lesions obtained within one year of developing stage IV disease for their recognition by autologous T cells. One skin (Ma-Mel-48a) and two lymph node (Ma-Mel-48b, Ma-Mel-48c) metastases were analyzed for T-cell infiltration. Melanoma cell lines established from the respective lesions were characterized, determining the T-cell-stimulatory capacity, expression of surface molecules involved in T-cell activation, and specific genetic alterations affecting the tumor-T-cell interaction. Metastases Ma-Mel-48a and Ma-Mel-48b, in contrast with Ma-Mel-48c, were infiltrated by T cells. The T-cell-stimulatory capacity was found to be strong for Ma-Mel-48a, lower for Ma-Mel-48b, and completely abrogated for Ma-Mel-48c cells. The latter proved to be HLA class I-negative due to an i...
The goal of the StemNet Project (http://www.stemnet.de) is to develop a knowledge management syst... more The goal of the StemNet Project (http://www.stemnet.de) is to develop a knowledge management system for Hematopoietic Stem Cell Transplantation and Immunogenetics [1] in order to assist biomedical researchers and practitioners in finding relevant information. The evolving knowledge service goes beyond tradtional approaches in that enables a targeted and fine-grained search for relevant biomedical entities (e.g. various protein functions, different types of immune cells, various sorts of antigens, blood diseases, clinical outcomes, etc.) in unstructured biomedical free text, in particular PubMed abstracts. At the same time, this information is linked to relevant biological database and ontology entries, such as UniProt, Entrez Gene, dbSNP, the Gene Ontology, the Sequence Ontology, and the Cell Ontology (see http://obo.sourceforge.net). Thus, StemNet enables the linking of heterogenuous knowledge sources to which the user only had separate access before.
We have recently shown that kidney transplant recipients with clinically stable condition can pro... more We have recently shown that kidney transplant recipients with clinically stable condition can produce almost normal antibody concentrations at month 1 after vaccination against Streptococcus pneumoniae. It was the aim of the present study to define the long-term efficacy of this vaccination in a similar cohort. Using Pneumovax 23, we immunized 49 kidney transplant recipients (21 women and 28 men, aged 29-74 years). Antibodies against 14 pneumococcal serotypes were determined before vaccination and at months 1 and 15 after vaccination by Luminex assay. The total antibody concentration (median [range]) increased from 18.2 mg/L (2.9-55.5 mg/L) before vaccination to 53.6 mg/L (4.5-132.4 mg/L) at month 1 and 41.3 mg/L (4.9-105.0 mg/L) at month 15 (P<0.0001 as compared with before vaccination). The antibody concentration at month 15 was 77% of the response at month 1. The number of pneumococcal serotypes recognized was 8 (0-13) before vaccination, 13 (0-14) at month 1, and 11 (0-14) at month 15. At month 15, the total antibody concentration and the number of serotypes with protective antibodies already displayed a significant decrease (P<0.0001 each) as compared with month 1. It could be shown that the decrease in antibody concentrations (months 1-15) was minor in younger patients, in women, in patients receiving cyclosporine A versus tacrolimus, and in patients with better kidney function. Our results demonstrate that, at month 15 after vaccination versus before vaccination, kidney transplant recipients with clinically stable condition still display higher antibody concentrations against pneumococci. Therefore, they should be partly protected against pneumococcal infection until month 15.
Mycophenolic acid (MPA) is the pharmacologically active compound of the immunosuppressive drug my... more Mycophenolic acid (MPA) is the pharmacologically active compound of the immunosuppressive drug mycophenolate mofetil. Dendritic cells (DC) are the key to initiating and priming the adaptive immune response leading to allograft rejection. We investigated the effects of MPA on human blood myeloid DC (MDC) homeostasis with a particular emphasis on their trafficking properties. Isolated peripheral blood mononuclear cells from healthy donors were cultured with MPA for 48 hr without the addition of exogenous growth factors. Flow cytometry was used for phenotypic and functional analysis of MDC within the cultured peripheral blood mononuclear cells population. Freshly isolated MDC were used for assessment of endocytotic and allostimulatory properties. Exposure to MPA decreased the expression of CC chemokine receptor (CCR)7 and increased the expression of CCR1 in MDC. In line with their CCR expression profile, MPA-treated MDC showed an enhanced migration toward inflammatory chemokines, whereas their migratory response toward lymph node chemokines decreased. MDC cultured with MPA exhibited an immature phenotype with higher endocytotic capacity, an impaired activation in response to toll-like receptor 3 ligation and loss of capacity to stimulate allogenic T cells in mixed lymphocyte reactions. MPA interferes with the initiation of acquired immunity and thus may promote allograft tolerance.
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Papers by Peter Horn