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F Strutz

Publications and source records attributed to F Strutz.

50 records · Page 3Linked to original sources
PubMed1995

Identification and characterization of a fibroblast marker: FSP1.

We performed subtractive and differential hybridization for transcript comparison between murine fibroblasts and isogenic epithelium, and observed only a few novel intracellular genes which were relatively specific for fibroblasts. One such gene encodes a filament-associated, calcium-binding protein, fibroblast-specific protein 1 (FSP1). The promoter/enhancer region driving this gene is active in fibroblasts but not in epithelium, mesangial cells or embryonic endoderm. During development, FSP1 is first detected by in situ hybridization after day 8.5 as a postgastrulation event, and is associated with cells of mesenchymal origin or of fibroblastic phenotype. Polyclonal antiserum raised to recombinant FSP1 protein stained the cytoplasm of fibroblasts, but not epithelium. Only occasional cells stain with specific anti-FSP1 antibodies in normal parenchymal tissue. However, in kidneys fibrosing from persistent inflammation, many fibroblasts could be identified in interstitial sites of collagen deposition and also in tubular epithelium adjacent to the inflammatory process. This pattern of anti-FSP1 staining during tissue fibrosis suggests, as a hypothesis, that fibroblasts in some cases arise, as needed, from the local conversion of epithelium. Consistent with this notion that FSP1 may be involved in the transition from epithelium to fibroblasts are experiments in which the in vitro overexpression of FSP1 cDNA in tubular epithelium is accompanied by conversion to a mesenchymal phenotype, as characterized by a more stellate and elongated fibroblast-like appearance, a reduction in cytokeratin, and new expression of vimentin. Similarly, tubular epithelium submerged in type I collagen gels exhibited the conversion to a fibroblast phenotype which includes de novo expression of FSP1 and vimentin. Use of the FSP1 marker, therefore, should further facilitate both the in vivo studies of fibrogenesis and the mapping of cell fate among fibroblasts.

3T3 Cells↗
PubMed1994

Characterization of a cis-acting regulatory element which silences expression of the class II-A beta gene in epithelium.

Class II major histocompatibility complex (MHC) genes encode for alpha/beta chain pairs that are constitutively expressed principally on mature B cells and dendritic cells in mice. These gene products are easily induced on macrophages with cytokines, and may also aberrantly appear on the surface of epithelium during immune injury. The appearance of class II determinants in parenchymal tissue potentially renders these somatic cells capable of antigen presentation to circulating CD4+ T lymphocytes, and their absence may be protective for normal tissues expressing self-antigens. The low surface class II expression observed on parenchymal cells generally correlates with low levels of mRNA, suggesting that transcription rate is a major element in class II regulation. To understand the transcriptional mechanism maintaining low basal surface expression of class II in somatic cells, we transiently transfected mini-gene reporter constructs to study the regulation of the murine A beta promoter in a cultured renal epithelial cell line. We describe here a negative cis-acting regulatory region located between -552 and -489 bp upstream of the A beta cap site that silences the transcriptional activity of the A beta promoter in epithelial cells in an orientation-dependent manner, and is also able to silence a heterologous promoter. This region is not active in class II-expressing B cells (BAL-17) in culture, but is functional in two other murine class II-negative cell lines, fibroblasts and thymoma T cells. Using competition electrophoretic mobility shift assays, we have localized the core protein binding site within this region to an 8-10-bp response element, designated A beta NRE, at -543 to -534 bp. A nuclear extract from BAL-17 cells does not bind to this element. Mutation of this site abrogates the transcriptional silencing activity of the region. We conclude that the transcription of class II-A beta in parenchymal cells, and some lymphocytes, can be actively repressed by an upstream silencing element.

Animals↗
PubMed1994

Pharmacokinetics of torasemide and its metabolites in end-stage renal disease.

The pharmacokinetics of torasemide, a new loop diuretic, as well as its active metabolites M1 and M3, and its inactive main metabolite, M5, were studied in 12 patients with end-stage renal failure during single i.v. (n = 6) or single oral (n = 6) dosing of 200 mg torasemide, and during chronic oral treatment for 9 days (n = 12). The elimination half-life (t1/2) of torasemide was unchanged in renal failure, whereas t1/2 of the torasemide metabolites M1, M3, and M5 were markedly prolonged. However t1/2 as well as the area under the plasma level time curve of torasemide and its metabolites were unchanged during chronic compared to acute administration. The results of this study suggest that despite the increased half-life of torasemide metabolites M1, M3 and M5 in end-stage renal failure patients, no accumulation of the parent drug torasemide and its metabolites during chronic dosing is demonstrable.

