Biomedical subjects

E de Heer

Publications and source records attributed to E de Heer.

75 records · Page 5Linked to original sources

PubMedDate not supplied

Evaluation of nephrotoxicity in vitro using a suspension of highly purified porcine proximal tubular cells and characterization of the cells in primary culture.

Proximal tubular cells (PTC) were isolated from porcine kidney by collagenase treatment, subsequently purified on a discontinuous density gradient and finally cultured. Porcine PTC (PPTC) in primary culture expressed keratin, characteristics of epithelia and brush border specific glycoproteins (FX1A). In addition, vimentin was present. All cells were negative for the endothelial marker pal-E. Less than 0.1% expressed the Tamm-Horsfall protein, characteristic of the distal tubule, while less than 0.3% of all cells in culture expressed desmin, characteristic of connective tissue (i.e. fibroblasts) and mesangial cells. Ultrastructural analysis revealed microvilli, tight junctions and abundant mitochondrial and lysosomes, all characteristics of proximal tubular cells. Freshly isolated PPTC were validated as in vitro model to detect nephrotoxicity by studying the effect of mercuric chloride, cis-platin, p-aminophenol and the halogenated alkenes 1,2 dichlorovinyl-l-cysteine, S-(1,1-difluoro-2,2-dichloroethyl)-L-cysteine (DCDFE-cys) and the glutathione conjugate of DCDFE on viability and mitochondrial membrane potential. The cells responded, time- and dose-dependently, to the nephrotoxic compounds with a decrease in mitochondrial membrane potential and loss of viability. The sensitivity of the porcine cells in detecting toxic effects corresponded favorably with in vitro systems derived from other animals.

Alkenes↗

PubMedDate not supplied

Synergistic effects of anti-gp330 and anti-dipeptidyl peptidase type IV antibodies in the induction of glomerular damage.

Passive Heymann nephritis (PHN) in the rat is induced by the administration of heterologous antibodies to renal tubular epithelium (RTE). The nephritogenic capacity of anti-RTE resides primarily in the antibody fraction directed against a 330-kD glycoprotein (gp330). However, monospecific anti-gp330 antibodies are less nephritogenic than anti-RTE antibodies. This discrepancy led us to study a possible synergizing role for different antibody specificities present within anti-RTE. The enzyme dipeptidyl peptidase type IV (DPP IV) is, like gp330, present in RTE as well as in the glomerulus. Anti-DPP IV antibodies have been shown to induce an acute, transient proteinuria. In this study, we investigated the nephritogenic effect of separate or simultaneous administration of heterologous anti-DPP IV and anti-gp330 antibodies. Injection of anti-DPP IV antibodies resulted in a short-lived glomerular binding, and in a dose-dependent polyuria, albuminuria or proteinuria. Binding of anti-gp330 antibodies was slower, but much more stable. Albuminuria could only be observed in the heterologous phase. Combined injection did not alter antibody-binding kinetics of either antibody nor the albuminuria induced by anti-gp330. However, in the presence of anti-gp330 antibodies, a lower dose of anti-DPP IV was capable to induce transient albuminuria as compared to anti-DPP IV alone. In conclusion, anti-DPP IV and anti-gp330 antibodies bind to different sites in the glomerulus with different kinetics. The presence of anti-gp330 deposits facilitated anti-DPP-IV-induced renal injury.

Albuminuria↗

PubMedDate not supplied

Role of the extracellular matrix in the development of glomerulosclerosis in experimental chronic serum sickness.

Glomerulosclerosis is a severe complication of many immunologically mediated kidney diseases and is associated with a poor prognosis with respect to renal function. The aim of this study was to elucidate the role of the extracellular matrix (ECM) in the development of glomerulosclerosis in experimental immune complex glomerulonephritis. Induction of chronic serum sickness by repetitive injections of human IgG into preimmunized Wistar rats leads to the development of immune complex nephritis and glomerulosclerosis. At an early stage of the disease fibrinogen accumulation was observed along the endothelial cells, presumably related to damage of the endothelial lining. mRNA levels for several collagen types, laminin B1 and B2, and fibronectin were increased in both whole-kidney tissue and in isolated glomeruli, but morphological changes were not observed. In situ hybridization experiments demonstrated increased ECM mRNA levels in glomerular and tubular cells. Starting at week 15, glomerular mesangial matrix expansion and thickening of the glomerular basement membrane (GBM) was observed. ECM components were abundantly present. Coagulation factors were not observed at this point. ECM mRNA levels were decreased as compared to week 0, but were still above normal. Focal and segmental end-stage sclerotic lesions developed at weeks 25-30, in which fibronectin and fibrinogen were the major constituents. Other ECM components were found peripherally from these lesions in the remnants of the mesangial matrix and GBM. Sclerotic matrices did not demonstrate an increase of cellular-fibronectin, and other constituents from the circulation were not present in the lesions. Glomerular ECM mRNA was decreased to normal levels. However, a dramatic increase of ECM mRNA expression was observed at sites of inflammatory infiltrate in the perivascular, interstitial, and periglomerular regions. In conclusion, the development of glomerulosclerosis in chronic serum sickness rats is preceded by mesangial matrix expansion in which several ECM components are increasingly expressed. Steady state mRNA levels for these components are increased before morphological changes are detectable. In the final stage there is a specific accumulation of exogenous fibronectin in the glomerular end-stage sclerotic lesions. Simultaneously, an interstitial inflammatory reaction takes place leading to increased ECM production in the tissue surrounding the damaged glomeruli.

Animals↗