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Hans Kreipe

Publications and source records attributed to Hans Kreipe.

At least 37 records · Page 2Linked to original sources
PubMed2005

Micronodular thymoma: an epithelial tumour with abnormal chemokine expression setting the stage for lymphoma development.

The aetiology of primary B-cell lymphomas of the thymus is enigmatic. Although thymic follicular lymphoid hyperplasia (TFH) is commonly associated with myasthenia gravis (MG), lymphoma is not a complication of this condition. The present paper reports a high frequency of monoclonal B-cell populations (6 of 18 cases; 33%) in micronodular thymoma (MNT), a peculiar thymic epithelial neoplasm with a B-cell-rich stroma, while B cells were consistently polyclonal in TFH (25 cases) and other types of thymomas (15 cases) (p < 0.001). An intratumoural lymphoma could be identified in three of the six monoclonal MNTs. Sequencing of the monoclonal IgH chain revealed partially overlapping VDJ gene usage in MNT and thymic mucosa-associated lymphoid tissue (MALT) lymphomas. The neoplastic epithelium of MNTs, but not of TFH and other types of thymoma, expressed high levels of dendritic cell, T-cell, and B-cell chemoattractants, such as CCL18, CCR6, and CCL20. It is concluded that abnormal chemokine expression in an epithelial tumour, MNT, can promote the recruitment of MALT, the emergence of monoclonal B cells, and, eventually, the subsequent development of mediastinal lymphomas. More generally, the concept that expression of a 'high-risk' spectrum of chemokines due to local or genetic factors may interfere with B-cell homeostasis and may contribute to MALT lymphoma development in chronic inflammatory states is proposed.

Adult↗
PubMed2005

BCR-ABL gene amplification and overexpression in a patient with chronic myeloid leukemia treated with imatinib.

Imatinib mesylate was designed as an inhibitor targeting the BCR-ABL tyrosine kinase, the molecular counterpart of the Philadelphia translocation t(9;22)(q34;q11). We report on a patient with chronic myeloid leukemia (CML) undergoing acceleration during imatinib treatment. Cytogenetic analysis revealed four different cell populations: 46,XX,t(9;22)(q34;q11),der(18)t(2;18)(p11;p11)[1]/47,idem,i(17)(q10),-der(18)t(2;18),+der(22)t(9;22)[1]/46,idem,-t(9;22),der(9)t(9;22),ider(22)t(9;22)[12]/ 47,idem,-t(9;22),der(9)t(9;22),+22,ider(22)t(9;22)x2[1]. FISH analysis confirmed the presence of these four clones. Moreover, 49% of the interphase nuclei contained either one or two clustered fusion signals, indicating a low-level amplification of the BCR-ABL fusion gene. With quantitative real-time RT-PCR, a BCR-ABL/G6PDH ratio of 0.8 was determined, which is comparable to that measured in the K562 cell line with a known BCR-ABL amplification and which is increased by more than about 60-fold compared to a CML at diagnosis with >80% Philadelphia-positive cells. We give further evidence that the genomic BCR-ABL amplification results in an increased level of BCR-ABL transcript linking two potent mechanisms of resistance against imatinib treatment.

Aged↗
PubMed2005

Up-regulation of DNA methyltransferases DNMT1, 3A, and 3B in myelodysplastic syndrome.

Analyzing bone marrow trephines from (myelodysplastic syndrome) MDS patients we show for the first time strong over-expression of the DNA methyltransferases 1, and 3A (and 3B to a much lesser extent) in the myelodysplastic syndrome FAB subtypes refractory anaemia (RA) and refractory anaemia with excess of blasts (RAEB). The increase in mRNA expression was much less pronounced in refractory anaemia with ringed sideroblasts (RARS). Classification according to the new WHO guidelines revealed distinct differences between RCMD and RARS. This elevated mRNA expression most probably contributes to the frequently found aberrant hypermethylation in MDS and might explain the promising clinical response of MDS patients treated with DNMT inhibitors.

Biopsy, Needle↗
PubMed2005

Absence of p21(CIP 1), p27(KIP 1) and p 57(KIP 2) methylation in MDS and AML.