Diuretics↗
PubMed1994

The role of lymphocytes in the progression of interstitial disease.

Chronic interstitial disease is a major cause of end-stage renal failure. The process is characterized mainly by tubular atrophy and interstitial fibrosis and may be the result of primary or secondary interstitial nephritis. The secondary form attends almost all instances of progressive glomerular and vascular diseases, determining in a large part their outcome. Both forms of interstitial nephritis are initially characterized by the presence of mononuclear infiltrates with the majority being T lymphocytes. The predominance of CD4+ or CD8+ T-cells depends on the underlying cause. Both cell types may lead directly or indirectly to the induction of tubulointerstitial fibrosis. Direct stimulation of fibroblasts to proliferate and produce extracellular matrix may be caused by TGF-beta, IL-4, TNF-alpha, and other fibroblast stimulating factors. Indirect induction of fibroblasts is mediated by stimulation of monocytes/macrophages through IL-2 and IFN-gamma. Furthermore, T cells may directly interact with epithelial cells, leading, for example, to a decrease in type IV collagen production in these cells, thus contributing directly to tubular atrophy. The role of MHC class II expression on tubular epithelial cells in the process of chronic interstitial disease remains to be fully elucidated.

Animals↗
PubMed1992

[Proteinuria and atherogenic risk].

The relationship between blood-lipid levels and severity of proteinuria was examined retrospectively in 30 patients (12 males, 18 females; mean age 39 [18-58] years). All patients had histologically confirmed glomerulonephritis (minimal change: n = 7, perimembranous: n = 8, focal sclerosing: n = 6, rapid progressive: n = 3, mesangio-proliferative: n = 4, membrano-proliferative: n = 1, diabetic glomerulosclerosis: n = 1). None was taking lipid-lowering drugs. Patients were classified according to the degree of proteinuria. In group 1 (proteinuria less than 5 g/d, n = 13) the LDL-HDL ratio averaged 4.4; in group 2 (proteinuria 5.0-10.0 g/d, n = 10) the average ratio was 8.8, and in group 3 (proteinuria greater than 10.0 g/d, n = 7) 13.3. Total cholesterol concentration also rose with increasing proteinuria (to 300 +/- 87 mg/dl, 375 +/- 168 mg/dl and 464 +/- 143 mg/d, respectively). The size of the LDL-HDL ratio and the level of total cholesterol did not correlate with the degree of excretory renal failure. These results point to an impressive correlation between the degree of proteinuria and the level of LDL-HDL ratio as a measure of atherogenic risk for a given patient.

Adult↗
PubMed1992

Human cytomegalovirus in rejected kidney grafts; detection by polymerase chain reaction.

Human cytomegalovirus (CMV) infections are frequently associated with graft rejection in the immunosuppressed patients following organ transplantation. Thirty-four tissue samples from rejected kidneys and 18 samples from normal adult kidneys obtained from autopsies were investigated for the presence of CMV-DNA by the polymerase chain reaction (PCR) and by immunohistochemistry. DNA extracted from renal tissues after proteinase K digestion was specifically amplified in 32 cycles using primers which flank a 147 bp DNA fragment of the immediate early CMV gene and analysed by slot-blot hybridization with digoxigenin-labelled detection oligonucleotides. CMV-DNA was detected by PCR in a range from 0.1 fg up to 100 fg in 14 (41%) rejected kidney transplants. Comparative immunohistological analysis revealed presence of CMV in only three biopsies of these rejected kidneys. Furthermore, CMV-DNA was also found in four of 18 (22%) normal donor kidneys. These results reveal that CMV is often present in rejected kidneys and that the infection can be transferred from the donor to the recipient, since the normal adult kidney appears to be a frequent site of latency for CMV. No differences in local immunological changes, characterized by interstitial mononuclear leukocyte infiltration as well as by aberrant expression of HLA-class II antigens and of ICAM1 on proximal tubular epithelial cells, could be detected by further immunohistological analysis between grafted kidneys at late stage of rejection with and without CMV infection.

Adolescent↗
PubMedDate not supplied

Mucocutaneous autoimmune syndrome following fludarabine therapy for low-grade non-Hodgkin's lymphoma of B-cell type (B-NHL).

