Joris Grond

Evidence for a migratory capability of rat Kupffer cells to portal tracts and hepatic lymph nodes

SummaryThe present study concerns the migratory ability of Kupffer cells in the rat. Phagocytic cells were labeled with colloidal carbon or gold, these markers being administered intravenously either into a tail vein, which resulted in generalized reticuloendothelial uptake, or in low dose into the portal vein, which produced uptake by Kupffer cells alone. Cells containing marker were observed in the portal tracts and in hepatic lymph nodes from 1 to 3 days after injection into the portal vein. The direct movement of single marker particles to the portal tracts could be excluded. Since injection of marker into the portal vein labeled Kupffer cells exclusively, whereas blood cells, splenic and bone marrow macrophages remained unlabeled, the labeled cells in the portal tracts and hepatic lymph nodes appeared to be former Kupffer cells migrating which had migrated to these sites.

LOCALIZATION AND DISTRIBUTION OF ANIONIC CHARGES IN THE GLOMERULAR MESANGIUM OF NORMAL AND NEPHROTIC RATS

SummarySulfated glycosaminoglycans and sialoglycoproteins are thought to play a pivotal role in the glomerular capillary wall barrier to filtration since these anionic charged elements are important in the maintenance of capillary wall integrity and constitute a charge-selective filter. The development of proteinuria in puromycin aminonucleoside (PAN) nephrosis is associated with polyanion loss from the glomerular capillary wall structures. Since in PAN nephrosis the permeability of the mesangial area to plasma proteins and tracer substances has also been shown to be increased, the purpose of this study was to analyse the localization and distribution of anionic charges in the glomerular mesangium in this experimental model.Glycosaminoglycans were labeled by perfusion of the kidneys with ruthenium red solution (RR). Electron microscopic examination revealed the presence of distinct small RR granules (“anionic sites”) in the mesangial intercellular matrix substance and in the laminae rarae of the glomerular basement membrane (GBM). The center-to-center spacing of the granules was measured and a frequency distribution of intervals in different interval classes was constructed. In normal glomeruli the anionic sites in the mesangial matrix showed a distribution pattern identical to the GBM with a maximal interval incidence at the 31–40 nm class. In nephrotic rats anionic site distributions in matrix and GBM did not change significantly. Sialoglycoproteins were labeled with colloidal iron (CI). In PAN nephrosis a decrease of CI binding was observed at the epithelial-basement membrane junction of the glomerular capillary wall. However, CI labeling of the mesangial matrix and mesangial cell membranes did not differ from that of normal glomeruli.In conclusion, the increased mesangial permeability in PAN nephrosis appears not to be associated with significant loss or altered configuration of mesangial anionic charged moieties.

HEPARINS MODULATE EXTRACELLULAR-MATRIX AND PROTEIN-SYNTHESIS OF CULTURED RAT MESANGIAL CELLS

SummaryHeparins blunt the development of glomerulosclerosis in several disease models in the rat and this protective effect may be related to suppression of glomerular cell proliferation. In this study the direct effect of heparins on another key event in glomerulosclerosis, extracellular matrix (ECM) deposition, was examined. Standard heparin (hep) and non-anticoagulant N-desulfated acetylated heparin (DSA-hep) significantly reduced the fibronectin content in the conditioned media of subconfluent, confluent, and supraconfluent rat glomerular mesangial cells (MCs) in culture, as assessed by a sandwich ELISA technique. Both heparins significantly increased the amount of cell-associated fibronectin in sparse and subconfluent MCs. DSA-hep, but not hep, increased the fibronectin content of ECM formed by confluent and supraconfluent MCs. Using3H-proline pulse-labeling, Hep and DSA-hep were found to significantly decrease cell-associated collagen in subconfluent but not in confluent MCs. No effects were seen on newly synthesized collagen secreted into the culture medium. Neither hep nor DSA-hep affected total protein synthesis, studied by metabolic labeling with35S-methionine. High resolution 2-D electrophoresis (molecular weight range, 120 to 10 Kd; isoelectric interval, 5.0 to 7.0) revealed one particular intracellular protein (molecular weight 54 Kd, pI 5.91) which was consistently overexpressed by MCs exposed to DSA-hep but underexpressed in hep. Both heparins affected an identical set of another 19 different intracellular MC proteins (over-/ underexpression or shift to higher molecular weights). In conclusion, the present data demonstrate the profound direct metabolic effects of hep and DSA-hep. In addition to their antiproliferative activity, heparins may also affect the course of glomerular disease in-vivo by direct modulation of ECM and protein synthesis of MCs.

Acute rejection in human liver grafts: A comparative histologic study of cases maintained on azathioprine and predni one versus cyclosporine a and low-dose steroids

The morphology of acute rejection (AR) in biopsies of liver allografts obtained in the first 2 weeks after transplantation was analyzed. Material from patients maintained on azathioprine and prednisone (AZA; Groningen, The Netherlands) was compared with that of patients receiving cyclosporine A and prednisone (with or without azathioprine) in low doses (CSA; Minneapolis). Strict selection criteria were applied to exclude circulatory and biliary complications and viral infection in this early observation period after transplantation. Follow-up biopsies ranged from 3 weeks to 1 year after transplantation. Time zero biopsies and/or pretransplant biopsies served as baseline histology, Our data revealed an identical morphologic picture during AR early after transplantation in both patient groups, except for a more marked degree of venous endothelialitis and hepatocyte ballooning in the Minnesota material. The follow-up biopsies suggested a spontaneous resolution of these early rejection episodes without antirejection treatment in six of the ten AZA patients. No differences in the long-term survival rate between the CSA- and AZA-treated patients were observed.