Transcriptional silencing of tumour suppressor genes (TSG) due to hypermethylation is a common event in human tumours. The three members of the KIP/CIP family of cyclin dependent kinase inhibitors (CDKIs), p21(CIP 1), p27(KIP 1), and p 57(KIP 2), play key roles in cell cycle regulation, but little is known about their methylation in myeloid neoplasia. Therefore, we analysed 9 haematopoietic cell lines, 67 myelodysplastic syndrome (MDS) and 26 acute myeloid leukaemia (AML) cases as well as 11 controls. p 57(KIP 2) hypermethylation was found in 4/9 cell lines, but methylation of p21(CIP 1) and p27(KIP 1) was infrequent. All patient samples analysed were methylation-negative for these three genes.

Acute Disease↗
PubMed2005

Osteosclerosis in advanced chronic idiopathic myelofibrosis is associated with endothelial overexpression of osteoprotegerin.

Advanced chronic idiopathic myelofibrosis (IMF) with osteosclerosis and increase and thickening of bone trabeculae is typically contrasted by the absence or sparse presence of osteoclasts. Because osteoclast formation can be inhibited by osteoprotegerin (OPG) we investigated OPG expression in IMF with severe fibrosis and osteosclerosis, which expressed significantly higher (up to 71-fold) OPG mRNA levels when compared with prefibrotic cellular IMF and control cases. The receptor activator of nuclear factor kappaB ligand (RANKL), a positive regulator of osteoclast differentiation and putative antagonist of OPG was overexpressed by up to 34-fold exclusively in advanced IMF. Case-specific calculation of the RANKL/OPG ratio in advanced IMF showed a wide range without significant differences when compared with the prefibrotic IMF and non-neoplastic haematopoiesis. Immunohistochemical detection of OPG protein revealed strong labelling of endothelial cells within proliferating vessels in fibrotic IMF and heterogeneously labelled megakaryocytes, and fibroblasts. Osteosclerosis and impaired osteoclast function in IMF appears to be associated with upregulated endothelial OPG expression but concomitant reduction of the antagonist RANKL could not be demonstrated. We conclude that osteosclerosis in IMF is associated with increased endothelial OPG expression without concomitant RANKL downregulation.

Adult↗
PubMed2005

Hypermethylation of the suppressor of cytokine signalling-1 (SOCS-1) in myelodysplastic syndrome.

Transcriptional silencing because of hypermethylation is now recognised to be a hallmark of human tumours. In contrast to acute myeloid leukaemia (AML), comparably little is known about aberrant methylation in myelodysplastic syndrome (MDS), a heterogeneous clonal stem cell disorder with a risk of transformation into secondary AML of up to 30%. Recent evidence demonstrates that suppressor of cytokine signalling SOCS-1, a negative regulator of cytokine pathways, may act as a tumour suppressor gene, and inactivation because of hypermethylation was shown in various malignancies. Employing a newly developed quantitative real-time polymerase chain reaction-based methylation assay we analysed, for the first time, SOCS-1 methylation in MDS and found disease-specific hypermethylation in 27 of 86 MDS patients (31%). Demethylation experiments provided direct evidence that aberrant methylation of SOCS-1 induces transcriptional silencing in myeloid cells. In addition, by analysing the expression of signal transducers and activators of transcription (STAT)-induced genes we provide for the first time evidence that the activity of the Janus kinase/STAT pathway is increased in primary patient samples showing SOCS-1 hypermethylation.

Acute Disease↗
PubMed2005

Quantitative mRNA expression analysis of co-stimulatory molecules in sequential biopsies from heart allografts.

Allograft-specific T-cell activation requires two signals, "signal one" via the T-cell receptor and "signal two" via costimulatory pathways. Animal models provide promising data that blockade of costimulatory signals can lead to T-cell anergy and tolerance. We analyzed 72 formalin-fixed and paraffin-embedded sequential heart allograft biopsies from 22 patients by quantitative real-time reverse transcriptase-polymerase chain reaction for the mRNA expression of the costimulatory molecules CD28, CD80, CD86, CD40, and CD154. mRNA expression levels were correlated to histological grade and time-point of rejection. mRNA expression of costimulatory molecules predominantly expressed by antigen-presenting cells (CD80, CD86, CD40), correlated with histological grade of cell-mediated acute rejection. Costimulatory molecules were up-regulated not only during rejection episodes early after transplantation, but also at late occurring rejection. The present results suggest a simultaneous and long-term therapeutical blockade of more than one costimulatory pathway for the prevention of repetitive T-cell mediated acute rejection episodes after heart transplantation.

