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H D Rupprecht

Publications and source records attributed to H D Rupprecht.

At least 19 recordsLinked to original sources
PubMed2005

[Lymphoproliferative disease following kidney transplantation].

HISTORY AND CLINICAL FINDINGS: A 31-year-old male patient was referred because of a worsening graft function 56 months after an allogenic kidney transplantation for interstitial nephritis. He had complained about diffuse abdominal pain and watery diarrhea during the preceding week. Correction of volume status did not result in an improvement of kidney function. Bacterial or viral enteritis could be excluded as well as a mucosa-associated lymphatic tissue lymphoma (MALT-lymphoma). Shortly thereafter, the patient developed a subileus. INVESTIGATIONS: Kidney biopsy showed a low degree nephrosclerosis and some interstitial fibrosis, but no signs of rejection. The abdominal CT scan showed enlarged lymph nodes partially obstructing the intestinal lumen. Histology showed an EBV-negative, highly aggressive B-blastic lymphoma. DIAGNOSIS: EBV-negative post-transplant lymphoproliferative disease (PTLD). TREATMENT AND COURSE: Because of the advanced lymphoma stage immunosuppressive therapy was reduced and immunochemotherapy according to the CHOP-protocol (cyclophosphamide, doxorubicin, vincristine, prednisone) in combination with rituximab (R-CHOP) was started. After 4 chemotherapy cycles the patient was in complete remission and another 2 therapy cycles were given for consolidation. The patient remained free of disease during the actual follow-up of 8 months. CONCLUSION: PTLD can present with unspecific abdominal symptoms including diarrhea and with signs of graft dysfunction.

Abdominal Pain↗
PubMed2004

[Differential diagnosis of proteinuria].

Normally, protein secretion in the urine is less than 150 mg/day or less than 100 mg/g creatinine. Orthostatic proteinuria, proteinuria in the presence of fever, and effort proteinuria are benign forms. In cases of persistent proteinuria, prerenal or overflow proteinuria are distinguished from renal and post-renal proteinuria. Renal forms can be differentiated into glomerular and tubular as well as mixed forms. The urine dipstick is of only low sensitivity, and is therefore unsuitable as a screening test for diabetic microalbuminuria. In addition, it cannot detect immunoglobulin light chains in Bence Jones proteinuria. For the differentiation between glomerular and tubular forms of proteinuria, the determination of marker proteins in the urine, for example, alpha1 microglobulin, albumin and IgG, has proven utility.

Albuminuria↗
PubMed2002

Introduction of DNA enzyme for Egr-1 into tubulointerstitial fibroblasts by electroporation reduced interstitial alpha-smooth muscle actin expression and fibrosis in unilateral ureteral obstruction (UUO) rats.

The phenotypic alteration of interstitial fibroblasts into 'myofibroblasts', acquiring characteristics of both fibroblasts and smooth muscle cells is a key event in the formation of tubulointerstitial fibrosis. The up-regulation of the early growth response gene 1 (Egr-1) preceded the increased interstitial expression of alpha-smooth muscle actin (alphaSMA), a marker of phenotypic changes, in obstructed kidney, a model of interstitial fibrosis. To target Egr-1 expression in the interstitium of obstructed kidneys, we introduced a DNA enzyme for Egr-1 (ED5) or scrambled DNA (SCR) into interstitial fibroblasts by electroporation-mediated gene transfer. Northern blot analysis confirmed an increase in the cortical mRNA expression of Egr-1 in the obstructed kidneys from untreated or SCR-treated rats, while ED5 transfection blocked Egr-1 expression with a concomitant reduction in TGF-beta, alphaSMA and type I collagen mRNA expression. Consequently, ED5 inhibited interstitial fibrosis. In conclusion, electroporation-mediated retrograde gene transfer can be an ideal vehicle into interstitial fibroblasts, and molecular intervention of Egr-1 in the interstitium may become a new therapeutic strategy for interstitial fibrosis.