A 40-year-old patient with low-grade B-NHL developed a generalized macular-papular rash following the first cycle of fludarabine treatment which progressed to a complete epidermal necrolysis following the second cycle. Clinical symptoms and the results of the direct and indirect immunofluorescence were consistent with a mucocutaneous autoimmune syndrome (pemphigus). Immunohistochemical analysis demonstrated a dense epidermal infiltration of CD8+ lymphocytes associated with the histological features of single-cell necrosis of keratinocytes. Early and aggressive immunosuppressive treatment with steroids, cyclophosphamide, and high-dose immunoglobulins resulted in regression of symptoms and complete reconstitution of epidermal integrity. The malignant lymphoma has completely regressed. The findings suggest a fludarabine-induced defect in immunosurveillance--resulting in the uncontrolled activation of autoaggressive T-cell clones--as a pathogenetic mechanism of this life-threatening dermatological complication.

Adult↗
PubMedDate not supplied

Role of fibroblast activation in inducing interstitial fibrosis.

Tubulointerstitial fibrosis is an obligate finding in end-stage diseased kidneys. Renal fibrosis is defined as excessive matrix deposition that leads to tissue destruction and impairment of renal function. This process is often independent of the initial underlying disease and is not self-limited, in contrast to normal wound healing. Fibroblasts are the main effector cells in fibrogenesis, and mainly contribute to increased synthesis of matrix components. Increased matrix production is preceeded by massive proliferation of fibroblasts. The transformation from quiescent interstitial cells to proliferating and excessively matrix-producing cells has been termed fibroblast activation, which includes functional implications as well as phenotypic changes such as the expression of alpha-smooth muscle actin ("myofibroblasts"). Activation of fibroblasts typically occurs through four distinct mechanisms: stimulation by growth factors ("auto- and paracrine"), by direct cell-cell contacts, by extracellular matrix via integrins, and by environmental conditions such as hyperglycemia or hypoxia in renal disease. The crucial step though, that distinguishes wound healing from fibrosis, is the perpetuation of the activated state. The clarification of cellular events connected with fibrogenesis has led to new approaches for therapy. Direct targeting of fibroblasts, inhibition of matrix deposition and specific inhibition of fibroblast activation have proved successful in experimental models and thus may lead to new approaches in the treatment of progressive renal disease.

Animals↗
PubMedDate not supplied

Cortical fibroblast culture from human biopsies.

BACKGROUND: Tubulointerstitial fibrosis is an integral part of progressive renal disease. Human cortical fibroblasts are believed to be key effector cells in fibrogenesis. Thus, a reliable culture of these cells is necessary for studies of their pathophysiology. METHODS: Cortical fibroblast culture from routine kidney biopsies were analyzed and the cells were characterized. Indirect immunofluorescence staining was done after the first passage for cytokeratin, vimentin, alpha-smooth muscle actin, CD 44, CD 54, CD 68, collagen types I, III, and HLA-DR. We then assessed the utility of the putative fibroblast markers CD 90, prolyl-4-hydroxylase (P4H) and F1b in simultaneous stainings of tubular epithelial cells. RESULTS: During the study period, 49 biopsy cores were cultured and cortical fibroblasts could be successfully established in 21 cases (42.9%). There was no relation between the success rate of culture and the degree of interstitial fibrosis, but an association was seen with the time of completion of the first passage. There was a negative correlation between the extent of scarring and the percentage of cytokeratin positive cells (r = -0.66, p < 0.001). All primary fibroblasts were negative for factor VIII, HLA-DR, CD 68, and cytokeratin. They expressed alpha-smooth muscle actin and collagen types I and III to variable degrees. There was a robust correlation between the percentage of alpha-smooth muscle actin positive cells and interstitial scarring but no such association with collagen type I or type III positive cells. The three putative fibroblast markers did not prove useful in differentiating between tubular epithelial cells and fibroblasts. However, since only fibroblasts stained positive for CD 90 and negative for cytokeratin, these two markers may suffice to distinguish fibroblasts from other renal cellular elements. CONCLUSIONS: Cortical renal fibroblasts can be easily cultured from kidney biopsy cores, though the success rate of pure cultures is below 50%. Staining for CD 90 and cytokeratin may suffice for initial characterization of these cells.

Biopsy↗