Adult↗
PubMed2005

Risk factors for chronic allograft nephropathy after renal transplantation: a protocol biopsy study.

BACKGROUND: Chronic allograft nephropathy (CAN) leads to chronic allograft dysfunction and loss. Regular renal transplant biopsies may be useful to find risk factors for CAN. METHODS: We carried out 688 protocol biopsies in 258 patients at 6, 12, and 26 weeks after renal transplantation. Patients with signs of CAN in the biopsy 3 (N= 70, CAN group), and those without (N= 120, non-CAN group), were compared. RESULTS: Chronic tubulointerstitial changes increased from biopsy 1 to 3 (5% vs. 37%, P < 0.0001). Fifty-six of 190 patients had acute rejection within 6 months (30%), 33 of which were found in protocol biopsies (17%). On univariate analysis, the CAN group had CAN more often at biopsy 2 than the non-CAN group (23% vs. 4%, P < 0.0001), had a lower calculated creatinine clearance at biopsy 1 and 2 (49.4 +/- 25.8 vs. 57 +/- 20.2 mL/min, P= 0.01; 47.3 +/- 21.2 vs. 57.9 +/- 19.5 mL/min, P= 0.001, respectively), had a living donor less often than a brain dead donor (7% vs. 18%, P= 0.045), had a longer cold ischemia time (17.4 +/- 7 vs. 14.9 +/- 8.1 hours, P= 0.04), and had arterionephrosclerosis more often (24% vs. 12%, P= 0.02). On multivariate analysis, the differences in CAN at biopsy 2 (P= 0.001) and lower GFR at biopsy 2 (P= 0.002) were confirmed; in addition, nephrocalcinosis (P= 0.006) and acute rejection (P= 0.046) were found to occur more often. CONCLUSION: Chronic tubulointerstitial changes develop early after renal transplantation and are associated with reduced kidney function. Risk factors for CAN are arterionephrosclerosis (donor-related), nephrocalcinosis (related to preexisting hyperparathyroidism), a long cold-ischemia time (ischemia-perfusion-related), and acute rejection. Renal functional decline precedes morphologic changes of CAN, expressed as tubular atrophy and interstitial fibrosis.

Atrophy↗
PubMed2005

Incidence of C4d stain in protocol biopsies from renal allografts: results from a multicenter trial.

C4d staining of renal allografts is regarded as an in situ marker of active humoral rejection. Few data are available about the incidence of C4d deposition in protocol biopsies compared to indication biopsies. To evaluate whether center-specific factors influence the incidence of C4d detection, we performed a multicenter study. From three European centers, 551 protocol and 377 indication biopsies were reclassified according to the updated Banff criteria and stained for C4d. C4d results were recorded as diffuse or focal positive and statistically correlated to clinical parameters, morphology and graft survival. In the protocol biopsies, a diffuse C4d stain was found in 2.0%, and a focal stain in 2.4%. In indication biopsies, 12.2% were diffusely and 8.5% focally C4d positive (protocol:indication p < 0.0001). The incidence of C4d deposition varied significantly between centers, attributable to variable numbers of presensitized patients with more C4d positive indication and protocol biopsies. Diffuse and focal C4d stain correlated with morphology of humoral rejection in protocol as well as in indication biopsies. Protocol biopsies show a significantly lower incidence of C4d deposition than indication biopsies. Subclinical C4d detection in protocol biopsies had no significant impact on allograft survival in our series.

Biopsy↗
PubMed2005

Local complement C3 expression is upregulated in humoral and cellular rejection of renal allografts.