Actins↗
PubMed2001

Antineutrophil cytoplasmic antibodies induce human monocytes to produce oxygen radicals in vitro.

OBJECTIVE: Antineutrophil cytoplasmic antibodies (ANCA) are believed to play a pathogenetic role in necrotizing small-vessel vasculitis. While the involvement of neutrophils in this disease has been extensively studied in vitro, we undertook to analyze thoroughly the contribution of monocytes to tissue destruction in systemic vasculitis. METHODS: Monocytes obtained from normal human individuals were stimulated by ANCA isolated from patients with active vasculitis. The formation of oxygen radicals was measured by a fluorometric assay using 2',7'-dichlorofluorescin diacetate. RESULTS: ANCA induced monocytes to produce oxygen radicals, resulting in a mean 43% increase (range 21-84%) in oxygen radical formation compared with normal IgG. The formation of reactive oxygen species was time and concentration dependent and was also induced by ANCA F(ab')2 fragments. Normal nonspecific IgG or their corresponding F(ab')2 fragments induced no release or very little release of oxygen radicals. Preincubation of monocytes with the Fcy receptor type II-blocking monoclonal antibody IV.3 before addition of ANCA greatly reduced formation of oxygen radicals. Using ligand affinity chromatography with proteinase 3 (PR3) and myeloperoxidase (MPO), ANCA were further purified by depletion of patient IgG. The stimulation of monocytes with these pure PR3- and MPO-ANCA confirmed that cellular activation was specifically induced by ANCA. CONCLUSION: These results show that ANCA induce the formation of reactive oxygen species in human monocytes. These findings support the notion that ANCA specifically activate monocytes by several mechanisms to participate in the inflammatory process of ANCA-associated vasculitis.

Antibodies, Antineutrophil Cytoplasmic↗
PubMed2000

Requirement of heat shock protein 90 in mesangial cell mitogenesis.

BACKGROUND: Hyperplasia of mesangial cells (MCs) is a frequent finding in glomerulonephritis. Heat shock protein 90 (HSP90) is a major cellular chaperone that assists protein folding under physiological and stress conditions. METHODS: To identify genes that are potentially involved in the pathogenesis of glomerulonephritis, we analyzed glomerular gene expression in mesangioproliferative rat anti-Thy1.1 nephritis by representational difference analysis (RDA). Expression of HSP90beta in anti-Thy1.1 nephritis was studied by Northern and Western blot analyses and immunohistochemistry. In cultured rat MCs, the requirement of HSP90 for mitogenic signaling steps and MC replication was studied by incubation with the specific HSP90 inhibitor geldanamycin. RESULTS: By RDA, a cDNA fragment homologous to HSP90beta was identified. Glomerular mRNA and protein expression of HSP90beta was markedly and transiently up-regulated during the course of anti-Thy1.1 nephritis, with a maximum at day 6, coinciding with the peak of MC proliferation. By immunohistochemistry, HSP90beta expression in normal glomeruli was detected in podocytes. However, in anti-Thy1.1 nephritis, glomerular HSP90beta protein expression was strongly and transiently increased in mesangial localization. In vitro, mitogenic stimulation of rat MCs led to the induction of HSP90beta mRNA and protein. Incubation of MCs with geldanamycin dose-dependently inhibited DNA synthesis and replication. Moreover, geldanamycin interfered with mitogen-induced phosphorylation of extracellular signal-regulated kinase and transcription of c-fos and Egr-1, but not with transactivation of STAT1 transcription factor. Cell cycle analysis of serum-stimulated MCs revealed that geldanamycin inhibited kinase activity of cyclin D1/CDK4 complexes and blocked progression in the G0/G1 phase and at the S/G2 phase transition. CONCLUSIONS: The up-regulation of HSP90beta in anti-Thy1.1 nephritis may reflect its functional involvement in phenotypical alterations of MCs in mesangioproliferative glomerulonephritis. Our in vitro studies indicate that HSP90 governs the capacity of MCs to respond to proliferative stimuli by regulating critical mitogenic signaling steps necessary for G1 entry and S-phase progression.