Glomerular mesangial uptake of intravenously injected colloidal carbon in the rat determined by an image analysing method: lack of influence of platelet aggregation or complement activation.

SummaryThe phagocytic capacity of the glomerular mesangium has been studied experimentally with a large number of tracers including colloidal carbon. After intravenous injection of colloidal carbon a marked platelet aggregation has been noted and factors released from the platelets may contribute to the mesangial permeability to carbon particles. Furthermore, pilot experiments revealed a systemic complement activation after intravenous injection of colloidal carbon. Circulating anaphylatoxins produced after complement activation may also influence mesangial permeability. In this paper, we have studied the mesangial uptake of intravenously injected colloidal carbon in platelet and complement depleted rats. Mesangial carbon content was assessed semiquantitatively 24 h after intravenous injection of 50 mg colloidal carbon/100 g body weight by an automatic scanning image analysing method using unstained paraffin sections. This method proved to be highly reproducible and showed a strong correlation with spectrophotometric determinations of the carbon content in isolated glomeruli.No influence of platelet aggregation or complement activation on mesangial carbon uptake was found. It is unlikely, therefore, that platelet factors or anaphylatoxins produced after complement activation are involved in the mesangial uptake of carbon under normal circumstances or in the increased mesangial carbon ingestion seen in aminonucleoside nephrosis and nephrotoxic serum nephritis. As mesangial congestion with macromolecules may result in the development of sclerosis, it is important to analyse further the factors that influence mesangial accessibility, such as the permeability of the overlying endothelium and the composition, and physical and electrochemical properties of the mesangial matrix.

IMMUNOPATHOLOGY OF ALKALINE PHOSPHATASE-INDUCED GRANULOMATOUS HEPATITIS IN RATS

SummaryGranulomatous inflammation is a specific type of chronic inflammation in which macrophages and T-cell-mediated immunity to the inciting agent play a pivotal role. In the present study, granulomatous hepatitis was induced in rats by the administration of a single intravenous dose of porcine intestinal alkaline phosphatase. The cellular composition of the hepatic granulomas was analyzed in-situ with a number of recently developed mouse anti-rat monoclonal antibodies to cells of the monocyte-macrophage lineage and lymphocyte subsets. Well-developed granulomas consisted of aggregates of macrophages with central modification into epithelioid cells, a peripheral rim of T-and B-lymphoid cells, including considerable numbers of immunoblasts and plasma cells. In addition, the periphery of the granulomas contained many fat storing cells, a sinusoidal cell type thought to play a central role in hepatic fibrosis. Moreover, intense immunostaining for the extracellular matrix proteins fibronectin and collagen type III was observed at the periphery of the lesions. The granulomas persisted for long periods without eliciting liver cirrhosis. Alkaline phosphatase induced hepatic granulomas in the rat may help to elucidate the contribution of cells of the B-lineage to chronic granulomatous inflammation.

Renal Antigens in Experimental Immune Complex Glomerulonephritis

The study of experimental glomerulonephritis has greatly extended our knowledge and understanding of human glomerulopathies. One of the models in experimental glomerulonephritis is the autologous immune complex glomerulonephritis (AIC), which was originally described by Heymann et al. (1959) and was given its present name by Edgington et al. (1967). They elucidated its pathogenesis and demonstrated glomerular deposition of immune complexes, consisting of an antigen normally present in the brush border of the proximal tubules of rat kidney and its specific antibody. The glomerulopathy can be induced in certain rat strains by immunization with a crude antigen fraction from the brush border (Fx1A) or with the purified nephritogenic antigen (RTEα5) in Freund’s complete adjuvant (Edgington et al., 1968). This procedure results after 6 weeks in glomerular deposition of immune complexes, which are localized exclusively at the epithelial side of the GBM. Morphologically and clinically the disease resembles human membranous glomerulopathy.

Angiotensin I — Converting enzyme inhibition in models of progressive glomerulosclerosis

Studies in experimental models have revealed that several pathogenetic mechanisms may lead to focal glomerulosclerosis (FGS) associated with proteinuria and loss of renal function. These pathogenetic mechanisms can be separated into primary events (Figure 1) in which the glomerular capillary tuft is exposed to harmful stimuli such as hypertension with mechanical stress, toxic compounds, and high levels of circulatory lipids, glucose or other metabolic factors [[1]–[3]]. A sequence of secondary events includes endothelial cell damage and thrombosis, leukocyte influx, endothelial and mesangial cell proliferation, excessive lipid accumulation and matrix production, glomerular hypertrophy with volume expansion and epithelial cell damage with detachment and hyalinosis [4] (see Figure 1).

Crp and SAA Serum Levels in Chronic Active Hepatitis

C-reactive protein (CRP) and serum amyloid A (SAA) were studied in chronic active hepatitis (CAH), a disease of the principal site of CRP and SAA production. CRP and SAA levels were compared with histological severity and levels of Cholinesterase (CHE), a representative of liver synthesis capacity.