Evidence on the role of the complement system in transplantation pathology has been accelerated by the discovery of C4d as an in situ marker of antibody-mediated rejection. However, a local or systemic source of complement expression during acute rejection is under discussion. Thus, we quantitatively analyzed local RNA expression of complement component C3 as a pivotal molecule in active humoral and cellular rejection of renal allografts. After laser microdissection, real-time RT-PCR was performed for C3 using RNA extracted from tubuli and glomeruli of 68 paraffin-embedded renal allograft biopsies. Protocol and indication biopsies with signs of humoral and/or cellular rejection were investigated. Quantitative expression analysis of cytokines (IFN gamma, MCP-1, IL2, IL8) potentially influencing local C3 expression was performed. We observed a significant increase in median expression level of C3 mRNA in tubuli of C4d-positive indication biopsies, and in tubuli from indication biopsies with signs of T-cell-mediated cellular rejection. Highest expression levels were found in C4d-positive indication biopsies with signs of cellular rejection. Biopsies with upregulated C3 showed increased IFN gamma expression, suggesting allograft-infiltrating T-cells as potential stimulus for local C3 expression. Therefore, locally synthesized complement component C3 contributes to both humoral and cellular rejection, with tubular epithelial cells being a major source.

Biopsy↗
PubMed2005

Aberrant expression of platelet-derived growth factor (PDGF) and PDGF receptor-alpha is associated with advanced bone marrow fibrosis in idiopathic myelofibrosis.

The expression of members of the platelet-derived growth factor (PDGF) system in bone marrow cells derived from Idiopathic myelofibrosis (IMF) has been investigated by real-time RT-PCR. Increased expression of PDGFs and the corresponding PDGF receptor a could be demonstrated to be a feature of advanced fibrosis in IMF that is not demonstrable in the prefibrotic phase of the disease.

Disease Progression↗
PubMed2005

Down-regulation of the IGF-2/H19 locus during normal and malignant hematopoiesis is independent of the imprinting pattern.

H19 and IGF-2 are two growth regulatory genes located on chromosome 11p15 implicated in tumorigenesis. Both genes are imprinted and regulated reciprocally under many circumstances. In order to elucidate the contribution of H19 and IGF-2 to leukemogenesis, the mRNA expression level of both genes were quantitated in bone marrow biopsies and peripheral blood samples from normal (n=98), chronic myelomonocytic leukemia (CMML, n=43), chronic myelogenous leukemia (CML, n=40) and, acute myelogenous leukemia (AML, n=32) cases. A concomitant reduction of H19 and IGF-2 expression was observed in all leukemic samples compared to the healthy controls. This down-regulation was not accompanied by changes in methylation of the differentially methylated region (DMR). Whereas the H19 gene showed strict monoallelic expression in all informative normal (n=31) and leukemic (n=54) samples, the imprinting pattern of the IGF2 gene was found to be heterogeneous. No correlations between imprinting status (mono- versus biallelic expression), quantitative mRNA expression levels and course of disease were found for the IGF-2 gene. The data suggest a disturbed regulation of the IGF-2/H19 locus in myeloid leukemias which is not caused by loss of imprinting.

Alleles↗
PubMed2005

Combined laser-assisted microdissection and short tandem repeat analysis for detection of in situ microchimerism after solid organ transplantation.

Following the transplantation of a solid organ leukocytes of donor origin migrate out of the organ, contributing to a chimeric blood cell population ("peripheral microchimerism"). At the same time, leukocytes and pluripotent precursor cells of the recipient migrate into the organ, creating an "in situ microchimerism." A method is described for the identification of cells with the recipient's genotype in the transplanted organ by combining laser-assisted microdissection and short tandem repeat analysis. The microdissection allows the contamination-free isolation of morphologically and immunohistochemically characterized cells or groups of cells from histological tissue sections. The subsequent analysis of highly polymorphic short tandem repeats enables unequivocal genotyping in nearly all donor-recipient instances. Employing this new methodological approach, we could identify in individual transplanted organs differentiated parenchymal cells of recipient's origin, which most probably are derived from circulating precursor cells from the bone marrow.

Humans↗
PubMed2004

Prognostic value of cytotoxic T-lymphocytes and CD40 in biopsies with early renal allograft rejection.

After renal transplantation, different immunological and non-immunological factors lead to long-term allograft deterioration. Acute rejection episodes are one risk factor for chronic renal allograft dysfunction (CRAD). Following the current Banff classification the histological grade in acute rejection episodes is of limited prognostic value, therefore, additional morphological surrogate markers would be helpful. We investigated the biopsies of 91 patients with early acute rejection episodes for the immunohistochemical expression of key molecules (perforin, granzyme B, TIA-1, CD40) in the T cell-mediated rejection process. Staining results were correlated to long-term allograft outcome. Patients with greater than 2% of granzyme B or greater than 25% of CD40-positive cells in the interstitial infiltrate showed significantly shorter allograft survival. Patients with a CD40-positive vascular rejection or greater than 2% of granzyme B-positive cells in the interstitial infiltrate were significantly correlated with an earlier onset of CRAD. Our findings provide potential morphological surrogate markers in biopsies with early acute rejection episodes after renal transplantation. These could become part of combined clinical and histological algorithms, allowing patient-specific risk estimation and customized therapy options to be made.