Animals↗
PubMed2000

Nitric oxide inhibits growth of glomerular mesangial cells: role of the transcription factor EGR-1.

UNLABELLED: Nitric oxide inhibits growth of glomerular mesangial cells: Role of the transcription factor Egr-1. BACKGROUND: In previous studies, we found a close link of early growth response gene-1 (Egr-1) expression to mesangial cell (MC) proliferation. Antiproliferative agents inhibited mitogen-induced Egr-1 expression. Here we investigated the effect of S-nitrosoglutathione (GSNO) on the proliferation of MCs, specifically asking how GSNO regulates the transcription factor Egr-1, which we have previously shown to be critical for the induction of MC mitogenesis. METHODS: The proliferation of MCs was measured by thymidine incorporation and cell counting. Egr-1 mRNA and protein levels were detected by Northern and Western blots. Electrophoretic mobility shift assays (EMSAs) and chloramphenicol acetyltransferase (CAT) assays were performed to test whether GSNO modulates DNA binding and transcriptional activation of Egr-1. RESULTS: GSNO strongly inhibited serum-induced MC proliferation (-84% at 1 mmol/L). A mild inhibition of serum-induced Egr-1 mRNA was observed at GSNO concentrations from 50 to 200 micromol/L, whereas mRNA levels increased again at concentrations above 500 micromol/L. This increased mRNA expression, however, was not translated into Egr-1 protein. Instead, Egr-1 protein induction was inhibited (-40%). EMSAs indicated that GSNO inhibited specific binding of Egr-1 to its DNA consensus sequence. Moreover, transcriptional activation by Egr-1 in CAT assays using a reporter plasmid bearing three Egr-1 binding sites was strongly suppressed by GSNO. CONCLUSIONS: Our data identify GSNO as a potent inhibitor of MC growth with potential beneficial effects in proliferative glomerular diseases. This antimitogenic property is mediated at least in part by inhibitory effects of GSNO on Egr-1 protein levels and by reducing the ability of Egr-1 to activate transcription by impairing its DNA binding activity.

Animals↗
PubMed1998

Lysophosphatidic acid-mediated signal-transduction pathways involved in the induction of the early-response genes prostaglandin G/H synthase-2 and Egr-1: a critical role for the mitogen-activated protein kinase p38 and for Rho proteins.

During inflammatory processes of the kidney, lesions of the glomerulus lead to aggregation of thrombocytes and infiltration of macrophages, which can release bioactive mediators. One of these important signalling molecules is lysophosphatidic acid (LPA). Incubation of rat mesangial cells with LPA induced mRNA and protein expression of the early-response genes pghs-2 (for prostaglandin G/H synthase-2/cyclo-oxygenase-2) and egr-1. As shown by antisense experiments, induction of egr-1 was related to the strong mitogenic effect of LPA. LPA-mediated gene expression was inhibited by pertussis toxin, indicating coupling to G-proteins of the Gi family. Specific inhibition of proteins of the small G-protein subfamily Rho with toxin B from Clostridium difficile led to changes in mesangial cell morphology without induction of apoptosis. LPA-mediated expression of pghs-2 and egr-1 was reduced to base-line levels by toxin B, indicating a role for Rho proteins in LPA-mediated gene induction. Of the two mitogen-activated protein kinase (MAPK) pathways investigated, the MAPK kinase-extracellular signal-regulated kinase pathway was involved in the induction of both pghs-2 and egr-1 mRNA expression, as shown by the inhibitory effect of PD98059. Activation of the MAPK p38, however, was only related to pghs-2 expression, whereas egr-1 expression was not affected by treatment of mesangial cells with the specific inhibitor SB203580. Taken together our data provide evidence that LPA-mediated activation of MAPK kinase and Rho proteins leads to the induction of the functionally distinct early-response genes pghs-2 and egr-1, whereas activation of MAPK p38 revealed considerable differences between the regulation of these two genes.