Acute Disease↗
PubMed2004

Cell cycle and no end.

Our knowledge about the molecular circuits regulating the duplication of the genetic material and the subsequent division of a cell into two daughter cells has exploded over the last decade. Aberrations in the regulation of the cell cycle belong to the hallmarks of malignant transformation, leading, in turn, to the development of tumours. After introducing the basics of eukaryotic cell-cycle regulation and describing the four phases of the cell cycle (namely, G1, S, G2 and M) in more detail, alterations of key components of the cell-cycle machinery in human malignancies and their functional consequences are presented. Principally, deregulation of the cell cycle can be caused by unrestricted activity of cell-cycle promoting factors (many oncogenes fall into this class) or by inactivation of inhibitory factors (many tumour suppressor genes belong to this class). Both types of deregulation have been described in human tumours and are discussed in detail. Perspectives concerning the translation of this knowledge into daily routine practice and future applications are discussed at the end. The molecular mechanisms of actual cell division (sister chromatid segregation and cytokinesis) are mentioned only briefly.

Animals↗
PubMed2004

Induction of aneuploidy by increasing chromosomal instability during dedifferentiation of hepatocellular carcinoma.

To gain more insight into the role of chromosomal instability (CIN), the cytogenetic hallmark of most solid tumors, we performed fluorescence in situ hybridization (FISH) on interphase nuclei of cytological specimens enabling the correct detection of chromosome copies in intact tumor cells of 18 well (G1), moderately (G2), or poorly (G3) differentiated hepatocellular carcinomas (HCCs). A close correlation between the morphological dedifferentiation and increasing copy numbers and variation of FISH signals was seen for chromosomes 1 and 8, respectively (P < or = 0.0002). Four HCC G1 had constant chromosome patterns for chromosomes 1 and/or 8 with a mean of signals per nucleus < or =5.08 and < or =3 different signal combinations, indicating a low level of CIN, as confirmed by FISH using probes for centromeres of chromosomes 3, 7, and 17. In contrast to this, five HCC G2-3 revealed > or =8.46 signals per nucleus and 23-41 different signal combinations, indicating high levels of CIN. In the remaining cases, signal counts from 5.96-8.46 and 7-15 combinations were seen. Here, nuclei with constant aberration patterns and low copy numbers occurred alongside nuclei with inconstant patterns and high copy numbers. It is evident that in these cases a transition from well to moderately differentiated HCC developed in parallel to an increase in CIN, possibly induced by a major dysregulation of mitotic control mechanisms. In conclusion, CIN may induce a stepwise increase of aneuploidy in HCC that is mirrored by the morphological dedifferentiation of tumor cells.

Aged↗
PubMed2004

Thrombopoietin receptor (Mpl) expression by megakaryocytes in myeloproliferative disorders.

The thrombopoietin receptor (Mpl) is involved in the pathogenesis of chronic myeloproliferative disorders (CMPD). In this study, we determined Mpl expression by bone marrow cells and megakaryocytes in CMPD by applying laser microdissection, real-time RT-PCR, and immunohistochemistry. Mpl mRNA expression was significantly increased up to 9-fold in total bone marrow cells (p < 0.001) and up to 4-fold in megakaryocytes in chronic myeloproliferative disorders (n = 73) compared to normal controls (n = 26, p = 0.01). Immunohistochemistry revealed heterogeneous Mpl expression by megakaryocytes in CMPD with a stronger accentuation in idiopathic myelofibrosis (IMF) in comparison to polycythaemia vera (PV) and essential thrombocythemia (ET). In addition to megakaryocytes, the erythropoietic lineage was prominently labelled by Mpl antiserum, with considerably stronger staining in polycythaemia vera. We conclude that, in CMPD, megakaryocytes and erythroid cells exhibit increased Mpl expression levels which may contribute to the sustained proliferation of both cell lineages in CMPD.

Adult↗