Animals↗
PubMed1998

Regulation of osteopontin expression in rat mesangial cells.

Hypercellularity and accumulation of extracellular matrix are common responses of renal glomeruli to inflammatory stimuli. Using the differential display approach, we compared the gene expression patterns of proliferating and differentiating rat mesangial cells in two- and three-dimensional cultures. Osteopontin, an extracellular matrix protein, was found to be transcribed, synthesized, and secreted by rat mesangial cells. Osteopontin transcription was not associated with cell proliferation and was found to be FCS-inducible in proliferating cells. Osteopontin expression was independent of exogenously supplied FCS in differentiating cells. The presented data indicate that osteopontin is differentially regulated in proliferating and differentiating mesangial cells.

Animals↗
PubMed1997

[Egr-1 transcription factor regulates the growth of glomerular mesangium cells].

BACKGROUND: The transcriptional regulator Early growth response gene-1 (Egr-1) is rapidly and transiently induced by various mitogens in cultured rat mesangial cells (MCs). METHOD AND RESULTS: Here we show Egr-1 induction in an in vivo model of mesangioproliferative glomerulonephritis (GN). A 14.9-fold increase in Egr-1 mRNA was observed 6 days after disease induction. A concomitant increase in Egr-1 protein was demonstrated by immunocytochemistry. Egr-1 was mainly localized to the nuclei of cells in mesangial localization. To test whether Egr-1 directly regulated MC proliferation, we preincubated cultured MCs with antisense oligonucleotides directed against Egr-1. The platelet-derived growth factor (PDGF)-induced increase in Egr-1 mRNA and protein levels was inhibited by 75% and 74%, respectively. At the same time Egr-1 antisense oligonucleotides dose-dependently inhibited MC-proliferation as determined by thymidine-uptake by up to 75%. Control oligonucleotides were without effects on Egr-1 mRNA, protein or MC growth. CONCLUSION: We conclude that Egr-1 induction is a necessary step in the mitogenic signaling cascade in glomerular MCs.

Animals↗
PubMed1997

Expression of the transcriptional regulator Egr-1 in experimental glomerulonephritis: requirement for mesangial cell proliferation.

The early growth response gene-1 (Egr-1), a zinc finger transcriptional regulator, was induced in a rat model of mesangioproliferative glomerulonephritis (GN). Northern blot analysis revealed a maximal 14.9-fold increase in glomerular Egr-1 mRNA at day 6 of GN. By immunohistochemistry Egr-1 protein expression was demonstrated to be mainly confined to glomerular mesangial cells (MC). To test whether Egr-1 directly regulates MC proliferation, cultured MCs were stimulated with platelet-derived growth factor (PDGF) after preincubation with different Egr-1 antisense oligonucleotides (ASOs). PDGF-induced rise in 3H-thymidine uptake by 83% and almost completely abrogated increase in MC number. We conclude that Egr-1 induction is of critical importance for PDGF-induced mitogenic signaling in MCs, and inhibition of Egr-1 in vivo may offer an approach to oppose glomerular MC proliferation in glomerular inflammatory disease.

Animals↗
PubMed1997

TGF-beta1-induced cell cycle arrest in renal mesangial cells involves inhibition of cyclin E-cdk 2 activation and retinoblastoma protein phosphorylation.

In glomerular disease, transforming growth factor-beta1 (TGF-beta1) has been demonstrated to exert anti-mitogenic and anti-inflammatory as well as fibrogenic effects. To better understand the TGF-beta1 action on glomerular cells at the molecular level, we investigated mechanisms of TGF-beta1-induced growth suppression in primary cultures of rat mesangial cells (MCs). TGF-beta1 (5 ng/ml) markedly inhibited proliferation of MCs incubated with PDGF, endothelin-1, bFGF, serotonin, or EGF, indicating that TGF-beta1 interferes with post-receptor signals of mitogenesis. TGF-beta1 did not affect mitogen-stimulated induction of the immediate early genes, c-fos, c-jun, and Egr-1 in MCs that occurred transiently at 30 to 120 minutes. Time-course studies revealed that TGF-beta1 inhibited DNA synthesis and MC replication when added up to six to eight hours after MC stimulation with PDGF. FACS analysis demonstrated that MCs had reached middle to late G1 phase of cell cycle progression at this timepoint. PDGF stimulation of MCs induced protein expression of the G1 phase cyclin D1 as well as the cyclin-dependent kinases cdk 4 and cdk 2. This was not significantly altered when MCs were coincubated with both, PDGF and TGF-beta1. However, TGF-beta1 prevented PDGF-elicited phosphorylation of the retinoblastoma tumor suppressor (pRb), a negative cell cycle regulator. Moreover, TGF-beta1 significantly reduced cyclin E-associated histone H1 kinase activity in the presence of PDGF. These results indicate that TGF-beta1 inhibits mitogen-stimulated MC growth by causing cell cycle arrest in late G1 phase. While TGF-beta1 does not alter the mitogen-induced expression and abundance of G1 phase cyclin D1 and cdks 4 and 2 in MCs, it inhibits cyclin E-cdk 2 activity, thus preventing mitogen-elicited phosphorylation and inactivation of pRb in G1 phase and transition to S phase.

Animals↗
PubMed1997

Factors controlling growth and matrix production in vascular smooth muscle and glomerular mesangial cells.

The vasculature wall is an active, integrated organ composed of endothelial cells and vascular smooth muscle cells, as well as other cell types depending on the specific vascular segment (e.g. fibroblasts in many vascular regions). The vascular wall is not static; the vascular components (cells and extracellular matrix) dynamically increase, decrease or reorganize, or both, in response to physiological and pathological stimuli. The vascular smooth muscle cells are the final common pathway for many of these dynamic changes in vascular wall structure. In the renal glomerulus, however, the glomerular mesangial cells-a cell phenotypically related to the vascular smooth muscle cells-also participate. Although sometimes beneficial, changes in vascular or glomerular structure often lead to cardiovascular (e.g. atherosclerosis, restenosis, intimal hyperplasia) and renovascular (e.g. glomerulosclerosis) diseases. Consequently, much effort has been expended to elucidate the mechanisms that control growth and extracellular matrix production by vascular smooth muscle cells and glomerular mesangial cells. The purpose of this review is to discuss recent developments.

Angiotensin II↗
PubMed1996

Transcription factor Egr-1 regulates glomerular mesangial cell proliferation.

Increase of glomerular mesangial cells (MCs) is a prominent histopathological finding in many types of glomerulonephritis. We have shown previously that expression of the zinc-finger transcription factor, early growth response gene-1 (egr-1), is closely correlated with the proliferation of cultured MCs. To elucidate whether Egr-1 is required for MC proliferation, we inhibited serum-induced Egr-1 expression by phosphothioate-modified antisense oligonucleotides (ODNs). Uptake of antisense ODNs into MCs was demonstrated, and five different egr-1 antisense ODNs were tested for their impact on serum-induced egr-1 mRNA and protein levels and on MC growth. The most potent egr-1 antisense ODN inhibited serum-induced egr-1 mRNA by 68%, protein induction by 58%, and MC replication as measured by [3H]thymidine uptake and cell counts by 78 and 46%, respectively. The effects of antisense ODNs on MC growth correlated closely with their ability to inhibit Egr-1 protein. ODNs acted in a dose-dependent manner, the minimal effective concentration being 1 microM. Control ODNs had no significant effects. In addition, antisense ODNs against egr-1 potently inhibited endothelin-1-induced Egr-1 expression and MC growth. Heparin, a known inhibitor of MC growth, suppressed serum-induced [3H]thymidine uptake by 39% and egr-1 mRNA expression by 44%. We conclude that Egr-1 is an essential part of the mitogenic signal transduction cascade in cultured MCs.

Animals↗